The immune compartment at the maternal-fetal interface throughout human pregnancy

During pregnancy a unique situation arises in which the mother's immune system accepts the fetus, which carries both maternal and paternal genes, and does not reject it as can occur in solid organ transplantation. The aim of this dissertation was to unravel the immunological mechanisms that ensure tolerance during a healthy pregnancy and uncover how alterations could contribute to the development of pregnancy complications, such as pre-eclampsia and preterm birth.We applied the new technique mass cytometry and the associated computational analyzes to map all immune cells of the mother during a healthy pregnancy. Furthermore, we demonstrated the presence of three types of functional regulatory CD4+ T cells, identified a phenotype of CD8+ T cells that can offer both tolerance and immunity against infections, and demonstrated potential cross-reactivity of T cells against fetal allo-antigens. The results described in this thesis have contributed to a better understanding of healthy pregnancies and form a basis on which further research can be built.LUMC / Geneeskund

Strategies to control the spectral properties of Au-Ni thin films

Gold and nickel have quite different dielectric functions. Here we use a combination of calculation and sample manufacture to assess two strategies by which thin films of these elements can be produced with a controlled range of far-field optical properties. In the first approach, control can be achieved by manipulating the density of states of metastable solid solutions, which in turn controls the dielectric function. In the second approach the optical properties of the films are controlled by varying the geometry of stacks fabricated from the constituent elements. We show that the two approaches can produce equivalent results so both are viable options in practice. Modeling is used to reveal how the structure controls the optical properties and to map out the possible color gamut. Predictions are tested with thin film samples fabricated by magnetron sputtering. © 2013 Elsevier B.V

On the Role of Penning Ionization in Photoassociation Spectroscopy

We study the role of Penning ionization on the photoassociation spectra of He(^3S)-He(^3S). The experimental setup is discussed and experimental results for different intensities of the probe laser are shown. For modelling the experimental results we consider coupled-channel calculations of the crossing of the ground state with the excited state at the Condon point. The coupled-channel calculations are first applied to model systems, where we consider two coupled channels without ionization, two coupled channels with ionization, and three coupled channels, for which only one of the excited states is ionizing. Finally, coupled-channel calculations are applied to photoassociation of He(^3S)-He(^3S) and good agreement is obtained between the model and the experimental results.Comment: 14 pages, 18 figures, submitted to the special issue on Cold Molecules of J. Phys.

Climate model boundary conditions for four Cretaceous time slices

International audienceGeneral circulation models (GCMs) are useful tools for investigating the characteristics and dynamics of past climates. Understanding of past climates contributes significantly to our overall understanding of Earth's climate system. One of the most time consuming, and often daunting, tasks facing the paleoclimate modeler, particularly those without a geological background, is the production of surface boundary conditions for past time periods. These boundary conditions consist of, at a minimum, continental configurations derived from plate tectonic modeling, topography, bathymetry, and a vegetation distribution. Typically, each researcher develops a unique set of boundary conditions for use in their simulations. Thus, unlike simulations of modern climate, basic assumptions in paleo surface boundary conditions can vary from researcher to researcher. This makes comparisons between results from multiple researchers difficult and, thus, hinders the integration of studies across the broader community. Unless special changes to surface conditions are warranted, researcher dependent boundary conditions are not the most efficient way to proceed in paleoclimate investigations. Here we present surface boundary conditions (land-sea distribution, paleotopography, paleobathymetry, and paleovegetation distribution) for four Cretaceous time slices (120 Ma, 110 Ma, 90 Ma, and 70 Ma). These boundary conditions are modified from base datasets to be appropriate for incorporation into numerical studies of Earth's climate and are available in NetCDF format upon request from the lead author. The land-sea distribution, bathymetry, and topography are based on the 1°×1° (latitude × longitude) paleo Digital Elevation Models (paleoDEMs) of Christopher Scotese. Those paleoDEMs were adjusted using the paleogeographical reconstructions of Ronald Blakey (Northern Arizona University) and published literature and were then modified for use in GCMs. The paleovegetation distribution is based on published data and reconstructions and consultation with members of the paleobotanical community and is represented as generalized biomes that should be easily translatable to many vegetation-modeling schemes

Hydrodynamic fluctuations in the Kolmogorov flow: Linear regime

The Landau-Lifshitz fluctuating hydrodynamics is used to study the statistical properties of the linearized Kolmogorov flow. The relative simplicity of this flow allows a detailed analysis of the fluctuation spectrum from near equilibrium regime up to the vicinity of the first convective instability threshold. It is shown that in the long time limit the flow behaves as an incompressible fluid, regardless of the value of the Reynolds number. This is not the case for the short time behavior where the incompressibility assumption leads in general to a wrong form of the static correlation functions, except near the instability threshold. The theoretical predictions are confirmed by numerical simulations of the full nonlinear fluctuating hydrodynamic equations.Comment: 20 pages, 4 figure

Investigating digital video applications in distance learning

The paper gives a brief overview of the use of digital video in distance education, the background to The Open University's Digital Video Applications (DiVA) Project, the contexts in which the Digital Video Library system is being used and some evaluation findings. Through DiVA, the university is investigating how it can use its video assets effectively, to support reuse of existing materials in course production. The project team is also evaluating student use of the system. The paper reports on an observation study which revealed several usability issues and stakeholders' opinions about potential uses of the DiVA system. This is followed by findings from an evaluation of student use of the system at a residential school and its use as part of an online learning activity undertaken by students accessing the system remotely. Evaluation findings to date indicate some quality and workload issues but they also show opportunities that come to light when using the DiVA system