Charmed Meson Production in Deep Inelastic Scattering

Charmed meson production in semi-inclusive deep inelastic scattering is investigated in the color dipole formalism. The transverse momentum distributions are calculated. We find good agreement with the H1 data using a hard fragmentation function.Comment: 24 pages, 10 figure

Critical adsorption on curved objects

A systematic fieldtheoretic description of critical adsorption on curved objects such as spherical or rodlike colloidal particles immersed in a fluid near criticality is presented. The temperature dependence of the corresponding order parameter profiles and of the excess adsorption are calculated explicitly. Critical adsorption on elongated rods is substantially more pronounced than on spherical particles. It turns out that, within the context of critical phenomena in confined geometries, critical adsorption on a microscopically thin `needle' represents a distinct universality class of its own. Under favorable conditions the results are relevant for the flocculation of colloidal particles.Comment: 52 pages, 10 figure

Critical adsorption near edges

Symmetry breaking surface fields give rise to nontrivial and long-ranged order parameter profiles for critical systems such as fluids, alloys or magnets confined to wedges. We discuss the properties of the corresponding universal scaling functions of the order parameter profile and the two-point correlation function and determine the critical exponents eta_parallel and eta_perpendicular for the so-called normal transition.Comment: 22 pages, 5 figures, accepted for publication in PR

Antiprogestins reduce epigenetic field cancerization in breast tissue of young healthy women

Background: Breast cancer is a leading cause of death in premenopausal women. Progesterone drives expansion of luminal progenitor cells, leading to the development of poor-prognostic breast cancers. However, it is not known if antagonising progesterone can prevent breast cancers in humans. We suggest that targeting progesterone signalling could be a means of reducing features which are known to promote breast cancer formation. Methods: In healthy premenopausal women with and without a BRCA mutation we studied (i) estrogen and progesterone levels in saliva over an entire menstrual cycle (n = 20); (ii) cancer-free normal breast-tissue from a control population who had no family or personal history of breast cancer and equivalently from BRCA1/2 mutation carriers (n = 28); triple negative breast cancer (TNBC) biopsies and healthy breast tissue taken from sites surrounding the TNBC in the same individuals (n = 14); and biopsies of ER+ve/PR+ve stage T1–T2 cancers and healthy breast tissue taken from sites surrounding the cancer in the same individuals (n = 31); and (iii) DNA methylation and DNA mutations in normal breast tissue (before and after treatment) from clinical trials that assessed the potential preventative effects of vitamins and antiprogestins (mifepristone and ulipristal acetate; n = 44). Results: Daily levels of progesterone were higher throughout the menstrual cycle of BRCA1/2 mutation carriers, raising the prospect of targeting progesterone signalling as a means of cancer risk reduction in this population. Furthermore, breast field cancerization DNA methylation signatures reflective of (i) the mitotic age of normal breast epithelium and (ii) the proportion of luminal progenitor cells were increased in breast cancers, indicating that luminal progenitor cells with elevated replicative age are more prone to malignant transformation. The progesterone receptor antagonist mifepristone reduced both the mitotic age and the proportion of luminal progenitor cells in normal breast tissue of all control women and in 64% of BRCA1/2 mutation carriers. These findings were validated by an alternate progesterone receptor antagonist, ulipristal acetate, which yielded similar results. Importantly, mifepristone reduced both the TP53 mutation frequency as well as the number of TP53 mutations in mitotic-age-responders. Conclusions: These data support the potential usage of antiprogestins for primary prevention of poor-prognostic breast cancers

6-Phosphofructo-2-kinase/fructose-2,6-biphosphatase 4 is essential for p53-null cancer cells.

The bifunctional enzyme 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase-4 (PFKFB4) controls metabolic flux through allosteric regulation of glycolysis. Here we show that p53 regulates the expression of PFKFB4 and that p53-deficient cancer cells are highly dependent on the function of this enzyme. We found that p53 downregulates PFKFB4 expression by binding to its promoter and mediating transcriptional repression via histone deacetylases. Depletion of PFKFB4 from p53-deficient cancer cells increased levels of the allosteric regulator fructose-2,6-bisphosphate, leading to increased glycolytic activity but decreased routing of metabolites through the oxidative arm of the pentose-phosphate pathway. PFKFB4 was also required to support the synthesis and regeneration of nicotinamide adenine dinucleotide phosphate (NADPH) in p53-deficient cancer cells. Moreover, depletion of PFKFB4-attenuated cellular biosynthetic activity and resulted in the accumulation of reactive oxygen species and cell death in the absence of p53. Finally, silencing of PFKFB4-induced apoptosis in p53-deficient cancer cells in vivo and interfered with tumour growth. These results demonstrate that PFKFB4 is essential to support anabolic metabolism in p53-deficient cancer cells and suggest that inhibition of PFKFB4 could be an effective strategy for cancer treatment.Cancer Research UK; German Cancer Aid (grant 111917); German Research Foundation (FOR 2314); CRUK-EPSRC Imaging Centre in Cambridge and Manchester (grant 16465

The potential of bamboo corals to record environmental conditions in their calcitic skeletons

The ocean’s physicochemical variability is not well understood despite its importance for the world’s climate because of rare instrumental time series. This issue can be resolved through natural archives that recorded past environmental conditions such as corals. Bamboo corals, thriving in water depths down to 4000 m, offer the potential to record environmental parameters over a wide range of oceanic conditions. This dissertation provides a detailed look into the chemical composition of bamboo coral skeletons to distinguish between environmental and biomineralisation controls over the skeletal composition. The ability of bamboo corals to record seawater temperature and nutrient availability was investigated by measuring the distribution of Mg and Ba, respectively, in the internode of an Atlantic specimen. The mean Mg/Ca composition of a bamboo coral can be used to reconstruct the ambient seawater temperature while mean Ba/Ca was found to record [Ba]SW. Conversely, the micron-scale skeletal Mg and Ba composition is strongly impacted by coral physiology. The use of skeletal Na and S concentrations as environmental proxies in marine calcifiers is debated and was therefore evaluated in two Atlantic bamboo corals. The microscale distribution of Na and S can show a concentric structure and zig zag patterns as found for Mg. The heterogeneity indicates a main control of the coral physiology over the skeletal composition. The B elemental as well as its isotopic composition in calcium carbonates have been used to study the ambient pH of the corals’ calcifying fluid (CF). The B/C and B isotopic spatial distribution in an Atlantic and a Pacific bamboo coral were measured in the bulk internode material and the purified calcite fraction. Our results suggest that besides CF pH, the skeletal boron isotopic composition of bamboo corals might be influenced by isotopically light borate influx to the CF, organic matter induced isotope fractionation or kinetic isotope effects

Strahlcharakterisierung von Freie-Elektronen-Lasern im weichen R\"{o}ntgen-Spektralbereich

Softcover, 17x24In den letzten Jahren haben mehrere Freie-Elektronen-Laser (FEL) im Röntgen-Spektralbereich den Nutzerbetrieb aufgenommen. Sie erzeugen 10-100 Femtosekunden lange Pulse mit hohem transversalen Kohärenzgrad und schmalbandigem Frequenzspektrum und erreichen gegenüber einfacher Undulatorstrahlung eine etwa zehn Größenordnungen höhere Spitzenbrillanz. Ein Hartmann-Wellenfrontsensor wurde für den EUV- und weichen Röntgen-Spektralbereich entwickelt, der bezogen auf die Wellenfrontrauigkeit wrms im Einzelpuls bei der Wellenlänge λ=13nm die Wiederholgenauigkeit λ/116 erreicht und an den Freie-Elektronen- Lasern FLASH in Hamburg und LCLS in Stanford zur Wellenfrontmessung und Strahlcharakterisierung eingesetzt wurde. Es wurden typische, durch den SASE- Erzeugungsprozess der Strahlung bedingte Schwankungen des Strahldurchmessers, der Strahllage und der Intensität festgestellt. Die Strahlqualität der einzelnen Pulse ist hoch mit Beugungsmaßzahl nahe eins. Durch Kontrolle und Justage der optischen Elemente, insbesondere der fokussierenden Spiegel, wurden die Strahleigenschaften an den Beamlines optimiert. Vergleichende Strahlprofilmessungen mittels einer EUV-Kamera um die Strahltaille bestätigen die aus der Hartmann-Messung gewonnenen Strahlparameter. Eine Rekonstruktion der Wignerfunktion des Strahls liefert zusätzliche Informationen über den Kohärenzgrad

Hartmann wavefront sensor for EUV radiation

A compact Hartmann wavefront sensor specifically optimized for the EUV spectral range was developed in a cooperation of Laser-Laboratorium Göttingen and DESY / Hamburg. Primarily designed for optics adjustment and beam characterization of the free electron laser FLASH, the self-supporting device can also be used in combination with any other EUV radiation source, as e.g. for at-wavelength fine-tuning of EUVL beam line optics. Tests performed at FLASH and LCLS indicate an average wavefront measurement repeatability of λ/116 (wrms) at λ=13.5nm for the EUV Hartmann sensor. The device can be successfully employed for characterization of the unfocused FEL beam, as well as for fine-adjustment of EUV optics, as demonstrated for an ellipsoidal focusing mirror at beam-line BL2 of FLASH. The wavefront monitored behind this mirror provided information on typical misalignment effects such as astigmatism or coma. Improved alignment allowed for reduction of the wavefront rms (wrms) from 3.9nm to 1.5nm. Tests performed with LPP EUV sources indicate that the new sensor can also be used for actinic optics characterization and real-time fine-tuning of EUVL optics systems. © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only