Search for gravitational-lensing signatures in the full third observing run of the LIGO-Virgo network

Gravitational lensing by massive objects along the line of sight to the source causes distortions of gravitational wave-signals; such distortions may reveal information about fundamental physics, cosmology and astrophysics. In this work, we have extended the search for lensing signatures to all binary black hole events from the third observing run of the LIGO--Virgo network. We search for repeated signals from strong lensing by 1) performing targeted searches for subthreshold signals, 2) calculating the degree of overlap amongst the intrinsic parameters and sky location of pairs of signals, 3) comparing the similarities of the spectrograms amongst pairs of signals, and 4) performing dual-signal Bayesian analysis that takes into account selection effects and astrophysical knowledge. We also search for distortions to the gravitational waveform caused by 1) frequency-independent phase shifts in strongly lensed images, and 2) frequency-dependent modulation of the amplitude and phase due to point masses. None of these searches yields significant evidence for lensing. Finally, we use the non-detection of gravitational-wave lensing to constrain the lensing rate based on the latest merger-rate estimates and the fraction of dark matter composed of compact objects

Search for eccentric black hole coalescences during the third observing run of LIGO and Virgo

Despite the growing number of confident binary black hole coalescences observed through gravitational waves so far, the astrophysical origin of these binaries remains uncertain. Orbital eccentricity is one of the clearest tracers of binary formation channels. Identifying binary eccentricity, however, remains challenging due to the limited availability of gravitational waveforms that include effects of eccentricity. Here, we present observational results for a waveform-independent search sensitive to eccentric black hole coalescences, covering the third observing run (O3) of the LIGO and Virgo detectors. We identified no new high-significance candidates beyond those that were already identified with searches focusing on quasi-circular binaries. We determine the sensitivity of our search to high-mass (total mass M>70 M⊙) binaries covering eccentricities up to 0.3 at 15 Hz orbital frequency, and use this to compare model predictions to search results. Assuming all detections are indeed quasi-circular, for our fiducial population model, we place an upper limit for the merger rate density of high-mass binaries with eccentricities 0<e≤0.3 at 0.33 Gpc−3 yr−1 at 90\% confidence level

Ultralight vector dark matter search using data from the KAGRA O3GK run

Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for U(1)B−L gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the stochastic nature of ultralight DM, upper bounds on the coupling strength between the U(1)B−L gauge boson and ordinary matter are obtained for a range of DM masses. While our constraints are less stringent than those derived from previous experiments, this study demonstrates the applicability of our method to the lower-mass vector DM search, which is made difficult in this measurement by the short observation time compared to the auto-correlation time scale of DM

Features of antibody responses after SARS-COV-2 infection in healthcare workers in the first wave of COVID-19 pandemic in Mexico City

Objective To investigate the antibody response to SARS-CoV-2 and identify associated factors in frontline and second-line healthcare workers (HCWs) at a large hospital in Mexico City during the first wave of COVID-19 pandemic. Methods This was a cross-sectional study of HCWs returning to work following mandatory isolation after recovering from COVID-19. Immunoglobulin (Ig) M and IgG antibodies elicited by SARS-CoV-2 were semiquantitatively measured using densitometric analysis of band intensities in lateral flow assay (LFA) devices. The mean pixel intensity (dots-per-inch [dpi]) of each band on the LFA was considered a measure of antibody titre. Results Of the 111 HCWs involved in the study, antibody responses were detected in 73/111 (66%) participants. Severe COVID symptoms was associated with old age. No differences in IgM intensity were observed between men and women, but IgG intensity was significantly higher in men than in women. Second-line HCWs produced a higher IgG intensity than firstline HCWs. The IgG intensity was high in severe cases. Conclusions For HCWs who may acquire SARS-CoV-2 infection, it is necessary to establish a routine program for detection of the virus to avoid risk of infection and spread of COVID-19

Small RNAs containing the pathogenic determinant of a chloroplast-replicating viroid guide the degradation of a host mRNA as predicted by RNA silencing

[EN] How viroids, tiny non-protein-coding RNAs (250–400 nt), incite disease is unclear. One hypothesis is that viroid-derived small RNAs (vd-sRNAs; 21–24 nt) resulting from the host defensive response, via RNA silencing, may target for cleavage cell mRNAs and trigger a signal cascade, eventually leading to symptoms. Peach latent mosaic viroid (PLMVd), a chloroplast-replicating viroid, is particularly appropriate to tackle this question because it induces an albinism (peach calico, PC) strictly associated with variants containing a specific 12–14-nt hairpin insertion. By dissecting albino and green leaf sectors of Prunus persica (peach) seedlings inoculated with PLMVd natural and artificial variants, and cloning their progeny, we have established that the hairpin insertion sequence is involved in PC. Furthermore, using deep sequencing, semi-quantitative RT-PCR and RNA ligase-mediated rapid amplification of cDNA ends (RACE), we have determined that two PLMVd-sRNAs containing the PC-associated insertion (PC-sRNA8a and PC-sRNA8b) target for cleavage the mRNA encoding the chloroplastic heat-shock protein 90 (cHSP90), thus implicating RNA silencing in the modulation of host gene expression by a viroid. Chloroplast malformations previously reported in PC-expressing tissues are consistent with the downregulation of cHSP90, which participates in chloroplast biogenesis and plastid-tonucleus signal transduction in Arabidopsis. Besides PC-sRNA8a and PC-sRNA8b, both deriving from the lessabundant PLMVd ()) strand, we have identified other PLMVd-sRNAs potentially targeting peach mRNAs. These results also suggest that sRNAs derived from other PLMVd regions may downregulate additional peach genes, ultimately resulting in other symptoms or in a more favorable host environment for viroid infection.This work was supported by a dedicated grant from the Italian Ministry of Economy and Finance to the CNR (Legge n. 191/2009), the Dipartimento Agroalimentare of the CNR of Italy (A. Leone and D. Mariotti 2008 award for advanced research in agriculture to FDS) and by the Ministerio de Ciencia e Innovacion of Spain (grants BFU2008-03154 and BFU2011-28443 to RF).Navarro, B.; Gisel, A.; Rodio, ME.; Delgado Villar, SG.; Flores Pedauye, R.; Di Serio, F. (2012). Small RNAs containing the pathogenic determinant of a chloroplast-replicating viroid guide the degradation of a host mRNA as predicted by RNA silencing. Plant Journal. 70(6):991-1003. https://doi.org/10.1111/j.1365-313X.2012.04940.x991100370

25 years of time series forecasting

We review the past 25 years of research into time series forecasting. In this silver jubilee issue, we naturally highlight results published in journals managed by the International Institute of Forecasters (Journal of Forecasting 1982-1985 and International Journal of Forecasting 1985-2005). During this period, over one third of all papers published in these journals concerned time series forecasting. We also review highly influential works on time series forecasting that have been published elsewhere during this period. Enormous progress has been made in many areas, but we find that there are a large number of topics in need of further development. We conclude with comments on possible future research directions in this field