There is an urgent need for harmonization between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serology platforms and assays prior to defining appropriate correlates of protection and ...as well inform the development of new rapid diagnostic tests that can be used for serosurveillance as new variants of concern (VOC) emerge. We compared multiple SARS-CoV-2 serology reference materials to the WHO International Standard (WHO IS) to determine their utility as secondary standards, using an international network of laboratories with high-throughput quantitative serology assays. This enabled the comparison of quantitative results between multiple serology platforms.
Between April and December 2020, 13 well-characterized and validated SARS-CoV-2 serology reference materials were recruited from six different providers to qualify as secondary standards to the WHO IS. All the samples were tested in parallel with the National Institute for Biological Standards and Control (NIBSC) 20/136 and parallel-line assays were used to calculate the relevant potency and binding antibody units.
All the samples saw varying levels of concordance between diagnostic methods at specific antigen-antibody combinations. Seven of the 12 candidate materials had high concordance for the spike-immunoglobulin G (IgG) analyte percent coefficient of variation (%CV) between 5 and 44%.
Despite some concordance between laboratories, qualification of secondary materials to the WHO IS using arbitrary international units or binding antibody units per milliliter (BAU/ml) does not provide any benefit to the reference materials overall, due to the lack of consistent agreeable international unit (IU) or BAU/ml conversions between laboratories. Secondary standards should be qualified to well-characterized reference materials, such as the WHO IS, using serology assays that are similar to the ones used for the original characterization of the WHO IS.
Abstract Aim The primary aim of the study is to define the post‐colonoscopy colorectal cancer (PCCRC) three‐year rate and the post‐endoscopy upper gastrointestinal cancer (PEUGIC) three‐year rate ...across public hospitals in Aotearoa New Zealand. Method This retrospective cohort study will be conducted via the trainee‐led STRATA Collaborative network. All public hospitals in Aotearoa New Zealand will be eligible to participate. Data will be collected on all adult patients who are diagnosed with colorectal adenocarcinoma within 6 to 48 months of a colonoscopy and all adult patients diagnosed with gastroesophageal cancer within 6 to 48 months of an upper gastrointestinal endoscopy. The study period will be from 2010 to 2022. The primary outcome is the PCCRC 3‐year rate and the PEUGIC 3‐year rate. Secondary aims are to define and characterize survival after PCCRC or PEUGIC, the cause of PCCRC as based on the World Endoscopy Organization System of Analysis definitions, trends over time, and centre level variation. Conclusion This protocol describes the methodology for a nationwide retrospective cohort study on PCCRC and PEUGIC in Aotearoa New Zealand. These data will lay the foundation for future studies and quality improvement initiatives.
We investigate the demagnetization dynamics of the cycloidal and sinusoidal phases of multiferroic TbMnO3 by means of time-resolved resonant soft x-ray diffraction following excitation by an optical ...pump. The use of orthogonal linear x-ray polarizations provides information on the contribution from the different magnetic moment directions, which can be interpreted as signatures from multiferroic cycloidal spin order and sinusoidal spin order. Tracking these signatures in the time domain enables us to identify the transient magnetic phase created by intense photoexcitation of the electrons and subsequent heating of the spin system on a picosecond time scale. The transient phase is shown to exhibit mostly spin density wave character, as in the adiabatic case, while nevertheless retaining the wave vector of the cycloidal long-range order. Two different pump photon energies, 1.55 and 3.1 eV, lead to population of the conduction band predominantly via intersite d−d or intrasite p−d transitions, respectively. We find that the nature of the optical excitation does not play an important role in determining the dynamics of magnetic order melting. Further, we observe that the orbital reconstruction, which is induced by the spin ordering, disappears on a time scale comparable to that of the cycloidal order, attesting to a direct coupling between magnetic order and orbital reconstruction. Our observations are discussed in the context of recent theoretical models of demagnetization dynamics in strongly correlated systems, revealing the potential of this type of measurement as a benchmark for such theoretical studies.
Phys. Rev. B 96, 184414 (2017) We investigate the demagnetization dynamics of the cycloidal and sinusoidal
phases of multiferroic TbMnO$_3$ by means of time-resolved resonant soft x-ray
diffraction ...following excitation by an optical pump. Using orthogonal linear
x-ray polarizations, we suceeded in disentangling the response of the
multiferroic cycloidal spin order from the sinusoidal antiferromagnetic order
in the time domain. This enables us to identify the transient magnetic phase
created by intense photoexcitation of the electrons and subsequent heating of
the spin system on a picosecond timescale. The transient phase is shown to be a
spin density wave, as in the adiabatic case, which nevertheless retains the
wave vector of the cycloidal long range order. Two different pump photon
energies, 1.55 eV and 3.1 eV, lead to population of the conduction band
predominantly via intersite $d$-$d$ transitions or intrasite $p$-$d$
transitions, respectively. We find that the nature of the optical excitation
does not play an important role in determining the dynamics of magnetic order
melting. Further, we observe that the orbital reconstruction, which is induced
by the spin ordering, disappears on a timescale comparable to that of the
cycloidal order, attesting to a direct coupling between magnetic and orbital
orders. Our observations are discussed in the context of recent theoretical
models of demagnetization dynamics in strongly correlated systems, revealing
the potential of this type of measurement as a benchmark for such complex
theoretical studies.
We investigate the demagnetization dynamics of the cycloidal and sinusoidal phases of multiferroic TbMnO\(_3\) by means of time-resolved resonant soft x-ray diffraction following excitation by an ...optical pump. Using orthogonal linear x-ray polarizations, we suceeded in disentangling the response of the multiferroic cycloidal spin order from the sinusoidal antiferromagnetic order in the time domain. This enables us to identify the transient magnetic phase created by intense photoexcitation of the electrons and subsequent heating of the spin system on a picosecond timescale. The transient phase is shown to be a spin density wave, as in the adiabatic case, which nevertheless retains the wave vector of the cycloidal long range order. Two different pump photon energies, 1.55 eV and 3.1 eV, lead to population of the conduction band predominantly via intersite \(d\)-\(d\) transitions or intrasite \(p\)-\(d\) transitions, respectively. We find that the nature of the optical excitation does not play an important role in determining the dynamics of magnetic order melting. Further, we observe that the orbital reconstruction, which is induced by the spin ordering, disappears on a timescale comparable to that of the cycloidal order, attesting to a direct coupling between magnetic and orbital orders. Our observations are discussed in the context of recent theoretical models of demagnetization dynamics in strongly correlated systems, revealing the potential of this type of measurement as a benchmark for such complex theoretical studies.
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