183 research outputs found
Quantum mechanical description of Stern-Gerlach experiments
The motion of neutral particles with magnetic moments in an inhomogeneous
magnetic field is described in a quantum mechanical framework. The validity of
the semi-classical approximations which are generally used to describe these
phenomena is discussed. Approximate expressions for the evolution operator are
derived and compared to the exact calculations. Focusing and spin-flip
phenomena are predicted. The reliability of Stern-Gerlach experiments to
measure spin projections is assessed in this framework.Comment: 12 pages, 7 eps figures included, revtex, submitted to PR
Difference between stable and exotic nuclei: medium polarization effects
The bare NN-potential, parametrized so as to reproduce the nuclear phase
shifts leads to a sizable Cooper pair binding energy in nuclei along the
stability valley. It is a much debated matter whether this value accounts for
the "empirical" value of the pairing gap or whether a similarly important
contribution arises from the exchange of collective vibrations between Cooper
pair partners. In keeping with the fact that two-particle transfer reactions
are the specific probe of pairing in nuclei, and that exotic halo nuclei like
11Li are extremely polarizable, we find that the recent studied reaction,
namely 11Li+p -> 9Li+t, provides direct evidence of phonon mediated pairing in
nuclei
Toward a complete theory for predicting inclusive deuteron breakup away from stability
We present an account of the current status of the theoretical treatment of
inclusive reactions in the breakup-fusion formalism, pointing to some
applications and making the connection with current experimental capabilities.
Three independent implementations of the reaction formalism have been recently
developed, making use of different numerical strategies. The codes also
originally relied on two different but equivalent representations, namely the
prior (Udagawa-Tamura, UT) and the post (Ichimura-Austern-Vincent, IAV)
representations.
The different implementations have been benchmarked, and then applied to the
Ca isotopic chain. The neutron-Ca propagator is described in the Dispersive
Optical Model (DOM) framework, and the interplay between elastic breakup (EB)
and non-elastic breakup (NEB) is studied for three Ca isotopes at two different
bombarding energies. The accuracy of the description of different reaction
observables is assessed by comparing with experimental data of on
Ca. We discuss the predictions of the model for the extreme case of
an isotope (Ca) currently unavailable experimentally, though possibly
available in future facilities (nominally within production reach at FRIB). We
explore the use of reactions as surrogates for processes,
by using the formalism to describe the compound nucleus formation in a
reaction as a function of excitation energy, spin, and parity.
The subsequent decay is then computed within a Hauser-Feshbach formalism.
Comparisons between the and induced gamma decay
spectra are discussed to inform efforts to infer neutron captures from
reactions. Finally, we identify areas of opportunity for future
developments, and discuss a possible path toward a predictive reaction theory
Cooper pair sizes in 11Li and in superfluid nuclei: a puzzle?
We point out a strong influence of the pairing force on the size of the two
neutron Cooper pair in Li, and to a lesser extent also in He. It
seems that these are quite unique situations, since Cooper pair sizes of stable
superfluid nuclei are very little influenced by the intensity of pairing, as
recently reported. We explore the difference between Li and heavier
superfulid nuclei, and discuss reasons for the exceptional situation in
Li.Comment: 9 pages. To be published in J. of Phys. G special issue on Open
Problems in Nuclear Structure (OPeNST
Is there a rationale for the continuous infusion of cefepime? A multidisciplinary approach
This review is the fruit of multidisciplinary discussions concerning the continuous administration of β-lactams, with a special focus on cefepime. Pooling of the analyses and viewpoints of all members of the group, based on a review of the literature on this subject, has made it possible to test the hypothesis concerning the applicability of this method of administering cefepime. Cefepime is a cephalosporin for injection which exhibits a broader spectrum of activity than that of older, third-generation cephalosporins for injection (cefotaxime, ceftriaxone, ceftazidime). The specific activity of cefepime is based on its more rapid penetration (probably due to its zwitterionic structure, this molecule being both positively and negatively charged) through the outer membrane of Gram-negative bacteria, its greater affinity for penicillin-binding proteins, its weak affinity for β-lactamases, and its stability versus certain β-lactamases, particularly derepressed cephalosporinases. The stability of cefepime in various solutions intended for parenteral administration has been studied, and the results obtained demonstrated the good compatibility of cefepime with these different solutions. These results thus permit the administration of cefepime in a continuous infusion over a 24-h period, using two consecutive syringes
Novel Methodologies for Providing In Situ Data to HAB Early Warning Systems in the European Atlantic Area: The PRIMROSE Experience
Harmful algal blooms (HABs) cause harm to human health or hinder sustainable use of the marine environment in Blue Economy sectors. HABs are temporally and spatially variable and hence their mitigation is closely linked to effective early warning. The European Union (EU) Interreg Atlantic Area project “PRIMROSE”, Predicting Risk and Impact of Harmful Events on the Aquaculture Sector, was focused on the joint development of HAB early warning systems in different regions along the European Atlantic Area. Advancement of the existing HAB forecasting systems requires development of forecasting tools, improvements in data flow and processing, but also additional data inputs to assess the distribution of HAB species, especially in areas away from national monitoring stations, usually located near aquaculture sites. In this contribution, we review different novel technologies for acquiring HAB data and report on the experience gained in several novel local data collection exercises performed during the project. Demonstrations include the deployment of autonomous imaging flow cytometry (IFC) sensors near two aquaculture areas: a mooring in the Daoulas estuary in the Bay of Brest and pumping from a bay in the Shetland Islands to an inland IFC; and several drone deployments, both of Unmanned Aerial Vehicles (UAV) and of Autonomous Surface vehicles (ASVs). Additionally, we have reviewed sampling approaches potentially relevant for HAB early warning including protocols for opportunistic water sampling by coastguard agencies. Experiences in the determination of marine biotoxins in non-traditional vectors and how they could complement standard routine HAB monitoring are also considered.En prens
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