Academic Ceremonies March 2009

“Innovative use of simulated patients for Educational purposes”

“Non-convulsive aspects of epilepsy in children”

“Vertrouwen in onderzoek naar verkiezingen”

 “Embodied Technological Change and Patterns of Investment in Austrian Manufacturing”

This research revolves around three major issues: one, it contributes to the burgeoning discussion as to what drives observed business cycles and identifies how much of the Austrian business cycles can be explained by technological change; two, it confirms the vital role investments as carriers of technological change play for macroeconomic performance and provides a rich and coherent picture of entrepreneurs’ investment strategies and, three, it assumes that observed investment patterns emerge in response to non-negligible costs associated with investment activities and simulates the underlying determining costs.

Key words:

Austrian manufacturing; technological change; business cycles; investments

“At Risk for Depression; the role of stress and serotonergic vulnerability”

Depression is one of the most common serious diseases worldwide. Therefore, in the field of psychology finding risk factors for depression is currently seen as an important challenge.  Vulnerability of the serotonergic system and stress experiencing appear to increase the risk of depression. Our research shows that people with a familial or genetic disposition to depression react more sensitively to serotonergic manipulations (tryptophan depletion) and are also more susceptible to stress. This supports the assumption that people with a serotonergic vulnerability run an increased risk of depression after experiencing stress. We also show that diet induced serotonin increases (via tryptophan increase with a tryptophan-rich protein hydrolysate) improve the mood and stress vulnerability. This can have important implications for prevention and treatment of depression. 

Key words:

depression, serotonin, stress

“Attention for Alcohol. On the changeability of appetitive motivational processes in alcohol abuse”

Heavy social drinkers and alcoholics have excessive selective attention for alcohol-related objects, such as a beer bottle, a bar or someone drinking from a wineglass. This ‘attention’ bias is related to someone’s drinking pattern and the strongest in heavy drinkers before they start to drink. Two studies showed that after consumption of small quantities of alcohol (up to about three glasses) there is a temporary increase in the attention bias and the desire for alcohol. After drinking very large quantities of alcohol, particularly the desire for alcohol becomes bigger, while the attention bias decreases and seems to no longer play a role. The researchers have developed a treatment (‘attention training’) that cures heavy drinkers and alcohol addicts of the attention bias. After this attention training, the addicts could leave the alcohol rehabilitation centre earlier and relapsed less quickly into their alcohol abuse. 

Key words:

alcohol, addiction, treatment

“Algorithmic Pricing”

Algorithmic pricing is the study in which the computational problem is considered that a company faces when trying to set prices for their items to maximize the revenue, knowing the preferences of the potential customers. In this thesis, two different algorithmic pricing problems are considered, namely single item pricing and affine pricing. First, we address the question how difficult the problems are. Then, we show how to actually tackle the problems. We describe practical settings in which the problems can be applied, and next to the theoretical results, we conduct several computational studies.

Key words:

Algorithmic pricing, revenue maximization, computational complexity, approximation algorithm

“3D dose verification for advanced radiotherapy”

The objective of radiotherapy is to give the tumour a high dose of radiation, sparing the healthy tissues and organs as much as possible. This requires a precise dosimetric and geometric design of the treatment plan. In this dissertation models were developed and procedures were described that give information about the dose emission, both before and during the treatment. This information can be converted into a three-dimensional (3D) image so that the information about the distribution of the dose of radiation in the patient’s body is visible. 3D-dose verification strategies are applied as a quality guarantee in a test irradiation prior to the treatment and during the treatment (in vivo dosimetrics). This dissertation studies both strategies and indicates how these advanced models can be implemented in a radiotherapy treatment. 

Key words:

radiotherapy, dose of radiation, 3D

“Online Consumer-to-Consumer Communication Networks; an economic exploration of their formation and value”

​Online Consumer-to-Consumer Communication Networks are characterized by informational and social benefits as well as time and effort costs for participants. Therefore, this dissertation takes an economic perspective on the network formation process as a determinant of value for consumers and indirectly for firms. Since in participants’ linking choices also others’ choices play a role, a game-theoretic model is introduced. It predicts which structures emerge dependent on manipulable properties, like the relative importance that is attached to informative versus social value and the presence or absence of a highly valued expert. Also the complexity of the setting can influence consumers’ decisions for certain links. Lab experiments show how people systematically simplify more complex value components, e.g., disregard what they receive from indirect neighbors and what they generate for others.

Key words:

Consumers, communication, network formation, virtual communities, decision making, game theory, lab experiments

“Excessive alcohol use in youth on holiday; an evaluation of two intervention methods”

Young people on vacation drink large quantities of alcohol which results in various health risks.  This research tests two possible strategies for pushing back this alcohol use: Community Intervention (CI) and Expectancy Challenge (EC). The first focuses on reducing the alcohol use by making alcohol less available to young people (for example by enforcing age limits). The second tries to reduce alcohol use by changing the expectations of young people with regard to the effects of alcohol. The EC had no influence on the alcohol use of young people on vacation. The CI must be further optimized before statements can be made about the effect on alcohol use. 

Key words:

alcohol use young people; alcohol use vacation; intervention alcohol use; age limits alcohol use

“The systematic recruitment of new blood donors”

This dissertation describes a series of studies in the field of donor recruitment. Three studies revealed the main determinants of blood donation, among others the expectation of fear and pain, reactions from others, sense of responsibility. Based on this, two research Lines were set up. The recruitment folder appeared to be mainly focused on knowledge transfer. The content was improved by adding determinant-relevant information. Subsequently, a donor-recruits-donor folder and postcards were developed and evaluated. The field study showed that this campaign is an effective way of recruiting new donors. 

Key words:

blood donation; donor recruitment; donation determinants

“Uitgelezen variatie” (‘Exquisite variation’)

“De oorlog van Bastiaans; de LSD-behandeling van het KZ-syndroom”

Prof. Dr. Jan Bastiaans (1917-1997) was one of the most influential and renowned psychiatrist in the post-war Netherlands. He was especially known for his LSD treatment of a special group of patients: the survivors of the German concentration and extermination camps. With a forceful political lobby, emotional blackmail and even threats Bastiaans and his adherents fought for the salvation of his method. How was it possible that ‘papa Bas’ continued his controversial method for such a long time?

In ‘De oorlog van Bastiaans’, psychologist Bram Enning describes the battle of Bastiaans and his patients by means of portraits of patients and developments in science and society. 

Key words:

psychiatry, Holocaust, therapy

“Arginine biosynthesis in organ development and function”

“Exploring the Design, Planning and Control of Mental Health Care Services”

“Vascular cognitive impairment and cholinergic function: an integrative analysis in rat brain”

After a cerebral infarction, many people suffer from cognitive complaints such as mental slowness and concentration problems. These complaints are probably caused by disorders in a specific nervous system of the brains: the cholinergic function. This dissertation shows that a part of the cognitive complaints after a cerebral infarction can be imitated in test animals. Furthermore, this research describes an MRI-technique that can visualize this specific nervous system in the brains of living test animals. In the future, this new imaging technique can possibly be used as a tool in diagnostics and treatment of people with cognitive complaints after a cerebral infarction. 

Key words:

cerebral infarction; cholinergic function; cognitive complaints

“Multidisciplinary approach to locally advanced and recurrent rectal cancer”

In the Netherlands, around 10.000 people per year get large intestine/rectal cancer. About 50% die of the disease. This dissertation provides new insights in the image and treatment of rectal cancer and it indicates how different disciplines such as radiology, surgery, radiotherapy, oncology, pathology and molecular biology can provide important information so that a patient with rectal cancer can be treated as optimally as possible. The treatment becomes increasingly patient-specific, so that an optimal balance is found between good oncologic result and a minimum of treatment-related disease rates.  A radical resection (operative tissue removal) turns out to be the main factor for survival. Radicality depends on preliminary treatment with chemo- and radiotherapy and of the location of the tumour. Furthermore it turned out that magnetic resonance imaging (MRI) is a good predictor of the extent of tumour growth. The extensiveness of operation can be adjusted to this. Pathological factors can well predict which patients run an increased risk of a recrudescence of their tumour.  

Key words:

rectal cancer; patient treatment; interdisciplinary patient information

“MRI in Rectal Cancer; prediction of the risk factors for a local recurrence”

Each year, there are over 7500 new cases of rectal cancer in the Netherlands. The rectum carcinoma shows, besides the risk of metastases, a risk of 3 % to 32 % of relapse.   Optimal surgical techniques and radio-chemotherapy have led to a better control of relapse. The two main risk factors for relapse are the local extent of the tumour and the lymph node status. A study with 296 patients (both in an expert centre and in regional hospitals) shows the high precision of MRI with the use of Sinerem for predicting both factors. This makes it possible to differentiate preoperative therapies and to create an alternative for the standard protocol of preoperative radiotherapy. In the low-risk groups preoperative radiotherapy can be avoided, in high-risk groups a more aggressive therapy can be applied.

Key words:

rectum carcinoma; rectal cancer; local relapse; preoperative therapy; MRI; Sinerem;

“MRI-based Tailored Treatment of Rectal Cancer: impact on surgical outcome”

“Wie kust doornroosje wakker?” (‘Who kisses sleeping beauty awake?’)