Azimuthal asymmetries in SIDIS di-hadron muoproduction off longitudinally polarized protons at COMPASS

In this review a first comprehensive study of azimuthal asymmetries in semi-inclusive deep inelastic muoproduction of hadron pairs off longitudinally polarized protons at COMPASS is presented. The study is based on data taken in 2007 and 2011, obtained by impinging a high-energetic $\mu^+$ beam of $160$ GeV/$\it{c}$, respectively $200$ GeV/$\it{c}$, momentum on a solid ammonia target. The discussion is focused on both leading and subleading longitudinal target-spin-dependent asymmetries arising in the di-hadron SIDIS cross section, addressing the role of spin-orbit couplings and quark-gluon correlations in the framework of collinear or transverse momentum dependent factorization.Comment: 5 pages, 5 figures, SPIN16 Conference Proceedin

Process for purification of silicon

The purification of metallurgically pure silicon having a silicon content of more than 95% by weight is accomplished by leaching with an acidic solution which substantially does not attack silicon. A mechanical treatment leading to continuous particle size reduction of the granulated silicon to be purified is combined with the chemical purification step

Nature of bonding and electronic structure in MgB2, a boron intercalation superconductor

Chemical bonding and electronic structure of MgB2, a boron-based newly discovered superconductor, is studied using self-consistent band structure techniques. Analysis of the transformation of the band structure for the hypothetical series of graphite - primitive graphite - primitive graphite-like boron - intercalated boron, shows that the band structure of MgB2 is graphite-like, with pi-bands falling deeper than in ordinary graphite. These bands possess a typically delocalized and metallic, as opposed to covalent, character. The in-plane sigma-bands retain their 2D covalent character, but exhibit a metallic hole-type conductivity. The coexistence of 2D covalent in-plane and 3D metallic-type interlayer conducting bands is a peculiar feature of MgB2. We analyze the 2D and 3D features of the band structure of MgB2 and related compounds, and their contributions to conductivity.Comment: 4 pages in revtex, 3 figures in 4 separate EPS file

Bonding Quality of Joined Glass Components Exposed to UV and Fluidic Influences

Components of structural glazing have to meet different requirements and resist various impacts, depending on the field of application. Within an international research project of the EU innovation program Horizon 2020, special glass panes with a fluid circulating in capillaries are developed exploiting solar energy. Major influences to this glazing are UV irradiation and the fluidic contact, effecting the mechanical and optical durability of the bonding material within the glass setup. Regarding to visual requirements, acrylate adhesives and EVA films are analyzed as possible bonding materials by destructive and non-destructive testing methods. Two types of specimen are presented for obtaining the mechanical behavior and the surface appearances of the bonding material

Die soziale Praxis der Fallarbeit in der Lehrer*innenbildung. Praxistheoretisch-videografische Einblicke in die Vollzugswirklichkeit kasuistischer Lehre

Zugleich: Dissertation, Universität Kassel, 202

Steigerung der Todesrezeptor-vermittelten Apoptose durch hyperosmotischen Stress

Der Todesligand TRAIL stellte nach seiner Entdeckung einen neuen Ansatz dar, selektiv in Tumorzellen Apoptose induzieren zu können. Vor dem Hintergrund, Therapieerfolge gerade auch bei Apoptose resistenten Tumorentitäten erzielen zu wollen, war es Ziel dieser Arbeit, TRAIL-resistente Zelllinien in vitro erneut für die Apoptose sensitivieren zu können. Wir konnten in unserer Arbeit osmotischen Stress im Tumorumfeld als neuen, verstärkenden Faktor einer TRAIL-induzierten Apoptose charakterisieren. Viele bereits klinisch eingesetzte Zytostatika zielen wirkmechanistisch auf eine Deregulation der Bcl-2 kontrollierten, intrinsischen Apoptose ab und auch in Tumorzellen unter hypertonen Bedingungen zeigte sich, dass das Mitochondrium als Kontrollzentrum der intrinsischen Apoptose entscheidend für eine gesteigerte TRAIL- induzierte Apoptose ist. In Vorarbeiten konnte gezeigt werden, dass durch die Hemmung und Bindung antiapoptotischer Bcl-2 Proteine Tumorzellen in ihrer Fähig-keit proapoptotische Signale kompensieren zu können kompromittiert werden. Mechanistisch konnten wir auch bei hyperosmotischen gestressten Zellen eine Art „mitochondriales Priming“ detekieren, welches zusammen mit dem ankommenden TRAIL-induzierten Todessignal die Zellen vermehrt in die Apoptose treibt. Eine Bcl-xL-Abhängigkeit der mitochondrialen Integrität könnte dabei zelltypspezifisch sein und in anderen Zelllinien von differenten Proteinen abhängen. Ein Transfer in die Klinik könnte perspektivisch auf zwei Wegen erfolgen: Zum einen über weiterführende, mechanistische Untersuchungen mit dem Ziel den Wirkmechanismus des kombinatorischen TRAIL und Osmostress-Einsatzes molekular zu mimikrieren oder über die Generierung eines lokalen, hypertonen Kompartiments

Measurement of the charged-pion polarisability

The COMPASS collaboration at CERN has investigated pion Compton scattering, $\pi^-\gamma\rightarrow \pi^-\gamma$, at centre-of-mass energy below 3.5 pion masses. The process is embedded in the reaction $\pi^-\mathrm{Ni}\rightarrow\pi^-\gamma\;\mathrm{Ni}$, which is initiated by 190\,GeV pions impinging on a nickel target. The exchange of quasi-real photons is selected by isolating the sharp Coulomb peak observed at smallest momentum transfers, $Q^2<0.0015$\,(GeV/$c$)$^2$. From a sample of 63\,000 events the pion electric polarisability is determined to be $\alpha_\pi\ =\ (\,2.0\ \pm\ 0.6_{\mbox{\scriptsize stat}}\ \pm\ 0.7_{\mbox{\scriptsize syst}}\,) \times 10^{-4}\,\mbox{fm}^3$under the assumption$\alpha_\pi=-\beta_\pi$, which relates the electric and magnetic dipole polarisabilities. It is the most precise measurement of this fundamental low-energy parameter of strong interaction, that has been addressed since long by various methods with conflicting outcomes. While this result is in tension with previous dedicated measurements, it is found in agreement with the expectation from chiral perturbation theory. An additional measurement replacing pions by muons, for which the cross-section behavior is unambigiously known, was performed for an independent estimate of the systematic uncertainty.Comment: Published version: 9 pages, 3 figures, 1 tabl

Interplay among transversity induced asymmetries in hadron leptoproduction

In the fragmentation of a transversely polarized quark several left-right asymmetries are possible for the hadrons in the jet. When only one unpolarized hadron is selected, it exhibits an azimuthal modulation known as Collins effect. When a pair of oppositely charged hadrons is observed, three asymmetries can be considered, a di-hadron asymmetry and two single hadron asymmetries. In lepton deep inelastic scattering on transversely polarized nucleons all these asymmetries are coupled with the transversity distribution. From the high statistics COMPASS data on oppositely charged hadron-pair production we have investigated for the first time the dependence of these three asymmetries on the difference of the azimuthal angles of the two hadrons. The similarity of transversity induced single and di-hadron asymmetries is discussed. A new analysis of the data allows to establish quantitative relationships among them, providing for the first time strong experimental indication that the underlying fragmentation mechanisms are all driven by a common physical process.Comment: 6 figure