Environmental influences on Arctic halogen chemistry: investigation of melt onset and snowpack properties

Thesis (M.S.) University of Alaska Fairbanks, 2016Reactive halogen radicals (e.g. Br, Cl and their oxide forms) dominate tropospheric oxidation mechanisms during Arctic springtime (Feb. – Apr.) by depleting ozone and changing the fate of pollutants. During ozone depletion events, reactive bromine radicals rapidly oxidize mercury which gets subsequently deposited, becoming more bioavailable. During Arctic springtime, a heterogeneous surface reaction (referred to as BrO recycling) between hypobromous acid (HOBr) and bromide (Br-) rapidly increases the abundance of reactive bromine episodically up to 40 pptv peaks. However, as spring transitions to summer (May - June), elevated reactive bromine levels suddenly decrease. There are two key requirements to maintain BrO recycling including surface area and sea salt (i.e. bromide) abundance. This study investigated environmental factors that impact BrO recycling during late spring (May-June) in the Arctic, including temperature, snowpack depth and rain/snow precipitation events. Near horizon BrO was measured using Multi-AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) at Barrow, AK and above frozen Arctic sea ice. The late spring “end” to elevated reactive bromine (referred as the Seasonal End Date, SED) was objectively determined at all sites (N=12). Air temperature derived melt onset dates were determined for all sites (N=12) and occurred within two days of the SED (RMS = 1.8 days, R² = 0.989). Through these studies, we determined BrO recycling is hindered by melt onset of snowpack, ending the reactive bromine season.Chapter 1: Introduction -- 1.1 Motivation -- 1.2 Arctic tropospheric chemistry -- 1.3 Bromine explosion mechanism -- 1.3.1 Saline surfaces -- 1.3.2 Snow surface area -- 1.4 Melt onset -- 1.5 Ion pulse -- 1.6 Gas-phase bromine seasonal behavior -- 1.7 Multi-AXis differential optical absorption spectroscopy (MAX-DOAS) -- 1.8 Thesis structure -- 1.9 References -- 1.10 Figures -- Chapter 2: Late spring snow melt onset hinders bromine monoxide heterogeneous recycling in the arctic -- 2.1 Introduction -- 2.2 Data sources and methods -- 2.2.1 Bromine monoxide measurement sites -- 2.2.2 Snow/ rain precipitation observations and snow depth measurements -- 2.2.3 Objective determination of seasonal end and recurrence events -- 2.2.4 Objective determination of melt onset dates using surface air temperature -- Results -- 2.3.1 Seasonal end date determination and sensitivity to threshold parameters -- 2.3.2 Melt onset determination and correlation to the seasonal end date -- 2.3.3 Snow depth changes at seasonal end and recurrence events -- 2.3.4 Rain/snow precipitation at seasonal end and recurrence events -- 2.4 Discussion -- 2.4.1 Seasonal end date is the melt onset date -- 2.4.2 Decaying snowpack and rain precipitation prevents BrO recycling -- 2.4.3 Below freezing temperatures and new surface area re-initialize BrO recycling -- 2.5 Conclusion -- 2.6 Acknowledgements -- 2.7 References -- 2.8 Figures -- Chapter 3: Conclusions and outlook -- 3.1 Conclusions -- 3.2 Future Outlook -- 3.3 References

Virulence, phenotype and genotype characteristics of invasive group B Streptococcus isolates obtained from Swedish pregnant women and neonates

Group B streptococci (GBS) are bacteria that can cause preterm birth and invasive neonatal disease. Heterogeneous expression of virulence factors enables GBS to exist as both commensal bacteria and to become highly invasive. A molecular epidemiological study comparing GBS bacterial traits, genotype and host characteristics may indicate whether it is possible to predict the risk of perinatal invasive GBS disease and more accurately target intrapartum antibiotic prophylaxis. A total of 229 invasive GBS isolates from Swedish pregnant women or neonates were assessed for virulence and phenotypic traits: hemolysis zone, hemolytic pigment (Granada agar), Streptococcus B Carrot Broth (SBCB) assay, CAMP factor, and hyaluronidase activity. Genes regulating hemolytic pigment synthesis (covR/covS, abx1, stk1, stp1) were sequenced. Of the virulence factors and phenotypes assessed, a Granada pigment or SBCB score ≥ 2 captured more than 90% of EOD isolates with excellent inter-rater reliability. High enzyme activity of hyaluronidase was observed in 16% (36/229) of the invasive GBS isolates and notably, in one case of stillbirth. Hyaluronidase activity was also significantly higher in GBS isolates obtained from pregnant/postpartum individuals versus the stillbirth or neonatal invasive isolates (p < 0.001). Sequencing analysis found that abx1 (g.T106I), stk1 (g.T211N), stp1 (g.K469R) and covS (g.V343M) variants were present significantly more often in the higher (Granada pigment score ≥ 2) versus lower pigmented isolates (p < 0.001, each variant). Among the 203 higher Granada pigment scoring isolates, 22 (10.8%) isolates had 3 of the four sequence variants and 10 (4.9%) had 2 of the four sequence variants. Although heterogeneity in GBS virulence factor expression was observed, the vast majority were more highly pigmented and contained several common sequence variants in genes regulating pigment synthesis. High activity of hyaluronidase may increase risk for stillbirth and invasive disease in pregnant or postpartum individuals. Our findings suggest that testing for GBS pigmentation and hyaluronidase may, albeit imperfectly, identify pregnant people at risk for invasive disease and represent a step towards a personalized medical approach for the administration of intrapartum antibiotic prophylaxis

Effect of remote ischaemic conditioning on clinical outcomes in patients with acute myocardial infarction (CONDI-2/ERIC-PPCI): a single-blind randomised controlled trial.

BACKGROUND: Remote ischaemic conditioning with transient ischaemia and reperfusion applied to the arm has been shown to reduce myocardial infarct size in patients with ST-elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI). We investigated whether remote ischaemic conditioning could reduce the incidence of cardiac death and hospitalisation for heart failure at 12 months. METHODS: We did an international investigator-initiated, prospective, single-blind, randomised controlled trial (CONDI-2/ERIC-PPCI) at 33 centres across the UK, Denmark, Spain, and Serbia. Patients (age >18 years) with suspected STEMI and who were eligible for PPCI were randomly allocated (1:1, stratified by centre with a permuted block method) to receive standard treatment (including a sham simulated remote ischaemic conditioning intervention at UK sites only) or remote ischaemic conditioning treatment (intermittent ischaemia and reperfusion applied to the arm through four cycles of 5-min inflation and 5-min deflation of an automated cuff device) before PPCI. Investigators responsible for data collection and outcome assessment were masked to treatment allocation. The primary combined endpoint was cardiac death or hospitalisation for heart failure at 12 months in the intention-to-treat population. This trial is registered with ClinicalTrials.gov (NCT02342522) and is completed. FINDINGS: Between Nov 6, 2013, and March 31, 2018, 5401 patients were randomly allocated to either the control group (n=2701) or the remote ischaemic conditioning group (n=2700). After exclusion of patients upon hospital arrival or loss to follow-up, 2569 patients in the control group and 2546 in the intervention group were included in the intention-to-treat analysis. At 12 months post-PPCI, the Kaplan-Meier-estimated frequencies of cardiac death or hospitalisation for heart failure (the primary endpoint) were 220 (8·6%) patients in the control group and 239 (9·4%) in the remote ischaemic conditioning group (hazard ratio 1·10 [95% CI 0·91-1·32], p=0·32 for intervention versus control). No important unexpected adverse events or side effects of remote ischaemic conditioning were observed. INTERPRETATION: Remote ischaemic conditioning does not improve clinical outcomes (cardiac death or hospitalisation for heart failure) at 12 months in patients with STEMI undergoing PPCI. FUNDING: British Heart Foundation, University College London Hospitals/University College London Biomedical Research Centre, Danish Innovation Foundation, Novo Nordisk Foundation, TrygFonden

Bias in mock investigator decision-making: The influence of prototypicality and emotional display on perceptions of victims during the reporting phase of a sexual assault case

The present research sought to examine the potentially interactive effects of victim emotional display (sadness vs. anger vs. calm (control)) and victim prototypicality (stranger vs. acquaintance suspect) during the reporting phase of a criminal sexual assault case on mock investigators’ perceptions of victim credibility and decision-making to proceed with the investigation

The Impact of Parent Sexual Identity on Lay Perceptions of Parental Competency

The current study investigates the effect of parent sexual identity on lay people’s perceptions of parental competency in a simulated child custody case. We will employ a 5 across (Parent sexual identity: heterosexual, formerly heterosexual male, formerly heterosexual female, gay, and lesbian) between-subjects design. Participants will read a vignette detailing a divorce filing and child custody hearing, render a custody agreement, write a qualitative explanation, and respond to related measures (e.g., anti-gay bias, sexism, and morality)

The Impact of Parent Sexual Identity on Lay Perceptions of Parental Competency

The current study investigates the effect of parent sexual identity on lay people’s perceptions of parental competency in a simulated child custody case. We will employ a 5 across (Parent sexual identity: heterosexual, formerly heterosexual male, formerly heterosexual female, gay, and lesbian) between-subjects design. Participants will read a vignette detailing a divorce filing and child custody hearing, render a custody agreement, write a qualitative explanation, and respond to related measures (e.g., anti-gay bias, sexism, and morality)