Dilepton production in proton-proton and quasifree proton-neutron reactions at 1.25 GeV

We investigate the pp --> pp e+e- and quasifree pn --> pn e+e- reactions within an effective Lagrangian model at the laboratory kinetic energy of 1.25 GeV for which experimental data have recently been reported by the HADES Collaboration. The model uses a meson-exchange approximation to describe the initial nucleon-nucleon (NN) scattering. Contributions to the reaction amplitudes are included from the NN bremsstrahlung as well as from the excitation, propagation and radiative decay of the Delta(1230) isobar state. It is found that the HADES data on the e+e- invariant mass distribution in the pp --> pp e+e- reaction are reproduced excellently by our model where the Delta isobar term dominates the spectrum. However, the quasifree pn --> pn e+e- cross sections are underpredicted in the invariant mass region of 0.40 - 0.55 GeV/c^2 even after including contributions of the eta Dalitz decay and the subthreshold production and decay of the rho^0 meson via the baryonic resonance N*(1520). In the case of the quasifree pn --> pn e+e- reaction, a strong sensitivity to the pion electromagnetic form factor is observed which helps to bring the calculated cross sections closer to the data in the higher dilepton mass region.Comment: 12 pages 3, figures, version to appear in Phys. Rev. C (Rapid Communications

Charged Current Neutrino Nucleus Interactions at Intermediate Energies

We have developed a model to describe the interactions of neutrinos with nucleons and nuclei, focusing on the region of the quasielastic and Delta(1232) peaks. We describe neutrino nucleon collisions with a fully relativistic formalism which incorporates state-of-the-art parametrizations of the form factors for both the nucleon and the N-Delta transition. The model has then been extended to finite nuclei, taking into account nuclear effects such as Fermi motion, Pauli blocking (both within the local density approximation), nuclear binding and final state interactions. The in-medium modification of the Delta resonance due to Pauli blocking and collisional broadening have also been included. Final state interactions are implemented by means of the Boltzmann-Uehling-Uhlenbeck (BUU) coupled-channel transport model. Results for charged current inclusive cross sections and exclusive channels as pion production and nucleon knockout are presented and discussed.Comment: 26 pages, 24 figures; v2: 2 figures and discussion added, version accepted for publication in Phys. Rev.

Host and microbe determinants that may influence the success of S. aureus colonization

Staphylococcus aureus may cause serious skin and soft tissue infections, deep abscesses, endocarditis, osteomyelitis, pneumonia, and sepsis. S. aureus persistently colonizes 25–30% of the adult human population, and S. aureus carriers have an increased risk for infections caused by the bacterium. The major site of colonization is the nose, i.e., the vestibulum nasi, which is covered with ordinary skin and hair follicles. Several host and microbe determinants are assumed to be associated with colonization. These include the presence and expression level of bacterial adhesins, which can adhere to various proteins in the extracellular matrix or on the cellular surface of human skin. The host expresses several antimicrobial peptides and lipids. The level of β-defensin 3, free sphingosine, and cis-6-hexadecenoic acid are found to be associated with nasal carriage of S. aureus. Other host factors are certain polymorphisms in Toll-like receptor 2, mannose-binding lectin, C-reactive protein, glucocorticoid-, and vitamin D receptor. Additional putative determinants for carriage include genetic variation and expression of microbial surface components recognizing adhesive matrix molecules and their interaction partners, as well as variation among humans in the ability of recognizing and responding appropriately to the bacteria. Moreover, the available microflora may influence the success of S. aureus colonization. In conclusion, colonization is a complex interplay between the bacteria and its host. Several bacterial and host factors are involved, and an increased molecular understanding of these are needed

Exclusive K+K^+ production in proton-nucleus collisions

The exclusive $K^+$ meson production in a proton-nucleus collision, leading to two body final states, is investigated in a fully covariant two-nucleon model based on the effective Lagrangian picture. The explicit kaon production vertex is described via creation, propagation and decay into relevant channel of $N^*$(1650), $N^*$(1710) and $N^*$(1720) intermediate baryonic states in the initial collision of the projectile nucleon with one of its target counterparts which is modeled by the one-pion exchange process. The calculated cross sections show strong sensitivity to the medium effects on pion propagator and to the final hypernuclear state excited in the reaction.Comment: Two new figures, version accepted for publication by Phys. Rev.

Candida auris

Candida auris (C. auris) er en gjærsopp som kan forårsake alvorlige infeksjoner hos mennesker. Infeksjoner med Candida auris forekommer i hovedsak i helseinstitusjoner og rammer som regel alvorlig syke pasienter. I tillegg er behandling vanskelig fordi soppen ofte er resistent/motstandsdyktig mot de vanligste medikamentene som brukes ved Candida-infeksjon

Vibrio vulnificus

Vibrio vulnificus er en bakterie som trives i saltvann over 20 grader og som kan gi sykdom hos personer med sår eller nedsatt immunforsvar (såkalt opportunistisk infeksjon). Alvorlige sykdom forekommer oftest nær Taiwan, Sør-Korea, Japan og i Mexicogolfen. I senere år er det rapportert flere tilfeller med alvorlige infeksjon med Vibrio vulnificus hos personer som har badet i nordiske kystområder. I løpet av den varme sommeren 2018 var det sju personer som ble alvorlig syke med denne infeksjonen i Norge. Det ble også registrert flere mindre alvorlige tilfeller. Vibrio vulnificus er bakterien som forårsaker de fleste sjømat-assosierte dødsfall i verden. Bakterien har evnen til å overleve i det krevende miljøet i mage-tarm-systemet, og kan derfor forårsake infeksjon her. Bakterien kan også trenge inn i åpne sår og dermed føre til hudinfeksjon. Trenger bakterien dypere ned i det underliggende vevet vil den kunne komme over i blodbanen og medføre sepsis (blodforgiftning). Dette er en tilstand med høy dødelighet, også kalt «badsårsfeber»

The pion-nucleon scattering lengths from pionic deuterium

We use the framework of effective field theories to discuss the determination of the S-wave \pi N scattering lengths from the recent high-precision measurements of pionic deuterium observables. The theoretical analysis proceeds in several steps. Initially, the precise value of the pion-deuteron scattering length a_{\pi d} is extracted from the data. Next, a_{\pi d} is related to the S-wave \pi N scattering lengths a_+ and a_-. We discuss the use of this information for constraining the values of these scattering lengths in the full analysis, which also includes the input from the pionic hydrogen energy shift and width measurements, and throughly investigate the accuracy limits for this procedure. In this paper, we also give a detailed comparison to other effective field theory approaches, as well as with the earlier work on the subject, carried out within the potential model and multiple scattering framework.Comment: The replacement includes an erratum, which is published in Eur. Phys. J.

Nucleon-nucleon potential in finite nuclei

We consider the spin-isospin-independent central part of the residual nucleon-nucleon potential in finite spherical nuclei taking into account the deformation effects of the nucleons within the surrounding nuclear environment. It is shown that inside the nucleus the short-range repulsive contribution of the potential is increased and the intermediate attraction is decreased. We identify the growth of the radial component of the spin-isospin independent short-range part of the in-medium nucleon-nucleon interaction as the responsible agent that prevents the radial collapse of the nucleus.Comment: 9 pages, 3 eps figure

DNA adducts in fish following an oil spill exposure

On 12 December 1999, one third of the load of the Erika tanker, amounting to about 10,000 t crude oil flowed into sea waters close to the French Atlantic Coast. This oil contained polycyclic aromatic compounds (PAC) that are known to be genotoxic. Genotoxic effects induce DNA adducts formation, which can thus be used as pollution biomarkers. Here, we assessed the genotoxic impact of the “Erika” oil spill by DNA adducts detection in the liver of immature fishes (Solea solea) from four locations of the French Brittany coasts. Two months after the spill, a high amount of DNA adducts was found in samples from all locations, amounting to 92–290 DNA adduct per 109 nucleotides. Then total DNA adduct levels decreased to reach about 50 adducts per 109 nucleotides nine months after the spill. In vitro experiments using human cell cultures and fish liver microsomes evidence the genotoxicity of the Erika fuel. They also prove the formation of reactive species able to create DNA adducts. Furthermore, in vitro and in vivo DNA adducts fingerprints are similar, thus confirming that DNA adducts are a result of the oil spill

Dilepton Production in Nucleon-Nucleon Interactions

Starting from a realistic one--boson--exchange--model fitted to the amplitudes of elastic nucleon--nucleon scattering and the process $NN\rightarrow N\Delta$ we perform a fully relativistic and gauge invariant calculation for the dilepton production in nucleon--nucleon collisions, including the important effect of propagating the $\Delta$--resonance. We compare the results of our calculations with the latest experimental data on dilepton production. We also show how to implement various electromagnetic formfactors for the hadrons in our calculations without loosing gauge--invariance and discuss their influence on dilepton spectra.Comment: 24 pages, figures will be sent on reques