Schmeh, Klaus: Versteckte Botschaften (TELEPOLIS): Die faszinierende Geschichte der Steganografie

Ohne Zusammenfassung     

Stability margin of uncertain control systems

Achieving stability is the essential issue in the control system design. In this paper, four approaches that can be used to calculate the stability margin of the interval plant family are summarized and compared. The μ approach gives the bounds of the stability margin, and good estimation can be obtained with the numerical method. The eigenvalue approach yields accurate value, and the MATLAB＇s function robuststab sometimes provides wrong results. Since the eigenvalue approach is both accurate and computationally efficient, it is recommended for the calculation of the stability margin, while utilization of the function robuststab should be avoided due to the unreliable results it gives.     

Human behavior between instinct, feelings and responsibility

The paper deals with the fundamental problem: How does the brain (in the way it is and the way it functions) influence human experience, behaviour and social interaction? Deriving from this question, there's the matter of how all this influences people as road users. After some epistemological considerations the following subjects are dealt with the article: the human perception and human "reality", the limits of human imagination, the basis of human learning, the complexity of processes within the brain, the reaction to changes and the ability to concentrate as well as McLean's theory of the triune brain. The subjects are complemented by aspects of biological and socio-cultural evolution of man, starting from evolutionary ethics going right up to the problem of responsibility.     

Mammalian class IV alcohol dehydrogenase (stomach alcohol dehydrogenase): structure, origin, and correlation with enzymology

The structure of a mammalian class IV alcohol dehydrogenase has been determined by peptide analysis of the protein isolated from rat stomach. The structure indicates that the enzyme constitutes a separate alcohol dehydrogenase class, in agreement with the distinct enzymatic properties; the class IV enzyme is somewhat closer to class I (the "classical" liver alcohol dehydrogenase; approximately 68% residue identities) than to the other classes (II, III, and V; approximately 60% residue identities), suggesting that class IV might have originated through duplication of an early vertebrate class I gene. The activity of the class IV protein toward ethanol is even higher than that of the classical liver enzyme. Both Km and kcat values are high, the latter being the highest of any class characterized so far. Structurally, these properties are correlated with replacements at the active site, affecting both substrate and coenzyme binding. In particular, Ala-294 (instead of valine) results in increased space in the middle section of the substrate cleft, Gly-47 (instead of a basic residue) results in decreased charge interactions with the coenzyme pyrophosphate, and Tyr-363 (instead of a basic residue) may also affect coenzyme binding. In combination, these exchanges are compatible with a promotion of the off dissociation and an increased turnover rate. In contrast, residues at the inner part of the substrate cleft are bulky, accounting for low activity toward secondary alcohols and cyclohexanol. Exchanges at positions 259-261 involve minor shifts in glycine residues at a reverse turn in the coenzyme-binding fold. Clearly, class IV is distinct in structure, ethanol turnover, stomach expression, and possible emergence from class I.     

The biological properties of Aerococcus antagonists, representatives of human microbiocenoses

The paper deals with the data on biology of Aerococcus, a slightly studied group of microorganisms. Physiological-biochemical properties of Aerococcus are described, data of their distribution in nature are given. Peculiar attention is paid to the estimate of the role of Aerococcus in human microbiocenoses. As a result of the profound and all-round study of this group of microorganisms the authors have developed new bacterial drug "A-bakterin" based on the aerococcus strain. Data presented about the results of clinical tests of "A-bakterin" are presented, a possibility to use Aerococcus lysate in the elaboration of new drugs is discussed.     

Hand and foot purpura ("glove and sock" syndrome) caused by parvovirus B19 infection

After a period of general nonspecific symptoms (weakness; nocturnal sweating) for a few days a 29-year-old man suddenly developed a purpura-like rash on both hands and feet ("glove and sock") with mild itching and oedema. A blood count demonstrated leukopenia (2100/microliters) with neutropenia (1100/microliters), thrombocytopenia (81,000/microliters) and reticulocytopenia (1/1000), while haemoglobin content was normal. The bone-marrow showed almost complete reduction of erythropoiesis with the presence of giant proerythroblasts. Granulopoiesis and megakaryopoiesis were unremarkable. Positive tests for IgM and IgG antibodies against parvovirus B19 established the diagnosis of infection with this organism. The rash, blood picture and bone-marrow changes all regressed spontaneously, without any treatment, within a week. The petechial or purpuric "glove and sock" syndrome may be a special form of parvovirus B19 infection.     

Angiogenesis of gynecologic tumors studied with color Doppler

Angiogenesis is obligatory event in solid tumors growth. Weak muscular layer in the newly formed tumoral vessels results in decreased resistance to blood flow and characteristic Doppler signal. The number and arrangement of the blood vessels differ between benign and malignant lesions as well. Parameters mentioned above enable a precise ultrasound differential diagnosis between benign and malignant tumors. Malignant uterine tumors are better perfused and have lower resistance to blood flow than benign ones. Benign lesions with secondary changes (necrosis) may have lowered resistance indices. The finding of pathological perfusion makes the diagnosis of endometrial carcinoma also very accurate. High sensitivity of the transvaginal color Doppler in detecting newly formed blood vessels in an early stages of ovarian cancer may establish this technique as a screening method for this still very high lethality disease.     

A case of paracetamol retard poisoning with fatal outcome

A case of fatal paracetamol (acetaminophen) poisoning in a 26-year-old woman who developed liver necrosis is described. The patient reported having ingested 11 g of a slow-release paracetamol preparation and a certain amount of alcohol and benzodiazepine. An unknown dose of phenobarbital (phenemal) had been ingested 24 hours previously, leading to a serum phenobarbital concentration of 0.195 mmol/l at the time of admission. The patient was initially treated with N-acetylcysteine intravenously. This treatment was discontinued after five hours due to a serum paracetamol concentration of 0.49 mmol/l, well below the "treatment line" paracetamol concentration of 0.8 mmol/l six hours after ingestion. Possible aggravating factors are discussed, including sustained high serum concentration of paracetamol due to the slow-release preparation and enzyme induction caused from concomitant phenobarbital and alcohol intake, as well as benzodiazepines displacing paracetamol from liver enzymes. These factors make serum paracetamol concentrations undependable; the importance of continuing N-acetylcysteine treatment in spite of "safe" serum concentrations in the above cases is stressed.