Boosting regulatory T cell function by CD4 stimulation enters the clinic

Understanding tolerance mechanisms at the cellular and molecular level holds the promise to establish novel immune intervention therapies in patients with allergy or autoimmunity and to prevent transplant rejection. Administration of mAb against the CD4 molecule has been found to be exceptionally well suited for intentional tolerance induction in rodent and non-human primate models as well as in humanized mouse models. Recent evidence demonstrated that regulatory T cells (Treg) are directly activated by non-depleting CD4 ligands and suggests Treg activation as a central mechanism in anti-CD4-mediated tolerance induction. This review summarizes the current knowledge on the role of Treg in peripheral tolerance, addresses the putative mechanisms of Treg-mediated suppression and discusses the clinical potential of harnessing Treg suppressive activity through CD4 stimulation

Canonical curves, scrolls and K3 surfaces

In this thesis we study minimal free resolutions of canonical curves C as well as so-called relative canonical resolutions of canonical curves inside scrolls swept out by a pencil of divisors on C. For general 5-gonal canonical curves we will show that all bundles in the relative canonical resolution are balanced. Furthermore, we will give a necessary and sufficient criterion for balancedness of the first syzygy bundle appearing in the relative canonical resolution of Brill-Noether general curves. For general genus 9 curves we will relate the unbalancedness of the second syzygy bundle to the existence of certain K3 surfaces of higher Picard rank which contain the curves. This yields an unirationality result for certain moduli spaces of lattice polarized K3 surfaces. Another subject of this thesis is the study of the homologies occurring in a linearized free resolution of (k-gonal) canonical curves. Based on computer algebra experiments we will also suggest a refinement of the classical Green-conjecture, which conjecturally also holds in positive characteristic.In dieser Arbeit studieren wir minimale freie Auflösungen von kanonischen Kurven C und sogenannte relative kanonische Auflösungen von kanonischen Kurven auf rationalen Regelvarietäten, die von einem Büschel von Divisoren auf C ausgeschnitten werden. Für eine allgemeine 5-gonale kanonische Kurve zeigen wir, dass alle Bündel in der relativen kanonischen Auflösung balanciert sind. Des Weiteren geben wir ein notwendiges und hinreichendes Kriterium für die Balanciertheit des ersten Syzgygienbündel in der relativen kanonischen Auflösung für Brill-Noether allgemeine Kurven an. Für Geschlecht 9 Kurven setzen wir die Unbalanciertheit des zweiten Syzygienbündels mit der Existenz von K3 Flächen von höherem Picardrang, welche die Kurve enthalten, in Verbindung. Dies führt zu Unirationalitätsresultaten für bestimmte Modulräume von gitterpolarisierten K3 Flächen. Ein weiteres Thema dieser Arbeit ist das Studium der Homologien in linearisierten freien Auflösungen von (k-gonalen) kanonischen Kurven. Auf Grund von Computeralgebra experimenten werden wir zudem eine Erweiterung der klassischen Greenschen Vermutung vorschlagen, welche mutmaßlich auch in positiver Charakteristik gilt

A 3-D Projection Model for X-ray Dark-field Imaging

Talbot-Lau X-ray phase-contrast imaging is a novel imaging modality, which provides not only an X-ray absorption image, but also additionally a differential phase image and a dark-field image. The dark-field image is related to small angle scattering and has an interesting property when canning oriented structures: the recorded signal depends on the relative orientation of the structure in the imaging system. Exactly this property allows to draw conclusions about the orientation and to reconstruct the structure. However, the reconstruction is a complex, non-trivial challenge. A lot of research was conducted towards this goal in the last years and several reconstruction algorithms were proposed. A key step of the reconstruction algorithm is the inversion of a forward projection model. Up until now, only 2-D projection models are available, with effectively limit the scanning trajectory to a 2-D plane. To obtain true 3-D information, this limitation requires to combine several 2-D scans, which leads to quite complex, impractical acquisitions schemes. Furthermore, it is not possible with these models to use 3-D trajectories that might allow simpler protocols, like for example a helical trajectory. To address these limitations, we propose in this work a very general 3-D projection model. Our projection model defines the dark-field signal dependent on an arbitrarily chosen ray and sensitivity direction. We derive the projection model under the assumption that the observed scatter distribution has a Gaussian shape. We theoretically show the consistency of our model with more constrained existing 2-D models. Furthermore, we experimentally show the compatibility of our model with dark-field measurements of two matchsticks. We believe that this 3-D projection model is an important step towards more flexible trajectories and imaging protocols that are much better applicable in practice.Comment: Shiyang Hu and Lina Felsner contributed equally to this wor

Evaluation of Methods for Semantic Segmentation of Endoscopic Images

We examined multiple semantic segmentation methods, which consider the information contained in endoscopic images at different levels of abstraction in order to predict semantic segmentation masks. These segmentations can be used to obtain position information of surgical instruments in endoscopic images, which is the foundation for many computer assisted systems, such as automatic instrument tracking systems. The methods in this paper were examined and compared in regard to their accuracy, effort to create the data set, and inference time. Of all the investigated approaches, the LinkNet34 encoder-decoder network scored best, achieving an Intersection over Union score of 0.838 with an inference time of 30.25 ms on a 640 x 480 pixel input image with a NVIDIA GTX 1070Ti GPU