Monitoring Broad Absorption-Line Quasar Variability

Winds generated by an accreting super massive black hole may provide feedback to the host galaxy and offer an explanation for the co-evolution of galaxies with their super massive black holes that has been reported in the literature. Some outflows are manifested as broad absorption line (BAL) troughs in quasar spectra, and are measured at velocities as high as 60, 000 km s 1 at ultra-violet wavelengths. These BAL troughs have been observed to vary on both long (years) and short (weeks) rest-frame time-scales and can emerge in a quasar that had none, or disappear completely. By monitoring the variability of absorption in BAL quasars, constraints can be placed on outflow models and the structure of quasars in general. In this study, we isolate a set of quasars that exhibit emergent C iv BALs in their spectra, by comparing archival data in the SDSS Data Release 7 to the BOSS Data Release 9 and 10. After visually defining a set of emergent BALs, follow-up observations were obtained with the Gemini Observatory for 105 quasars. BALs were formally detected in all but two of the quasars in the dataset, and we report 219 absorption complexes in the entire set. After a BAL has emerged, we find it is equally likely to continue increasing as it is to start decreasing in a subsequent observation. Based on the range of time between our observations, this indicates the coherence time-scale of BALs is less than 100 days. There is a strong signal of coordinated variability among two troughs in the same quasar. Further, coordination is stronger if the velocity separation between the two troughs is smaller. We conclude the variability is likely due to changes in the ionizing flux incident on the absorbing cloud, which agrees with the results of Filiz Ak et al. (2013). In this work we also test two competing models of BAL variability (bulk motion and ionization changes) in the context of a case study of the quasar SDSS J023011.28+005913.6, which had two high-velocity emergent troughs. Both models yield plausible results

Online Health Information-Seeking Behaviour among People of African Descent in the United Kingdom: A Qualitative Study

Effective public health interventions rely on understanding how individuals access, interpret, and utilise health information. Studying the health information-seeking behaviour (HISB) of a community can provide valuable insights to inform strategies that address community health needs and challenges. This study explored the online HISBs of People of African Descent (PoAD) in the United Kingdom (UK), a demographic that comprises four percent of the UK population and has a 92.8% active Internet usage rate. Data on the HISB were collected from 21 PoAD across various UK regions through online semi-structured interviews before being analysed using reflexive Thematic Analysis (TA). The participants ranged in age from 20 to 70 years and had a mean age of 42.8 (SD ± 11.4). Our analysis of the interview transcripts revealed five key themes: Internet usage and preferences, attitudes toward social media, barriers to seeking health information online, trust in online health information, and cultural influences on online HISB. Our findings indicate a proactive engagement among PoAD in seeking health information online that is underscored by a preference for professional sources over ethnic congruence. However, concerns about misinformation exist, and there are barriers to accessing health information online, including data privacy, unreliable information, and information relevance and overload. We also found that cultural factors and traditional beliefs impact the adoption of Internet-based interventions among PoAD, highlighting the need for culturally sensitive approaches. Preferences regarding the frequency and delivery of online health information varied among participants, with a majority preferring a weekly update. This study emphasises the critical need for accessible, culturally appropriate, secure, and reliable online health resources tailored to the needs and preferences of the PoAD

Emergence and Variability of Broad Absorption Line Quasar Outflows

We isolate a set of quasars that exhibit emergent C iv broad absorption lines (BALs) in their spectra by comparing spectra in the SDSS Data Release 7 and the SDSS/BOSS Data Releases 9 and 10. After visually defining a set of emergent BALs, follow-up observations were obtained with the Gemini Observatory for 105 quasars. We find an emergence rate consistent with the previously reported disappearance rate of BAL quasars given the relative numbers of non-BAL and BAL quasars in the SDSS. We find candidate newly emerged BALs are preferentially drawn from among BALs with smaller balnicity indices, shallower depths, larger velocities, and smaller widths. Within two rest-frame years (average) after a BAL has emerged, we find it equally likely to continue increasing in equivalent width in an observation six months later (average) as it is to start decreasing. From the time separations between our observations, we conclude the coherence time-scale of BALs is less than 100 rest-frame days. We observe coordinated variability among pairs of troughs in the same quasar, likely due to clouds at different velocities responding to the same changes in ionizing flux; and the coordination is stronger if the velocity separation between the two troughs is smaller. We speculate the latter effect may be due to clouds having on average lower densities at higher velocities due to mass conservation in an accelerating flow, causing the absorbing gas in those clouds to respond on different timescales to the same ionizing flux variations.Comment: 37 pages, 25 figure

Maternal–Fetal Microtransfusions and HIV-1 Mother-to-Child Transmission in Malawi

Background: Between 25% and 35% of infants born to HIV-infected mothers become HIV-1 infected. One potential route of mother-to-child transmission (MTCT) could be through a breakdown in the placental barrier (i.e., maternal–fetal microtransfusions). Methods and Findings: Placental alkaline phosphatase (PLAP) is a 130-kD maternal enzyme that cannot cross the intact placental barrier. We measured PLAP activity in umbilical vein serum as an indicator of maternal–fetal microtransfusion, and related this to the risk of HIV-1 MTCT. A case-cohort study was conducted of 149 women randomly selected from a cohort of HIV-1-infected pregnant Malawians; these women served as a reference group for 36 cases of in utero MTCT and 43 cases of intrapartum (IP) MTCT. Cord PLAP activity was measured with an immunocatalytic assay. Infant HIV status was determined by real-time PCR. The association between cord PLAP activity and HIV-1 MTCT was measured with logistic regression using generalized estimating equations. Among vaginal deliveries, PLAP was associated with IP MTCT (risk ratio, 2.25 per $log_{10}$ ng/ml PLAP; 95% confidence interval, 0.95–5.32) but not in utero MTCT. In a multivariable model adjusted for HIV-1 RNA load, chorioamnionitis, and self-reported fever, the risk of IP MTCT almost tripled for every $log_{10}$ increase in cord PLAP activity (risk ratio, 2.87; 95% confidence interval, 1.05–7.83). Conclusion: These results suggest that during vaginal deliveries, placental microtransfusions are a risk factor for IP HIV-1 MTCT. Future studies are needed to identify factors that increase the risk for microtransfusions in order to prevent IP HIV-1 MTCT

Malaria during pregnancy and foetal haematological status in Blantyre, Malawi

BACKGROUND: Although maternal anaemia often stems from malaria infection during pregnancy, its effects on foetal haemoglobin levels are not straightforward. Lower-than-expected cord haemoglobin values in malarious versus non-malarious regions were noted by one review, which hypothesized they resulted from foetal immune activation to maternal malaria. This study addressed this idea by examining cord haemoglobin levels in relation to maternal malaria, anaemia, and markers of foetal immune activation. METHODS: Cord haemoglobin levels were examined in 32 malaria-infected and 58 uninfected women in Blantyre, Malawi, in relation to maternal haemoglobin levels, malaria status, and markers of foetal haematological status, hypoxia, and inflammation, including TNF-α, TGF-β, and ferritin. All women were HIV-negative. RESULTS: Although malaria was associated with a reduction in maternal haemoglobin (10.8 g/dL vs. 12.1 g/dL, p < 0.001), no reduction in cord haemoglobin and no significant relationship between maternal and cord haemoglobin levels were found. Cord blood markers of haematological and hypoxic statuses did not differ between malaria-infected and uninfected women. Maternal malaria was associated with decreased TGF-β and increased cord ferritin, the latter of which was positively correlated with parasitaemia (r = 0.474, p = 0.009). Increased cord ferritin was associated with significantly decreased birth weight and gestational length, although maternal and cord haemoglobin levels and malaria status had no effect on birth outcome. CONCLUSION: In this population, cord haemoglobin levels were protected from the effect of maternal malaria. However, decreased TGF-β and elevated ferritin levels in cord blood suggest foetal immune activation to maternal malaria, which may help explain poor birth outcomes

Chandra X-Ray Observations of Two Unusual BAL Quasars

We report sensitive Chandra X-ray non-detections of two unusual, luminous Iron Low-Ionization Broad Absorption Line Quasars (FeLoBALs). The observations do detect a non-BAL, wide-binary companion quasar to one of the FeLoBAL quasars. We combine X-ray-derived column density lower limits (assuming solar metallicity) with column densities measured from ultraviolet spectra and CLOUDY photoionization simulations to explore whether constant density slabs at broad line region densities can match the physical parameters of these two BAL outflows, and find that they cannot. In the "overlapping-trough" object SDSS J0300+0048, we measure the column density of the X-ray absorbing gas to be N_H >= 1.8 x 1024 cm-2. From the presence of Fe II UV78 absorption but lack of Fe II UV195/UV196 absorption, we infer the density in that part of the absorbing region to be n_e ~ 106 cm-3. We do find that a slab of gas at that density might be able to explain this object's absorption. In the Fe III-dominant object SDSS J2215-0045, the X-ray absorbing column density of N_H >= 3.4 x 1024 cm-2 is consistent with the Fe III-derived N_H >= 2 x 1022 cm-2 provided the ionization parameter is log U > 1.0 for both the n_e = 1011 cm-3 and n_e = 1012 cm-3 scenarios considered (such densities are required to produce Fe III absorption without Fe II absorption). However, the velocity width of the absorption rules out its being concentrated in a single slab at these densities. Instead, this object's spectrum can be explained by a low density, high ionization and high temperature disk wind that encounters and ablates higher density, lower ionization Fe III-emitting clumps.Comment: 18 pages, 6 figure

Maternal‐Fetal DNA Admixture Is Associated with Intrapartum Mother‐to‐Child Transmission of HIV‐1 in Blantyre, Malawi

The mechanism of HIV-1 mother-to-child transmission (MTCT) is not well described

A Randomized Controlled Pilot Trial of Azithromycin or Artesunate Added to Sulfadoxine-Pyrimethamine as Treatment for Malaria in Pregnant Women

New anti-malarial regimens are urgently needed in sub-Saharan Africa because of the increase in drug resistance. We investigated the safety and efficacy of azithromycin or artesunate combined with sulfadoxine-pyrimethamine used for treatment of malaria in pregnant women in Blantyre, Malawi