A Multidisciplinary Study of Biomarkers in Hydrothermal Deposits: Applications to the Search for Life on Mars

Hydrothermal systems have been suggested as suitable environments for the appearance of life on the Early Earth and may provide habitats for microorganisms on Mars. The deposits created by these systems are preserved in the geological record. This research investigates the key mineralogical, textural and biological markers found in terrestrial hydrothermal deposits that can be used as analogues in the search for evidence of life on Mars. Samples of silica sinter from Iceland and New Zealand, the Rhynie Chert 396 Ma old deposit from Aberdeenshire and hydrothermally altered impactites from the Chicxulub impact crater have been analysed to understand the mineralogical properties unique to the different hydrothermal conditions and the evidence of extant or extinct microorganisms within them. Re-colonisation of basaltic substrates by hot spring-derived cultures was also carried out. This research was conducted using a multidisciplinary approach with the analytical techniques and instruments involved currently used for in-situ and orbital observations of planetary bodies. The principal techniques, Fourier Transform Infrared (FTIR) spectroscopy and Gas Chromatography Mass Spectrometry (GCMS), were used due to their combined capabilities in the identification of a variety of rocks and minerals, and a wide range of organic compounds. This PhD research has shown that FTIR in particular is an exceptional analytical technique for use in astrobiological investigations. This research has characterised hydrothermal deposits of different ages and created by different processes on Earth to ascertain their potential for preserving organic compounds in similar deposits on Mars. Results indicate that siliceous hydrothermal deposits of recent and ancient formation yield biomolecular evidence for past and present microbial colonisation as do hydrothermally altered impact deposits and re-colonised basaltic substrates. The identification of mineralogical and biological information using FTIR reflectance spectroscopy has wide implications in the search for life on Mars and other planetary bodies

A Multidisciplinary Study of Biomarkers in Hydrothermal Deposits : Applications to the Search for Life on Mars

Hydrothermal systems have been suggested as suitable environments for the appearance of life on the Early Earth and may provide habitats for microorganisms on Mars. The deposits created by these systems are preserved in the geological record. This research investigates the key mineralogical, textural and biological markers found in terrestrial hydrothermal deposits that can be used as analogues in the search for evidence of life on Mars. Samples of silica sinter from Iceland and New Zealand, the Rhynie Chert 396 Ma old deposit from Aberdeenshire and hydrothermally altered impactites from the Chicxulub impact crater have been analysed to understand the mineralogical properties unique to the different hydrothermal conditions and the evidence of extant or extinct microorganisms within them. Re-colonisation of basaltic substrates by hot spring-derived cultures was also carried out. This research was conducted using a multidisciplinary approach with the analytical techniques and instruments involved currently used for in-situ and orbital observations of planetary bodies. The principal techniques, Fourier Transform Infrared (FTIR) spectroscopy and Gas Chromatography Mass Spectrometry (GCMS), were used due to their combined capabilities in the identification of a variety of rocks and minerals, and a wide range of organic compounds. This PhD research has shown that FTIR in particular is an exceptional analytical technique for use in astrobiological investigations. This research has characterised hydrothermal deposits of different ages and created by different processes on Earth to ascertain their potential for preserving organic compounds in similar deposits on Mars. Results indicate that siliceous hydrothermal deposits of recent and ancient formation yield biomolecular evidence for past and present microbial colonisation as do hydrothermally altered impact deposits and re-colonised basaltic substrates. The identification of mineralogical and biological information using FTIR reflectance spectroscopy has wide implications in the search for life on Mars and other planetary bodies.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Genomic reconstruction of the SARS-CoV-2 epidemic in England

AbstractThe evolution of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus leads to new variants that warrant timely epidemiological characterization. Here we use the dense genomic surveillance data generated by the COVID-19 Genomics UK Consortium to reconstruct the dynamics of 71 different lineages in each of 315 English local authorities between September 2020 and June 2021. This analysis reveals a series of subepidemics that peaked in early autumn 2020, followed by a jump in transmissibility of the B.1.1.7/Alpha lineage. The Alpha variant grew when other lineages declined during the second national lockdown and regionally tiered restrictions between November and December 2020. A third more stringent national lockdown suppressed the Alpha variant and eliminated nearly all other lineages in early 2021. Yet a series of variants (most of which contained the spike E484K mutation) defied these trends and persisted at moderately increasing proportions. However, by accounting for sustained introductions, we found that the transmissibility of these variants is unlikely to have exceeded the transmissibility of the Alpha variant. Finally, B.1.617.2/Delta was repeatedly introduced in England and grew rapidly in early summer 2021, constituting approximately 98% of sampled SARS-CoV-2 genomes on 26 June 2021.</jats:p

Empagliflozin in Patients with Chronic Kidney Disease

Background The effects of empagliflozin in patients with chronic kidney disease who are at risk for disease progression are not well understood. The EMPA-KIDNEY trial was designed to assess the effects of treatment with empagliflozin in a broad range of such patients. Methods We enrolled patients with chronic kidney disease who had an estimated glomerular filtration rate (eGFR) of at least 20 but less than 45 ml per minute per 1.73 m(2) of body-surface area, or who had an eGFR of at least 45 but less than 90 ml per minute per 1.73 m(2) with a urinary albumin-to-creatinine ratio (with albumin measured in milligrams and creatinine measured in grams) of at least 200. Patients were randomly assigned to receive empagliflozin (10 mg once daily) or matching placebo. The primary outcome was a composite of progression of kidney disease (defined as end-stage kidney disease, a sustained decrease in eGFR to &lt; 10 ml per minute per 1.73 m(2), a sustained decrease in eGFR of &amp; GE;40% from baseline, or death from renal causes) or death from cardiovascular causes. Results A total of 6609 patients underwent randomization. During a median of 2.0 years of follow-up, progression of kidney disease or death from cardiovascular causes occurred in 432 of 3304 patients (13.1%) in the empagliflozin group and in 558 of 3305 patients (16.9%) in the placebo group (hazard ratio, 0.72; 95% confidence interval [CI], 0.64 to 0.82; P &lt; 0.001). Results were consistent among patients with or without diabetes and across subgroups defined according to eGFR ranges. The rate of hospitalization from any cause was lower in the empagliflozin group than in the placebo group (hazard ratio, 0.86; 95% CI, 0.78 to 0.95; P=0.003), but there were no significant between-group differences with respect to the composite outcome of hospitalization for heart failure or death from cardiovascular causes (which occurred in 4.0% in the empagliflozin group and 4.6% in the placebo group) or death from any cause (in 4.5% and 5.1%, respectively). The rates of serious adverse events were similar in the two groups. Conclusions Among a wide range of patients with chronic kidney disease who were at risk for disease progression, empagliflozin therapy led to a lower risk of progression of kidney disease or death from cardiovascular causes than placebo