OR-Modelle zur Planung flexibler Fertigungssysteme Ein Überblick

Zusammenfassung In diesem Beitrag wird ein Überblic über die Probleme vermittelt, die sich bei der Konfiguration und dem Betrieb eines flexiblen Fertigungssystems stellen. Die zur Behandlung der wichtigsten Problemtypen verfügbaren Modellierungsansätze werden systematisch beschrieben und auf ihren möglichen Einsatz zur Entscheidungsunterstützung für die betriebliche Praxis hin untersucht.     

In vivo parathyroid hormone stimulates in vitro bone resorption by bovine monocytes

Cells of the monocyte-macrophage lineage have been thought to play a role in bone resorption. We examined the effects of in vivo administration of parathyroid hormone and 1,25-dihydroxyvitamin D3 on the ability of monocytes to degrade bone in vitro. Administration of parathyroid hormone for 4 d resulted in sustained hypercalcemia and a transient 1-d increase in plasma 1,25-dihydroxyvitamin D3. Parathyroid hormone significantly stimulated bone degradation by monocytes 2.6 times more than that of pretreatment controls. Parathyroid hormone treatment significantly enhanced (threefold) release of superoxide anion by monocytes stimulated with phorbol 12-myristate 13-acetate and increased migration of monocytes to bone particles in vitro. Continuous 7-d infusion of 1,25-dihydroxyvitamin D3 (50 micrograms/d) elevated plasma 1,25-dihydroxyvitamin D3 until infusions were discontinued. Increased 1,25-dihydroxyvitamin D3 was associated with hypercalcemia, which continued for several days postinfusion. In vivo administration of 1,25-dihydroxyvitamin D3 did not affect in vitro ability of monocytes to degrade bone. We concluded that in vivo administration of parathyroid hormone enhanced in vitro responsiveness of isolated monocytes in a manner consistent with a role for monocytes in bone remodeling. Furthermore, these data suggested that circulating monocytes could be a useful experimental model for further studies on parathyroid hormone responsiveness and bone resorption for the cow with milk fever.     

The Effect of High Pressure Processing on the Integrity of Polymeric Packaging – Analysis and Categorization of Occurring Defects

As high‐pressure processing is used increasingly for the treatment of packed products, different packaging has been investigated with respect to their structural behaviour and stability under high‐pressure processing. Often, failures and changes of the polymeric structure occur. Common damage symptoms of high‐pressure‐treated packaging materials are defined and classified in this review. These damage symptoms are allocated to the physico‐chemical effects that created them. The effects may be separated into direct effects induced by the action of the high‐pressure alone and indirect effects that are mediated via compressed contents of the package, i.e. filled product and gaseous headspace. The direct effects split up again in reversible and irreversible structural changes. The indirect effects are generated by compressed headspace gases, other compressed substances and the consequences of increased amounts of gases dissolved in the polymers. If applicable, current theoretical approaches have been allocated to the different categories of damage. Copyright © 2013 John Wiley & Sons, Ltd.