Elevated central serotonin levels inhibit emotional crying

Previous research has suggested a possible role of serotonin in emotional expressions, such as crying. We have found that a transient increase of central serotonin levels by means of oral administration of paroxetine reduces crying in response to emotional movies in healthy female volunteers. This is the first direct evidence of an important role of serotonin in this uniquely human emotional response

Control of repair activities at DNA double strand breaks and telomeres

The DNA in our cells, storing the information that every cell needs to perform its specific function, needs to be carefully protected. Various sources, both externally and from inside the cell, constantly threaten the integrity of the DNA, causing DNA damage. DNA double strand breaks (DSBs) are the most detrimental to the cell, and lack of repair, or incorrect repair of such breaks can lead to cell death. Moreover, incorrect repair can introduce errors in the DNA such as mutations or chromosomal rearrangements, resulting in genomic instability which can eventually contribute to the development of cancer. Cells have therefore developed mechanisms that detect the damage and ensure rapid and correct DNA repair, and this is collectively referred to as the ‘DNA damage response’. Importantly, the ends of natural chromosomes resemble DSBs, but repair activities at chromosome-ends would have severe consequences for genome integrity. The ends of chromosomes are therefore protected by specialized structures known as telomeres. The aim of this thesis is to increase our understanding of how repair activities at DSBs and telomeres are controlled. For this we used various methods aiming at identifying novel proteins that act in the DNA damage response and mechanistically understand their function

The Soft Molecular Landing Machine:Ultra-High Vacuum Deposition of Non-Volatile Solution-Processable Organic Materials and Polymers

In de zoektocht naar geschikte materialen voor organische zonnecellen is het belangrijk om de materialen op een juiste manier te kunnen bestuderen. Veel van de materialen voor organische zonnecellen zijn oplosbaar in oplosmiddelen en niet goed naar de gasfase te brengen. Om de eigenschappen van deze materialen goed te kunnen meten hebben we schone lagen nodig van de materialen, zonder vervuilingen. In dit proefschrift beschrijven wij de bouw van een vacuümdepositie machine, welke ons de mogelijkheid geeft om deze schone lagen te vormen en de metingen te verrichten. De nieuwgebouwde machine stelt ons in staat om de zonnecellen laag voor laag op te bouwen binnen een vacuümkamer, waardoor er geen vervuilingen in de lagen komen. Naast het meten van de eigenschappen van de pure materialen, kunnen we hiermee ook goed de grenslagen tussen verschillende materialen bestuderen, waar interessante fysica plaatsvindt. De metingen die we verrichten op deze lagen gebeuren tevens binnen dezelfde vacuümmachine. We brengen de gewenste materialen in de gasfase in de vorm van een moleculaire bundel door middel van een proces dat electrospray genoemd wordt.In dit proefschrift beschrijven we de bouw van de machine, de karakterisering van de moleculaire bundels die in de machine gevormd worden, en eerste metingen die laten zien dat de machine inderdaad lagen vormt van de gewenste materialen; fullerenen en polymeren. Door een beter begrip te krijgen van de processen die zich in een organische zonnecel voltrekken kunnen we organische zonnecellen maken met hogere efficiëntie.In the search for suitable materials for organic photovoltaics, it is important to be able to study those materials in the correct way. Many of the materials for organic photovoltaics are solution processable and not easy brought into the gas phase. In order to study the properties of these materials well, we need to be able to form clean layers, without contaminations. In this thesis, we describe the construction of a vacuum deposition machine, which enables us to create these layers and perform the measurements. The newly build machine allows us to build the solar cells layer-by-layer within a single vacuum machine, which drastically reduces the amount of contamination in the cells. In addition to being able to measure the pure materials, we can also study the interfaces between the various materials in the cell, where interesting physics happens. Even the measurements are performed within the same vacuum system. The materials we want to study are brought into the gas phase and form a molecular beam through a process called electrospray.In this thesis, we describe the design of this new machine, the characterisation of the molecular beams formed within the machine, and measurements that show that the machine does indeed form layers of our desired materials. The machine was shown be able to deposit both fullerene molecules and polymers. By gaining a better understanding of the processes within an organic solar cell, it will be possible to develop organic solar cells with higher power conversion efficiencies