Atmospheric bromoform at Mace Head, Ireland: Evidence for a peatland source

International audienceIn situ atmospheric observations of bromoform (CHBr3) made over a 2.5 year period at Mace Head, Ireland from May 2001?December 2003, including during the NAMBLEX (North Atlantic Marine Boundary Layer Experiment) campaign, show broad maxima from spring until autumn and winter minima, with mixing ratios of 5.3+1.0 pptv (mid March?mid October) and 1.8+0.8 pptv (December?February). This indicates that, unlike CHCl3, which has a summer minimum and winter maximum at Mace Head, local biological sources of CHBr3 have a greater influence on the atmospheric data than photochemical decay during long-range transport. The emission sources are predominantly macroalgal, but we find evidence for a small terrestrial flux from peatland ecosystems, which so far has not been accounted for in the CHBr3 budget. Sharp increases in CHCl3 and CHBr3 concentrations and decreases in O3 concentrations occurred at night when the wind direction switched from an ocean- to a land-based sector (land breeze) and the wind speed dropped to below 5 ms?1. These observations infer a shallow atmospheric boundary layer with increased O3 deposition and concentration of local emissions of both CHCl3 and CHBr3. The ratio of ?CHCl3/?CHBr3 varied strongly according to the prevailing wind direction; from 0.6+0.1 in south-easterly (100?170°) air to 1.9+0.8 in north-easterly (40?70°) air. Of these land-sectors, the south-easterly air masses are likely to be strongly influenced by macroalgal beds along the coast and the emission ratios probably reflect those from seaweeds in addition to land sources. The north-easterly airmasses however have a fetch predominantly over land, which locally is comprised of coastal peatland ecosystems (peat bogs and coastal conifer plantations), previously identified as being strong sources of atmospheric CHCl3 under these conditions. Although we cannot entirely rule out other local land or coastal sources, our observations also suggest peatland ecosystem emissions of CHBr3. We use correlations between CHCl3 and CHBr3 during the land breeze events in conjunction with previous estimates of local wetland CHCl3 release to tentatively deduce a global wetland CHBr3 source of 26.9 (0.5?1247) Gg yr?1, which is approximately 10% of the total global source

Empowering Teaching Assistants to Support Students: Impact of Training and Experience on Perceptions and Practices

Teaching assistants (TAs) have a major impact on the undergraduate science student experience, and therefore training TAs is critical to support engagement and learning. We ran a one-day TA training program for two years and found that participation in the program increased TAs’ reflective practice and student-centered teaching over a semester of teaching. Open-ended pre-survey responses indicated that in addition to wanting to learn pedagogical approaches, TAs sought help managing challenging situations and student behaviour. Post-surveys confirmed that the program fulfilled most learning goals of TAs and they subsequently applied the new teaching approaches. Participants indicated high levels of empowerment within their teaching roles across the cognitions of impact, competence and meaningfulness, but low self-determination. All aspects of empowerment increased with experience

Atmospheric bromoform at Mace Head, Ireland: seasonality and evidence for a peatland source

In situ atmospheric observations of bromoform (CHBr₃) made over a 2.5 year period at Mace Head, Ireland from May 2001- Dec 2003, including during the NAMBLEX (North Atlantic Marine Boundary Layer Experiment) campaign, show broad maxima from spring until autumn and winter minima, with mixing ratios of 5.3+1.0 pptv (mid March - mid October) and 1.8+0.8 pptv (December-February). This indicates that, unlike CHCl₃, which has a summer minimum and winter maximum at Mace Head, local biological sources of CHBr₃ have a greater influence on the atmospheric data than photochemical decay during long-range transport. The emission sources are predominantly macroalgal, but we find evidence for a small terrestrial flux from peatland ecosystems, which so far has not been accounted for in the CHBr₃ budget. Sharp increases in CHCl₃ and CHBr₃ concentrations and decreases in O₃ concentrations occurred at night when the wind direction switched from an ocean- to a land-based sector (land breeze) and the wind speed dropped to below 5 ms^-1. These observations infer a shallow atmospheric boundary layer with increased O₃ deposition and concentration of local emissions of both CHCl₃ and CHBr₃. The ratio of ΔCHCl₃/ΔCHBr₃ varied strongly according to the prevailing wind direction; from 0.60+0.15 in south-easterly (100-170° and northerly (340-20°) air to 2.5+0.4 in north-easterly (40-70°) air. Of these land-sectors, the south-easterly air masses are likely to be strongly influenced by macroalgal beds along the coast and the emission ratios probably reflect those from seaweeds in addition to land sources. The north-easterly airmasses however had an immediate fetch inland, which locally is comprised of coastal peatland ecosystems (peat bogs and coastal conifer plantations), previously identified as being strong sources of atmospheric CHCl₃ under these conditions. Although we cannot entirely rule out other local land or coastal sources, our observations also suggest peatland ecosystem emissions of CHBr₃. We use correlations between CHCl₃ and CHBr₃ during the north-easterly land breeze events in conjunction with previous estimates of local wetland CHCl₃ release to tentatively deduce a global wetland CHBr₃ source of 20.4(0.4-948) Gg yr^-1, which is approximately 7% of the total global source

The experiences of sessional academics in undergraduate science education during the COVID-19 pandemic

The impact of the COVID-19 pandemic on the higher education sector is undeniable. Sessional academics had to adapt to online teaching practices from their traditional teaching practices (e.g., face-to-face laboratories) with little to no training or prior experience. Recent literature describes the anecdotal experiences of individual teaching staff (or teams), such as lack of social interaction and communication (Bartolic et al., 2022; Pather et al., 2020). Sessional academics play a crucial role in the higher education sector, as they are responsible for a majority of face-to-face laboratory teaching and other teaching activities. Due to the sudden transition to online teaching, these casual staff had to learn new software and tools, while isolated in a home environment and often with increased home responsibilities (Bartolic et al., 2022). This project aimed to capture the individual experiences and circumstances of sessional science teaching academics during the pandemic in order to keep a record of what happened and to draw together threads for future online teaching. The study was conducted with the tutors and demonstrators within the faculties of Science at The University of Sydney and Deakin University. Semi-structured interviews were conducted with 20 teaching assistants at these institutions located in different states. The states and institutions had different responses to COVID-19, which led to different impacts on the sessional staff. Lack of interaction with students, difficulty in monitoring student engagement, and most importantly, job insecurity, were the main causes of dissatisfaction and anxiety. It was mentioned by some participants that teaching online could provide flexibility in terms of work-life balance, while some stated that it was difficult for them to separate work from personal life due to working from home. Most participants agreed that the level of support they received from the university management and unit coordinators was adequate although the support could have been better.    Interesting findings from the interviews will be highlighted in this presentation alongside proposed future directions to support sessional academics. REFERENCES Bartolic, S. K., Boud, D., Agapito, J., Verpoorten, D., Williams, S., Lutze-Mann, L., Matzat, U., Ma Monica Moreno, M. M., Patsie Polly, P., Tai, J., Marsh, H., L., Lin, L., Burgess, J., Habtu, S., Rodrigo, M. M. M., Roth, M., Heap, T. & Guppy, N. (2022) A multi-institutional assessment of changes in higher education teaching and learning in the face of COVID-19, Educational Review, 74(3), 517-533. Pather, N., Blyth, P., Chapman, J. A., Dayal, M. R., Flack, M. S., Fogg, Q. A., Green, R. A., Hulme, A. K., Johnson, I. P., Meyer, A. J., Morley, J. W., Shortland, P. J., Štrkalj, G., Štrkalj, M., Valter, K., Webb, A. L., Woodley, S. J., & Lazarus, M. D. (2020). Forced Disruption of Anatomy Education in Australia and New Zealand: An Acute Response to the Covid-19 Pandemic. Anatomical Sciences Education, 13(3), 284-30

Sessional staff training for improved student experience

It is widely recognised that the quality of the undergraduate experience in science often depends on student interactions with sessional staff. In some cases, sessional staff have primary responsibility for teaching within tutorials, workshops and practicals, on field trips, and sometimes in lectures. Preparing postgraduate students to teach requires them to accept responsibilities that they may not have signed up for when they decided to become scientists, and they are unlikely to have been exposed to pedagogical theories in their science studies. In their role as teachers, postgraduate students and other sessional staff bring their own experiences, knowledge and attitudes towards teaching, which will influence their personal teaching practice. We held a full-day workshop with the goal of improving the learning experiences of undergraduate students by improving the training of sessional staff in teaching. This was designed based on the latest literature with three aims: 1. To enhance sessional staff’s sense of psychological empowerment; 2. To develop the belief that sessional staff can enhance undergraduate students’ learning experiences; 3. To increase the level of communication and harmonise experiences across campuses. Results from surveys and interviews before and after the workshop will be presented

Direct evidence for coastal iodine particles from <i>Laminaria</i> macroalgae ? linkage to emissions of molecular iodine

International audienceRenewal of ultrafine aerosols in the marine boundary layer may lead to repopulation of the marine distribution and ultimately determine the concentration of cloud condensation nuclei (CCN). Thus the formation of nanometre-scale particles can lead to enhanced scattering of incoming radiation and a net cooling of the atmosphere. The recent demonstration of the chamber formation of new particles from the photolytic production of condensable iodine-containing compounds from diiodomethane (CH2I2), (O'Dowd et al., 2002; Kolb, 2002; Jimenez et al., 2003a; Burkholder and Ravishankara, 2003), provides an additional mechanism to the gas-to-particle conversion of sulphuric acid formed in the photo-oxidation of dimethylsulphide for marine aerosol repopulation. CH2I2 is emitted from seaweeds (Carpenter et al., 1999, 2000) and has been suggested as an initiator of particle formation. We demonstrate here for the first time that ultrafine iodine-containing particles are produced by intertidal macroalgae exposed to ambient levels of ozone. The particle composition is very similar both to those formed in the chamber photo-oxidation of diiodomethane and in the oxidation of molecular iodine by ozone. The particles formed in all three systems are similarly aspherical and behave alike when exposed to increased humidity environments. Direct coastal boundary layer observations of molecular iodine, ultrafine particle production and iodocarbons are reported. Using a newly measured molecular iodine photolysis rate, it is shown that, if atomic iodine is involved in the observed particle bursts, it is of the order of at least 1000 times more likely to result from molecular iodine photolysis than diiodomethane photolysis. A hypothesis for molecular iodine release from intertidal macroalgae is presented and the potential importance of macroalgal iodine particles in their contribution to CCN and global radiative forcing are discussed

SAVVY Vaginal Gel (C31G) for Prevention of HIV Infection: A Randomized Controlled Trial in Nigeria

The objective of this trial was to determine the effectiveness of 1.0% C31G (SAVVY) in preventing male-to-female vaginal transmission of HIV infection among women at high risk.This was a Phase 3, double-blind, randomized, placebo-controlled trial. Participants made up to 12 monthly follow-up visits for HIV testing, adverse event reporting, and study product supply. The study was conducted between September 2004 and December 2006 in Lagos and Ibadan, Nigeria, where we enrolled 2153 HIV-negative women at high risk of HIV infection. Participants were randomized 1 ratio 1 to SAVVY or placebo. The effectiveness endpoint was incidence of HIV infection as indicated by detection of HIV antibodies in oral mucosal transudate (rapid test) or blood (ELISA), and confirmed by Western blot or PCR testing. We observed 33 seroconversions (21 in the SAVVY group, 12 in the placebo group). The Kaplan-Meier estimates of the cumulative probability of HIV infection at 12 months were 0.028 in the SAVVY group and 0.015 in the placebo group (2-sided p-value for the log-rank test of treatment effect 0.121). The point estimate of the hazard ratio was 1.7 for SAVVY versus placebo (95% confidence interval 0.9, 3.5). Because of lower-than-expected HIV incidence, we did not observe the required number of HIV infections (66) for adequate power to detect an effect of SAVVY. Follow-up frequencies of adverse events, reproductive tract adverse events, abnormal pelvic examination findings, chlamydial infections and vaginal infections were similar in the study arms. No serious adverse event was attributable to SAVVY use.SAVVY did not reduce the incidence of HIV infection. Although the hazard ratio was higher in the SAVVY than the placebo group, we cannot conclude that there was a harmful treatment effect of SAVVY