3,116 research outputs found
Ground state properties of neutron-rich Mg isotopes: the "island of inversion" studied with laser and -NMR spectroscopy
Studies in regions of the nuclear chart in which the model predictions of properties of nuclei fail can bring a better understanding of the strong interaction in the nuclear medium. To such regions belongs the so called "island of inversion" centered around Ne, Na and Mg isotopes with 20 neutrons in which unexpected ground-state spins, large deformations and dense low-energy spectra appear. This is a strong argument that the magic N=20 is not a closed shell in this area. In this thesis investigations of isotope shifts of stable Mg, as well as spins and magnetic moments of short-lived Mg are presented. The successful studies were performed at the ISOLDE facility at CERN using collinear laser and -NMR spectroscopy techniques. The isotopes were investigated as single-charged ions in the 280 nm transition from the atomic ground state S to one of the two lowest excited states P using continuous wave laser beams. The isotope-shift measurements with fluorescence detection for the three stable isotopes show that it is feasible to perform the same studies on radioactive Mg isotopes up to the "island of inversion". This will allow to determine differences in the mean charge square radii and interpret them in terms of deformation. The high detection efficiency for - particles and optical pumping close to saturation allowed to obtain very good -asymmetry signals for Mg and Mg with half-lives around 1 s and production yields about 10 ions/s. For this purpose the ions were implanted into a host crystal lattice. Such detection of the atomic resonances revealed their hyperfine structure, which gives the sign and a first estimate of the value of the magnetic moment. The nuclear magnetic resonance gave also their -factors with the relative uncertainty smaller than 0.2%. By combining the two techniques also the nuclear spin of both isotopes could be unambiguously determined. The measured spins and -factors show that Mg with 17 neutrons lies outside the ``island of inversion". On the other hand, Mg with 19 neutrons has an unexpected ground-state spin which can be explained only by promoting at least two neutrons across the N=20 shell gap. This places the above nucleus inside the "island". However, modern shell-model approaches cannot predict this level as the ground state but only as one of the low-lying states, even though they reproduce very well the experimental -factor. This indicates that modifications to the available interactions are required. Future measurements include isotope shift measurements on radioactive Mg isotopes and -NMR studies on Mg
Traceability to ensure food safety and consumer protection as typified by case studies of three meat processing plants
Ensuring food safety is a legal obligation of the manufacturer or of the entity that places the product on sale. Traceability is one of the tools that are used to ensure food safety. It allows the withdrawal of a dangerous or non-compliant product from the market and determines the source of a threat. The aim of the study was to compare the functioning and effectiveness of traceability systems in selected approved meat industry plants. The system functioning in a large meat processing plant, in which the circulation of documents was implemented in a computer system, was compared with two smaller ones, in which paper documentation was carried out, but supported by a computer system. In these plants, the traceability system was based on internal procedures. Properly developed traceability procedures and simulations support and enable response in a crisis. Computer systems streamline and facilitate the traceability process. However, the comparative analysis showed that the use of paper records allowed for efficient identification of the source of the threat. The possibility of performing product traceability was confirmed in these plants. Internal markings and codes and documentation flow, staff training, and awareness proved helpful
Recommended from our members
A Data-informed Public Health Policy-Makers Platform
Hearing loss is a disease exhibiting a growing trend due to the number of factors, including but not limited to the mundane exposure to the noise and ever-increasing amount of older population. In the framework of a public health policymaking process, modeling of the hearing loss disease based on data is a key factor in alleviating the issues related to the disease issuing effective public health policies. First, the paper describes the steps of the data-driven policymaking process. Afterward, a scenario along with the part of the proposed platform, responsible for supporting policymaking are presented. With the aim of demonstrating the capabilities and usability of the platform for the policy-makers, some initial results of preliminary analytics are presented in a framework of a policy-making process. Ultimately, the utility of the approach is validated throughout the results of the survey which was presented to the health system policy-makers professionals involved in the policy development process in Croatia
PCN17 SYSTEMATIC REVIEW OF THE EFFICACY AND SAFETY OF IMIQUIMOD 5% CREAM FOR THE TREATMENT OF SUPERFICIAL BASAL CELL CARCINOMA
- …