Final Results of GERDA on the Two-Neutrino Double-ß Decay Half-Life of

We present the measurement of the two-neutrino double-ß decay rate of ^{76}Ge performed with the GERDA Phase II experiment. With a subset of the entire GERDA exposure, 11.8 kg yr, the half-life of the process has been determined: T_{1/2}^{2ν}=(2.022±0.018_{stat}±0.038_{syst})×10^{21} yr. This is the most precise determination of the ^{76}Ge two-neutrino double-ß decay half-life and one of the most precise measurements of a double-ß decay process. The relevant nuclear matrix element can be extracted: M_{eff}^{2ν}=(0.101±0.001).

Search for tri-nucleon decays of 76Ge in GERDA.

We search for tri-nucleon decays of 76Ge in the dataset from the GERmanium Detector Array (GERDA) experiment. Decays that populate excited levels of the daughter nucleus above the threshold for particle emission lead to disintegration and are not considered. The ppp-, ppn-, and pnn-decays lead to 73Cu, 73Zn, and 73Ga nuclei, respectively. These nuclei are unstable and eventually proceed by the beta decay of 73Ga to 73Ge (stable). We search for the 73Ga decay exploiting the fact that it dominantly populates the 66.7 keV 73mGa state with half-life of 0.5 s. The nnn-decays of 76Ge that proceed via 73mGe are also included in our analysis. We find no signal candidate and place a limit on the sum of the decay widths of the inclusive tri-nucleon decays that corresponds to a lower lifetime limit of 1.2×1026 yr  (90% credible interval). This result improves previous limits for tri-nucleon decays by one to three orders of magnitude.

Liquid argon light collection and veto modeling in GERDA Phase II.

The ability to detect liquid argon scintillation light from within a densely packed high-purity germanium detector array allowed the Gerda experiment to reach an exceptionally low background rate in the search for neutrinoless double beta decay of 76 Ge. Proper modeling of the light propagation throughout the experimental setup, from any origin in the liquid argon volume to its eventual detection by the novel light read-out system, provides insight into the rejection capability and is a necessary ingredient to obtain robust background predictions. In this paper, we present a model of the Gerda liquid argon veto, as obtained by Monte Carlo simulations and constrained by calibration data, and highlight its application for background decomposition.

Mucociliary clearance techniques for treating non-cystic fibrosis bronchiectasis: Is there evidence?

Non-cystic fibrosis bronchiectasis (nCFb) is an acquired condition of variable etiology. An impaired mucociliary clearance seems to be one of the mechanisms behind nCFb, and treatment involves antibiotics, mucoactive agents, and airway clearance techniques (ACTs). Traditional ACTs have four components: postural drainage, percussion, vibration of the chest wall, and coughing. Reviewing the international medical literature on the use of ACTs for patients with nCFb from 1989 to the present day, we retrieved 93 articles, of which 35 met our selection criteria for this analysis. We reviewed active cycle of breathing techniques (ACBT), forced expiration techniques (FET), autogenic drainage, postural drainage, oscillating positive expiratory pressure (OPep), high frequency chest wall oscillation (HFCWO), and exercise or pulmonary rehabilitation. Overall, ACTs appear to be safe for individuals (adults and children) with stable bronchiectasis; where there may be improvements in sputum expectoration, selected measures of lung function, and health-related quality of life. Unfortunately, there is a lack of RCTs in nCFb patients, especially in children. Moreover, none of the studies describes long-term effects of ACTs. It should be noted that a single intervention might not reflect the longer-term outcome and there is no evidence to recommend or contest any type of ACTs in nCFb management. Multicenter RCTs are necessary to evaluate the different techniques of ACTs especially in children with nCFb.

Inhaled mucoactive drugs for treating non-cystic fibrosis bronchiectasis in children.

Non-cystic fibrosis bronchiectasis (nCFb) is an acquired condition of variable etiology. Medical treatment basically involves antibiotics and chest physiotherapy. An impaired mucociliary clearance seems to be one of the mechanisms behind nCFb, and inhaled therapy with mucoactive agents has frequently been used to try to correct it. The most often used mucoactive agents in this setting are N-acetylcysteine, hypertonic saline solution (HS), mannitol powder and recombinant human DNase (rhDNase). Reviewing the international medical literature on the use of these drugs for patients with nCFb from 1992 to the present day, we retrieved 88 articles, only 12 of which met our selection criteria for this analysis. We found only 2 papers and 2 reviews on the use of rhDNase in children, and in adults 3 trials on HS, 5 on mannitol powder and 2 on rhDNase. In conclusion, no observational or randomized controlled trials (RCT) have been published on the use of these drugs in children with nCFb, while the few conducted on adult patients report some evidence of their effects. Further studies are needed on inhaled mucoactive drugs for the treatment of children with nCFb.