A Quasar-based Supermassive Black Hole Binary Population Model: Implications for the Gravitational Wave Background

The nanohertz gravitational wave background (GWB) is believed to be dominated by GW emission from supermassive black hole binaries (SMBHBs). Observations of several dual-active galactic nuclei (AGN) strongly suggest a link between AGN and SMBHBs, given that these dual-AGN systems will eventually form bound binary pairs. Here we develop an exploratory SMBHB population model based on empirically constrained quasar populations, allowing us to decompose the GWB amplitude into an underlying distribution of SMBH masses, SMBHB number density, and volume enclosing the GWB. Our approach also allows us to self-consistently predict the number of local SMBHB systems from the GWB amplitude. Interestingly, we find the local number density of SMBHBs implied by the common-process signal in the NANOGrav 12.5-yr data set to be roughly five times larger than previously predicted by other models. We also find that at most ∼25% of SMBHBs can be associated with quasars. Furthermore, our quasar-based approach predicts ≳95% of the GWB signal comes from z ≲ 2.5, and that SMBHBs contributing to the GWB have masses ≳108 M ⊙. We also explore how different empirical galaxy–black hole scaling relations affect the local number density of GW sources, and find that relations predicting more massive black holes decrease the local number density of SMBHBs. Overall, our results point to the important role that a measurement of the GWB will play in directly constraining the cosmic population of SMBHBs, as well as their connections to quasars and galaxy mergers.

The Income Gradient in Mortality during the Covid-19 Crisis: Evidence from Belgium

We use population-wide data from linked administrative registers to study the distributional pattern of mortality before and during the first wave of the Covid-19 pandemic in Belgium. Over the March-May 2020 study period, excess mortality is only found among those aged 65 and over. For this group, we find a significant negative income gradient in excess mortality, with excess deaths in the bottom income decile more than twice as high as in the top income decile for both men and women. However, given the high inequality in mortality in normal times, the income gradient in all-cause mortality is only marginally steeper during the peak of the health crisis when expressed in relative terms. Leveraging our individual-level data, we gauge the robustness of our results for other socioeconomic factors and decompose the role of individual vs. local effects. We provide direct evidence that geographic location effects on individual mortality are particularly strong during the first wave of the Covid-19 pandemic, channeling through the local number of Covid infections. This makes inference about the income gradient in excess mortality based on geographic variation misguided.

Implementation of a training protocol on intrauterine device insertion for resident physicians

Objective: To implement a training protocol on intrauterine device (IUD) insertion for resident physicians to improve women’s access to this method. Methods: The staff identified poor access to family planning, in Vila Lobato health center, specially to IUD, there were only 15 IUD insertions in 2015. This implementation research evaluated and identified the barriers of access to IUD use. Then, stakeholders and staff defined the access flow of patients to the health unit and, eventually, the training provided to resident physicians in gynecology and obstetrics (GO) and family medicine (FM). This is a retrospective cohort of the IUD insertions performed by residents between 2016 and 2018. Results : 252 copper IUDs were inserted from 2016 to 2018 and there was a progressive increase in the number of insertions (45 in 2016, 80 in 2017, and 126 in 2018). Thirty-four (16.4%) inadequate insertions and 15 (8.6%) expulsions were observed. There was no case of uterine perforation. Conclusion: The implementation of the protocol on IUD insertion for residents in the primary care setting increased the local number of IUD insertion and might be a strategy to improve the access to the contraceptive method.

Fracture, aggregation and segregation in dry, granular flows

Particle fracture, the formation of small particles as the result of the breakage of large ones, and aggregation, the formation of large particles as the result of the combination of small ones, have important implications in industry (e.g. food processing, pharmaceutical production) and geophysics (e.g., snow avalanches and rock debris flows). Also, the presence of particles of different size that result from fracture and aggregation can induce segregation, resulting in the migration of large and small particles to different regions of the flow. Here, we formulate simple models for fracture and agglomeration and analyze the evolution of measures of the relative concentration of two sizes of spheres due the combined effects of fracture, aggregation, and segregation in dense, dry, granular flows. Particle breakage and combination is influenced by the frequency of collisions, by the local number density of the spheres, and by the particle kinetic energy. Segregation is predicted using a kinetic theory proposed by Larcher & Jenkins [2].

The importance of magnification effects in galaxy-galaxy lensing

Magnification changes the observed local number density of galaxies on the sky. This biases the observed tangential shear profiles around galaxies: the so-called galaxy-galaxy lensing (GGL) signal. Inference of physical quantities, such as the mean mass profile of halos around galaxies, are correspondingly affected by magnification effects. We used simulated shear and galaxy data from the Millennium Simulation to quantify the effect on shear and mass estimates from the magnified lens and source number counts. The former is due to the large-scale matter distribution in the foreground of the lenses; the latter is caused by magnification of the source population by the matter associated with the lenses. The GGL signal is calculated from the simulations by an efficient fast Fourier transform, which can also be applied to real data. The numerical treatment is complemented by a leading-order analytical description of the magnification effects, which is shown to fit the numerical shear data well. We find the magnification effect is strongest for steep galaxy luminosity functions and high redshifts. For a KiDS+VIKING+GAMA-like survey with lens galaxies at redshift zd = 0.36 and source galaxies in the last three redshift bins with a mean redshift of ¯zs = 0.79, the magnification correction changes the shear profile up to 2%, and the mass is biased by up to 8%. We further considered an even higher redshift fiducial lens sample at zd = 0.83, with a limited magnitude of 22 mag in the r-band and a source redshift of zs = 0.99. Through this, we find that a magnification correction changes the shear profile up to 45% and that the mass is biased by up to 55%. As expected, the sign of the bias depends on the local slope of the lens luminosity function αd, where the mass is biased low for αd < 1 and biased high for αd > 1. While the magnification effect of sources is rarely more than 1% of the measured GGL signal, the statistical power of future weak lensing surveys warrants correction for this effect.

The way healthcare is funded is wrong: it should be linked to deaths as well as age, gender and social deprivation

Background: most spending on health occurs in the last few months of life. This study explored the number of deaths in England and their relationship to healthcare funding. Methods: post hoc analysis Results: the number of deaths range from 3.3 to 15.1/1000/year, and the number of deaths per general practitioner from 5.2 to 27.3/year. Hospital deaths range from 12 to 52/1000 admissions. The correlation between the allocation index used for funding and deaths is not perfect and suggests that some regions may get up to17% less and others 14% more funding than is equitable. Conclusion: there is considerable variation in the prevalence of death throughout England. If healthcare funding considered the local number of deaths it would be more equitable.