Hadron Structure in the Non-Perturbative Regime of QCD: Isospin Symmetry and its Violation

I discuss recent progress made in calculating electromagnetic corrections in the framework of the effective field theory of QCD. In the case of elastic pion-pion scattering, strong interaction predictions have been worked out to two loop accuracy. I present first results for the electromagnetic corrections in the case of neutral pions. Here, the only sizeable effect comes from the charged to neutral pion mass difference. In the presence of nucleons, isospin violation can be measured in threshold pion photoproduction. I review the present status of the theoretical predictions and the experimental data. I argue that a deeper understanding of isospin violation based on a more precise study of such reactions can be achieved.Comment: 10 pp, LaTeX file, 3 figures, uses espcrc1.sty and epsf, plenary talk, QULEN '97, Osaka, May 1997, to be published in the proceeding

Intravitreal S100B Injection Leads to Progressive Glaucoma Like Damage in Retina and Optic Nerve

The glial protein S100B, which belongs to a calcium binding protein family, is up-regulated in neurological diseases, like multiple sclerosis or glaucoma. In previous studies, S100B immunization led to retinal ganglion cell (RGC) loss in an experimental autoimmune glaucoma (EAG) model. Now, the direct degenerative impact of S100B on the retina and optic nerve was evaluated. Therefore, 2 μl of S100B was intravitreally injected in two concentrations (0.2 and 0.5 μg/μl). At day 3, 14 and 21, retinal neurons, such as RGCs, amacrine and bipolar cells, as well as apoptotic mechanisms were analyzed. Furthermore, neurofilaments, myelin fibers and axons of optic nerves were evaluated. In addition, retinal function and immunoglobulin G (IgG) level in the serum were measured. At day 3, RGCs were unaffected in the S100B groups, when compared to the PBS group. Later, at days 14 and 21, the RGC number as well as the β-III tubulin protein level was reduced in the S100B groups. Only at day 14, active apoptotic mechanisms were noted. The number of amacrine cells was first affected at day 21, while the bipolar cell amount remained comparable to the PBS group. Also, the optic nerve neurofilament structure was damaged from day 3 on. At day 14, numerous swollen axons were observed. The intraocular injection of S100B is a new model for a glaucoma like degeneration. Although the application site was the eye, the optic nerve degenerated first, already at day 3. From day 14 on, retinal damage and loss of function was noted. The RGCs in the middle part of the retina were first affected. At day 21, the damage expanded and RGCs had degenerated in all areas of the retina as well as amacrine cells. Furthermore, elevated IgG levels in the serum were measured at day 21, which could be a sign of a late and S100B independet immune response. In summary, S100B had a direct destroying impact on the axons of the optic nerve. The damage of the retinal cell bodies seems to be a consequence of this axon loss

Analyse der S100B-vermittelten degenerativen Prozesse in Retina und Sehnerv nach intraokulärer Injektion im Tiermodell

Das Glaukom ist eine neurodegenerative Erkrankung des Auges mit einem progredienten Verlust von retinalen Ganglienzellen und Axonen. In dem Promotionsvorhaben geht es um die Etablierung eines neuen Normaldruckglaukom-Modells durch die intraokuläre Injektion des Proteins S100B. Hierbei wurden verschiedene Konzentrationen des Proteins S100B verwendet. Die intraokuläre Injektion von S100B bedingt eine zeitabhängige, aber konzentrationsunabhängige Degeneration retinaler Ganglienzellen, welche mit einer erhöhten apoptotischen Aktivität in den retinalen Ganglienzellen assoziiert ist. Gleichzeitig kommt es zu einer ebenfalls im Zeitverlauf progredienten und konzentrationsunabhängigen Degeneration der Neurofilamente. Die neuroretinale Infiltration aktivierter Mikrogliazellen bei koinzidenter Degeneration von Retina und Sehnerv ist hinweisend auf die Wirkung von S100B als Mediator

Towards attosecond imaging at the nanoscale using broadband holography-assisted coherent imaging in the extreme ultraviolet

In recent years nanoscale coherent imaging has emerged as an indispensable imaging modality allowing to surpass the resolution limit given by classical imaging optics. At the same time, attosecond science has experienced enormous progress and has revealed the ultrafast dynamics in atoms, molecules, and complex materials. Combining attosecond temporal resolution of pump-probe experiments with nanometer spatial resolution would allow studying ultrafast dynamics on the smallest spatio-temporal scales but has not been demonstrated yet. Unfortunately, the large bandwidth of attosecond pulses usually hinders high-resolution coherent imaging. Here we present a robust holography-enhanced coherent imaging method, which allows combining high quality and high spatial resolution coherent imaging with a large spectral bandwidth. By implementing our method at a high harmonic source we demonstrate, for the first time, a spatial resolution of 34 nm (2.5 {\lambda}) in combination with a spectral bandwidth supporting a Fourier limited pulse duration of only 380 as. The method is single-shot capable, additionally retrieves the spectrum from the measured diffraction pattern, and is thus immune against shot-to-shot fluctuations. This paves the way for an ultrafast view on nanoscale dynamics e.g. ultrafast charge transfer or ultrafast spin currents being relevant for Petahertz electronics and future data storage