A Comparison of Biased Simulation Schemes for Stochastic Volatility Models

When using an Euler discretisation to simulate a mean-reverting square root process, one runs into the problem that while the process itself is guaranteed to be nonnegative, the discretisation is not. Although an exact and efficient simulation algorithm exists for this process, at present this is not the case for the Heston stochastic volatility model, where the variance is modelled as a square root process. Consequently, when using an Euler discretisation, one must carefully think about how to fix negative variances. Our contribution is threefold. Firstly, we unify all Euler fixes into a single general framework. Secondly, we introduce the new full truncation scheme, tailored to minimise the upward bias found when pricing European options. Thirdly and finally, we numerically compare all Euler fixes to a recent quasi-second order scheme of Kahl and Jäckel and the exact scheme of Broadie and Kaya. The choice of fix is found to be extremely important. The full truncation scheme by far outperforms all biased schemes in terms of bias, root-mean-squared error, and hence should be the preferred discretisation method for simulation of the Heston model and extensions thereof

Visions of Dutch Empire: Towards a Long-Term Global Perspective

What were the major developments in thinking about Dutch empire from the early modern period to the twenty-first century? What moral, political, legal and economic arguments have been put forth to justify, criticize or reform empire? How and under what circumstances did these visions and arguments change or remain the same? This article outlines a research agenda that addresses these questions. It argues for an approach that includes a long-term perspective from the early modern period to the postcolonial situation, which sees ‘Dutch’ history broadly, moving beyond national borders, and instead explicitly informed by influences and actors from across the globe. This implies a transnational and transimperial approach that can highlight these global connections as well as tensions; and finally, an approach that understands intellectual history as going beyond the big names of systemic thinkers, and includes visions of empire as negotiated in (day-to-day) practice.History and International Relation

Introduction. Intellectual history in imperial practice

The introduction asks where the Dutch empire fits in the intellectual history of empire. It explains the need to examine the trope of Dutch exceptionalism over the long term in transnational and transimperial perspectives. Methodologically it argues for including meaningful practices as sources and to look beyond systemic thinkers and examine how ‘intermediate thinkers of empire’ from across the globe articulated their visions in practice. Drawing on the concepts of upward and downward hermeneutics, this entails examining the interactions between ideas and practice; how ideas formed and were formed by socio-cultural and political practice. Such a history of visions of empire sheds new light on historiography and public debate, precisely because dominant notions within these are rooted in the intellectual history of Dutch imperial practice.NWO275-52-015History and International RelationsColonial and Global HistoryCities, Migration and Global Interdependenc

Collaborative Care for patients with severe borderline and NOS personality disorders: A comparative multiple case study on processes and outcomes

<p>Abstract</p> <p>Background</p> <p>Structured psychotherapy is recommended as the preferred treatment of personality disorders. A substantial group of patients, however, has no access to these therapies or does not benefit. For those patients who have no (longer) access to psychotherapy a Collaborative Care Program (CCP) is developed. Collaborative Care originated in somatic health care to increase shared decision making and to enhance self management skills of chronic patients. Nurses have a prominent position in CCP's as they are responsible for optimal continuity and coordination of care. The aim of the CCP is to improve quality of life and self management skills, and reduce destructive behaviour and other manifestations of the personality disorder.</p> <p>Methods/design</p> <p>Quantitative and qualitative data are combined in a comparative multiple case study. This makes it possible to test the feasibility of the CCP, and also provides insight into the preliminary outcomes of CCP. Two treatment conditions will be compared, one in which the CCP is provided, the other in which Care as Usual is offered. In both conditions 16 patients will be included. The perspectives of patients, their informal carers and nurses are integrated in this study. Data (questionnaires, documents, and interviews) will be collected among these three groups of participants. The process of treatment and care within both research conditions is described with qualitative research methods. Additional quantitative data provide insight in the preliminary results of the CCP compared to CAU. With a stepped analysis plan the 'black box' of the application of the program will be revealed in order to understand which characteristics and influencing factors are indicative for positive or negative outcomes.</p> <p>Discussion</p> <p>The present study is, as to the best of our knowledge, the first to examine Collaborative Care for patients with severe personality disorders receiving outpatient mental health care. With the chosen design we want to examine how and which elements of the CC Program could contribute to a better quality of life for the patients.</p> <p>Trial registration</p> <p>Netherlands Trial Register (NTR): <a href="http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=2763">NTR2763</a></p

Collaborative Care for patients with severe borderline and NOS personality disorders: A comparative multiple case study on processes and outcomes

<p>Abstract</p> <p>Background</p> <p>Structured psychotherapy is recommended as the preferred treatment of personality disorders. A substantial group of patients, however, has no access to these therapies or does not benefit. For those patients who have no (longer) access to psychotherapy a Collaborative Care Program (CCP) is developed. Collaborative Care originated in somatic health care to increase shared decision making and to enhance self management skills of chronic patients. Nurses have a prominent position in CCP's as they are responsible for optimal continuity and coordination of care. The aim of the CCP is to improve quality of life and self management skills, and reduce destructive behaviour and other manifestations of the personality disorder.</p> <p>Methods/design</p> <p>Quantitative and qualitative data are combined in a comparative multiple case study. This makes it possible to test the feasibility of the CCP, and also provides insight into the preliminary outcomes of CCP. Two treatment conditions will be compared, one in which the CCP is provided, the other in which Care as Usual is offered. In both conditions 16 patients will be included. The perspectives of patients, their informal carers and nurses are integrated in this study. Data (questionnaires, documents, and interviews) will be collected among these three groups of participants. The process of treatment and care within both research conditions is described with qualitative research methods. Additional quantitative data provide insight in the preliminary results of the CCP compared to CAU. With a stepped analysis plan the 'black box' of the application of the program will be revealed in order to understand which characteristics and influencing factors are indicative for positive or negative outcomes.</p> <p>Discussion</p> <p>The present study is, as to the best of our knowledge, the first to examine Collaborative Care for patients with severe personality disorders receiving outpatient mental health care. With the chosen design we want to examine how and which elements of the CC Program could contribute to a better quality of life for the patients.</p> <p>Trial registration</p> <p>Netherlands Trial Register (NTR): <a href="http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=2763">NTR2763</a></p

Anatomical Pathways Involved in Generating and Sensing Rhythmic Whisker Movements

The rodent whisker system is widely used as a model system for investigating sensorimotor integration, neural mechanisms of complex cognitive tasks, neural development, and robotics. The whisker pathways to the barrel cortex have received considerable attention. However, many subcortical structures are paramount to the whisker system. They contribute to important processes, like filtering out salient features, integration with other senses, and adaptation of the whisker system to the general behavioral state of the animal. We present here an overview of the brain regions and their connections involved in the whisker system. We do not only describe the anatomy and functional roles of the cerebral cortex, but also those of subcortical structures like the striatum, superior colliculus, cerebellum, pontomedullary reticular formation, zona incerta, and anterior pretectal nucleus as well as those of level setting systems like the cholinergic, histaminergic, serotonergic, and noradrenergic pathways. We conclude by discussing how these brain regions may affect each other and how they together may control the precise timing of whisker movements and coordinate whisker perception

Sturing kwaliteit en houdbaarheid potplant door toevoeging van klei aan substraten

In de potplantenteelt ligt de nadruk op de teeltfase, waarbij aandacht voor de houdbaarheid en kwaliteit tijdens de “transport- en vensterbankfase” relatief is achtergebleven. Er zijn echter sterke aanwijzingen dat de teeltwijze en kleitoevoeging aan het substraat, grote invloed hebben op de kwaliteit bij de consument. Daarnaast zou door kleitoevoeging aan het substraat en de teeltwijze de input aan chemicaliën (met name remstoffen) teruggedrongen kunnen worden. In dit onderzoek zijn effecten van toevoeging van verschillende kleiproducten op de chemische en fysische eigenschappen van substraat in relatie tot groeibeheersing, kwaliteit en houdbaarheid van potplanten onderzocht en beschreven