Complexity,Tight–Coupling and Reliability: Connecting Normal Accidents Theory and High Reliability Theory

In this article, the theoretical debate between two dominant schools on the origins of accidents and reliability, Normal Accident Theory and High Reliability Theory, is continued and evaluated. Normal Accident Theory holds that, no matter what organizations do, accidents are inevitable in complex, tightly–coupled systems. High Reliability Theory asserts that organizations can contribute significantly to the prevention of accidents. To break through this deadlock, the mutual effects of complexity and tight–coupling, on the one hand, and reliability–enhancing strategies, on the other, are examined. It becomes clear that the theories are sometimes in conflict but that sometimes they also reach similar conclusions when applied to case events or generic safety problems. Cross–fertilization is, therefore, possible.     

Embedding Branch and Bound within Evolutionary Algorithms

A framework for hybridizing evolutionary algorithms with the branch-and-bound algorithm (B&B) is presented in this paper. This framework is based on using B&B as an operator embedded in the evolutionary algorithm. The resulting hybrid operator will intelligently explore the dynastic potential (possible children) of the solutions being recombined, providing the best combination of formae (generalized schemata) that can be constructed without introducing implicit mutation. As a basis for studying this operator, the general functioning of transmitting recombination is considered. Two important concepts are introduced, compatibility sets, and granularity of the representation. These concepts are studied in the context of different kinds of representation: orthogonal, non-orthogonal separable, and non-separable.The results of an extensive experimental evaluation are reported. It is shown that this model can be useful when problem knowledge is available in the form of an optimistic evaluation function. Scalability issues are also considered. A control mechanism is proposed to alleviate the increasing computational cost of the algorithm for highly multidimensional problems.     

The effect of metal and solution phase resistances on the current distribution in cylindrical electrochemical reactors

The mathematical modelling of cylindrical electrochemical reactors has been performed taking into account the resistance of the metal phase of the inner electrode and the resistance of the electrolyte. The model assumes that the external electrode is isopotential, the electrochemical reaction on the external electrode has a low polarization resistance (di/dη→∞) and at each axial position in the electrolyte the current is independent of the radial coordinate. The experimental and theoretical current density distributions are compared in order to determine the predictive suitability of the model and a good agreement is observed between them. Furthermore, a comparison is made between this model and a simpler earlier one and an important improvement in the prediction is observed.     

New redox deposition-precipitation method for preparation of supported manganese oxide catalysts

A new preparation method has been developed to produce homogeneous coatings of manganese compounds on alumina-coated monoliths by redox deposition-precipitation using acetone as solvent. The deposition is produced by reduction of manganese permanganate with ethanol. The Lewis acid sites on the alumina catalyze this reaction. Thus, the precipitation is produced preferentially on the surface of the monolith and not in the bulk of the solution. Monoliths prepared by this method are very active for the complete oxidation of oxygenated volatile organic compounds (VOCs). These monoliths consist of a mixture of complex phases including aluminum, sulfated alumina, potassium sulfate and manganese oxide.     

Comparison of Cuban and Anglo-American cultural values in a clinical population.

Attempted to replicate an earlier study investigating cultural differences between Cuban immigrants and Anglo-Americans. Whereas the earlier study used a nonclinical adolescent population, the current study used 52 adults in outpatient treatment. Ss were given a biographical questionnaire and the Value Orientation scales. Results indicate that the groups differed in relational, temporal, and person–nature orientations, confirming previous findings and clinical observations. (3 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparison of different advanced oxidation process to reduce toxicity and mineralisation of tannery wastewater.

Many organic compounds contained in wastewater are resistant to conventional chemical and/or biological treatment. Because of this reason different degradation techniques are studied as an alternative to biological and classical physico-chemical processes. Advanced Oxidation Processes (AOPs) probably have developed to become the best options in the near future. AOP while making use of different reaction systems, are all characterised by the same chemical feature: production of OH radicals (*OH). The versatility of AOPs is also enhanced by the fact that they offer different possibilities for OH radical production, thus allowing them to conform to specific treatment requirements. The main problem with AOPs is their high cost. The application of solar technologies to these processes could help to diminish that problem by reducing the energy consumption required for generating UV radiation. In this work, different AOPs (O3, TiO2/UV, Fenton and H2O2/UV) were examined to treat tannery wastewater or as a pre-treatment step for improving the biodegradation of tannery wastewater, at different pH and dosage of the chemicals. Under certain circumstances retardation in biodegradation and/or an increase in toxicity may be observed within these treatment steps. Two different bioassays (Daphnia magna and Vibrio fischeri) have been used for testing the progress of toxicity during the treatment. In parallel other objectives were to analyse and identify organic compounds present in the untreated wastewater and arising degradation products in AOP treated wastewater samples. For this purpose substance specific techniques, e.g., gas chromatography-mass spectrometry (GC-MS) in positive electron impact (El(+)) mode and atmospheric pressure ionisation (API) in combination with flow injection analysis (FIA) or liquid chromatography-mass and tandem mass spectrometry (LC-MS or LC-MS-MS) were performed.     

Morphology of poly(hexamethylene oxide) fractions

The supermolecular structure of crystallised molecular weight fractions of poly(hexa-methylene oxide), covering the molecular weight range (M) 4.5. × 10³ to 8. 5 × 10⁴, was studied by polarised light microscopy and small angle light scattering. Different forms were observed as a function of molecular weight and crystallisation temperatures. Perfect spherulites are formed after rapid crystallisation, and these forms deteriorate as both the molecular weight and crystallisation temperature increase. The morphology in the isothermal crystallisation region corresponds to an intermediate state which represents a transition from spherulites to hedrites.     

The escape response of juvenile Psammodromus algirus lizards.

The timing, magnitude, and orientation of the escape response from a model predator were examined. A high proportion of the responses were touch-evoked; the lizards responded only immediately after the model contacted them. When the model approached at a higher speed, lizards (Psammodromus algirus) initiated the escape sooner, ran at higher speeds, and escaped to longer distances, but their reactive distances did not vary. Model speed did not affect the escape duration or the directness of the response. Escape trajectories were not random. Responses away from the model occurred more often than responses toward the model, but initial orientation affected the direction of escape trajectories. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Megalomicin inhibits HIV-1 replication and interferes with gp160 processing

The inhibitory effects on HIV replication of megalomicin (MGM, an inhibitor of intra-Golgi vesicle transport, have been studied. In experiments at low multiplicity of infection on Jurkat and MT2 cell lines. MGM inhibited the production of p24 antigen, the formation of syncytia, and the induction of apoptosis at concentrations below 5 microM. Furthermore, PCR analysis of genomic DNA showed that, in the presence of MGM, HIV-1 had been eradicated from the culture. MGM also inhibited replication of primary isolates of HIV-1 in blood lymphoblasts and more importantly, at 1 microM, MGM inhibited depletion of CD4+ T cells in cultures of blood lymphocytes from seropositive patients. Finally, MGM inhibited the generation of infectious virions and the processing of the envelope protein precursor gp160 to its mature forms, resulting in the rapid degradation of gp 160. These data suggest that MGM induces a powerful inhibitory effect on HIV-1 replication at nontoxic concentrations by preventing the processing of HIV-1 gp160 envelope protein and the subsequent formation of infectious viral particles.     

Terrestrial radio links engineering for frequencies above 10 GHz with reference to rain attenuation

This paper describes the theoretical background and the process of obtaining maximum hop lengths and minimum fading margins (if the terminal or repeater locations are fixed) in any region of the world and gives a set of curves providing these characteristics for 1 km with availability of 99.7 % of the time (per 2 500 km), for a given frequency and polarization. Correction factors for other availabilities are also given.