A large, long-lived structure near the trojan L5 point in the post common-envelope binary SDSS J1021+1744

SDSS J1021+1744 is a detached, eclipsing white dwarf / M dwarf binary discovered in the Sloan Digital Sky Survey. Outside the primary eclipse, the light curves of such systems are usually smooth and characterised by low-level variations caused by tidal distortion and heating of the M star component. Early data on SDSS J1021+1744 obtained in June 2012 was unusual in showing a dip in flux of uncertain origin shortly after the white dwarf’s eclipse. Here we present high-time resolution, multi-wavelength observations of 35 more eclipses over 1.3 years, showing that the dip has a lifetime extending over many orbits. Moreover the “dip” is in fact a series of dips that vary in depth, number and position, although they are always placed in the phase interval 1.06 to 1.26 after the white dwarf’s eclipse, near the L5 point in this system. Since SDSS J1021+1744 is a detached binary, it follows that the dips are caused by the transit of the white dwarf by material around the Lagrangian L5 point. A possible interpretation is that they are the signatures of prominences, a phenomenon already known from Hα observations of rapidly rotating single stars as well as binaries. What makes SDSS J1021+1744 peculiar is that the material is dense enough to block continuum light. The dips appear to have finally faded out around 2015 May after the first detection by Parsons et al. in 2012, suggesting a lifetime of year

Optical detection of the rapidly spinning white dwarf in V1460 Her

Accreting magnetic white dwarfs offer an opportunity to understand the interplay between spin-up and spin-down torques in binary systems. Monitoring of the white dwarf spin may reveal whether the white dwarf spin is currently in a state of near-equilibrium, or of uni-directional evolution towards longer or shorter periods, reflecting the recent history of the system and providing constraints for evolutionary models. This makes the monitoring of the spin history of magnetic white dwarfs of high interest. In this paper we report the results of a campaign of follow-up optical photometry to detect and track the 39 sec white dwarf spin pulses recently discovered in Hubble Space Telescope data of the cataclysmic variable V1460 Her. We find the spin pulsations to be present in g-band photometry at a typical amplitude of 0.4 per cent. Under favourable observing conditions, the spin signal is detectable using 2-meter class telescopes. We measured pulse-arrival times for all our observations, which allowed us to derive a precise ephemeris for the white dwarf spin. We have also derived an orbital modulation correction that can be applied to the measurements. With our limited baseline of just over four years, we detect no evidence yet for spin-up or spin-down of the white dwarf, obtaining a lower limit of |P/P˙|>4×107 years, which is already 4 to 8 times longer than the timescales measured in two other cataclysmic variable systems containing rapidly rotating white dwarfs, AE Aqr and AR Sco

Optical detection of the rapidly spinning white dwarf in V1460 Her

Accreting magnetic white dwarfs offer an opportunity to understand the interplay between spin-up and spin-down torques in binary systems. Monitoring of the white dwarf spin may reveal whether the white dwarf spin is currently in a state of near-equilibrium, or of unidirectional evolution towards longer or shorter periods, reflecting the recent history of the system and providing constraints for evolutionary models. This makes the monitoring of the spin history of magnetic white dwarfs of high interest. In this paper, we report the results of a campaign of follow-up optical photometry to detect and track the 39- s white dwarf spin pulses recently discovered in Hubble Space Telescope data of the cataclysmic variable V1460 Her. We find the spin pulsations to be present in the g-band photometry at a typical amplitude of 0.4 per cent. Under favourable observing conditions, the spin signal is detectable using 2-m class telescopes. We measured pulse-arrival times for all our observations, which allowed us to derive a precise ephemeris for the white dwarf spin. We have also derived an orbital modulation correction that can be applied to the measurements. With our limited baseline of just over 4 yr, we detect no evidence yet for spin-up or spin-down of the white dwarf, obtaining a lower limit of $|P/\dot{P}| \gt 4\times 10^{7}$ yr, which is already four to eight times longer than the time-scales measured in two other cataclysmic variable systems containing rapidly rotating white dwarfs, AE Aqr and AR Sco.</p

Immigrant Woman at Risk for Post-Partum Depression: Integrative Review

Immigrant Woman at Risk for Post-Partum Depression: Integrative Review March 14, 2022 Brooke Ashton, University of Windsor Melissa Gjetaj, University of Windsor Amie Hawkins, University of Windsor Sabreena Mirza, University of Windsor Chanthorn Sok, University of Windsor Background and Introduction Understanding the risk for immigrant mothers developing postpartum depression (PPD) is essential for implementing early intervention. An integrative review (IR) helps to identify methodological gaps and limitations which guide our practice. The purpose of this IR is to collect, analyze and integrate the literature focused on immigrant mothers ages 20-35 years of age in relation to PPD. Quantitative statistics is reviewed that reflect the interventions, study design and interpretation of the use of screening tools to effectively capture risk factors for perinatal depression in marginalized populations (Daoud. et al., 2019). Methods An IR conducted by 5 group members, identified and evaluated peer-reviewed research studies exploring risks for immigrant mothers developing PPD. A systematic analytic method of date reduction was used to identify alignment and divergence of the data, gaps in the literature, and limitations. Results This IR is being conducted on an ongoing basis. Twenty published research journals from 2006-2020 have been analyzed thus far. Questionnaires and scales are used to determine the level of risk of PPD. Most often used is the Edinburgh Postnatal Depression Scale. The preliminary results indicate that early detection of symptomology of PPD creates an environment of support and better health outcomes. Conclusion As a result of this review, we hope to utilize screening tools to aid in the early identification of at-risk immigrant women and provide culturally sensitive interventions and follow-up (Dharma. et al., 2019). Keywords Immigrant; PPD; intervention; nursing; immigrant women; postpartum depression; screening for postpartum depression; perinatal depression; ethnicity; Canada; intervention; nurse; environment References Dharma, C., Lefebvre, D. L., Lu, Z., Lou, W. Y. W., Becker, A. B., Mandhane, P. J., Turvey, S. E., Moraes, T. J., Azad, M. B., Chen, E., Elliott, S. J., Kozyrskyj, A. L., Sears, M. R., & Subbarao, P. (2019). Risk for Maternal Depressive Symptoms and Perceived Stress by Ethnicities in Canada: From Pregnancy Through the Preschool Years: Risque de symptômes dépressifs maternels et stress perçu par les ethnies au Canada : de la grossesse aux années préscolaires. Canadian Journal of Psychiatry, 64(3), 190–198. https://doi-org.ledproxy2.uwindsor.ca/10.1177/0706743718792190 Daoud, N., O’Brien, K., O’Campo, P., Harney, S., Harney, E., Bebee, K., Bourgeois, C., & Smylie, J. (2019). Postpartum depression prevalence and risk factors among Indigenous, non-Indigenous and immigrant women in Canada. Canadian Journal of Public Health, 110(4), 440–452. https://doi. org.ledproxy2.uwindsor.ca/10.17269/s41997-019-00182-

Reliability of Macaques as Seed Dispersers

Seed dispersal is an ecological process crucial for forest regeneration and recruitment. To date, most studies on frugivore seed dispersal have used the seed dispersal effectiveness framework and have documented seed‐handling mechanisms, dispersal distances and the effect of seed handling on germination. In contrast, there has been no exploration of “disperser reliability” which is essential to determine if a frugivore is an effective disperser only in particular regions/years/seasons or across a range of spatio‐temporal scales. In this paper, we propose a practical framework to assess the spatial reliability of frugivores as seed dispersers. We suggest that a frugivore genus would be a reliable disperser of certain plant families/genera if: (a) fruits of these plant families/genera are represented in the diets of most of the species of that frugivore, (b) these are consumed by the frugivore genus across different kinds of habitats, and (c) these fruits feature among the yearly staples and preferred fruits in the diets of the frugivore genus. Using this framework, we reviewed frugivory by the genus&nbsp;Macaca&nbsp;across Asia to assess its spatial reliability as seed dispersers. We found that the macaques dispersed the seeds of 11 plant families and five plant genera including at least 82 species across habitats. Differences in fruit consumption/preference between different groups of macaques were driven by variation in plant community composition across habitats. We posit that it is essential to maintain viable populations of macaques across their range and keep human interventions at a minimum to ensure that they continue to reliably disperse the seeds of a broad range of plant species in the Anthropocene. We further suggest that this framework be used for assessing the spatial reliability of other taxonomic groups as seed dispersers

Patterns of nitrogen-fixing tree abundance in forests across Asia and America

Abstract 1. Symbiotic nitrogen (N)‐fixing trees can provide large quantities of new N to ecosystems, but only if they are sufficiently abundant. The overall abundance and latitudinal abundance distributions of N‐fixing trees are well characterised in the Americas, but less well outside the Americas. 2. Here, we characterised the abundance of N‐fixing trees in a network of forest plots spanning five continents, ~5,000 tree species and ~4 million trees.The majority of the plots (86%)were in America o rAsia. In addition, we examined whether the observed pattern of abundance of N‐fixing trees was correlated with mean annual temperature and precipitation. 3.Outside the tropics, N‐fixing trees were consistently rare in the forest plots we examined. Within the tropics, N‐fixing trees were abundant in American but not Asian forest plots (~7% versus ~1% of basal area and stems). This disparity was not explained by mean annual temperature or precipitation. Our finding of low N‐fixing tree abundance in the Asian tropics casts some doubt on recent high estimates of N fixation rates in this region, which do not account for disparities in N‐fixing tree abundance between the Asian and American tropics. 4. Synthesis. Inputs of nitrogen to forests depend on symbiotic nitrogen fixation, which is constrained by the abundance of N‐fixing trees. By analysing a large dataset of ~4 million trees, we found that N‐fixing trees were consistently rare in the Asian tropics as well as across higher latitudes in Asia, America and Europe. The rarity of N‐fixing trees in the Asian tropics compared with the American tropics might stem from lower intrinsic N limitation in Asian tropical forests, although direct support for any mechanism is lacking. The paucity of N‐fixing trees throughout Asian forests suggests that N inputs to the Asian tropics might be lower than previously though