The technic of x-ray histochemistry applied to neurohistology

Zusammenfassung Demonstrationsvergleich röntgenmikroskopisch behandelter Zellen und Blutgefässe von Ratten sowie von menschlichem Gehirngewebe mit optischen Standardmethoden, wobei Gomoris Bleisulfidtechnik zur Bestimmung der Phosphataseenzymaktivität angewandt wurde. Die Brauchbarkeit der histochemischen Technik für die Röntgenologie wird diskutiert.

---

---

This work formed part of the research submitted for a Master of Science degree at Dalhousie University. It was supported in part by MRC Grant No. MT-752 and carried out under the supervision and with the kind assistance of Prof. R. L. de C. H.Saunders.     

The micro-focal x-ray unit and its application to bio-medical research.

The micro-focal X-ray unit is a modified Cosslett and Nixon X-ray microscope of greater operational stability and flexibility. Its combination with a closed circuit television system provides a quick method of obtaining a point source of X-rays to examine the detailed structure of organs and biological specimens.     

Microbial energetics applied to waste repositories

Summary Through their catalytic abilities microbes can increase rates of chemical reactions which would take a very long time to reach equilibrium under abiotic conditions. Microbes also alter the concentration and composition of chemicals in the environment, thereby creating new conditions for further biological and chemical reactions. Rates of degradation and possible indirect consequences on leaching rates in waste repositories are a function of the presence or absence of microbes and of the conditions which allow them to become catalytically active.Microbially mediated reactions are no exception to the rule that all chemical processes are basically governed by thermodynamic laws. Naturally occurring processes proceed in the direction that leads to the minimal potential energy level attained when equilibrium is reached. A continuous supply of energy to an ecosystem in the form of biochemically unstable compounds maintains non-equilibrium conditions, a prerequisite for all chemotrophic life. Energy is released as a chemical reaction progresses towards equilibrium. Microbes scavenge that portion of the free energy of reaction (G_r) which can be converted into biochemically usable forms during the chemical oxidation processes. As electrontransfer catalysts, the microorganisms mediate reactions which are thermodynamically possible thereby stimulating reaction rates. Decomposition and mineralization in systems without a continuous supply of substrates and oxidants will lead to equilibria with minimal free energy levels at which point further microbial action would cease. The differences in the free energy levels of reactions (G_r), represent the maximal energy which is available to microorganisms for maintenance and growth. How much of the released free energy will be conserved in energy-rich bonds, compounds (e.g. ATP), and chemical potentials (e.g. emf) useful for biosynthesis and biological work is characteristic for the microbes involved and the processes and metabolic routes employed.Materials whose elements are not present in the most oxidized form attainable in the oxic environment of our planet are potentially reactive. Microbial activities are associated only with chemical reactions whose free energy changes are exergonic. This should be kept in mind for all investigations related to the role of microbes in repositories or in the layout of proper waste storage conditions. Rigorous application of thermodynamic concepts to environmental microbiology allows one to develop models and design experiments which are often difficult to conceive of in complex natural systems from physiological information alone. Thermodynamic considerations also aid in selecting proper deposition conditions and in carrying out thoughtful experiments in areas related to microbial ecology of waste repositories.     

New biochemical techniques applied to avian systematics

Résumé Les protéines solubles de la lentille et des muscles des oiseaux furent examinés au moyen de la micro-électrophorèse en agargel. La mobilité des fractions protéiques s'est présentée comme un caractère systématique important: il y a généralement des différences nettes et constantes, mais parfois aussi des ressemblances, qui indiquent probablement des relations de parenté.     

The histochemistry of the dehydrogenase systems in the aortae of rabbits with experimental atherosclerosis

Zusammenfassung In Aorten von Kaninchen mit experimenteller Atherosklerose wurden die folgenden Dehydrogenasen untersucht: DPN-Diaphorase, Lactat- und Malat-Dehydrogenase, TPN-Diaphorase, Succinat-, Glucoso-6-phosphat-und Glutamat-Dehydrogenase. Die Aktivität der fünf erstgenannten war in den Endothelien, Makrophagen (Lipophagen) und Fibrozyten der verdickten Intima und kleiner atherosklerotischer Beete deutlich erhöht. Die Befunde stehen im Einklang mit der Ansicht, dass die Stoffwechselaktivität der Intima am Anfang der experimentellen Atherogenesis erhöht ist.

---

---

Further work on the dehydrogenase systems in plaques in rabbit, rats, and humans is in progress and will be reported in detail elsewhere.     

Molar attraction constants applied to structure activity relationships

Zusammenfassung Molare Anziehungskonstanten wurden herangezogen, um Beziehungen zwischen chemischer Struktur und biologischer Wirkung zu verstehen.     

Neural network pruning applied to real exchange rate analysis

Neural networks are fitted to real exchange rates of several industrialized countries. The size and topology of the networks is found through the use of multiple correlation coefficients, principal component analysis of residuals and graphical analysis of network output per hidden layer cell and input layer cell. These pruned neural networks are good approximations to varying non‐linear trends in real exchange rates. Non‐linear dynamic analysis shows that the long‐term equilibrium values of several European currencies correspond to the actual values within the European Monetary System. Based on its long‐term equilibrium value, the Euro appears to be undervalued vis‐à‐vis the US dollar at the introduction of the Euro on 1 January 1999. Copyright © 2002 John Wiley & Sons, Ltd.     

Multivariate Bayesian regression applied to the problem of network security

An Erratum has been published for this article in Journal of Forecasting 23(6): 461 (2004) . This paper examines the problem of intrusion in computer systems that causes major breaches or allows unauthorized information manipulation. A new intrusion‐detection system using Bayesian multivariate regression is proposed to predict such unauthorized invasions before they occur and to take further action. We develop and use a multivariate dynamic linear model based on a unique approach leaving the unknown observational variance matrix distribution unspecified. The result is simultaneous forecasting free of the Wishart limitations that is proved faster and more reliable. Our proposed system uses software agent technology. The distributed software agent environment places an agent in each of the computer system workstations. The agent environment creates a user profile for each user. Every user has his or her profile monitored by the agent system and according to our statistical model prediction is possible. Implementation aspects are discussed using real data and an assessment of the model is provided. Copyright © 2002 John Wiley & Sons, Ltd.     

The dose reduction factor produced by topically applied dimethyl sulfoxide

Zusammenfassung Die früheren positiven Strahlenschutzmittel-Versuche mit äusserlich angewandtem Dimethyl-sulfoxid wurden mit verschieden grossen Strahlendosen erweitert, um den Strahlendosisreduktionsfaktor genauer zu ermitteln. Es zeigte sich, dass dieser Faktor einer Grösse von 1.35 entspricht.     

Hierarchical bayes forecasts of multinomial dirichlet data applied to coupon redemptions

This paper considers forecasting count data from a multinomial Dirichlet distribution. The forecasting procedure implements hierarchical Bayes methods in order to develop a prior distribution for a new series of data. The methodology is applied to the redemption of cents-off promotional coupons. In a forecasting experiment, early forecasts of new series are similar to those from pooling all redemptions from previous coupon promotions. However, the hierarchical Bayes model provides realistic estimates of forecasting errors, while those for the pooled forecasts are consistently optimistic. As the current series evolves, the hierarchical Bayes forecasts adapt more rapidly and are more accurate than pooled forecasts.