Microtextures of Cyanobacterial Mats in Siliciclastic Sedimentary Environments (Modern & Ancient): Applications to the Search for Life on Mars

The current Mars Exploration Rover Program (MER) is one of NASA\u27s most successful missions. The aim of the MER is to explore for possible life on the surface of Mars. My thesis developed new methods of how to detect and to identify microbial mats in siliciclastic sediments (modern and ancient), and to make recommendations on the applicability of MISS as biosignatures. Predominantly, I employed instrumentation portable by future rovers. To search for life on other planets, we need to have information on how this life might look. Most astrobiological studies therefore focus on Earthly analogues of life and its habitats. \u27Microbially induced sedimentary structures (MISS)\u27 are formed by benthic cyanobacteria in shallow-marine settings by the interaction of the microbiota with physical sediment dynamics. MISS are found exclusively in siliciclastic sedimentary environments, setting them apart from stromatolites that form in chemically controlled settings. Because the MISS occur since the earliest Archean, the structures constitute important biosignatures. It is noteworthy that we can study both modern as well as fossil examples. In order to compare fossil and modem MISS, I used rock material from the 2.9 Ga old Archean Pongola and Witwatersrand Supergroups, South Africa, that record former tidal and shelf settings. I also investigated modern examples on Fishermans Island, located on the coast of Virginia at the mouth of the Chesapeake Bay. To describe and to quantify various microtextures such as bacterial filaments, extracellular polymeric substances, mat fabrics, etc., I coupled morphometric and geochemical analyses. Optical microscopy and confocal scanning laser microscopy (CSLM) revealed that the morphology and structure of the microtextures of both Archean and modern material are very similar. Raman spectroscopy and electron microprobe analyses on the fossil material indicate their mineralogical and elemental composition. I distinguished alternating bands of iron hydroxides, titanium oxides, and carbon, as well as mica with striae of titanium oxides and carbon, that reflect the mineralization of the organic components of ancient microbial mat fabrics. These microfossils are the result of in situ biomineralization of organic material right after burial during diagenesis and also possibly during recrystallization in the course of post-diagenetic and tectonic overprinting of the host rock. Carbon isotope analyses on the fossil filament-like textures show δ13C values between -22.0-24.2+/-0.5%, typical for preserved organic matter. The morphological and geochemical results, support the presence of cyanobacteria in rocks of at least 2.9 Ga age, and provide Earthly analogs for use on Mars

Spectroscopic characterization of samples from different environments in a Volcano-Glacial region in Iceland: Implications for in situ planetary exploration

Raman spectroscopy and laser induced breakdown spectroscopy (LIBS) are complementary techniques that together can provide a comprehensive characterization of geologic environments. For landed missions with constrained access to target materials on other planetary bodies, discerning signatures of life and habitability can be daunting, particularly where the preservation of organic compounds that contain the building blocks of life is limited. The main challenge facing any spectroscopy measurements of natural samples is the complicated spectra that often contain signatures for multiple components, particularly in rocks that are composed of several minerals with surfaces colonized by microbes. The goal of this study was to use the combination of Raman spectroscopy and LIBS to discern different environmental regimes based on the identification of minerals and biomolecules in rocks and sediments. Iceland is a terrestrial volcano-glacial location that offers a range of planetary analog environments, including volcanically active regions, extensive lava fields, geothermal springs, and large swaths of ice-covered terrain that are relevant to both rocky and icy planetary bodies. We combined portable VIS (532 nm) and NIR (785 nm) Raman spectroscopy, VIS micro-Raman spectroscopic mapping, and UV/VIS/NIR (200 – 1000 nm) and Mid-IR (5.6 – 10 μm, 1785 – 1000 cm−1) laser induced breakdown spectroscopy (LIBS) to characterize the mineral assemblages, hydrated components, and biomolecules in rock and sediment samples collected from three main sites in the volcanically active Kverkfjöll-Vatnajökull region of Iceland: basalt and basalt-hosted carbonate rind from Hveragil geothermal stream, volcanic sediments from the base of Vatnajökull glacier at Kverkfjöll, and lava from the nearby Holuhraun lava field. With our combination of techniques, we were able to identify major mineral polytypes typical for each sample set, as well as a large diversity of biomolecules typical for lichen communities across all samples. The anatase we observed using micro-Raman spectroscopic mapping of the lava compared with the volcanic sediment suggested different formation pathways: lava anatase formed authigenically, sediment anatase could have formed in association with microbial weathering. Mn-oxide, only detected in the carbonate samples, seems to have two possible formation pathways, either by fluvial or microbial weathering or both. Even with our ability to detect a wide diversity of biomolecules and minerals in all of the samples, there was not enough variation between each set to distinguish different environments based on the limited measurements done for this study

The Search for Lipids on Mars: Examining the Influence of Mineralogy on the Pyrolysis of Carboxylic Acids

International audienceLipids, such as fatty acids and waxes, are essential for all life on Earth. As early Mars shared many similarities with the early Earth multiple missions have examined ancient martian sediments for the presence of fatty acids and other organic species. No clear detection of lipids has been made so far, instead only small simple molecules have been observed, with the results dominated by species containing chlorine or sulfur. It has become clear that further developing our understanding of how organic and inorganic phases interact, both in situ and within flight instrumentation on Mars, is greatly needed. In this work, we mixed various fatty acid standards with different Mars-relevant minerals and examined them with a range of flight-relevant analytical methods. We also investigated how certain minerals might trap and preserve organics as they crystallize out of solution. The result inform how fatty acids may appear to the heating experiments used by past and present missions and the laser and spectroscopic methods included in upcoming science payloads

Impacto orcamentario da utilizacao do Metodo Canguru no cuidado neonatal

OBJETIVO Estimar o impacto orçamentário da utilização do Método Canguru na rede municipal de saúde. MÉTODOS Um modelo de decisão analítico foi desenvolvido para simular os custos do Método Canguru e Unidade Intermediária Neonatal no Rio de Janeiro, RJ, em 2011. A população de referência foi constituída pelos recém-nascidos estáveis clinicamente, que podem receber assistência nas duas modalidades de cuidado. O impacto orçamentário foi estimado para uma coorte hipotética de 1.000 recém-nascidos elegíveis em um ano. A proporção de recém-nascidos elegíveis que recebem assistência nas duas modalidades foi obtida por coleta de dados nas maternidades incluídas no estudo. As probabilidades dos eventos e o consumo de recursos de saúde, no período da assistência, foram incorporados ao modelo. Cenários foram desenvolvidos para refletir a adoção do método Canguru em maior ou menor escala. RESULTADOS A utilização do Método Canguru significou redução de gastos equivalente a 16% em um ano, se todos os recém-nascidos elegíveis fossem assistidos por esse método. CONCLUSÕES A opção Método Canguru é de menor custo comparado com a da Unidade Intermediária Neonatal. A análise de impacto orçamentário da utilização desse método no Sistema Único de Saúde indicou economia importante para o período de um ano

Impact of partial versus whole breast radiation therapy on fatigue, perceived stress, quality of life and natural killer cell activity in women with breast cancer

<p>Abstract</p> <p>Introduction</p> <p>This pilot study used a prospective longitudinal design to compare the effect of adjuvant whole breast radiation therapy (WBRT) versus partial breast radiation therapy (PBRT) on fatigue, perceived stress, quality of life and natural killer cell activity (NKCA) in women receiving radiation after breast cancer surgery.</p> <p>Methods</p> <p>Women (N = 30) with early-stage breast cancer received either PBRT, Mammosite brachytherapy at dose of 34 Gy 10 fractions/5 days, (N = 15) or WBRT, 3-D conformal techniques at dose of 50 Gy +10 Gy Boost/30 fractions, (N = 15). Treatment was determined by the attending oncologist after discussion with the patient and the choice was based on tumor stage and clinical need. Women were assessed prior to initiation of radiation therapy and twice after completion of radiation therapy. At each assessment, blood was obtained for determination of NKCA and the following instruments were administered: Perceived Stress Scale (PSS), Functional Assessment of Cancer Therapy-Fatigue (FACT-F), and Functional Assessment of Cancer Therapy-General (FACT-G). Hierarchical linear modeling (HLM) was used to evaluate group differences in initial outcomes and change in outcomes over time.</p> <p>Results</p> <p>Fatigue (FACT-F) levels, which were similar prior to radiation therapy, demonstrated a significant difference in trajectory. Women who received PBRT reported progressively lower fatigue; conversely fatigue worsened over time for women who received WBRT. No difference in perceived stress was observed between women who received PBRT or WBRT. Both groups of women reported similar levels of quality of life (FACT-G) prior to initiation of radiation therapy. However, HLM analysis revealed significant group differences in the trajectory of quality of life, such that women receiving PBRT exhibited a linear increase in quality of life over time after completion of radiation therapy; whereas women receiving WBRT showed a decreasing trajectory. NKCA was also similar between therapy groups but additional <it>post hoc</it> analysis revealed that better quality of life significantly predicted higher NKCA regardless of therapy.</p> <p>Conclusions</p> <p>Compared to WBRT, PBRT results in more rapid recovery from cancer-related fatigue with improved restoration of quality of life after radiation therapy. Additionally, better quality of life predicts higher NKCA against tumor targets, emphasizing the importance of fostering quality of life for women undergoing adjuvant radiation therapy.</p