The categorical limit of a sequence of dynamical systems

Modeling a sequence of design steps, or a sequence of parameter settings, yields a sequence of dynamical systems. In many cases, such a sequence is intended to approximate a certain limit case. However, formally defining that limit turns out to be subject to ambiguity. Depending on the interpretation of the sequence, i.e. depending on how the behaviors of the systems in the sequence are related, it may vary what the limit should be. Topologies, and in particular metrics, define limits uniquely, if they exist. Thus they select one interpretation implicitly and leave no room for other interpretations. In this paper, we define limits using category theory, and use the mentioned relations between system behaviors explicitly. This resolves the problem of ambiguity in a more controlled way. We introduce a category of prefix orders on executions and partial history preserving maps between them to describe both discrete and continuous branching time dynamics. We prove that in this category all projective limits exist, and illustrate how ambiguity in the definition of limits is resolved using an example. Moreover, we show how various problems with known topological approaches are now resolved, and how the construction of projective limits enables us to approximate continuous time dynamics as a sequence of discrete time systems.Comment: In Proceedings EXPRESS/SOS 2013, arXiv:1307.690

Balancing fertilization strategy with crop requirements in organic greenhouse cultivation of sweet pepper

An on-farm field trial was set up in an organic greenhouse in order to balance the N-uptake by a sweet pepper crop and the mineralization of the organic fertilizers was applied. The effects of six fertilizer treatments were compared regarding yield, nutrient availability and mineral balance. Application of high levels of compost turned out to be favourable in order to reduce surplusses of available-N on the short term. On the long term, such high levels of compost are unfavourable as a high pool of mineralizable-N in the soil organic matter restricts the possiblities for precise fertilization adapted to plant uptake. Application of lower levels of farm yard manure in combination with additional fertilization with feathermeal turned out to be a good fertilization strategy both on the short and the long term unless there is a need for minimizing salt levels in the applied fertilizers

Design of asynchronous supervisors

One of the main drawbacks while implementing the interaction between a plant and a supervisor, synthesised by the supervisory control theory of \citeauthor{RW:1987}, is the inexact synchronisation. \citeauthor{balemiphdt} was the first to consider this problem, and the solutions given in his PhD thesis were in the domain of automata theory. Our goal is to address the issue of inexact synchronisation in a process algebra setting, because we get concepts like modularity and abstraction for free, which are useful to further analyze the synthesised system. In this paper, we propose four methods to check a closed loop system in an asynchronous setting such that it is branching bisimilar to the modified (asynchronous) closed loop system. We modify a given closed loop system by introducing buffers either in the plant models, the supervisor models, or the output channels of both supervisor and plant models, or in the input channels of both supervisor and plant models. A notion of desynchronisable closed loop system is introduced, which is a class of synchronous closed loop systems such that they are branching bisimilar to their corresponding asynchronous versions. Finally we study different case studies in an asynchronous setting and then try to summarise the observations (or conditions) which will be helpful in order to formulate a theory of desynchronisable closed loop systems

Costs and benefits of inter-departmental innovation collaboration

Inter-departmental innovation collaboration facilitates innovation performance. At the same time, it has been identified as source of increased coordination costs. Using organizational information processing theory, this paper builds and tests hypotheses on the costs and benefits of innovation-related collaboration within firms. Based on a sample of 433 German manufacturing firms we show inter-departmental innovation collaboration to increase process innovation performance, but also to produce costs in terms of project delay and project termination. These costs, however, do not affect innovation performance at the firm level. This finding suggests firms to be well able to balance the costs and benefits of interdepartmental collaboration across their innovation project portfolio. Theoretical and managerial implications are discussed. --Inter-departmental innovation collaboration,innovation performance,project delay,project termination

Psychological treatment of depression: A meta-analytic database of randomized studies

Abstract Background A large number of randomized controlled studies have clearly demonstrated that psychological interventions are effective in the treatment of depression. The number of studies in this area is increasing rapidly. In this paper, we present a database of controlled and comparative outcome studies on psychological treatments of depression, based on a series of meta-analyses published by our group. The database can be accessed freely through the Internet. Description We conducted a comprehensive literature search of the major bibliographical databases (Pubmed; Psycinfo; Embase; Cochrane Central Register of Controlled Trials) and we examined the references of 22 earlier meta-analyses of psychological treatment of depression. We included randomized studies in which the effects of a psychological therapy on adults with depression were compared to a control condition, another psychological intervention, or a combined treatment (psychological plus pharmacological). We conducted nine meta-analyses of subgroups of studies taken from this dataset. The 149 studies included in these 9 meta-analyses are included in the current database. In the 149 included studies, a total of 11,369 patients participated. In the database, we present selected characteristics of each study, including characteristics of the patients (the study population, recruitment method, definition of depression); characteristics of the experimental conditions and interventions (the experimental conditions, N per condition, format, number of sessions); and study characteristics (measurement times, measures used, attrition, type of analysis and country). Conclusion The data on the 149 included studies are presented in order to give other researchers access to the studies we collected, and to give background information about the meta-analyses we have published using this dataset. The number of studies examining the effects of psychological treatments of depression has increased considerably in the past decades, and this will continue in the future. The database we have presented in this paper can help to integrate the results of these studies in future meta-analyses and systematic reviews on psychological treatments for depression

Voluntary adoption of non-local GAAP in the European Union: a study of determinants

This study examines the determinants of voluntary adoption of non-local accounting principles for financial reporting (non-local GAAP) by non-financial companies listed and domiciled in the European Union. We restrict ourselves to the two most predominant internationally accepted sets of accounting standards: International Accounting Standards (IAS) and United States generally accepted accounting principles (US GAAP). The maintained hypothesis is that firms will switch from local to non-local GAAP if the benefits outweigh the costs. This study provides insight in the characteristics of firms that experience positive net-benefits from non-local GAAP adoption. Considering that mandatory adoption of IAS is envisaged for listed EU companies from 2005 on, the results are of potential interest to EU and national financial reporting regulators.We have used various sources to identify EU companies that use non-local GAAP. The 1999 annual reports of all these companies were examined. We find that 133 non-financial companies in the EU voluntarily adopted non-local GAAP in 1999. This suggests that the net-benefits of using non-local GAAP are positive for only a small minority of EU companies.Companies that do voluntarily use non-local GAAP are more likely to be listed on a US exchange, the EASDAQ exchange in Brussels, and have more geographically dispersed operations. Furthermore, they are more likely to be domiciled in a country with lower quality financial reporting and where IAS is explicitly allowed as an alternative to local GAAP.accounting and auditing ;

Mental health nurses’ support to caregivers of older adults with severe mental illness : a qualitative study

Background: Literature has shown the serious impact of severe mental illness on the daily life of caregivers. We studied reported caregiver support practices by mental health nurses for use in the development of a nursing intervention. We aimed to explore current caregiver support practices by mental health nurses. Methods: Twenty-one participants completed semi-structured interviews, and 17 participants attended two focus groups. All interviews were audio-taped, transcribed and coded for qualitative analysis. Results: The diversity in caregiver support could best be described by three prototypes: the tolerator, the preventer and the concerner, representing three approaches of involvement with caregivers. At one end of the spectrum are mental health nurses (MHN) who are essentially only concerned with the wellbeing of the care recipient and see the caregiver as a potential impediment in reaching the client’s goals. We call these the tolerators. At the other end of the spectrum are the MHNs who see the caregiver and the care recipient as inextricably connected with each other. In these cases the MHN directs her/his intervention towards both the informal caregiver and the care recipient. We call these the concerners. In the middle position are MHNs who realize that caregivers are important agents in the achievement of the client’s goals, and therefore consider preventing them from becoming overburdened as an important goal. We call these the preventers. Conclusions: Based on the extent to which the MHNs believe that the informal caregiver plays a necessary role in the client’s support system, and the degree to which they feel responsible for the caregiver’s wellbeing, three MHN prototypes can be distinguished. These prototypes determine how the nurses’ vision directs their understanding of their role and responsibilities and the content of their behaviour. This implies that a change in behaviour needs to be preceded by a change in vision. Therefore, promoting family support cannot be achieved by one-size-fits-all-programmes