525 research outputs found
Pygmy dipole strength close to particle-separation energies - the case of the Mo isotopes
The distribution of electromagnetic dipole strength in 92, 98, 100 Mo has
been investigated by photon scattering using bremsstrahlung from the new ELBE
facility. The experimental data for well separated nuclear resonances indicate
a transition from a regular to a chaotic behaviour above 4 MeV of excitation
energy. As the strength distributions follow a Porter-Thomas distribution much
of the dipole strength is found in weak and in unresolved resonances appearing
as fluctuating cross section. An analysis of this quasi-continuum - here
applied to nuclear resonance fluorescence in a novel way - delivers dipole
strength functions, which are combining smoothly to those obtained from
(g,n)-data. Enhancements at 6.5 MeV and at ~9 MeV are linked to the pygmy
dipole resonances postulated to occur in heavy nuclei.Comment: 6 pages, 5 figures, proceedings Nuclear Physics in Astrophysics II,
May 16-20, Debrecen, Hungary. The original publication is available at
www.eurphysj.or
Numerical modeling of the electron temperature crashes observed in Wendelstein 7-X stellarator experiments
Effectiveness and cost-effectiveness of self-help plus (sh+) for preventing mental disorders in refugees and asylum seekers in Europe and Turkey: Study protocols for two randomised controlled trials
Introduction This article describes two randomised controlled trials that will evaluate the effectiveness and cost-effectiveness of Self-Help Plus (SH+), a group self-help intervention developed by the WHO to reduce distress. In these trials SH+ is being tested as a preventative intervention to lower the incidence of mental disorders in asylum seekers and refugees with psychological distress resettled in Europe and Turkey. Methods and analysis Two prospective, multicentre, randomised, rater-blinded, parallel-group studies will follow participants over a period of 12 months. One trial will be conducted in Europe and one in Turkey. In each trial, 600 asylum seekers and refugees screening positive on the General Health Questionnaire (≥3), but without a formal diagnosis of any mental disorders according to the Mini International Neuropsychiatric Interview, will be randomly allocated to SH+or to enhanced treatment-as-usual. The primary outcome will be a lower incidence of mental disorders at 6 month follow-up. Secondary outcomes will include the evaluation of psychological symptoms, functioning, well-being, treatment acceptability and indicators of intervention cost-effectiveness. Ethics and dissemination The two trials received ethical clearance from the local Ethics Committees of the participating sites (seven sites), as well as from the WHO Ethics Committee. All participants will provide informed consent before screening and before study inclusion (a two-step procedure). The results of the trials will be disseminated in agreement with a dissemination plan that includes publication(s) in peer-reviewed journals and presentations at relevant national and international conferences and meetings. Trials registration numbers NCT03571347, NCT03587896
Spallation reactions. A successful interplay between modeling and applications
The spallation reactions are a type of nuclear reaction which occur in space
by interaction of the cosmic rays with interstellar bodies. The first
spallation reactions induced with an accelerator took place in 1947 at the
Berkeley cyclotron (University of California) with 200 MeV deuterons and 400
MeV alpha beams. They highlighted the multiple emission of neutrons and charged
particles and the production of a large number of residual nuclei far different
from the target nuclei. The same year R. Serber describes the reaction in two
steps: a first and fast one with high-energy particle emission leading to an
excited remnant nucleus, and a second one, much slower, the de-excitation of
the remnant. In 2010 IAEA organized a worskhop to present the results of the
most widely used spallation codes within a benchmark of spallation models. If
one of the goals was to understand the deficiencies, if any, in each code, one
remarkable outcome points out the overall high-quality level of some models and
so the great improvements achieved since Serber. Particle transport codes can
then rely on such spallation models to treat the reactions between a light
particle and an atomic nucleus with energies spanning from few tens of MeV up
to some GeV. An overview of the spallation reactions modeling is presented in
order to point out the incomparable contribution of models based on basic
physics to numerous applications where such reactions occur. Validations or
benchmarks, which are necessary steps in the improvement process, are also
addressed, as well as the potential future domains of development. Spallation
reactions modeling is a representative case of continuous studies aiming at
understanding a reaction mechanism and which end up in a powerful tool.Comment: 59 pages, 54 figures, Revie
A Computing and Detector Simulation Framework for the HIBEAM/NNBAR Experimental Program at the ESS
The HIBEAM/NNBAR program is a proposed two-stage experiment at the European
Spallation Source focusing on searches for baryon number violation via
processes in which neutrons convert to antineutrons. This paper outlines the
computing and detector simulation framework for the HIBEAM/NNBAR program. The
simulation is based on predictions of neutron flux and neutronics together with
signal and background generation. A range of diverse simulation packages are
incorporated, including Monte Carlo transport codes, neutron ray-tracing
simulation packages, and detector simulation software. The common simulation
package in which these elements are interfaced together is discussed. Data
management plans and triggers are also described.Comment: Contribution to CHEP2021. Accepted for publication in the European
Physical Journal (EPJ) Web of Conference
Development of a High Intensity Neutron Source at the European Spallation Source: The HighNESS project
The European Spallation Source (ESS), presently under construction in Lund,
Sweden, is a multidisciplinary international laboratory that will operate the
world's most powerful pulsed neutron source. Supported by a 3M Euro Research
and Innovation Action within the EU Horizon 2020 program, a design study
(HighNESS) is now underway to develop a second neutron source below the
spallation target. Compared to the first source, located above the spallation
target and designed for high cold and thermal brightness, the new source will
provide higher intensity, and a shift to longer wavelengths in the spectral
regions of cold (2 /- 20 {\AA}), very cold (VCN, 10 /- 120 {\AA}), and ultra
cold (UCN, > 500 {\AA}) neutrons. The core of the second source will consist of
a large liquid deuterium moderator to deliver a high flux of cold neutrons and
to serve secondary VCN and UCN sources, for which different options are under
study. The features of these new sources will boost several areas of condensed
matter research and will provide unique opportunities in fundamental physics.
Part of the HighNESS project is also dedicated to the development of future
instruments that will make use of the new source and will complement the
initial suite of instruments in construction at ESS. The HighNESS project
started in October 2020. In this paper, the ongoing developments and the
results obtained in the first year are described.Comment: 10 pages, 10 figures, 14th International Topical Meeting on Nuclear
Applications of Accelerators, November 30 to December 4, 2021, Washington, D
TRY plant trait database - enhanced coverage and open access
Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives
Identification of Phosphoproteins as Possible Differentiation Markers in All-Trans-Retinoic Acid-Treated Neuroblastoma Cells
BACKGROUND: Neuroblastic tumors account for 9-10% of pediatric tumors and neuroblastoma (NB) is the first cause of death in pre-school age children. NB is classified in four stages, depending on the extent of spreading. A fifth type of NB, so-called stage 4S (S for special), includes patients with metastatic tumors but with an overall survival that approximates 75% at five years. In most of these cases, the tumor regresses spontaneously and regression is probably associated with delayed neuroblast cell differentiation. METHODOLOGY/PRINCIPAL FINDINGS: In order to identify new early markers to follow and predict this process for diagnostic and therapeutics intents, we mimicked the differentiation process treating NB cell line SJ-NK-P with all-trans-retinoic acid (ATRA) at different times; therefore the cell proteomic pattern by mass spectrometry and the phosphoproteomic pattern by a 2-DE approach coupled with anti-phosphoserine and anti-phosphotyrosine western blotting were studied. CONCLUSIONS/SIGNIFICANCE: Proteomic analysis identified only two proteins whose expression was significantly different in treated cells versus control cells: nucleoside diphosphate kinase A (NDKA) and reticulocalbin-1 (RCN1), which were both downregulated after 9 days of ATRA treatment. However, phosphoproteomic analysis identified 8 proteins that were differentially serine-phosphorylated and 3 that were differentially tyrosine-phosphorylated after ATRA treatment. All proteins were significantly regulated (at least 0.5-fold down-regulated). Our results suggest that differentially phosphorylated proteins could be considered as more promising markers of differentiation for NB than differentially expressed proteins
The HIBEAM program: search for neutron oscillations at the ESS
With the construction of the European Spallation Source, a remarkable
opportunity has emerged to conduct high sensitivity searches for neutron
oscillations, including a first search for thirty years for free neutrons
converting to antineutrons. Furthermore, searches can be made for transitions
of neutrons and antineutrons to sterile neutron states. The HIBEAM program
provides an increase in sensitivity of an order of magnitude compared to
previous work.
The HIBEAM program corresponds to baryon number violation by one and two
units. The observation of a process satisfying a Sakharov condition addresses
the open question of the origin of the matter-antimatter asymmetry in the
Universe. Sterile neutron states would belong to a `dark' sector of particles
which may explain dark matter. As electrically neutral, meta-stable objects
that can be copiously produced and studied, neutrons represent an attractive
portal to a `dark' sector.
This paper describes the capability, design, infrastructure, and potential of
the HIBEAM program. This includes a dedicated beamline, neutron optical system,
magnetic shielding and control, and detectors for neutrons and antineutrons.Comment: 41 pages, 12 figure
The Development of the NNBAR Experiment
The NNBAR experiment for the European Spallation Source will search for free
neutrons converting to antineutrons with a sensitivity improvement of three
orders of magnitude compared to the last such search. This paper describes
progress towards a conceptual design report for NNBAR. The design of a
moderator, neutron reflector, beamline, shielding and annihilation detector is
reported. The simulations used form part of a model which will be used for
optimisation of the experiment design and quantification of its sensitivity.Comment: 30 pages, 26 figures, accepted for publication in Journal of
Instrumentation (JINST
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