Approximation der optimalen Vorhersage der Ausgabe stochastischer Quellen

This paper discusses the prediction of the output of a stochastic sourceQ having positive transition function. If the sourceQ has two output alphabets,X andY, then there exists such a stochastic automaton \(\mathfrak{A}(V_{opt} )\) with input alphabetX, output alphabetY, and a countable set of states, that realizes the optimal predictionV _opt fromX toY. Here it will be shown thatV _opt can be approximated with any precision by a predictionV which is realized by a stochastic automaton with finite set of states.     

Experimente zum Strömungswiderstand in gekrümmten,rotierenden Kanälen mit quadratischem Querschnitt

Zusammenfassung Bei ausgebildeter Strömung wurde der Druckverlust in rotierenden, gekrümmten Kanalstrecken experimentell ermittelt. Speziell interssierte der Einfluß der Krümmung auf den Reibungswiderstand und im besonderen der der Rotation, die sowohl in Richtung der Durchflußgeschwindigkeit als auch entgegengesetzt dazu erfolgte. Die strömungsspezifischen Parameter wie Reynolds-und Taylor-Zahl erfuhren eine Änderung im Bereich 3·10²<Re<2·10⁵ und 0Ta<10⁵. Das Krümmungsverhältnis variierte zwischen 0,0496a/r _m 0,337. Aufgezeigt wird die Möglichkeit einer universellen Darstellung des Widerstandsbeiwertes für den nicht rotierenden Kanal bei einerseits laminarer und anderseits bei turbulenter Bewegung. Im rotierenden Kanal beobachtet man beträchtliche Druckverlusterhöhungen, deren Größe von der Rotationsrichtung abhängt. Bei großen Taylor-Zahlen wurde eine Unabhängigkeit des Strömungswiderstandes vom Krümmungsverhältnis festgestellt.

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Experimental investigations on the friction resistance in rotating curved channels with square cross-section

Summary For fully developed flow the pressure loss in rotating curved channels was investigated experimentally. The influence of the curvature on the friction coefficient and particularly on the rotation, which was realized in the direction of the through flow as well as in the opposite direction was of special interest. The specific parameters of the flow field, like the Reynolds-number and the Taylor-number were varied within the range of 3·10²<Re<2·10⁵ and 0Ta<10⁵. The curvature ratio were varied within 0,0496a/r _m 0,337. The possibility of an universal presentation of the friction coefficient for the nonrotating channel is shown for laminar and turbulent through flow. In the rotating channel a considerable pressure loss increase can be observed. The magnitude depends on the direction of rotation. In case of great Taylor-numbers the curvature ratio was found to be independent of the friction resistance.

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Bezeichnungen a Kantenlänge - mittlere Geschwindigkeit - l Kanallänge - r _m Krümmungsradius - Volumenstrom - _p Druckdifferenz - Widerstandsbeiwert - =57/Re Widerstandsbeiwert des geraden Kanals - dynamische Viskosität - Dichte - Winkelgeschwindigkeit - Dean-Zahl - Reynolds-Zahl - Taylor-Zahl Mit 6 Abbildungen     

On grammar forms with terminal context

Summary A context-free grammar form G defines a family of context-free grammars {ie397-01}(G). In this paper {ie397-02}(G) is extended to give the family of terminal context grammars {ie397-03}(G), which were introduced by Book [4]. It is shown that the families of languages defined by {ie397-04}(G) and {ie397-05}(G) are equal when G is an -free context-free grammar form. This generalizes the result of Book [4] for context-free grammars and underlines the usefulness of the notion of grammar forms in formal language theory.The work of the second author was carried out partially under a National Research Council of Canada Grant. No. A-7700 and partially under the auspices of the University of Karlsruhe     

On a direct algorithm for the generation of log-normal pseudo-random numbers

The random variable \(\left( {\prod {_{i = 1}^n {{X_i } \mathord{\left/ {\vphantom {{X_i } {X_{i + n} }}} \right. \kern-0em} {X_{i + n} }}} } \right)^{{1 \mathord{\left/ {\vphantom {1 {\sqrt {2n} }}} \right. \kern-0em} {\sqrt {2n} }}}\) is used to generate standard log-normal variables Λ(0, 1), where theX _i are independent uniform variables on [0, 1].     

Polynomoperatoren in C k [a,b]

Some estimations for the relative projection constantP(∏ _n+k ^k ,Csik[a,b]) are given. By constructing an associated polynomial operatorL _n :C ⁰[a,b]→∏ _n ⁰ to a given polynomial operatorH _n+k :C ^k [a,b]→∏ _n+k ^k we get a lower bound for the projection constant. An upper bound forP(∏ _n+k ^k ,C ^k [a,b]) is obtained by the determination of the norms of appropriate polynomial operatorsP _n+k :C ^k [a,b]→∏ _n+k ^k . Further we give a convergence property for the sequence (P _n+k ) _n∈?.     

Einleitung und Abbruch der künstlichen Ernährung beim einwilligungsunfähigen Patienten

Definition of the problem: In Austria the legal discussion on initiating and withdrawing artificial nutrition in incompetent patients has just begun. Arguments and conclusion: Legal regulations are lacking, but there appears to be agreement on accepting advance directives under specific criteria. This would mean that a presumed will and documented refusal of treatment and nutrition has to be respected by physicians. However, there is no consensus with regard to the “supposed will” of an incompetent patient to refuse treatment and nutrition. At present, surrogate decision making with regard to refusing life-sustaining treatment or nutrition is only accepted according to a declared and documented directive of the patient himself. When the patient’s will has to be “surmised” the protection of life has priority. In Austria this concept is based on the national constitution and its duty to protect life.     

Perinatal Obesity Induces Hepatic Growth Restriction with Increased DNA Damage Response,Senescence, and Dysregulated Igf-1-Akt-Foxo1 Signaling in Male Offspring of Obese Mice

Maternal obesity predisposes for hepato-metabolic disorders early in life. However, the underlying mechanisms causing early onset dysfunction of the liver and metabolism remain elusive. Since obesity is associated with subacute chronic inflammation and accelerated aging, we test the hypothesis whether maternal obesity induces aging processes in the developing liver and determines thereby hepatic growth. To this end, maternal obesity was induced with high-fat diet (HFD) in C57BL/6N mice and male offspring were studied at the end of the lactation [postnatal day 21 (P21)]. Maternal obesity induced an obese body composition with metabolic inflammation and a marked hepatic growth restriction in the male offspring at P21. Proteomic and molecular analyses revealed three interrelated mechanisms that might account for the impaired hepatic growth pattern, indicating prematurely induced aging processes: (1) Increased DNA damage response (γH2AX), (2) significant upregulation of hepatocellular senescence markers (Cdnk1a, Cdkn2a); and (3) inhibition of hepatic insulin/insulin-like growth factor (IGF)-1-AKT-p38-FoxO1 signaling with an insufficient proliferative growth response. In conclusion, our murine data demonstrate that perinatal obesity induces an obese body composition in male offspring with hepatic growth restriction through a possible premature hepatic aging that is indicated by a pathologic sequence of inflammation, DNA damage, senescence, and signs of a possibly insufficient regenerative capacity.     

Oxidative Damage in Sporadic Colorectal Cancer: Molecular Mapping of Base Excision Repair Glycosylases MUTYH and hOGG1 in Colorectal Cancer Patients

Oxidative stress, oxidative DNA damage and resulting mutations play a role in colorectal carcinogenesis. Impaired equilibrium between DNA damage formation, antioxidant status, and DNA repair capacity is responsible for the accumulation of genetic mutations and genomic instability. The lesion-specific DNA glycosylases, e.g., hOGG1 and MUTYH, initiate the repair of oxidative DNA damage. Hereditary syndromes (MUTYH-associated polyposis, NTHL1-associated tumor syndrome) with germline mutations causing a loss-of-function in base excision repair glycosylases, serve as straight forward evidence on the role of oxidative DNA damage and its repair. Altered or inhibited function of above glycosylases result in an accumulation of oxidative DNA damage and contribute to the adenoma-adenocarcinoma transition. Oxidative DNA damage, unless repaired, often gives rise G:C > T:A mutations in tumor suppressor genes and proto-oncogenes with subsequent occurrence of chromosomal copy-neutral loss of heterozygosity. For instance, G>T transversions in position c.34 of a KRAS gene serves as a pre-screening tool for MUTYH-associated polyposis diagnosis. Since sporadic colorectal cancer represents more complex and heterogenous disease, the situation is more complicated. In the present study we focused on the roles of base excision repair glycosylases (hOGG1, MUTYH) in colorectal cancer patients by investigating tumor and adjacent mucosa tissues. Although we found downregulation of both glycosylases and significantly lower expression of hOGG1 in tumor tissues, accompanied with G>T mutations in KRAS gene, oxidative DNA damage and its repair cannot solely explain the onset of sporadic colorectal cancer. In this respect, other factors (especially microenvironment) per se or in combination with oxidative DNA damage warrant further attention. Base excision repair characteristics determined in colorectal cancer tissues and their association with disease prognosis have been discussed as well.     

Modulation of Steroid and Triterpenoid Metabolism in Calendula officinalis Plants and Hairy Root Cultures Exposed to Cadmium Stress

The present study investigated the changes in the content of steroids and triterpenoids in C. officinalis hairy root cultures and plants exposed to cadmium stress. The observed effects included the content and composition of analyzed groups of compounds, particularly the proportions among individual sterols (e.g., stigmasterol-to-sitosterol ratio), their ester and glycoside conjugates. The total sterol content increased in roots (by 30%) and hairy root culture (by 44%), whereas it decreased in shoots (by 15%); moreover, these effects were inversely correlated with Cd-induced growth suppression. Metabolic alterations of sterols and their forms seemed to play a greater role in the response to Cd stress in roots than in shoots. The symptoms of the competition between general metabolites (sterols) and specialized metabolites (triterpenoids) were also observed, i.e., the increase of the sterol biosynthesis parallel to the decrease of the triterpenoid content in C. officinalis plant roots and hairy root culture, and the inverse phenomenon in shoots. The similarity of the metabolic modifications observed in the present study on C. officinalis plant roots and hairy roots confirmed the possibility of application of plant in vitro cultures in initial studies for physiological research on plant response to environmental stresses.