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221 result(s) for "Danon, Y."
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Chronic urticaria: association with thyroid autoimmunity
Background: Though autoimmune phenomena have been regularly associated with chronic urticaria in adults, data in children are sparse. Aim: To describe our experience with children and adolescents with chronic urticaria and autoimmunity. Methods and Results: Of 187 patients referred for evaluation of chronic urticaria during a 7.5 year period, eight (4.3%), all females aged 7–17 years, had increased levels of antithyroid antibody, either antithyroid peroxidase antibody (n = 4, >75 IU/ml), antithyroglobulin antibody (n = 2, >150 IU/ml), or both (n = 2). The duration of urticaria was four months to seven years. Five patients were euthyroid, one of whom was found to have increased antithyroid antibody levels five years after onset of the urticaria. One patient was diagnosed with Hashimoto thyroiditis three years before the urticaria, and was receiving treatment with thyroxine. Two other hypothyroid patients were diagnosed during the initial work up for urticaria (thyroxine 9.2 pmol/l, thyroid stimulating hormone (TSH) 40.2 mIU/l) and five years after onset of the urticaria (thyroxine 14 pmol/l, TSH 10.3 mIU/l). Both were treated with thyroxine but neither had remission of the urticaria. Five patients had a low positive titre of antinuclear antibodies. Conclusion: Children with chronic urticaria should be screened periodically for thyroxine, TSH, and antithyroid antibodies, as thyroid autoimmunity and hypothyroidism may appear several years after onset of the urticaria.
Recent Nuclear Data Activity at the RPI Gaerttner LINAC Center
The nuclear data group at the RPI Gaerttner LINAC Laboratory uses a 60 MeV pulsed electron LINAC to produce short pulses of neutrons and perform cross section and other nuclear data measurements in a wide energy range from below 1 meV to about 20 MeV. This paper will cover several recent activities that are of interest to nuclear applications. Interest in thermal neutron scattering evaluations prompted the need for accurate thermal total cross section measurements for validation. To improve the neutron flux in the sub-thermal region (below 0.01 eV) a cold moderator was designed and installed. A polyethylene moderator operating at about 26 K resulted in a factor of 8 increase in neutron flux below 0.01 eV. Using this new capability, several transmission measurements were performed with samples of polyethylene, polystyrene, Plexiglas, and yttrium hydride. Neutron capture and transmission measurements in the keV energy range were made for 54 Fe, which will be used in an evaluation effort that is underway. Capture measurements were collected on an array of C 6 D 6 detectors that was expanded from 4 to 7 detectors, and a complementary transmission measurement was also performed. Finally, research aimed at experimental validation of neutron capture gamma production is in progress. Energy dependent capture gamma cascades are measured with the RPI 16-segment gamma multiplicity detector. Measurements are then compared to capture gamma cascades generated from nuclear structure evaluations processed with DICEBOX and transported with a modified version of MCNP. This system provides important information on the completeness of primary gamma-ray databases.
HPRL – International cooperation to identify and monitor priority nuclear data needs for nuclear applications
The OECD-NEA High Priority Request List (HPRL) is a point of reference to guide and stimulate the improvement of nuclear data for nuclear energy and other applications, and a tool to bridge the gap between data users and producers. The HPRL is application-driven and the requests are submitted by nuclear data users or representatives of the user’s communities. A panel of international experts reviews and monitors the requests in the framework of an Expert Group mandated by the NEA Nuclear Science Committee Working Party on International Nuclear Data Evaluation Cooperation (WPEC). After approval, individual requests are classified to three categories: high priority requests, general requests, and special purpose requests (e.g., dosimetry, standards). The HPRL is hosted by the NEA in the form of a relational database publicly available on the web. This paper provides an overview of HPRL entries, status and outlook. Examples of requests successfully completed are given and new requests are described with emphasis on updated nuclear data needs in the fields of nuclear energy, neutron standards and dosimetry.
Progress in the Evaluation and Validation of n+56,57Fe Cross Sections
There has been a continued effort since 2019 within the IAEA INDEN collaboration to improve the evaluation of neutron induced reactions on iron isotopes. The reason for the 30% underestimation of the neutron leakage spectrum from a thick iron sphere was found primarily to be due to the overestimation of the inelastic cross sections in the 56Fe evaluated data file produced within the CIELO project of the OECD/NEA Data Bank. The over-estimation of the neutron flux between the resonances near 300 keV was traced to neglecting the fluctuating nature of the total cross section of 57Fe in the fast neutron energy range, since the evaluated resolved resonance range of 57Fe extended only up to 190 keV. The added 1/v background in the \"iron window\" below 28 keV is in excellent agreement with the independently evaluated one in the JENDL-5.0 library that included the direct capture component in the evaluation. Performance of the updated 56,57Fe evaluations was tested on a set of criticality benchmarks from the ICSBEP Handbook, including the dependence on reflector thickness and on new deep penetration shielding benchmark using a 252Cf(sf) neutron source undertaken at Rez, Czech Republic. Neutron leakage for 43 MeV incident neutrons was also validated.
Neutron capture measurements and resonance parameters of dysprosium
. Neutron capture yields of dysprosium isotopes ( 161 Dy, 162 Dy, 163 Dy, and 164 Dy were measured using the time-of-flight method with a 16 segment sodium iodide multiplicity detector. The measurements were made at the 25m flight station at the Gaerttner LINAC Center at Rensselaer Polytechnic Institute. Resonance parameters were obtained using the multilevel R-matrix Bayesian code SAMMY. The neutron capture data for four enriched dysprosium isotopes and one natural dysprosium sample were sequentially fitted. New resonances not listed in ENDF/B-VII.1 were observed. There were 29 and 17 new resonances from 161 Dy and 163 Dy isotopes, respectively. Six resonances from 161 Dy isotope, two resonances from 163 Dy, and four resonances from 164 Dy were not observed. The capture resonance integrals of each isotope were calculated with the resulting resonance parameters and those of ENDF/B-VII.1 in the energy region from 0.5eV to 20MeV and were compared to the capture resonance integrals with the resonance parameters from ENDF/B-VII.1. A resonance integral value of the natural dysprosium calculated with present resonance parameters was 1405 ± 3 . 5 barn. The value is ∼ 0 . 3 % higher than that obtained with the ENDF/B-VII.1 parameters. The distributions of the present and ENDF/B-VII.1 neutron widths were compared to a Porter-Thomas distribution. Neutron strength functions for 161 Dy and 163 Dy were calculated with the present resonance parameters and both values were in between the values of “Atlas of Neutron Resonances” and ENDF/B-VII.1. The present radiation width distributions of 161 Dy and 163 Dy were fitted with the χ 2 distribution by varying the degrees of freedom.
Erratum to: Neutron capture measurements and resonance parameters of dysprosium
. After publication of the paper, the authors realized that the acknowledgements were not correct. Their correct version appears in this erratum.
Pulse Mass Measles Vaccination Across Age Cohorts
Although vaccines against measles have been routinely applied over a quarter of a century, measles is still persistent in Israel, with major epidemics roughly every 5 years. Recent serological analyses have shown that only 85% of Israelis aged 18 years have anti-measles IgG antibodies. Considering the high transmissibility of the virus and the high level of herd immunity required for disease eradication, the Israeli vaccination policy against measles is now being reevaluated. Motivated by theoretical studies of populations in perturbed environments, we examined the possibility of replacing the conventional cohort vaccination strategy by a pulse strategy-i.e., periodic vaccination of several age cohorts at the same time. Numerical studies of a deterministic age-structured model suggest that vaccination, which renders immunity to no more than 85% of the susceptible children aged 1-7 years, once every 5 years will suffice to prevent epidemics in Israel, where infection rate is highest amongst schoolchildren. The model suggests that by using such a strategy the density of susceptible individuals is always kept below the threshold above which recurrent epidemics will be maintained. Analysis of simpler, non-age-structured, models serves to clarify the basic properties of the proposed strategy. Our theoretical results indicate that the advantages and disadvantages of a pulse strategy should be seriously examined in Israel and in countries with similar patterns of measles virus transmission.
Recent Developments in Nuclear Data Measurement capabilities at the Gaerttner LINAC Center at RPI
The Gaerttner LINAC Center at RPI uses a 60 MeV electron linear accelerator to produce short pulses of neutrons with duration of 5-5000 ns. The main research thrust at the Center is nuclear data for nuclear reactors and criticality safety applications. The Center includes several setups for time-of-flight measurements including neutron transmission, capture and scattering detectors, and a lead slowing-down spectrometer. Experiments were designed to produce neutron interaction cross sections that cover the energy range of 0.01 eV to 20 MeV. Recently added experiments include: setups for keV and fast neutron transmission, a C6D6 detector array for keV neutron capture measurements, and a fast neutron scattering system. Results discussed here include fast neutron scattering and angular distributions for natFe, iron capture measurements for incident neutrons from 1 keV to 2 MeV, fast neutron transmission through W and H2O samples, and keV transmission through Mo isotopes.
Therapeutic Dose from a Pyroelectric Electron Accelerator
Simple heating of pyroelectric crystals has been used as the basis for compact sources of X rays, electrons, ions and neutrons. We report on the evaluation of the feasibility of using a portable pyroelectric electron accelerator to deliver a therapeutic dose to tissue. Such a device could be mass produced as a handheld, battery-powered instrument. Experiments were conducted with several crystal sizes in which the crystal was heated inside a vacuum chamber and the emitted electrons were allowed to penetrate a thin beryllium window into the surrounding air. A Faraday cup was used to count the number of electrons that exited the window. The energy of these electrons was determined by measuring the energy spectrum of the X rays that resulted from the electron interactions with the Faraday cup. Based on these measurements, the dose that this source could deliver to tissue was calculated using Monte Carlo calculations. It was found that 1013 electrons with a peak energy of the order of 100 keV were emitted from the beryllium window and could deliver a dose of 1664 Gy to a 2-cm-diameter, 110-µm-deep region of tissue located 1.5 cm from the window with air between the window and the tissue. This dose level is high enough to consider this technology for medical applications in which shallow energy deposition is beneficial.
Using the vesicular stomatitis virus vector (rVSV vector) platform for SARS-CoV-2 vaccine development: Phase 1/2 safety and immunogenicity of IIBR-100 in healthy adults
We investigated the safety and immunogenicity of the IIBR-100 (rVSV-SARS-CoV-2-S) vaccine, a recombinant VSV-ΔG-spike vaccine against SARS-CoV-2 virus. In a phase 1/2, randomized, observer-blind, placebo-controlled study (ClinicalTrials.gov: NCT 04608305), healthy younger (18–55 years) and older (56–85 years) adults were recruited from eight clinical sites in Israel. In the phase 1 study, low (1 × 105 PFU), mid (1 × 106 PFU), and high doses (1 × 107 PFU) of IIBR-100 were tested in a single-dose treatment regimen, with an additional booster dose for the low-dose group only. Based on the phase 1 study results, only mid- and high-dose prime-boost regimens alongside an additional top dose (1 × 108 PFU) were tested in the phase 2 study. Participants, randomly assigned to either IIBR-100 or placebo, were followed for 12 months from the last vaccination for safety and immunogenicity outcomes. No safety concerns were observed in the phase 1 study (N = 82); therefore, the study moved on to phase 2. In phase 2 (N = 762), for both age groups, the most common AEs included injection-site pain (20–64 %), fatigue (21–33 %), and headache (15–22 %). In the top-dose group, neutralizing and binding antibody titers peaked on Days 35 and 42, respectively; seroconversion rates reached maximal levels by Day 56 for neutralizing antibody and binding antibody (spike and RBD). The IIBR-100 vaccine against SARS-CoV-2 in prime-boost regimens at 1 × 107 PFU/mL and 1 × 108 PFU/mL doses is safe, well tolerated, and immunogenic in healthy adults. This trial is registered at ClinicalTrials.gov (NCT 04608305) and in the trial registry of the Israeli Ministry of Health website. •IIBR-100 at prime-boost regimens up to 1 × 108 PFU/mL is safe and well tolerated.•The most common adverse events were injection-site pain, fatigue, and headache.•Neutralizing and binding antibody titers peaked on Day 35 and 42, respectively.•Neutralizing and binding antibodies reached max seroconversion levels by Day 56.•IIBR-100 was immunogenic in younger (18–55 years) and older (56–85 years) adults.