Batch scheduling in process industries: an application of resource-constrained project scheduling

The paper deals with batch scheduling problems in process industries where final products arise from several successive chemical or physical transformations of raw materials using multi–purpose equipment. In batch production mode, the total requirements of intermediate and final products are partitioned into batches. The production start of a batch at a given level requires the availability of all input products. We consider the problem of scheduling the production of given batches such that the makespan is minimized. Constraints like minimum and maximum time lags between successive production levels, sequence–dependent facility setup times, finite intermediate storages, production breaks, and time–varying manpower contribute to the complexity of this problem. We propose a new solution approach using models and methods of resource–constrained project scheduling, which (approximately) solves problems of industrial size within a reasonable amount of time.

Endstation Notfallstation: Perzeption und Rezeption des Begriffs «palliativer Patient» sowie Ansätze zur Verbesserung der interdisziplinären Zusammenarbeit – ein Survey unter notfallmedizinischem Personal auf einer Schweizer Notfallstation

Hintergrund: Wegen sich verändernder Strukturen im Spitalbereich sowie im Bereich der Hausarztabdeckung als auch infolge zunehmenden Drucks auf das Gesundheitssystem kommen mehr Patienten auf die Notfallstationen, die aufgrund ihrer Grunderkrankung und des fortgeschrittenen Krankheitsstadiums von einem palliativen Behandlungskonzept profitieren. Eine wesentliche Herausforderung ist hierbei bereits die Definition von «Palliative Care» (PC), sowie die Klärung, was genau die palliative Versorgung beinhaltet. Häufig vermischt wird der Terminus «Palliative Care» mit «End of life care». Die vorliegende Studie ist eine Standortbestimmung im Universitären Notfallzentrum des Inselspitals Bern (UNZ), das jährlich rund 32 400 Patienten versorgt. Ziel ist es, mehr über den Wissensstand und die persönliche Einstellung der Mitarbeiter zu palliativen Fragestellungen und speziell zum Begriff «Palliative Care» zu erhalten. Methodik: Die Mitarbeiter des Universitären Notfallzentrums des Inselspitals Bern (UNZ) wurden mittels einer Online-Umfrage durch eine spitalexterne Fachinstitution interviewt. Diese Befragung basiert auf einem Instrument [1], das in einer vergleichbaren Studie auf einer Notfallstation in den USA entwickelt und validiert wurde. Resultate: Von 154 Mitarbeitenden (Pflege und Ärzte) füllten 60 Mitarbeitende die Befragung vollständig aus, entsprechend einer Antwortrate von 39%. Die Definition von Palliative Care (von n=60) war sehr heterogen und konnte in sechs Themenbereiche eingeteilt werden. Bei den Fragen nach spezifischen Leistungsangeboten äusserten die Mitarbeitenden den Wunsch nach einem erleichterten Zugang zu bestehenden Patientendaten, nach einem 24-Stunden-Palliative-Care-Konsiliardienst und nach mehr Besprechungszeit für Fragestellungen der PC im klinischen Alltag. Schlussfolgerungen: Die heterogene Begriffsdefinition von «Palliative Care» bestätigt sich. Es besteht kein klares Vorgehen, und zudem lässt sich ein Zeitmangel für ausführliche Patientengespräche in palliativen Situationen im UNZ feststellen. Der Patientenwunsch oder Patientenverfügungen mit DNR/DNI-Prozedere stehen nicht im Widerspruch zu den persönlichen Wertvorstellungen der meisten Mitarbeitenden. Die 24-Stunden-Verfügbarkeit eines spezialisierten PC-Teams, das Erarbeiten von Guidelines und vermehrtes Training für PC würde von den UNZ-Mitarbeitenden begrüsst.

Momentan verfügbare Selbstkontrollkraft: Vorstellung eines Messinstruments und erste Befunde aus pädagogisch-psychologischen Kontexten

Selbstkontrolle spielt in pädagogischen Kontexten oft eine entscheidende Rolle, beispielsweise wenn Lernende attraktiven Handlungsalternativen widerstehen müssen. Etliche Studien zeigen, dass die erfolgreiche Ausübung von Selbstkontrolle von der momentanen Verfügbarkeit an Selbstkontrollkraft abhängt. Zur Erfassung der momentanen Selbstkontrollkraft in deutschsprachigen Stichproben, wurde die State Self-Control Capacity Scale ins Deutsche adaptiert. In der vorliegenden Arbeit wird über fünf Teilstudien berichtet, in denen die psychometrische Güte dieser Skala überprüft wurde. Über alle Studien hinweg erwies sich die eindimensionale Skala als sehr reliabel (Cronbachs Alphas ≥ .93). Bezüglich ihrer Validität zeigten sich erwartete Zusammenhänge mit Validitätskriterien (z. B. Angst, Stress, am gegenwärtigen Tag bereits in Lehrveranstaltungen verbrachte Zeit); zusätzlich gelang die empirische Trennung von verschiedenen Stimmungsaspekten. Des Weiteren bildete die neue Skala (quasi-) experimentell im Labor und im Feld (Hochschule) induzierte Unterschiede in der Selbstkontrollkraft ab. Auch eine aus zehn Items bestehende Kurzskala erwies sich als hinreichend reliabel und valide.

Umsetzung subjektiver Sporthäufigkeitsstandards: zur Rolle dispositionell verfügbarer Selbstkontrollkraft

In dieser Arbeit wurde untersucht, ob Personen mit höherer dispositioneller Verfügbarkeit von Selbstkontrollkraft höhere subjektive Sporthäufigkeitsstandards eher einhalten. Auf Basis früherer Forschung gingen wir davon aus, dass die Verfügbarkeit von Selbstkontrollkraft eine Voraussetzung für willentliche Handlungen ist. Ein subjektiver Sporthäufigkeitsstandard bezeichnet die eigene Auffassung einer Person, wie häufig sie Sport treiben sollte. Insgesamt 93 Studierende gaben an, an wie vielen Tagen in der Woche sie aus ihrer Sicht Sport treiben sollten und an wie vielen Tagen in der Woche sie tatsächlich Sport treiben. Außerdem beantworteten sie eine Skala zur Messung der dispositionellen Verfügbarkeit von Selbstkontrollkraft. Eine hierarchische multiple Regressionsanalyse mit anschließenden Simple-Slope-Analysen erbrachte den erwarteten Befund: Teilnehmende mit höherer Verfügbarkeit von Selbstkontrollkraft setzten höhere Sporthäufigkeitsstandards eher um. Wir diskutieren den Befund u. a. im Hinblick auf die Förderung sportlicher Aktivität.

German Total Ankle Replacement Register of the German Foot and Ankle Society (D. A. F.) - presentation of design and reliability of the data as well as first results

INTRODUCTION Even though arthroplasty of the ankle joint is considered to be an established procedure, only about 1,300 endoprostheses are implanted in Germany annually. Arthrodeses of the ankle joint are performed almost three times more often. This may be due to the availability of the procedure - more than twice as many providers perform arthrodesis - as well as the postulated high frequency of revision procedures of arthroplasties in the literature. In those publications, however, there is often no clear differentiation between revision surgery with exchange of components, subsequent interventions due to complications and subsequent surgery not associated with complications. The German Orthopaedic Foot and Ankle Association's (D. A. F.) registry for total ankle replacement collects data pertaining to perioperative complications as well as cause, nature and extent of the subsequent interventions, and postoperative patient satisfaction. MATERIAL AND METHODS The D. A. F.'s total ankle replacement register is a nation-wide, voluntary registry. After giving written informed consent, the patients can be added to the database by participating providers. Data are collected during hospital stay for surgical treatment, during routine follow-up inspections and in the context of revision surgery. The information can be submitted in paper-based or online formats. The survey instruments are available as minimum data sets or scientific questionnaires which include patient-reported outcome measures (PROMs). The pseudonymous clinical data are collected and evaluated at the Institute for Evaluative Research in Medicine, University of Bern/Switzerland (IEFM). The patient-related data remain on the register's module server in North Rhine-Westphalia, Germany. The registry's methodology as well as the results of the revisions and patient satisfaction for 115 patients with a two year follow-up period are presented. Statistical analyses are performed with SAS™ (Version 9.4, SAS Institute, Inc., Cary, NC, USA). RESULTS About 2½ years after the register was launched there are 621 datasets on primary implantations, 1,427 on follow-ups and 121 records on re-operation available. 49 % of the patients received their implants due to post-traumatic osteoarthritis, 27 % because of a primary osteoarthritis and 15 % of patients suffered from a rheumatic disease. More than 90 % of the primary interventions proceeded without complications. Subsequent interventions were recorded for 84 patients, which corresponds to a rate of 13.5 % with respect to the primary implantations. It should be noted that these secondary procedures also include two-stage procedures not due to a complication. "True revisions" are interventions with exchange of components due to mechanical complications and/or infection and were present in 7.6 % of patients. 415 of the patients commented on their satisfaction with the operative result during the last follow-up: 89.9 % of patients evaluate their outcome as excellent or good, 9.4 % as moderate and only 0.7 % (3 patients) as poor. In these three cases a component loosening or symptomatic USG osteoarthritis was present. Two-year follow-up data using the American Orthopedic Foot and Ankle Society Ankle and Hindfoot Scale (AOFAS-AHS) are already available for 115 patients. The median AOFAS-AHS score increased from 33 points preoperatively to more than 80 points three to six months postoperatively. This increase remained nearly constant over the entire two-year follow-up period. CONCLUSION Covering less than 10 % of the approximately 240 providers in Germany and approximately 12 % of the annually implanted total ankle-replacements, the D. A. F.-register is still far from being seen as a national registry. Nevertheless, geographical coverage and inclusion of "high-" (more than 100 total ankle replacements a year) and "low-volume surgeons" (less than 5 total ankle replacements a year) make the register representative for Germany. The registry data show that the number of subsequent interventions and in particular the "true revision" procedures are markedly lower than the 20 % often postulated in the literature. In addition, a high level of patient satisfaction over the short and medium term is recorded. From the perspective of the authors, these results indicate that total ankle arthroplasty - given a correct indication and appropriate selection of patients - is not inferior to an ankle arthrodesis concerning patients' satisfaction and function. First valid survival rates can be expected about 10 years after the register's start.

Biotic and abiotic controls of nitrogen and phosphorus cycling in Central European forests

The functioning and services of Central European forests are threatened by global change and a loss of biodiversity. Nutrient cycling as a key forest function is affected by biotic drivers (e.g., dominant tree species, understory plants, soil organisms) that interact with abiotic conditions (e.g., climate, soil properties). In contrast to grassland ecosystems, evidence for the relationship of nutrient cycles and biodiversity in forests is scarce because the structural complexity of forests limits experimental control of driving factors. Alternatively, observational studies along gradients in abiotic conditions and biotic properties may elucidate the role of biodiversity for forest nutrient cycles. This thesis aims to improve the understanding of the functional importance of biodiversity for nutrient cycles in forests by analyzing water-bound fluxes of nitrogen (N) and phosphorus (P) along gradients in biodiversity in three regions of Germany. The tested hypotheses included: (1) temperate forest canopies retain atmospheric N and retention increases with increasing plant diversity, (2) N release from organic layers increases with resource availability and population size of decomposers but N leaching decreases along a gradient in plant diversity, (3) P leaching from forest canopies increases with improved P supply from recalcitrant P fractions by a more diverse ectomycorrhizal fungal community. In the canopies of 27 forest stands from three regions, 16 % to 51 % of atmospheric N inputs were retained. Regional differences in N retention likely resulted from different in N availability in the soil. Canopy N retention was greater in coniferous than in beech forests, but this was not the case on loessderived soils. Nitrogen retention increased with increasing tree and shrub diversity which suggested complementary aboveground N uptake. The strength of the diversity effect on canopy N uptake differed among regions and between coniferous and deciduous forests. The N processing in the canopy directly coupled back to N leaching from organic layers in beech forests because throughfall-derived N flushed almost completely through the mull-type organic layers at the 12 studied beech sites. The N release from organic layers increased with stand basal area but was rather low (< 10 % of annual aboveground litterfall) because of a potentially high microbial N immobilization and intensive incorporation of litter into the mineral soil by bioturbation. Soil fauna biomass stimulated N mineralization through trophic interactions with primary producers and soil microorganisms. Both gross and net leaching from organic layers decreased with increasing plant diversity. Especially the diversity but not the cover of herbs increased N uptake. In contrast to N, P was leached from the canopy. Throughfall-derived P was also flushed quickly through the mull-type organic layers and leached P was predominantly immobilized in non directly plant-available P fractions in the mineral soil. Concentrations of plant-available phosphate in mineral soil solution were low and P leaching from the canopy increased with increasing concentrations of the moderately labile P fraction in soil and increasing ectomycorrhiza diversity while leaf C:P ratios decreased. This suggested that tree P supply benefited from complementary mining of diverse mycorrhizal communities for recalcitrant P. Canopy P leaching increased in years with pronounced spring drought which could lead to a deterioration of P supply by an increasing frequency of drought events. This thesis showed that N and P cycling in Central European forests is controlled by a complex interplay of abiotic site conditions with biological processes mediated by various groups of organisms, and that diverse plant communities contribute to tightening the N cycle in Central European forests and that diverse mycorrhizal communities improve the limited P availability. Maintaining forest biodiversity seems essential to ensure forest services in the light of environmental change.