179 research outputs found
â¶ÂłCu(n,Îł ) cross section measured via 25 keV activation and time of flight
In the nuclear mass range Aâ60 to 90 of the solar abundance distribution the weak s-process component is the dominant contributor. In this scenario, which is related to massive stars, the overall neutron exposure is not sufficient for the s process to reach mass flow equilibrium. Hence, abundances and isotopic ratios are very sensitive to the neutron capture cross sections of single isotopes, and nucleosynthesis models need accurate experimental data. In this work we report on a new measurement of the Cu63(n,Îł) cross section for which the existing experimental data show large discrepancies. The Cu63(n,Îł) cross section at kBT=25 keV was determined via activation with a quasistellar neutron spectrum at the Joint Research Centre (JRC) in Geel, and the energy dependence was determined with the time-of-flight technique and the calorimetric 4ÏBaF2 detector array DANCE at the Los Alamos National Laboratory. We provide new cross section data for the whole astrophysically relevant energy range
Simulations of the High-Energy Beam-Transport (HEBT) section at FRANZ
The neutron source FRANZ (Frankfurter Neutronenquelle am
Stern-Gerlach-Zentrum), which is currently under construction, will be the neutron source with the highest intensity in the nuclear-astrophysically relevant energy
region. The TraceWin code was used to design the High-Energy Beam-Transport section with regard to the experimental requirements at different target positions
Effects of silver sulfide nanomaterials on mycorrhizal colonization of tomato plants and soil microbial communities in biosolid-amended soil
We investigated effects of Ag2S engineered nanomaterials (ENMs), polyvinylpyrrolidone (PVP) coated Ag ENMs (PVP-Ag), and Ag+ on arbuscular mycorrhizal fungi (AMF), their colonization of tomato (Solanum lycopersicum), and overall microbial community structure in biosolids-amended soil. Concentration-dependent uptake was measured in all treatments. Plants exposed to 100 mg kgâ1 PVP-Ag ENMs and 100 mg kgâ1 Ag+ exhibited reduced biomass and greatly reduced mycorrhizal colonization. Bacteria, actinomycetes and fungi were inhibited by all treatment classes, with the largest reductions measured in 100 mg kgâ1 PVP-Ag ENMs and 100 mg kgâ1 Ag+. Overall, Ag2S ENMs were less toxic to plants, less disruptive to plant-mycorrhizal symbiosis, and less inhibitory to the soil microbial community than PVP-Ag ENMs or Ag+. However, significant effects were observed at 1 mg kgâ1 Ag2S ENMs, suggesting that the potential exists for microbial communities and the ecosystem services they provide to be disrupted by environmentally relevant concentrations of Ag2S ENMs.Jonathan D. Judy, Jason K. Kirby, Courtney Creamer, Mike J. McLaughlin, Cathy Fiebiger, Claire Wright, Timothy R. Cavagnaro, Paul M. Bertsc
Normal Utilization as the Adjusting Variable in Neo-Kaleckian Growth Models: A Critique
As well-known, the canonical Neo-Kaleckian growth model fails to reconcile actual and normal rates of utilization in equilibrium. Some recent contributions revive an old proposal for solving this problem â making the normal rate of utilization an endogenous variable that converges to the actual utilization rate â justifying it with new, micro-founded premises. We argue that these new justifications for the convergence of normal to actual utilization do not stand closer scrutiny. First, the proposed microeconomic model relies on various restrictive assumptions, some of which are mutually inconsistent. Second, the derivation of the macroeconomic adjustment mechanism from the microeconomic analysis involves a logical leap, that can be justified only by a very arbitrary assumption with little economic justification. Finally, we discuss the way in which this mechanism has been incorporated into the Neo-Kaleckian growth model by proposers of this approach. We show that, even if one puts aside, for the sake of argument, the first two points, the existence of autonomous components of demand is sufficient to invalidate the resulting macroeconomic model
Somatostatin-receptor scintigraphy for staging and follow-up of patients with extraintestinal marginal zone B-cell lymphoma of the mucosa associated lymphoid tissue (MALT)-type
The majority of lymphomas of the mucosa-associated lymphoid tissue (MALT)-type arise in the stomach, but extragastric locations are also frequently encountered. Due to previous results indicating that somatostatin receptor (SSTR)-expression distinguishes between gastric and extragastric MALT-type lymphoma, we have initiated a study to evaluate the role of SSTR-scintigraphy for staging and follow-up of patients with extragastric manifestations of MALT-type lymphoma. A total of 30 consecutive patients, including 24 with primary extragastric MALT-type lymphoma, 5 patients with dissemination to extragastric sites (including colon, lung, parotid, ocular adnexa and breast) following an initial gastric MALT-lymphoma and one patient with spread to stomach, lung and lymph nodes following parotid lymphoma were prospectively studied. All patients had histologically verified MALT-type lymphoma: 2 patients had lymphoma presenting in the lung, 9 in the ocular adnexa, 7 had lymphomas in the parotid, 2 patients had disease located in the breast, 3 patients had lymph-node relapse following MALT-type lymphoma of the parotid, the lacrimal gland and the thyroid, and 1 had primary MALT-lymphoma of the liver. All patients underwent SSTR-scintigraphy using 111In-DTPA-D-Phe1-Octreotide (111In-OCT) before initiation of therapy, while 13 also had a second scan after treatment. The results of gamma camera imaging were compared to conventional staging. No positive scans could be obtained in patients with dissemination following gastric lymphoma, while all patients with primary extragastric lymphoma had positive scans at the site of histologically documented involvement before initiation of therapy. In addition, also the patient with secondary spread to stomach, lung and lymph nodes was positive in all documented lymphoma sites. In one patient, focal tracer uptake in projection to the maxillary sinus was documented, which was bioptically verified as inflammation. In the scans performed after therapy, focal tracer accumulation in the left orbit indicated persistance of disease following irradiation in one patient with otherwise negative work-up, which was verified by MRI and biopsy 6 months later. In another patient, a positive scan indicated disease relapse in the lacrimal gland 9 months before clinical verification by means of ultrasound. In one patient, a focus not present in the pretherapeutic scan was found in the ethmoidal sinus, corresponding to a hyperplastic polyp. Both SST-scan as well as CT indicated disease persistance in one case, while negative scans corresponding to complete remission as judged by conventional staging were obtained following therapy in the remaining patients, and absence of relapse has been confirmed for a median follow-up of 2 years. These results indicate that 111In-OCT is an excellent tool for staging and non-invasive therapy-monitoring in extragastric MALT-type lymphomas. These data further confirm our initial finding that gastric MALT-type lymphomas do not express relevant amounts of respective SSTR, and that SSTR-scanning is able to distinguish between gastric vs extragastric origin of MALT-type lymphoma irrespective of the site of presentation.© 2001 Cancer Research Campaignââhttp://www.bjcancer.co
Neutron activation of Ga and Ga at kBTâ25 keV
Background: About 50% of heavy elements are produced by the slow neutron capture process (s process) in stars. The element gallium is mostly produced during the weak s process in massive stars.
Purpose: Our activation at kTâ25 keV is the first experiment in a series of activation and time-of-flight measurements on Ga and Ga relevant for astrophysics.
Methods: We activated Ga and Ga with a neutron distribution that corresponds to a quasistellar distribution with kT=25 keV at the Joint Research Centre (JRC), Geel, Belgium. Protons were provided by an electrostatic Van de Graaff accelerator to produce neutrons via the reaction Li(p,n). The produced activity was measured via the Îł emission by the decaying product nuclei by high-purity germanium detectors.
Results: We provide spectrum-averaged cross sections (SACS) and ratios of the cross sections Ï/Ï for the neutron spectrum of the activation. We obtain values of Ï=(186±12) mb and Ï = (112±7) mb, and cross section ratios of Ï/Ï=0.29±0.02 and Ï/Ï = 0.17±0.01.
Conclusions: Our data disagree with the available evaluated data provided by KADoNiS v0.3, our cross-section ratio is about 20% higher for Ga and about 20% lower for Ga
Approaching the Gamow Window with Stored Ions : Direct Measurement of Xe 124 (p,Îł) in the ESR Storage Ring
© 2019 American Physical Society. All rights reserved.We report the first measurement of low-energy proton-capture cross sections of Xe124 in a heavy-ion storage ring. Xe12454+ ions of five different beam energies between 5.5 and 8 AMeV were stored to collide with a windowless hydrogen target. The Cs125 reaction products were directly detected. The interaction energies are located on the high energy tail of the Gamow window for hot, explosive scenarios such as supernovae and x-ray binaries. The results serve as an important test of predicted astrophysical reaction rates in this mass range. Good agreement in the prediction of the astrophysically important proton width at low energy is found, with only a 30% difference between measurement and theory. Larger deviations are found above the neutron emission threshold, where also neutron and γ widths significantly impact the cross sections. The newly established experimental method is a very powerful tool to investigate nuclear reactions on rare ion beams at low center-of-mass energies.Peer reviewedFinal Published versio
A Soluble Form of the High Affinity IgE Receptor, Fc-Epsilon-RI, Circulates in Human Serum
Soluble IgE receptors are potential in vivo modulators of
IgE-mediated immune responses and are thus important for our basic understanding
of allergic responses. We here characterize a novel soluble version of the
IgE-binding alpha-chain of Fc-epsilon-RI (sFcΔRI), the high affinity
receptor for IgE. sFcΔRI immunoprecipitates as a protein of âŒ40 kDa and
contains an intact IgE-binding site. In human serum, sFcΔRI is found as a
soluble free IgE receptor as well as a complex with IgE. Using a newly
established ELISA, we show that serum sFcΔRI levels correlate with serum IgE
in patients with elevated IgE. We also show that serum of individuals with
normal IgE levels can be found to contain high levels of sFcΔRI. After
IgE-antigen-mediated crosslinking of surface FcΔRI, we detect sFcΔRI in
the exosome-depleted, soluble fraction of cell culture supernatants. We further
show that sFcΔRI can block binding of IgE to FcΔRI expressed at the cell
surface. In summary, we here describe the alpha-chain of FcΔRI as a
circulating soluble IgE receptor isoform in human serum
Relationships between Levels of Serum IgE, Cell-Bound IgE, and IgE-Receptors on Peripheral Blood Cells in a Pediatric Population
Background: Elevated serum immunoglobulin (Ig) E is a diagnostic marker of immediate-type allergic reactions. We hypothesize that serum IgE does not necessarily reflect total body IgE because in vivo IgE can be bound to cell surface receptors such as FcΔRI and FcΔRII (CD23). The aim of this study was to analyze the relationships between levels of serum IgE, cell-bound IgE, and IgE-receptors on peripheral blood cells in a pediatric population. Methodology: Whole blood samples from 48 children (26 boys, 22 girls, mean age 10,3±5,4 years) were analyzed by flow cytometry for FcΔRI, CD23, and cell-bound IgE on dendritic cells (CD11c+MHC class II+), monocytes (CD14+), basophils (CD123+MHC class II-) and neutrophils (myeloperoxidase+). Total serum IgE was measured by ELISA and converted into z-units to account for age-dependent normal ranges. Correlations were calculated using Spearman rank correlation test. Principal Findings: Dendritic cells, monocytes, basophils, and neutrophils expressed the high affinity IgE-receptor FcΔRI. Dendritic cells and monocytes also expressed the low affinity receptor CD23. The majority of IgE-receptor positive cells carried IgE on their surface. Expression of both IgE receptors was tightly correlated with cell-bound IgE. In general, cell-bound IgE on FcΔRI+ cells correlated well with serum IgE. However, some patients carried high amounts of cell-bound IgE despite low total serum IgE levels. Conclusion/Significance: In pediatric patients, levels of age-adjusted serum IgE, cell-bound IgE, and FcΔRI correlate. Even in the absence of elevated levels of serum IgE, cell-bound IgE can be detected on peripheral blood cells in a subgroup of patients
- âŠ