1,773 research outputs found

    Near-threshold production of a0(980) mesons in the reaction pp -> d K^+ \bar{K}^0

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    Using an effective Lagrangian approach as well as the Quark-Gluon Strings Model we analyze near-threshold production of a0(980)-mesons in the reaction NN -> d K \bar{K} as well as the background of non-resonant K\bar{K}-pair production. We argue that the reaction pp -> d K^+ \bar{K}^0 at an energy release Q<=100 MeV is dominated by the intermediate production of the a0(980)-resonance. At larger energies the non-resonant K^+\bar{K}^0-pair production - where the kaons are produced in a relative P-wave - becomes important. Then effects of final-state interactions are evaluated in a unitarized scattering-length approach and found to be in the order of a 20% suppression close to threshold. Thus in present experiments at the Cooler Synchrotron COSY-J\"ulich for Q<=107 MeV the a_0^+ signal can reliably be separated from the non-resonant K^+\bar{K^0} background.Comment: 14 pages, 12 figures, submitted to EPJ

    a0(980)-f0(980) mixing and isospin violation in the reactions pN -> d a0, pd -> 3He/3H a0 and dd -> 4He a0

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    It is demonstrated that f_0-a_0 mixing can lead to a comparatively large isospin violation in the reactions pN -> da_0, pd -> ^3He/^3H a_0 and dd -> ^4He a_0 close to the corresponding production thresholds. The observation of such mixing effects is possible, e.g., by measuring the forward-backward asymmetry in the reaction pn -> d a_0^0 -> d eta pi^0.Comment: 14 pages, 5 figure

    Production of a0a_0-mesons in the reactions πN→a0N\pi N \to a_0 N and pp→da0+p p \to d a_0^+ at GeV energies

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    We investigate the reactions πN→a0N\pi N \to a_0 N and pp→da0+p p \to d a_0^+ near threshold and at medium energies. An effective Lagragian approach and the Regge pole model are applied to analyze different contributions to the cross section of the reaction πN→a0N\pi N \to a_0 N. These results are used to calculate the differential and total cross sections of the reaction pp→da0+p p \to d a_0^+ within the framework of the two-step model in which two nucleons produce an a0a_0-meson via π\pi -meson exchange and fuse to a deuteron. The necessity of new measurements on a0a_0 production and branching fractions (of its decay to the KKˉK\bar K and πη\pi\eta channels) is emphasized for clarifying the a0a_0 structure. Detailed predictions for the reaction pp→da0+pp \to d a_0^+ are presented for the energy regime of the proton synchrotron COSY-J\"ulich.Comment: 9 pages, including 6 eps figure

    Nanosecond Pulsed Electric Field Induced Cytoskeleton, Nuclear Membrane and Telomere Damage Adversely Impact Cell Survival

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    We investigated the effects of nanosecond pulsed electric fields (nsPEF) on three human cell lines and demonstrated cell shrinkage, breakdown of the cytoskeleton, nuclear membrane and chromosomal telomere damage. There was a differential response between cell types coinciding with cell survival. Jurkat cells showed cytoskeleton, nuclear membrane and telomere damage that severely impacted cell survival compared to two adherent cell lines. Interestingly, disruption of the actin cytoskeleton in adherent cells prior to nsPEF exposure significantly reduced cell survival. We conclude that nsPEF applications are able to induce damage to the cytoskeleton and nuclear membrane. Telomere sequences, regions that tether and stabilize DNA to the nuclear membrane, are severely compromised as measured by a pan-telomere probe. Internal pore formation following nsPEF applications has been described as a factor in induced cell death. Here we suggest that nsPEF induced physical changes to the cell in addition to pore formation need to be considered as an alternative method of cell death. We suggest nsPEF electrochemical induced depolymerization of actin filaments may account for cytoskeleton and nuclear membrane anomalies leading to sensitization

    Medium effects in the production and pi0 gamma decay of omega-mesons in pA collisions in the GeV region

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    The omega-resonance production and its pi0 gamma decay in p-A reactions close to threshold is considered within the Intranuclear Cascade (INC) Model. The pi0 gamma invariant mass distribution shows two components which correspond to the omega decay 'inside' and 'outside' the nucleus, respectively. The 'inside' component is distorted by medium effects, which introduce a mass shift as well as collisional broadening for the omega-meson and its decaying pion. The relative contribution of the 'inside' component is analyzed in detail for different kinematical conditions and nuclear targets. It is demonstrated that a measurement of the correlation in azimuthal angle between the pi0 and gamma momenta allows to separate events related to the 'inside' omega decay from different sources of background when uncorrelated pi0's and gamma's are produced.Comment: 24 pages, 11 figure

    Foresight Review on Design for Safety

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    This review explores how a culture of design for safety can enhance the safety of the world around us. Design for safety goes beyond legislation, regulations and standards. These all play an important role for established products and services but their limited scope often leads to missed opportunities to enhance safety by taking a broader perspective. Design is applied to both mature industries (which have many years of experience and a good understanding of risks and how to reduce them) and emerging industries (that use new technologies requiring new ways of controlling risk which may not yet be known or understood). An example of an emerging risk is the internet that is enabling rapid innovation of new products which generate data. This data is widely shared across the internet and the risks associated with this are as yet not fully understood by the public. A design for safety culture takes a holistic approach to understanding the influences that affect safety. Such influences are varied and take into account the broader environment within which design operates, including complex interactions, behaviour and culture. It goes beyond traditional design methods and focuses on the goal of a safer design. Implementing design for safety requires an understanding of the challenges and the methods to address them. It needs multidisciplinary teams that bring together people with the relevant skills to understand the challenges and a collaborative approach of ‘designing with’ rather than the more traditional approach of ‘designing for’. This can be achieved through an international diverse community that works together to identify and share best practices

    Evidence of kaon nuclear and Coulomb potential effects on soft K+ production from nuclei

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    The ratio of forward K+ production on copper, silver and gold targets to that on carbon has been measured at proton beam energies between 1.5 and 2.3 GeV as a function of the kaon momentum p_K using the ANKE spectrometer at COSY-Juelich. The strong suppression in the ratios observed for p_K<200-250 MeV/c can be ascribed to a combination of Coulomb and nuclear repulsion in the K+A system. This opens a new way to investigate the interaction of K+-mesons in the nuclear medium. Our data are consistent with a K+A nuclear potential of V_K~20 MeV at low kaon momenta and normal nuclear density. Given the sensitivity of the data to the kaon potential, the current experimental precision might allow one to determine V_K to better than 3 MeV.Comment: 9 pages, 3 figures; changed conten

    Severe acute hepatitis and acute liver failure of unknown origin in children:a questionnaire-based study within 34 paediatric liver centres in 22 European countries and Israel, April 2022

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    To detect potential concern about severe acute hepatitis in children, we conducted a survey among 50 ERN RARE-LIVER centres. By 26 April 2022, 34 centres, including 25 transplant centres, reported an estimated median of 3-5, 0-2 and 3-5 cases in 2021, 2020 and 2019 and a mean of 2 (range: 0-8) cases between January and April 2022 (mean in 10 large liver transplant centres: 3). Twelve centres reported suspicion of an increase, but no rise. Following a report by the United Kingdom (UK) on 5 April 2022 on the occurrence of cases of severe acute hepatitis in children aged 16 years or under, the World Health Organization (WHO) raised concerns about the possibility of an epidemic [1,2]. By 21 April, 169 possible or confirmed cases were reported fulfilling the WHO case definition [3]. The cause of the hepatitis is unknown but a link to a virus infection has been suggested due to the epidemiological pattern of cases [4,5]. The hepatitis can progress to paediatric acute liver failure (pALF) necessitating urgent liver transplantation to avoid multi-organ failure [6]. We intended to assess whether a rise in incidence of severe acute hepatitis or pALF could be observed between 1 January and 26 April 2022 in comparison to previous years, within the European Reference Network on Hepatological Diseases (ERN RARE-LIVER) [7]
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