Fairness and conspiracies

We define a hierarchy of fairness postulates; k-fairness (∞-fairness) means the absence of any infinite execution in which some transition occurs only finitely often but is enabled infinitely often by some sequence of length ? k (of unrestricted length, respectively).We show (i) that for Petri nets in general, ∞-fairness equals k-fairness for all k, and (ii) that for a large subclass of nets, (k+1)-fairness equals k-fairness for all k. The transferral of these results to concurrent programs is also discussed.     

Alkyl phosphocholines: Toxicity and anticancer properties

The study reports on the investigation of acute and subacute toxicity and on antineoplastic activity of hexadecylphosphocholine (HPC), the first compound of a new class of antineoplastic chemotherapeutics. In rats, the LD₅₀ of HPC was 606 μmol/kg; the maximum tolerable dose over four weeks was 39 μmol/kg. Symptoms of toxicity were enteritis, spider cell activation in the liver, hemosiderosis in the spleen and reversible transaminase increase. The best therapeutic effect was observed on methylnitrosourea (MNU)-induced mammary carcinoma in the rat. Two transplantable mammary carcinomas in the rat and autochthonous benzo(a)pyrene-induced sarcomas exhibited low-grade sensitivity to HPC. The MXT mammary carcinoma of the mouse, the Walker 256 carcinosarcoma of the rat, and autochthonous acetoxymethylmethylnitrosamine-induced colonic tumors of the rat were not chemosensitive to HPC.     

Behavioral reputation: A cross-age perspective.

This study examined the measurement of peer perceptions of behavioral reputation within the contexts of elementary, middle, and high school environments (Grades 2-12, N=2,812) through the systematic evaluation of the psychometric properties of the Revised Class Play (A. S. Masten, P. Morison, & D. S. Pellegrini, 1985). Confirmatory factor analyses demonstrated that the data did not fit A. S. Masten et al.'s original 3-factor structure. Cross-loading of items and different patterns of association between subscales across age groups (elementary, middle, and high school) contributed to the overall poor fit. Exploratory factor analyses revealed an alternative 4-factor structure as a more reliable and valid means of assessing behavioral reputation regardless of the age of the peer group sampled. Both convergent and divergent patterns of associations emerged across developmental levels. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Usefulness of screening investigations in neurofibromatosis type 1. A study of 152 patients

OBJECTIVE: To evaluate the usefulness of screening investigations in patients with neurofibromatosis type 1 (NF1). DESIGN: Clinical and screening data were retrospectively collected from a case series of patients with NF1. Screening investigations included an opthalmologic consultation, chest x-ray film, abdominal ultrasonography, cerebral imaging, and analysis of urinary catecholamine levels. Clinical features and complications of patients with NF1 were compared with those of the Neurofibromatoses Institute Clinical Research Program and of the Southeast Wales study patients. SETTING: Ambulatory care in a referral center. PATIENTS: Between 1988 and 1992, 152 patients classified as having NF1 according to the criteria of the National Institutes of Health Consensus Development Conference Statement were studied. MAIN OUTCOME MEASURE: Complications requiring therapeutic action detected using screening investigations vs clinical examination. RESULTS: Systemic chest x-ray films were taken of 134 patients, and intrathoracic nodules thought to be neurofibromas were discovered in 2 patients. Ninety-three asymptomatic patients had cerebral imaging performed, which showed optic pathway glioma in 12 patients. Abdominal ultrasonography was performed on 62 asymptomatic patients, results of which showed internal neurofibromas in 4 patients. In 2 of these patients, abdominal surgery was performed. Eighty-three patients without hypertension had 24-hour urinary specific catecholamine levels analyzed, which were within the normal range. Clinical features and complications were not different from other large clinical studies. Nearly 400 systematic investigations were performed without clinical orientation, detecting 21 abnormalities. In only 2 cases, these discoveries led to therapeutic action. On the other hand, 22 complications requiring treatment were detected by clinical examination. CONCLUSION: Clinical follow-up seems to be more beneficial than systematic investigations in patients with NF1.     

Die Entwicklung des virtuellen Speichers

Ohne Zusammenfassung     

Contactless technique for the measurement of electrical resistivity in anisotropic materials

Measurement of basal plane electrical resistivities in quasi-two-dimensional materials by conventional four-point bridge techniques is extremely difficult. In making measurements of room temperature basal plane resistivities in highly conducting highly anisotropic synthetic metals we have developed an rf inductive technique which is both simple to use and provides accurate results. At the frequency we employ (100 kHz) the method is appropriate for resistivities in the range 10 (-3)-10(-7)Omega cm. Samples are thin square plates 5 mm on a side. The system is calibrated by fitting data from a series of samples of known resistivity to semi-empirical formulae. The theoretical motivation leading to these expressions is discussed and extensive calibration data are presented. The advantages of rf techniques in general have already been discussed. Two advantages commend the particular technique we describe here. First, it is simple in design and easily constructed. Second, with careful calibration, highly accurate resistivity measurements can be made in a very straightforward manner.     

Silica biomineralization in diatoms: the model organism Thalassiosira pseudonana

After complete genome sequencing, the diatom Thalassiosira pseudonana has become an attractive model organism for silica biomineralization studies. Recent progress, especially with respect to intracellular silicic acid processing, as well as to the natures of the biomolecules involved in diatom cell wall formation, is described. On the one hand, considerable progress has been made with respect to silicon uptake by special proteins (SITs) from the surrounding water, as well as to the storage and processing of silicon before cell division. On the other hand, the discovery and characterisation of remarkable biomolecules such as silaffins, polyamines and--quite recently--of silacidins in the siliceous cell walls of diatoms strongly impacts the growing field of biomimetic materials synthesis.