University of Hamburg

About: University of Hamburg is a education organization based out in Hamburg, Germany. It is known for research contribution in the topics: Population & Laser. The organization has 45564 authors who have published 89286 publications receiving 2850161 citations. The organization is also known as: Hamburg University.

Molecular subgroups of medulloblastoma: an international meta-analysis of transcriptome, genetic aberrations, and clinical data of WNT, SHH, Group 3, and Group 4 medulloblastomas

Abstract: Medulloblastoma is the most common malignant brain tumor in childhood. Molecular studies from several groups around the world demonstrated that medulloblastoma is not one disease but comprises a collection of distinct molecular subgroups. However, all these studies reported on different numbers of subgroups. The current consensus is that there are only four core subgroups, which should be termed WNT, SHH, Group 3 and Group 4. Based on this, we performed a meta-analysis of all molecular and clinical data of 550 medulloblastomas brought together from seven independent studies. All cases were analyzed by gene expression profiling and for most cases SNP or array-CGH data were available. Data are presented for all medulloblastomas together and for each subgroup separately. For validation purposes, we compared the results of this meta-analysis with another large medulloblastoma cohort (n = 402) for which subgroup information was obtained by immunohistochemistry. Results from both cohorts are highly similar and show how distinct the molecular subtypes are with respect to their transcriptome, DNA copy-number aberrations, demographics, and survival. Results from these analyses will form the basis for prospective multi-center studies and will have an impact on how the different subgroups of medulloblastoma will be treated in the future.

The diagnosis of thoracic aortic dissection by noninvasive imaging procedures.

Abstract: Background and Methods This study was designed to assess the safety and reliability of new noninvasive imaging methods as compared with aortography in the diagnosis of dissection of the thoracic aorta. One hundred ten patients with clinically suspected aortic dissection followed a diagnostic protocol that included transthoracic and transesophageal color-flow Doppler echocardiography (TTE and TEE), contrast-enhanced x-ray computed tomography (CT), and magnetic resonance imaging (MRI). Imaging results were compared in a blinded fashion and validated independently against intraoperative findings in 62 patients, autopsy findings in 7, and the results of contrast angiography in 64. Results The sensitivities of MRI, TEE and x-ray CT for detecting dissection were similar, at 98.3, 97.7, and 93.8 percent, respectively; TTE had a sensitivity of only 59.3 percent (P<0.005). The specificities of both TTE (83.0 percent) and TEE (76.9 percent) were lower than those of x-ray CT (87.1 percent) and MRI (97.8 percent; P<0...

Electron spectroscopies for Ce compounds in the impurity model

Abstract: We present a method for calculating the core-level x-ray photoemission (XPS), the $3d\ensuremath{\rightarrow}4f$ x-ray absorption (XAS), the valence photoemission, and the bremsstrahlung isochromat spectra in a slightly modified Anderson impurity model of a Ce compound at zero temperature. Both the spin and orbital degeneracies of the $f$ level are included and the Coulomb interaction between the $f$ electrons is taken into account. The spectra are expressed in terms of a resolvent operator. A many-electron basis set is introduced, and the resolvent is obtained from a matrix inversion. The particular form of the Anderson model allows us to find a small but sufficiently complete basis set, if the degeneracy ${N}_{f}$ of the $f$ level is large. In particular, we consider the limit ${N}_{f}\ensuremath{\rightarrow}\ensuremath{\infty}$, and show that the method is exact for the XPS, XAS, and valence photoemission spectra in this limit. It is also demonstrated that for ${N}_{f}\ensuremath{\gtrsim}6$, the method provides accurate spectra. Analytical results are obtained for the valence photoemission spectrum ${\ensuremath{\rho}}_{v}(\ensuremath{\epsilon})$. The spectrum has a sharp rise close to the Fermi energy ${\ensuremath{\epsilon}}_{F}$, which goes over to a "Kondo peak" in the spin-fluctuation limit. An exact relation between ${\ensuremath{\rho}}_{v}({\ensuremath{\epsilon}}_{F})$ and the $f$-level occupancy ${n}_{f}$ is shown to be satisfied to within 10% for ${N}_{f}\ensuremath{\ge}6$. We discuss how core-level XPS spectra can be used to estimate the $f$-level occupancy ${n}_{f}$ and the coupling $\ensuremath{\Delta}$ between the $f$ level and the conduction states. We find that the values of ${n}_{f}$ and $\ensuremath{\Delta}$ obtained from core-level XPS are basically consistent with the other spectroscopies and the static, $T=0$ susceptibility. It is, therefore, possible to describe these experiments in the Anderson model, using essentially the same set of parameters for all the experiments. Typically, we find ${n}_{f}g0.7$ and $\ensuremath{\Delta}\ensuremath{\sim}0.1$ eV.

Temperature- and light-responsive smart polymer materials

Abstract: Stimuli-responsive polymers have been attracting great interest within the scientific community for several decades. The unique feature to respond to small changes in the environmental conditions has made this class of materials very promising for several applications in the field of nanoscience, nanotechnology and nanomedicine. So far, several different chemical, physical or biochemical stimuli have been investigated within natural or synthetic polymers. Very interesting and appealing seems to be the combination of several stimuli to tune the properties of these materials in manifold ways. Within this present review, we want to highlight the recent progress in the field of synthetic stimuli-responsive polymers combining temperature and light responsiveness.