Impact of Depression on Maternal Sensitivity to One-Year-Old Infants

This thesis investigated the relationship between postnatal depression (PND) and maternal sensitivity. Part one is a systematic literature review. This review summarizes the evidence regarding the relationship between PND and a number of maternal parenting behaviour constructs, including maternal sensitivity. There seemed to be more evidence of a negative association between PND and some maternal parenting behaviour constructs more than others. Part two describes a cross-sectional study of the relationship between PND and maternal sensitivity in a disadvantaged and high risk sample of 86 mothers. The findings revealed no evidence of an association between PND and maternal sensitivity, though there was some evidence of an association between antenatal depression and sensitivity. Finally, a critical appraisal of the entire research is presented in part three. Therein, reflections are proffered on issues related to the coding of sensitivity, the role for qualitative research in this area as well as further clinical implications and directions for future research. This was a joint thesis undertaken in conjunction with Roberts (2018), whom coded half of the data for sensitivity (please see Appendix A for further details)

7-Carboxy-7-deazaguanine Synthase: A Radical

Radical S-adenosyl-L-methionine (SAM) enzymes are widely distributed and catalyze diverse reactions. SAM binds to the unique iron atom of a site-differentiated [4Fe-4S] cluster and is reductively cleaved to generate a 5'-deoxyadenosyl radical, which initiates turnover. 7-Carboxy-7-deazaguanine (CDG) synthase (QueE) catalyzes a key step in the biosynthesis of 7-deazapurine containing natural products. 6-Carboxypterin (6-CP), an oxidized analogue of the natural substrate 6-carboxy-5,6,7,8-tetrahydropterin (CPH4), is shown to be an alternate substrate for CDG synthase. Under reducing conditions that would promote the reductive cleavage of SAM, 6-CP is turned over to 6-deoxyadenosylpterin (6-dAP), presumably by radical addition of the 5'-deoxyadenosine followed by oxidative decarboxylation to the product. By contrast, in the absence of the strong reductant, dithionite, the carboxylate of 6-CP is esterified to generate 6-carboxypterin-5'-deoxyadenosyl ester (6-CP-dAdo ester). Structural studies with 6-CP and SAM also reveal electron density consistent with the ester product being formed in crystallo. The differential reactivity of 6-CP under reducing and nonreducing conditions highlights the ability of radical SAM enzymes to carry out both polar and radical transformations in the same active site

Would firm generators facilitate or deter variable renewable energy in a carbon-free electricity system?

To reduce atmospheric carbon dioxide emissions and mitigate impacts of climate change, countries across the world have mandated quotas for renewable electricity. But a question has remained largely unexplored: would low-cost, firm, zero-carbon electricity generation technologies enhance—or would they displace—deployment of variable renewable electricity generation technologies, i.e., wind and solar photovoltaics, in a least-cost, fully reliable, and deeply decarbonized electricity system? To address this question, we modeled idealized electricity systems based on historical weather data and considered only technoeconomic factors. We did not apply a predetermined use model. We found that cost reductions in firm generation technologies (starting at current costs, ramping down to nearly zero) uniformly resulted in increased penetration of the firm technologies and decreased penetration of variable renewable electricity generation, in electricity systems where technology deployment is primarily driven by relative costs, and across a wide array of future technology cost assumptions. Similarly, reduced costs of variable renewable electricity (starting at current costs, ramping down to nearly zero) drove out firm generation technologies. Yet relative to deployment of “must-run” firm generation technologies, and when the studied firm technologies have high fixed costs relative to variable costs, the addition of flexibility to firm generation technologies had only limited impacts on the system cost, less than a 9% system cost reduction in our idealized model. These results reveal that policies and funding that support particular technologies for low- or zero-carbon electricity generation can inhibit the development of other low- or zero-carbon alternatives