High-order harmonic generation with a strong laser field and an attosecond-pulse train: the Dirac Delta comb and monochromatic limits

In recent publications, it has been shown that high-order harmonic generation can be manipulated by employing a time-delayed attosecond pulse train superposed to a strong, near-infrared laser field. It is an open question, however, which is the most adequate way to approximate the attosecond pulse train in a semi-analytic framework. Employing the Strong-Field Approximation and saddle-point methods, we make a detailed assessment of the spectra obtained by modeling the attosecond pulse train by either a monochromatic wave or a Dirac-Delta comb. These are the two extreme limits of a real train, which is composed by a finite set of harmonics. Specifically, in the monochromatic limit, we find the downhill and uphill sets of orbits reported in the literature, and analyze their influence on the high-harmonic spectra. We show that, in principle, the downhill trajectories lead to stronger harmonics, and pronounced enhancements in the low-plateau region. These features are analyzed in terms of quantum interference effects between pairs of quantum orbits, and compared to those obtained in the Dirac-Delta limit.Comment: 10 pages, 7 figures (eps files). To appear in Laser Physic

High clinical performance and quantitative assessment of antibody kinetics using a dual recognition assay for the detection of SARS-CoV-2 IgM and IgG antibodies

Objectives: Several serological SARS-CoV-2 immunoassays have been developed recently but require external validation before widespread use. This study aims at assessing the analytical and clinical performance of the iFlash® anti-SARS-CoV-2 chemiluminescence assay for the detection of both IgM and IgG antibodies. The kinetics of the antibody response was also evaluated. Design & Methods: The precision, carry-over, linearity, limit of blank, detection and quantification were assessed. Sensitivity analysis was performed by using 178 sera collected from 154 RT-PCR confirmed COVID-19 patients. The specificity analysis was performed from 75 selected non-SARS-CoV-2 sera with a potential cross-reaction to the SARS-CoV-2 immunoassay. Results: This iFlash® SARS-CoV-2 assay showed excellent analytical performance. After 2 weeks since symptom onset, the sensitivities for IgM and IgG were 62.2% (95% CI: 52.3–71.2%) and 92.9%% (95% CI: 85.7–96.7%), respectively by using the cut-off provided by the manufacturer. After cut-off optimization (i.e. >2.81 for IgM and >4.86 for IgG), the sensitivity for IgM and IgG were 81.6 (95% CI: 72.7–88.1%) and 95.9% (95% CI: 89.4–98.7%), respectively. Optimized cut-off for IgG improved the sensitivity to reach 100% (95%CI: 87.6–100) from 28 days since symptom onset. Conclusions: This study shows that the iFlash® SARS-CoV-2 assay from YHLO biotechnology, has satisfactory analytical performance. Nevertheless, the sensitivity of the IgM is limited for a proper clinical use compared to IgG. The determination of anti-SARS-CoV-2 IgG antibodies from 28 days since symptom onset was associated with high sensitivity, especially using optimized cut-offs (i.e. 100%).SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Laser-Induced Electron Diffraction in Chiral Molecules

Strong laser pulses enable probing molecules with their own electrons. The oscillating electric field tears electrons off a molecule, accelerates them, and drives them back toward their parent ion within a few femtoseconds. The electrons are then diffracted by the molecular potential, encoding its structure and dynamics with angstrom and attosecond resolutions. Using elliptically polarized laser pulses, we show that laser-induced electron diffraction is sensitive to the chirality of the target. The field selectively ionizes molecules of a given orientation and drives the electrons along different sets of trajectories, leading them to recollide from different directions. Depending on the handedness of the molecule, the electrons are preferentially diffracted forward or backward along the light propagation axis. This asymmetry, reaching several percent, can be reversed for electrons recolliding from two ends of the molecule. The chiral sensitivity of laser-induced electron diffraction opens a new path to resolve ultrafast chiral dynamics

Les colorimètres numériques (une solution d'avenir pour la prise de teinte ?)

LILLE2-BU Santé-Recherche (593502101) / SudocLILLE2-UFR Odontologie (593502202) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Dysfunction

"DYSFUNCTION is a free artistic and academic journal printed on newsprint created by Natalia Bobadilla, Antoine Lefebvre and Philippe Mairesse as part of the research program ANR ABRIR, which was a collaboration between artists researchers from the ART & FLUX team and management researchers of the DRM MOST, between 2013 and 2017. DYSFUNCTION is hybrid, both an artist publication and a research object. Each issue highlights a project that combines art and research in social sciences and humanities, and disseminates research findings through artistic forms. DYSFUNCTION is published by antoine lefebvre editions in an edition of 1000 copies under the Creative Commons BY-NC-SA license." -- Periodical's website

Analytical performances and biological variation of PIVKA-II (des-y-carboxy-prothrombin) in European healthy adults.

BACKGROUND: PIVKA-II (DCP) is increasingly used for the diagnosis and the surveillance of hepatocellular carcinoma (HCC) in at-risk populations. However, to date, few data are available concerning the intra- and inter-individual variability of this marker, which makes the interpretation of serial measurements difficult in the context of monitoring. METHODS: 19 European healthy volunteers (HVs) were taken each week during five consecutive weeks. Samples were analyzed in duplicate on the Lumipulse® analyzer (Fujirebio, Gent, Belgium). Analytical variation (CVA), within-subject biological variation (CVI) and between-subject biological variation (CVG) were calculated using nested ANOVA following normality assessment, outlier exclusion, and homogeneity of variance analysis. RESULTS: No significant difference was observed for the mean values (p = 0.23) between men (mean: 30.66 mAU/mL) and women (mean: 33.90 mAU/mL) subgroups. CVA was 2.82% while sex-independent CVI and CVG were 13.35% and 16.05%, respectively. Taking these values, the calculated reference change value (RCV) and index of individuality were 37.70% and 0.85, respectively. CONCLUSION: We reported for the first-time biological variation data for PIVKA-II in a cohort of European HVs. We believe that our results can be used to set analytical specification goals as well as to improve the interpretation of serial measurements of PIVKA-II for monitoring purposes

Absolute gas density profiling in high-order harmonic generation: erratum

In this erratum, we correct two numerical errors due to conversion mistakes from our previous published manuscript [Opt. Express 26, 6001 (2018)]. In the original manuscript, the two errors compensated each other such that the conclusions remain perfectly unchanged