[en] We describe a novel method for estimating the rate of destruction of the acetylcholine receptor (AChR) associated with the motor end-plate in the living animal. After the intramuscular injection of a nontoxic dose of alpha-bungarotoxin that had been monoiodinated with ₁₂₅I (₁₂₅I-BGT), the loss of radioactivity from the injected site is monitored by an externally positioned gamma counter. Two days after labeling, the decline of radioactivity in the injected muscle parallels the decline of end-plate specific radioactivity and can be used for the estimation of the degradation rate and half-life of end-plate AChR. Using this method, we measured AChR half-life in normal and in myasthenic rats and found a 2.5-fold decrease of AChR half-life in the myasthenic animals. This in vivo method has potential clinical applications

[en] A consideration of the critical potential and the protection potential of localized corrosion is given. From a hypothesis about when a fully developed localized attack can occur a definition of the field of protection potential has been attempted. The potentiostatic method was used to define this field relative to solution heat treated AISI 304L stainless steel in 0.1 M HCl at 20 deg C, with test times of >= 150 h. The results obtained differ significantly from what can be deduced from the potentiodynamic technique, and they confirm the formulated hypothesis and definitions. In the active loop of potentiodynamic curves, the nucleation and development of pitting, together with general corrosion, is documented by SEM. The hypothesis can be advanced that such pitting corrosion is a direct consequence of inhibition phenomena resulting from products formed during overall corrosion. (author)

[en] This paper describes the results of a study concerning the influence of cold working upon the corrosion behaviour of an AISI 304L in HCl 0.1 M at room temperature. Potentiostatic tests, with test times of >= 150 h, followed by SEM observations, revealed that even though cold working lowers the critical pitting potential, it does not impair the susceptibility to localized corrosion. Evidence is provided for (1) pitting activity below the primary passivation potential, and (2) preferential attack on either the austenitic matrix or the martensitic phase, depending upon the corrosion potential below the protection field. It can be hypothesized that the above-mentioned behaviour is a consequence of the formation of corrosion products favoured by the presence of two metallic phases. Such products have inhibiting properties which determine pitting corrosion below the primary passivation potential and, in addition, they hinder the formation of passivity films and facilitate their local destruction. (author)

[en] The UA2 detector has recently undergone an extensive upgrading program in preparation for running with the new ACOL anti-proton source at the CERN SPS Collider. This upgrade required a corresponding improvement in the performance of the data acquisition and trigger systems. In particular, a new front-end system, including three levels of event selection in a hierarchical trigger system, and two stages of event processing and buffering, has been constructed. In this contribution, we describe the overall structure of the new data acquisition system, placing particular emphasis on the configuration of the front-end along with some of the general principles which influenced its design. In addition, a short discussion of the performance of this system during the initial 1987 Collider run is included. (author). 2 refs, 1 fig

[en] A thin scintillator detector (thickness 10 μm) is studied. It is suitable as a trigger for time-of-flight measurements and for particle identification through energy loss straggling. (orig.)

[en] The data acquisition of a HEP experiment requires the setting, querying and manipulation of many parameters to be accessed by different parts of the DAQ system. Object-Oriented DataBase Management Systems (OODBMS) appear to fit the requirements of such applications quite successfully. In this paper the authors present their experiences and impressions while evaluating two commercial OODBMS, GemStone and ITASCA, as part of the RD13 project to study DAQ systems in view of LHC-like experiments. The goal of the evaluation was to compare the two systems and study the applicability of the Object-Oriented approach with respect to the relational systems already in use

[en] anti p-⁴He and anti p-Ne reaction cross sections have been measured at 48.7 and 179.8 MeV using a self-shunted streamer chamber in a magnetic field. Charged prong multiplicity (for ⁴He and Ne), branching ratios and ³He production probability (for) ⁴He are given. Comparison between anti p-⁴He and existing anti p-²He data is performed

[en] In chloride-containing environments, passive films on corrosion-resistant alloys (CRA) are characterised by instability phenomena. These in turn depend on environmental conditions, type of alloy, sample geometry and heterogeneities on the metal surface. The localised corrosion process for these systems can be described by a three-state model: (1) passivity, (2) metastability, and (3) localised corrosion. Corrosion resistance is based on the permanence of states 1 or 2, while transition to state 3 indicates the beginning of a localised attack. In this paper, the metastability state of passive films on CRA is studied in order to find a suitable model for predicting the transition from metastability (state 2) to localised corrosion (state 3). Samples are tested for properties such as frequency and charge quantity of metastability phenomena, and time versus survival probability distribution is also investigated. Our working hypothesis is that localised corrosion can be described by a Markov chain stochastic process. Using this model, two indexes are calculated for localised corrosion resistance, and their use in establishing a ranking of specific systems is considered

[en] The system of multiplane drift chambers for the forward-backward toroidal spectrometers of the UA2 experiment at the SPS panti p collider is described. Details about mechanical design and construction techniques are given. Results on the performance of the chambers are reported. (orig.)

[en] The measurement of angles and momenta, as well as the identification of the masses of the products of anti p ⁴He annihilation events detected in a self-shunted streamer chamber are described. (orig.)