Applications of Mathematical Programming in Personnel Scheduling

In the few decades of its existence, mathematical programming has evolved into an important branch of operations research and management science. This thesis consists of four papers in which we apply mathematical programming to real-life personnel scheduling and project management problems. We develop exact mathematical programming formulations. Furthermore, we propose effective heuristic strategies to decompose the original problems into subproblems that can be solved effciently with tailored mathematical programming formulations. We opt for solution methods that are based on mathematical programming, because their advantages in practice are a) the exibility to easily accommodate changes in the problem setting, b) the possibility to evaluate the quality of the solutions obtained, and c) the possibility to use general-purpose solvers, which are often the only software available in practice

Switzerland: Political Developments and Data in 2021

In 2021, as in the previous year, political dynamics in Switzerland were strongly influenced by the Covid-19 pandemic. Institutionally, the ‘special situation’ according to the Federal Law of Epidemics affected the power distribution between federal government and the subnational units. Moreover, compared with the first pandemic year, 2021 was marked by strong polarization of society and the political parties on several pandemic-related issues. One consequence of this were two referendums held on the Covid-19 law, which served as a legal basis for the Federal Council to mitigate the negative effects of the coronavirus pandemic on society and the economy. While voters supported the federal government in both cases, the rich direct-democratic year in Switzerland was otherwise dominated by a rejection of the other main governmental proposition, namely the revised CO2 law

Vergleichsuntersuchungen zur Restenoserate nach Implantation von antithrombotisch (Hirudin, Iloprost) und/oder antiproliferativ (Dexamethason) beschichteten Stents in der Femoralarterie des Schweines

Restenosis constitutes a serious problem during therapeutical use of stents. It is a multifactorial event composed of inflammatory reactions, thrombus formation, proliferation of muscle cells, and the design of the stent. This study is due to test the influence of various antithrombogenic and/or antiproliferative stent coatings on in-stent restenosis by comparison. Methods: 10 mm InFlow Dynamics Flex-Stents were dip-coated aseptically. Polylactic acid (PLA) is used as a carrier as well as being a testgroup itself. Into this carrier, different pharmaceuticals were incorporated alone or in combination with each other up to 20 % of the PLA concentration. There is around 200 µg of coating material per stent. The groups and their numbers are: PLA (n = 10), IH: 2 % iloprost + 5 % PEG-hirudin (n =11), IHD: 2% iloprost + 5% PEG-hirudin + 5% dexamethasone acetate (n = 11), DD: 5% dexamethasone acetate + 15% dexamethasone (n = 12) and UNC: uncoated bare stents (n = 16) as control group. By random, the stents were implanted into both femoral arteries (one into each) of 30 German Landrace pigs. After four weeks, the animals were euthanised and the stented vessels were analysed at three different levels. The histomorphometrical assessment included the absolute neointimal area, the neointimal thickness, and the thickness of neointima at the struts. Histomorphologically, the mean injury score as well as the symmetry of stent distension were analysed. Results: The biggest trauma of vessel wall was found with the uncoated control stents. The PLA stents showed the most asymmetrical extension, as well as the biggest thickness at the struts and neointimal thickness, and neointimal area. There is no significant difference between the groups. None of the groups is outstanding regarding the reduction of restenosis. Only the uncoated stents are noteworthy having no higher rate of restenosis contrary to expectations. Conclusion: Neither dexamethasone, nor iloprost or hirudin alone or in combination were able to inhibit proliferation of smooth muscle cells. There were no differences regarding neointimal proliferation between the antithrombotics iloprost and hirudin, the antiproliferative substance dexamethasone or the carrier polylactic acid or their combinations

Foliar nutrient concentrations of European beech in Switzerland: relations with nitrogen deposition, ozone, climate and soil chemistry

Excess deposition of the mineral nutrient nitrogen (N) is a serious threat for European forests. Its effect on foliar nutrient concentrations of Fagus sylvatica, along with other predictors, was analyzed in the present study which bases on 30 year's observation data in 74 forest monitoring plots in Switzerland. The data include gradients in soil chemistry, climate, nitrogen (N) deposition, and ozone concentration. This long-term forest monitoring study shows that foliar concentrations of phosphorus (P), magnesium (Mg), and potassium (K) decreased over time. Current foliar P concentrations indicate acute P deficiency, assessed both from the concentration and the N:P ratio thresholds. In addition, also the relation between N deposition and foliar concentrations of N and P changed over time. Initially, the N concentrations were positively and the P concentrations not correlated with N deposition. Today, N concentrations are negatively and P strongly negatively related, suggesting a progressive N saturation. Interactions between N deposition and soil chemistry suggest an impaired uptake of K and P at higher N loads. The decline of foliar Mg concentrations seems to be a result of soil acidification mediated by N deposition. Additionally, ozone impaired foliar P uptake.We could observe an increase in leaf weight over time while there was no time trend in P and K mass per leaf. This could be interpreted as a dilution effect but detailed regression analysis argues against the dilution hypothesis. Overall, the changing relation between N deposition and foliar N and P support the nitrogen saturation hypothesis

Atmospheric Deposition on Swiss Long-Term Forest Ecosystem Research (LWF) Plots

Atmospheric deposition of the major elements was estimated from throughfall and bulk deposition measurements on 13 plots of the Swiss Long-Term Forest Ecosystem Research (LWF) between 1995 and 2001. Independent estimates of the wet and dry deposition of nitrogen (N) and sulfur (S) on these same plots were gained from combined simplified models. The highest deposition fluxes were measured at Novaggio (Southern Switzerland), exposed to heavy air pollution originating from the Po Plain, with throughfall fluxes averaging 29 kg ha−1 a−1 for N and 15 kg ha−1 a−1 for S. Low deposition fluxes were measured on the plots above 1800 m, with throughfall fluxes lower than 4.5 kg ha−1 a−1 for N and lower than 3 kg ha−1 a−1 for S. The wet deposition of N and S derived from bulk deposition was close to the modeled wet deposition, but the dry deposition derived from throughfall was significantly lower than the modeled dry deposition for both compounds. However, both the throughfall method and the model yielded total deposition estimates of N which exceeded the critical loads calculated on the basis of long-term mass balance considerations. These estimates were within or above the range of empirical critical loads except above 1800

Epidemiological estimate of growth reduction by ozone in Fagus sylvatica L. and Picea abies karst.: sensitivity analysis and comparison with experimental results

The critical level of ozone flux for forest trees is based entirely on biomass data from fumigation experiments with saplings, mostly in open-top chambers. Extrapolation to mature forests asks, therefore, for validation, which may be performed by epidemiological data analysis. This requires a multivariable regression analysis with a number of covariates to account for potential confounding factors. The present paper analyses the ozone sensitivity of volume increments of mature European beech (Fagus sylvatica) and Norway spruce (Picea abies), with the addition, or removal, of covariates. The comparison of the epidemiological dose-response relationship with experimental data shows very good agreement in beech and a more sensitive relationship in the epidemiological analysis of Norway spruce compared to the experiments. In Norway spruce, there was also a strong interaction between the effects of ozone and temperature; at high July temperatures, the ozone effect was stronger. This interaction may explain the disagreement between the epidemiological study and the experiments, of which the majority were performed in Sweden

Hydroborierungsreaktionen von Fischer-Carbinkomplexen sowie Synthese und Charakterisierung von Carbonylclusterkomplexen mit flächenüberbrückenden Cyclooctatetraen-Liganden

Der erste Teil der Arbeit beschäftigt sich mit Hydroborierungsreaktionen von Fischer-Carbin Komplexen. Hierbei werden Verbindungen des Typs [TpX(CO)2W(CR)] (TpX = verschieden substituierte Hydrotrispyrazolylborat-Anionen; R = Aryl- bzw. Alkylsubstituenten) mit Hydroboranen zur Reaktion gebracht. Untersucht wird der Einfluß sterischer Effekte auf den Reaktionsverlauf und das entstehende Reaktionsprodukt. Die Umsetzungen mit Diethylboran führen zur Zersetzung der Edukte. Mit Phenylboran erhält man in einigen Fällen neue Borylmetallkompexverbindungen. Im zweiten Teil wird die Synthese und Reaktivität von Carbonylclusterkomplexen der Übergangsmetalle Rhodium und Iridium mit flächenüberbrückenden Cyclooctatetraen-Liganden beschrieben. Es werden Reaktionen von [Rh4(CO)6(C8H8)2] mit 14 Valenzelektronenfragmenten beschrieben. Diese führen entweder zur Substitution des 'apicalen' cyclischen Olefins oder aber zu neuen, aufgestockten Clusterkomplexen

Röntgen-Strukturuntersuchungen an Celluloseregeneratfasern

Röntgen-Strukturuntersuchungen an Celluloseregeneratfasern von Rainer Friedrich Rihm. Im Mittelpunkt der Arbeit stehen Röntgen-Strukturuntersuchungen an Cellulose-regeneratfasern. Hauptsächlich wurden Fasern untersucht, die mit dem umweltfreundlichen CARBACELL-Prozeß hergestellt wurden. Aufgabe war es, die Struktur dieser neuartigen Cellulose-carbamatfasern in Abhängigkeit von der Variation der Prozeßparameter zu charakterisieren sowie Struktur-Eigenschaftsbeziehungen aufzuzeigen. Anhand von Planfilmaufnahmen konnten charakteristische intensitätsstarke Röntgenweitwinkelreflexe indiziert werden. Die Winkellagen der gefundenen Reflexe erlauben es, die untersuchten Faserproben der Cellulosemodifikation des Typs II zuzuordnen. Über Röntgenweitwinkeluntersuchungen wurden die Kristallinität und die Kristallitdimensionen der Proben ermittelt. Die Kristallinität der Cellulose-carbamatfasern kann in Abhängigkeit von den variierten Prozeßparametern in einem weiten Bereich eingestellt werden. Vor allem die Reife der Spinnlösung und der Cellulosecarbamatgehalt in den Fasern haben einen signifikanten Einfluß auf die Kristallinität. Ein Vergleich der ermittelten Kristallit-dimensionen ergibt, daß die mittlere Kristallitgröße senkrecht zur (1-10)-Ebene bei den Cellulosecarbamatfasern etwas kleiner ist als bei Viskose- und Lyocellproben; die Kristallitgröße senkrecht zur (110)-Ebene fällt in der Regel etwas größer aus. Die Kristallitdimensionen in Faserrichtung der Cellulosecarbamatfasern sind mit denen der Viskosefasern vergleichbar; NewCell weist deutlich größere Kristallitdimensionen in Faserrichtung auf. Die ermittelten Orientierungsfaktoren bestätigten, daß vor allem die Orientierung der Kettensegmente in den amorphen Regionen sehr sensibel auf Änderungen im Herstellungsprozeß regiert. An Faserproben, die unterschiedlich stark gereckt wurden, wurde mit steigendem Reckfaktor eine Zunahme der Kristallinität und des Kristallitwachstum sowie ein Anstieg der Orientierung ermittelt. Weiter wurden Zusammenhänge zwischen den röntgenographisch ermittelten Struktur-charakteristika und den mechanischen Kennwerten der Celluloseregeneratfasern aufgezeigt. Die gefundenen Ergebnisse sprechen dafür, daß die mechanischen Eigenschaften im wesentlichen von den Kettensegmenten in den nichtkristallinen Regionen beeinflußt werden. Die mechanischen Kennwerte der betrachteten Cellulosecarbamatfasern gleichen denen von EnkaViskose. Bei der Charakterisierung der Porenstruktur mittels Röntgenkleinwinkelbeugung wurde festgestellt, daß die Luftfeuchtigkeit während der Lagerung der Proben einen großen Einfluß auf die Ergebnisse hat. Punktfokusaufnahmen an gequollenen Faserproben wurden hinsichtlich einer Änderung der Porenstruktur diskutiert. Strukturänderungen infolge von Mahl- und Wärmebehandlungen ergaben, daß durch den Mahlprozeß die Kristallinität der Proben abnimmt; Wärmebehandlungen führen zu veränderten Röntgenbeugungs-bildern und zu veränderten NMR-Spektren