293 research outputs found
Gamma-widths, lifetimes and fluctuations in the nuclear quasi-continuum
Statistical -decay from highly excited states is determined by the
nuclear level density (NLD) and the -ray strength function
(SF). These average quantities have been measured for several nuclei
using the Oslo method. For the first time, we exploit the NLD and SF to
evaluate the -width in the energy region below the neutron binding
energy, often called the quasi-continuum region. The lifetimes of states in the
quasi-continuum are important benchmarks for a theoretical description of
nuclear structure and dynamics at high temperature. The lifetimes may also have
impact on reaction rates for the rapid neutron-capture process, now
demonstrated to take place in neutron star mergers.Comment: CGS16, Shanghai 2017, Proceedings, 5 pages, 3 figure
Statistical properties of Pu, and Pu(n,) cross section calculation
The level density and gamma-ray strength function (gammaSF) of 243Pu have
been measured in the quasi-continuum using the Oslo method. Excited states in
243Pu were populated using the 242Pu(d,p) reaction. The level density closely
follows the constant-temperature level density formula for excitation energies
above the pairing gap. The gammaSF displays a double-humped resonance at low
energy as also seen in previous investigations of actinide isotopes. The
structure is interpreted as the scissors resonance and has a centroid of
omega_{SR}=2.42(5)MeV and a total strength of B_{SR}=10.1(15)mu_N^2, which is
in excellent agreement with sum-rule estimates. The measured level density and
gammaSF were used to calculate the 242Pu(n,gamma) cross section in a neutron
energy range for which there were previously no measured data.Comment: 9 pages, 8 figure
The Nlrp3 inflammasome regulates acute graft-versus-host disease
The success of allogeneic hematopoietic cell transplantation is limited by acute graft-versus-host disease (GvHD), a severe complication accompanied by high mortality rates. Yet, the molecular mechanisms initiating this disease remain poorly defined. In this study, we show that, after conditioning therapy, intestinal commensal bacteria and the damage-associated molecular pattern uric acid contribute to Nlrp3 inflammasome-mediated IL-1β production and that gastrointestinal decontamination and uric acid depletion reduced GvHD severity. Early blockade of IL-1β or genetic deficiency of the IL-1 receptor in dendritic cells (DCs) and T cells improved survival. The Nlrp3 inflammasome components Nlrp3 and Asc, which are required for pro-IL-1β cleavage, were critical for the full manifestation of GvHD. In transplanted mice, IL-1β originated from multiple intestinal cell compartments and exerted its effects on DCs and T cells, the latter being preferentially skewed toward Th17. Compatible with these mouse data, increased levels of active caspase-1 and IL-1β were found in circulating leukocytes and intestinal GvHD lesions of patients. Thus, the identification of a crucial role for the Nlrp3 inflammasome sheds new light on the pathogenesis of GvHD and opens a potential new avenue for the targeted therapy of this severe complication
Statistical properties of the well deformed Sm nuclei and the scissors resonance
The Nuclear Level Densities (NLDs) and the -ray Strength Functions
(SFs) of Sm have been extracted from (d,p)
coincidences using the Oslo method. The experimental NLD of Sm is
higher than the NLD of Sm, in accordance with microscopic calculations.
The SFs of Sm are in fair agreement with QRPA calculations
based on the D1M Gogny interaction. An enhancement is observed in the
SF for both Sm nuclei around 3 MeV in excitation energy and
is attributed to the M1 Scissors Resonance (SR). Their integrated strengths
were found to be in the range 1.3 - 2.1 and 4.4 - 6.4 for
Sm and Sm, respectively. The strength of the SR for Sm
is comparable to those for deformed even-even Sm isotopes from nuclear
resonance fluorescence measurements, while that of Sm is lower than
expected
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