High-resolution and low-background 163^{163}Ho spectrum: interpretation of the resonance tails

The determination of the effective electron neutrino mass via kinematic analysis of beta and electron capture spectra is considered to be model-independent since it relies on energy and momentum conservation. At the same time the precise description of the expected spectrum goes beyond the simple phase space term. In particular for electron capture processes, many-body electron-electron interactions lead to additional structures besides the main resonances in calorimetrically measured spectra. A precise description of the $^{163}$Ho spectrum is fundamental for understanding the impact of low intensity structures at the endpoint region where a finite neutrino mass affects the shape most strongly. We present a low-background and high-energy resolution measurement of the $^{163}$Ho spectrum obtained in the framework of the ECHo experiment. We study the line shape of the main resonances and multiplets with intensities spanning three orders of magnitude. We discuss the need to introduce an asymmetric line shape contribution due to Auger–Meitner decay of states above the auto-ionisation threshold. With this we determine an enhancement of count rate at the endpoint region of about a factor of 2, which in turn leads to an equal reduction in the required exposure of the experiment to achieve a given sensitivity on the effective electron neutrino mass

Entwicklung und Erprobung eines kombinierten Untersuchungsverfahrens zum Nachweis und zur Bewertung mutagener Stoffe im Wasser. Bd. 2 Ausfuehrliche Beschreibung der Untersuchungsmethoden und deren Ergebnisse

SIGLETIB: FR 1461(2) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Positive GABAA receptor modulators from Acorus calamus L. , and structural analysis of (+) dioxosarcoguaiacol by 1D and 2D NMR and molecular modeling

[Image: see text] In a two-microelectrode voltage clamp with Xenopus laevis oocytes, a petroleum ether extract of Acorus calamus rhizomes enhanced the GABA-induced chloride current through GABA(A) receptors of the α(1)β(2)γ(2S) subtype by 277% ± 9.7% (100 μg/mL). β-Asarone (1), (+)-dioxosarcoguaiacol (2), (+)-shyobunone (3), and (+)-preisocalamenediol (4) were subsequently identified as main active principles through HPLC-based activity profiling and targeted isolation. The compounds induced maximum potentiation of the chloride current ranging from 588% ± 126% (EC(50): 65.3 ± 21.6 μM) (2) to 1200% ± 163% (EC(50): 171.5 ± 34.6 μM) (1), whereas (−)-isoshyobunone (5) and (−)-acorenone (6) exhibited weak GABA(A) modulating properties (5: 164% ± 42.9%; EC(50): 109.4 ± 46.6 μM and 6: 241% ± 23.1%; EC(50): 34.0 ± 6.7 μM). The relative configuration of 2 was established as 4R*8S*10R* by NOESY experiments and conformational analysis