Fairtrade Labelling in a Bertrand Competition Model with Monopsony Power

This model examines the impact of a fairtrade labelling scheme on global and country-specific welfare in a two-stage north-south trade framework. In the first stage (the producer market) two northern processors buy a commodity from a group of small–scale agricultural producers in the south producing the commodity under perfect competitive market conditions. One of the processors buys a conventional produced commodity and uses its monopsony power to cut the commodity’s price. The second processor is a fairtrade processor, i.e. meets the necessary requirements for being awarded a fairtrade label like paying a minimum price for the commodity to the producers and a license fee to the labelling organization. In the second stage (the consumer market) both firms are processing the commodity and selling their products to the northern consumers. The price is determined by Bertrand compe- tition. Consuming a labelled product is assumed to generate additional utility on behalf of a warm glow effect. I show how changes of certain parameters crucial to the fairtrade system influence welfare in both the northern and the southern country.Fairtrade, Bertrand Competition, Duopsony, Warm Glow

Fairtrade Labelling in a Bertrand Competition Model with Monopsony Power

This model examines the impact of a fairtrade labelling scheme on global and country-specific welfare in a two-stage north-south trade framework. In the first stage (the producer market) two northern processors buy a commodity from a group of small scale agricultural producers in the south producing the commodity under perfect competitive market conditions. One of the processors buys a conventional produced commodity and uses its monopsony power to cut the commodity's price. The second processor is a fairtrade processor, i.e. meets the necessary requirements for being awarded a fairtrade label like paying a minimum price for the commodity to the producers and a license fee to the labelling organization. In the second stage (the consumer market) both firms are processing the commodity and selling their products to the northern consumers. The price is determined by Bertrand compe- tition. Consuming a labelled product is assumed to generate additional utility on behalf of a warm glow effect. I show how changes of certain parameters crucial to the fairtrade system influence welfare in both the northern and the southern country

Der Einfluss von hyperthermer intraperitonealer Chemotherapie (HIPEC) auf das Überleben von Patienten mit Peritonealkarzinose aufgrund eines Magenkarzinoms: Eine retrospektive Studie

Das peritoneal metastasierte Magenkarzinom ist mit einer schlechten Überlebensprognose verbunden. Bereits in den 1980ern wurde deshalb damit begonnen, die Peritonealkarzinose mit zytoreduktiver Chirurgie (CRS) und hyperthermer intraperitonealer Chemotherapie (HIPEC) zu behandeln. Die vorliegende Studie untersucht den Einfluss der HIPEC auf das Gesamtüberleben für 38 Patienten, welche aufgrund einer Peritonealkarzinose mit Primarius Magenkarzinom in den Zeiträumen Januar 2006 bis Juli 2012 an der Klinik und Poliklinik für Chirurgie der Universität Regensburg und Februar 2011 bis Januar 2013 an der Klinik für Allgemein- und Viszeralchirurgie am Krankenhaus Barmherzige Brüder in Regensburg mit einer HIPEC behandelt wurden. Zur Beurteilung der Wirksamkeit der HIPEC wurden diesen Patienten als Vergleichsgruppen 38 gastrektomierte Patienten mit Magenkarzinom ohne Metastasierung, 27 gastrektomierte Patienten mit Peritonealkarzinose ohne HIPEC-Behandlung und 31 Patienten mit Peritonealkarzinose ohne chirurgische Therapie anhand von Geschlecht, Tumorausdehnung, Lymphknotenstatus und Alter zugeordnet. In der Überlebenszeitanalyse zeigte sich, dass das Überleben nach Peritonealkarzinose-Erstdiagnose der mit HIPEC behandelten Patienten im Vergleich zur Gruppe der gastrektomierten Patienten mit Peritonealkarzinose ohne HIPEC-Behandlung signifikant um 11,2 Monate im Mittel und um 6,2 Monate im Median länger ist. Vergleicht man das Überleben der HIPEC-Patienten mit der Palliativgruppe ohne chirurgische Therapie, so beträgt der Überlebensvorteil der HIPEC-Patienten im Mittel 15,3 Monate und im Median 9,5 Monate. Wird hingegen die HIPEC-Gruppe mit den Magenkarzinom-Patienten ohne Fernmetastasierung verglichen, so zeigt sich kein signifikanter Unterschied im Überleben dieser beiden Gruppen. In Zusammenschau der Ergebnisse kann die HIPEC als wirksame Therapie für Patienten mit peritoneal metastasiertem Magenkarzinom bezeichnet werden und sollte deshalb bei passenden Patienten Anwendung finden. Die aggressive chirurgische Therapie mit CRS und HIPEC führt zu einem längeren Überleben, eine tatsächliche längerfristige Heilung konnte im betrachteten Patientenkollektiv jedoch nicht erzielt werden

A modular framework for distributed model predictive control of nonlinear continuous-time systems (GRAMPC-D)

The modular open-source framework GRAMPC-D for model predictive control of distributed systems is presented in this paper. The modular concept allows to solve optimal control problems in a centralized and distributed fashion using the same problem description. It is tailored to computational efficiency with the focus on embedded hardware. The distributed solution is based on the alternating direction method of multipliers and uses the concept of neighbor approximation to enhance convergence speed. The presented framework can be accessed through C++ and Python and also supports plug-and-play and data exchange between agents over a network

Combined Feedforward/Model Predictive Tracking Control Design for Nonlinear Diffusion-Convection-Reaction-Systems

Part 4: Stabilization, Feedback, and Model Predictive ControlInternational audienceThe tracking control design for setpoint transitions of a quasi-linear diffusion-convection-reaction system with boundary control is considered. For this a suitable model-based feedforward control is determined that relies on the flatness-based parametrization of the control input. A receding horizon feedback control is added within a two-degrees-of-freedom control scheme to account for disturbances, model inaccuracies, and input constraints.The tracking performance of this control scheme is shown by means of simulation studies

Transformation of optimal control problems with a state constraint avoiding interior boundary conditions

International audienceA well–known problem in constrained optimal control is the presence of interior boundary conditions for constrained arcs which require a–priori knowledge of the optimal solution. This paper presents a saturation function method to transform an optimal control problem (OCP) with a state constraint into an unconstrained OCP in new coordinates. The approach allows a tangential entry and exit of constrained arcs without involving interior boundary conditions. An additional regularization term is used in the new OCP to avoid singular arcs which correspond to constrained arcs in the original OCP. Interestingly, the continuity order of the saturation function plays an important role for the existence of bounded trajectories which represent inverse images of the optimal constrained solution in the original coordinates

Handling constraints in optimal control with saturation functions and system extension

International audienceA method is presented to systematically transform a general inequality-constrained optimal control problem (OCP) into a new equality-constrained OCP by means of saturation functions. The transformed OCP can be treated more conveniently within the standard calculus of variations compared to the original constrained OCP. In detail, state constraints are substituted by saturation functions and successively constructed dynamical subsystems, which constitute a (dynamical) system extension. The dimension of the subsystems corresponds to the relative degree (or order) of the respective state constraints. These dynamical subsystems are linked to the original dynamics via algebraic coupling equations. The approach results in a new equality-constrained OCP with extended state and input vectors. An additional regularization term is used in the cost to regularize the new OCP with respect to the new inputs. The regularization term has to be successively reduced to approach the original constrained solution. The new OCP can be solved in a convenient manner, since the stationarity conditions are easily determined and exploited. An important aspect of the saturation function formulation is that the constraints cannot be violated during the numerical solution. The approach is illustrated for an extended version of the well-known Goddard problem with thrust and dynamic pressure constraints and using a collocation method for its numerical solution