218 research outputs found
Effects of glucagon-like peptide-1 receptor agonists on weight loss: systematic review and meta-analyses of randomised controlled trials
Objective To determine whether treatment with agonists of glucagon-like peptide-1 receptor (GLP-1R) result in weight loss in overweight or obese patients with or without type 2 diabetes mellitus
Kartlegging av Stillehavsøsters (Crassostrea gigas) - Bestandskartlegging Karmøy - Svenskegrensa 2017 - 2019
Med endringer i havmiljøene, vil ogsĂĽ dynamikken i marine økosystemer kunne endres og nye arter vil kunne etableres seg i norske farvann slik som stillehavsøsters ( Magallana gigas ). Arten etablerte seg allerede pĂĽ 1990 tallet i Vadehavet pĂĽ den danske vestkysten og fra 2006 spredde den seg videre langs skagerrakkysten. Arten er definert som fremmed, invasiv og er plassert i risikokategorien ÂŤHøy Ăkologisk RisikoÂť, pĂĽ grunn av spredningspotensiale og økologisk effekt (Artsdatabanken). Stillehavsøsters anses om bioinvasiv og er en art som endrer de økosystemene hvor den etablere seg, og som vil kunne ha en direkte negativ effekt pĂĽ stedegne arter, som for eksempel blĂĽskjell og flatøsters. Arten har ogsĂĽ uønskede negative sosioøkonomiske effekter knyttet til forringelse av strender og andre naturomrĂĽder.publishedVersio
Neutron-induced background by an alpha-beam incident on a deuterium gas target and its implications for the study of the 2H(alpha,gamma)6Li reaction at LUNA
The production of the stable isotope Li-6 in standard Big Bang
nucleosynthesis has recently attracted much interest. Recent observations in
metal-poor stars suggest that a cosmological Li-6 plateau may exist. If true,
this plateau would come in addition to the well-known Spite plateau of Li-7
abundances and would point to a predominantly primordial origin of Li-6,
contrary to the results of standard Big Bang nucleosynthesis calculations.
Therefore, the nuclear physics underlying Big Bang Li-6 production must be
revisited. The main production channel for Li-6 in the Big Bang is the
2H(alpha,gamma)6Li reaction. The present work reports on neutron-induced
effects in a high-purity germanium detector that were encountered in a new
study of this reaction. In the experiment, an {\alpha}-beam from the
underground accelerator LUNA in Gran Sasso, Italy, and a windowless deuterium
gas target are used. A low neutron flux is induced by energetic deuterons from
elastic scattering and, subsequently, the 2H(d,n)3He reaction. Due to the
ultra-low laboratory neutron background at LUNA, the effect of this weak flux
of 2-3 MeV neutrons on well-shielded high-purity germanium detectors has been
studied in detail. Data have been taken at 280 and 400 keV alpha-beam energy
and for comparison also using an americium-beryllium neutron source.Comment: Submitted to EPJA; 13 pages, 8 figure
First Direct Measurement of the ^{17}O(p,\gamma)^{18}F Reaction Cross-Section at Gamow Energies for Classical Novae
Classical novae are important contributors to the abundances of key isotopes,
such as the radioactive ^{18}F, whose observation by satellite missions could
provide constraints on nucleosynthesis models in novae. The
^{17}O(p,\gamma)^{18}F reaction plays a critical role in the synthesis of both
oxygen and fluorine isotopes but its reaction rate is not well determined
because of the lack of experimental data at energies relevant to novae
explosions. In this study, the reaction cross section has been measured
directly for the first time in a wide energy range Ecm = 200 - 370 keV
appropriate to hydrogen burning in classical novae. In addition, the E=183 keV
resonance strength, \omega \gamma=1.67\pm0.12 \mueV, has been measured with the
highest precision to date. The uncertainty on the ^{17}O(p,\gamma)^{18}F
reaction rate has been reduced by a factor of 4, thus leading to firmer
constraints on accurate models of novae nucleosynthesis.Comment: accepted by Phys. Rev. Let
Preparation and characterisation of isotopically enriched TaO targets for nuclear astrophysics studies
The direct measurement of reaction cross sections at astrophysical energies
often requires the use of solid targets of known thickness, isotopic
composition, and stoichiometry that are able to withstand high beam currents
for extended periods of time. Here, we report on the production and
characterisation of isotopically enriched TaO targets for the study of
proton-induced reactions at the Laboratory for Underground Nuclear Astrophysics
facility of the Laboratori Nazionali del Gran Sasso. The targets were prepared
by anodisation of tantalum backings in enriched water (up to 66% in O
and up to 96% in O). Special care was devoted to minimising the presence
of any contaminants that could induce unwanted background reactions with the
beam in the energy region of astrophysical interest. Results from target
characterisation measurements are reported, and the conclusions for proton
capture measurements with these targets are drawn.Comment: accepted to EPJ
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