Transitive Packing: A Unifying Concept in Combinatorial Optimization

This paper attempts to give a better understanding of the facial structure of previously separately investigated polyhedra. It introduces the notion of transitive packing and the transitive packing polytope. Polytopes that turn out to be special cases of the transitive packing polytope are, among others, the node packing polytope, the acyclic subdigraph polytope, the bipartite subgraph polytope, the planar subgraph polytope, the clique partitioning polytope, the partition polytope, the transitive acyclic subdigraph polytope, the interval order polytope, and the relatively transitive subgraph polytope. We give cutting plane proofs for several rich classes of valid inequalities of the transitive packing polytope,in this way introducing generalized cycle, generalized clique, generalized antihole, generalized antiweb, and odd partition inequalities. These classes subsume several known classes of valid inequalities for several of the special cases and give also many new inequalities for several other special cases. For some of the classes we also prove a lower bound for their Gomory-Chvdtal rank. Finally, we relate the concept of transitive packing to generalized (set) packing and covering as well as to balanced and ideal matrices

Combined Effects of Knowledge About Others' Opinions and Anticipation of Group Discussion on Confirmatory Information Search

There is conclusive evidence that information search processes are typically biased in favor of the information seeker’s own opinion (confirmation bias). Less is known about how knowledge about others’ opinions affects this confirmatory information search. In the present study, the authors manipulated feedback about others’ opinions and anticipation of group interaction. As predicted, the effect of knowledge about others’ opinions on confirmatory information search depended on whether participants anticipated interacting with these others. Specifically, minority members anticipating a group discussion exhibited a particularly strong confirmation bias, whereas minority members who did not anticipate a discussion predominantly sought information opposing their opinion. For participants not anticipating group interaction, confidence about the correctness of one’s decision mediated the impact of knowledge about others’ opinions on confirmatory information search. Results are discussed with regard to the debiasing effect of preference heterogeneity on confirmatory information search in groups

Beyond group-level explanations for the failure of groups to solve hidden profiles: The individual preference effect revisited

The individual preference effect supplements the predominant group-level explanations for the failure of groups to solve hidden profiles. Even in the absence of dysfunctional group-level processes, group members tend to stick to their suboptimal initial decision preferences due to preference-consistent evaluation of information. However, previous experiments demonstrating this effect retained two group-level processes, namely (a) social validation of information supporting the group members’ initial preferences and (b) presentation of the additional information in a discussion format. Therefore, it was unclear whether the individual preference effect depends on the co-occurrence of these group-level processes. Here, we report two experiments demonstrating that the individual preference effect is indeed an individual-level phenomenon. Moreover, by a comparison to real interacting groups, we can show that even when all relevant information is exchanged and when no coordination losses occur, almost half of all groups would fail to solve hidden profiles due to the individual preference effect

Biased Information Search in Homogeneous Groups: Confidence as a Moderator for the Effect of Anticipated Task Requirements

When searching for information, groups that are homogeneous regarding their members’ prediscussion decision preferences show a strong bias for information that supports rather than conflicts with the prevailing opinion (confirmation bias). The present research examined whether homogeneous groups blindly search for information confirming their beliefs irrespective of the anticipated task or whether they are sensitive to the usefulness of new information for this forthcoming task. Results of three experiments show that task sensitivity depends on the groups’ confidence in the correctness of their decision: Moderately confident groups displayed a strong confirmation bias when they anticipated having to give reasons for their decision but showed a balanced information search or even a disconfirmation bias (i.e., predominately seeking conflicting information) when they anticipated having to refute unterarguments. In contrast, highly confident groups demonstrated a strong confirmation bias independent of the anticipated task requirements

Die "bio-logische” Stabilisierung der subtrochantären Femurfraktur mit einer Kondylenplatte

Zusammenfassung: Operationsziel: Indirekte Reposition von subtrochantären Frakturen über die Ligamentotaxis ohne chirurgische Traumatisierung der Frakturzone (keine devaskularisierten Fragmente!) und übungsstabile Osteosynthese mit einer Kondylenplatte. Indikationen: Geschlossene und offene subtrochantäre Trümmerfrakturen des Femurs, insbesondere bei Beteiligung der Schenkelhalsbasis. Kontraindikationen: Keine, außer bei polytraumatisierten Patienten mit lebensbedrohlichen Verletzungen. Operationstechnik: Osteosynthese mit einer Kondylenplatte. Kapsulotomie, um die korrekte Position der Klinge zu prüfen. Reposition der Fraktur an den Schaft der Kondylenplatte unter Kontrolle von Länge, Rotation und Achse, aber ohne anatomische Reposition der einzelnen Fragmente. Kompression der Fraktur, falls möglich, mit dem Spanngerät. Weiterbehandlung: Frühe funktionelle Nachbehandlung mit 15 kg Teilbelastung ab zweitem postoperativen Tag. Ergebnisse: Von 1992 bis 1995 wurden 25 Patienten mit subtrochantärer Femurfraktur (Typ A: n=10; Typ B: n=8; Typ C: n=7 [nach AO-Klassifikation]; vier offene Frakturen) mit Kondylenplatte behandelt. Operationszeit: im Mittel 1,9 Stunden; intraoperativer Blutverlust: durchschnittlich 1300 ml. Normale Frakturheilung: 24/25 Patienten. Komplikationen: Infektpseudarthrose: n=1. Konsolidation der Fraktur nach mehrfachen Débridements und Reosteosynthese mit Wellenplatte. Achsenfehlstellungen: n=3 (Varus: n=2; Verkürzung: n=1; intertrochantäre Korrekturosteotomie: n=1). Entfernung der Platte wegen chronischer Trochanterirritation: n=

Reference values of impulse oscillometric lung function indices in adults of advanced age.

Impulse oscillometry (IOS) is a non-demanding lung function test. Its diagnostic use may be particularly useful in patients of advanced age with physical or mental limitations unable to perform spirometry. Only few reference equations are available for Caucasians, none of them covering the old age. Here, we provide reference equations up to advanced age and compare them with currently available equations. IOS was performed in a population-based sample of 1990 subjects, aged 45-91 years, from KORA cohorts (Augsburg, Germany). From those, 397 never-smoking, lung healthy subjects with normal spirometry were identified and sex-specific quantile regression models with age, height and body weight as predictors for respiratory system impedance, resistance, reactance, and other parameters of IOS applied. Women (n = 243) showed higher resistance values than men (n = 154), while reactance at low frequencies (up to 20 Hz) was lower (p<0.05). A significant age dependency was observed for the difference between resistance values at 5 Hz and 20 Hz (R5-R20), the integrated area of low-frequency reactance (AX), and resonant frequency (Fres) in both sexes whereas reactance at 5 Hz (X5) was age dependent only in females. In the healthy subjects (n = 397), mean differences between observed values and predictions for resistance (5 Hz and 20 Hz) and reactance (5 Hz) ranged between -1% and 5% when using the present model. In contrast, differences based on the currently applied equations (Vogel & Smidt 1994) ranged between -34% and 76%. Regarding our equations the indices were beyond the limits of normal in 8.1% to 18.6% of the entire KORA cohort (n = 1990), and in 0.7% to 9.4% with the currently applied equations. Our study provides up-to-date reference equations for IOS in Caucasians aged 45 to 85 years. We suggest the use of the present equations particularly in advanced age in order to detect airway dysfunction

Rentabilität vegetabiler Düngemittel im ökologischen Gemüsebau am Beispiel eines süddeutschen Gemischtbetriebes

For a given organic farm with livestock and vegetable production in Southern Germany the economic viability of on farm produced legume seed meal as Plant Based Organic Fertiliser (PBOF) is analysed by means of a Linear Programming (LP) model in order to asses under which conditions such a fertiliser use may be profitable. Yields, labour demand and gross margins of the different farming activities are taken from data collections and adapted based on information provided by the farmer, whose specific crop rotation, labour and stable restrictions are also implemented in the LP model. Nitrogen supplies and demands of the different farming activities are drawn from data collections and information by plant scientists. Our calculations show that legume seed meal as PBOF is profitable in case that cheap purchasable organic nitrogen fertilisers are not available. In future, further model calculations shall show whether this result also holds for other farming and site conditions than those underlying the quite specific conditions of our model farm

Inkubationsversuche zum Einfluss von Sorte und Textur auf den Umsatz von Lupinenkörnerschroten im Boden bei unterschiedlichen Temperaturen

Organically produced legume seed meals are an upcoming alternative to established fast mineralising organic fertilisers based on plant and animal waste products with suspect origin (e.g. hornmeal). The turnover in soil was investigated with respect to the influence of legume variety and seed meal texture. Variety specific differences in net N mineralisation could be attributed to differences in C/N ratio and cellulose content. The influence of texture classes on net N mineralisation was considerably smaller than the influence of differences between the investigated species

Social validation in group decision making: differential effects on the decisional impact of preference-consistent and preference-inconsistent information

"Shared information has a stronger impact on group decisions than unshared information. A prominent explanation for this phenomenon is that shared information can be socially validated during group discussion and, hence, is perceived as more accurate and relevant than unshared information. In the present study we argue that this explanation only holds for preference-inconsistent information (i.e., information contradicting the group members’ initial preferences) but not for preference-consistent information. In Experiments 1 and 2 participants studied the protocol of a fictitious group discussion. In this protocol, we manipulated which types of information were socially validated. As predicted, social validation increased the decisional impact of preference-inconsistent but not preference-consistent information. In both experiments the effect of social validation was mediated by the perceived quality of information. Experiment 3 replicated the results of the first two experiments in an interactive setting in which two confederates discussed a decision case face-to-face with one participant." [author's abstract