Ownership Structures in Network Industries when the Rationality of Regulators is Bounded

This paper analyses the implication for allocative efficiencyof diffrent ownership structures of vertically related industriesin a simple game-theoretic setting. The upstream sector is monoplizedand regulated, while the downstream sector is imperfectly competitive.Regulation is imperfect in that the regulatory authority suffersfrom bounded rationality, and is not able to enforce optimalregulation. We consider both bomogenous and differentiated compositegoods. It generally turns out that when the regulator's enforcementcapabilities are limited, preventing the upstream monoplistfrom entering the downstream industry is socially undesirableunless the independent downstream rival enjoys a substantialproduction cost advantage. This holds true in spiteof the downstreamindustry is socially undesirable, unless the independent downstreamrival enjoys a substantial production cost advantage. This holdstrue in spite of the incentiveof the vertically integrated monopolistto manipulate accounts in order to raise the costs of the downstreamrival. Such reasoning especially applies when composite goodsare close substitures for one another.     

An Optimal Value-Based Admission Policy and its Reflective Use in Real-Time Systems

This paper deals with planning system activities to support applications that have different contrasting requirements including timing constraints on tasks execution and correctness requirements. Our approach is based on a simple yet effective formulation of a value structure associated to the application tasks. Values are associated to each relevant outcome thus accounting for successful executions as well as for those which violate the application requirements. Moreover we assume degradable real time systems equipped with several execution techniques characterised by different execution costs and different levels of fulfilment of requirements (and associated reward). We propose an admission algorithm to select the part of the offered load to be executed, should overload occur. For all the admitted tasks the algorithm selects also the most suitable execution technique (among those available) to optimise the expected cumulated reward. We show that the algorithm provides the best solution to the optimisation problem resorting to the linear programming theory. Then we discuss the applicability of this result to systems operating in dynamic environments. A planner component is defined, responsible to collect information on the current status of the system and of its environment. The planner decides when a new plan is required, and dynamically executes the admission algorithm to properly tune the usage of system resources.     

New and classical spoilage bacteria causing widespread blowing in Argentinean soft and semihard cheeses

A total of 16 soft and semihard Argentinean cheeses, and 95 pasteurized cheese–milk samples, were analysed for microorganisms responsible for blowing. Lactic acid bacteria (starter microflora) resulted in high numbers (> 10⁷ colony‐forming units (cfu)/g). Coliform and yeast counts were lower than 10⁴ cfu/g. Cremoso cheeses were blown by leuconostocs, lactobacilli and Bacillus polymyxa. Mozzarella was spoiled by B. polymyxa and Bacillus macerans. Semihard cheeses were affected by spore‐forming (Clostridium and Bacillus), propionic and lactobacilli strains. Clostridia, Bacillus, leuconostocs and heterofermentative lactobacilli were detected in pasteurized milk. Bacillus strains were not previously associated with blowing in soft and semihard cheeses.     

PURIFICATION AND CHARACTERIZATION OF A PROTEASE FROM THE PYLORIC CAECA OF MENHADEN (Brevoortia spp) AND MULLET (Mugil spp) FROM THE SOUTHWEST ATLANTIC REGION

A protease classified as trypsin was isolated and purified from the pyloric caeca of two species of fishes: Brevoortia spp (menhaden) and Mugil spp. (mullet). The characterization of both enzymes as trypsin was based on their molecular weight (24 kDa) determined by SDS-PAGE, their inhibition by some known trypsin inhibitors (PMSF, SBTI, TLCK and benzamidine), and their ability to hydrolyze the synthetic trypsin substrate N-α-Benzoyl-DL-arginine-p-nitroanilide (BAPA). Menhaden trypsin had maximum activity at pH 9.5 and was stable for 30 min between pH 6.0 and 10.0 at 0, 10 and 25C. On the other hand, mullet trypsin showed maximum activity at pH's from 7.8 to 9.0, and was stable over a wider pH range (7.0–10.0). The optimum temperature for menhaden and mullet trypsin was 63C and 60C respectively. Thermostability for menhaden trypsin was up to 50C, whereas mullet trypsin was stable up to 60C. The Km(BAPA) values for menhaden trypsin were conserved in the temperature range from 10 to 30C, while for mullet trypsin the Km(BAPA) was conserved between 10 and 25C.     

A multiaxial fatigue criterion for random loading

ABSTRACT A multiaxial fatigue criterion for random loading is proposed. Firstly, the orientation of the critical plane, where fatigue life estimation is carried out, is determined from the weighted mean position of the principal stress directions. Then, the scalar value of the normal stress vector N (t) perpendicular to the critical plane is taken as the cycle counting variable since the direction of such a vector is fixed with respect to time (conversely to the time‐varying direction of the shear stress vector C (t)), and a nonlinear combination of normal and shear stress components acting on the critical plane is used to define an equivalent stress amplitude. Finally, a damage accumulation model is employed to process such an equivalent stress amplitude and to determine fatigue endurance. This criterion is herein applied to some relevant random fatigue tests (proportional bending and torsion).     

Latent crack path and service life predictions for unnotched concrete under bending by digital speckle correlation method

The critical factor for flexural fracture of an unnotched concrete structure is the local damage with stress concentration. The latent critical crack path on the concrete surface is difficult to inspect using ordinary experimental methods. In the present paper, the digital speckle correlation method (DSCM) is employed to obtain the latent critical crack and to calculate the strain and displacement distributions on the surface of unnotched concrete under flexural load. The relationships of static flexural load versus longitudinal strain and load-direction displacement as well as fracture toughness are inherent material parameters. Furthermore, the cohesive energy density (CED) around the latent critical crack for unnotched concrete and the brittleness number are also determined by using the DSCM results. Then, the tensile performance of concrete and the residual service life are evaluated through the above material parameters. It is found that the latent crack path on the concrete surface depends on the strain fields after the bending force applied to the specimen reaches 30% of concrete flexural strength, and the cohesive stress does not rapidly increase until reaching 75% of concrete flexural strength. The service life of unnotched concrete without steel bars is dependent on the local cohesive performance around the latent crack path. Finally, the experimental results show that DSCM is useful to confirm the connection between the local damage of the material and the whole structure safety.