Regional Atmospheric Dynamics of Water on Mars

The investigation of water on Mars continues to be a quintessential objective in planetary exploration since water represents a critical link to Mars’ past and present climate, geology, and its potential for habitability. Direct observations of water at the regional scale is limited, and the distribution and behavior of water in the planetary boundary layer remains an outstanding question. The research in this dissertation investigates the radiative and dynamical processes governing the regional water cycle on Mars. Using global and mesoscale atmospheric models, simulations of the regional water circulation revealed a highly non-homogeneous local distribution of water that is strongly modulated by diurnal transport. Terrain-following air parcels forced along the slopes of the Tharsis volcanoes and the steep canyon walls of Valles Marineris significantly impact the local water concentration and the associated conditions for cloud formation in these regions. An investigation of water ice fogs inside Valles Marineris showed significant variability between the local atmospheric environment inside versus outside the canyon. Formation of water ice clouds is possible in Valles Marineris, but their formation is highly influenced by radiative feedbacks forced by the thermal properties of the underlying surface. An evaluation of the potential influences of the atmosphere on recurring slope lineae (RSL) activity revealed an upper limit of ~1 µm per sol for the quantity of water that can be extracted from the atmosphere through deliquescence. Ongoing efforts to understand how regional atmospheric dynamics govern the distribution of water in the planetary boundary layer represent a significant step towards a comprehensive understanding of the water cycle on Mars.Release after 03/15/202

Hemolysis and methemoglobinemia due to hepatitis E virus infection in patient with G6PD deficiency

published_or_final_versionSpringer Open Choice, 21 Feb 201

Towards a global partnership model in interprofessional education for cross-sector problem-solving

Objectives A partnership model in interprofessional education (IPE) is important in promoting a sense of global citizenship while preparing students for cross-sector problem-solving. However, the literature remains scant in providing useful guidance for the development of an IPE programme co-implemented by external partners. In this pioneering study, we describe the processes of forging global partnerships in co-implementing IPE and evaluate the programme in light of the preliminary data available. Methods This study is generally quantitative. We collected data from a total of 747 health and social care students from four higher education institutions. We utilized a descriptive narrative format and a quantitative design to present our experiences of running IPE with external partners and performed independent t-tests and analysis of variance to examine pretest and posttest mean differences in students’ data. Results We identified factors in establishing a cross-institutional IPE programme. These factors include complementarity of expertise, mutual benefits, internet connectivity, interactivity of design, and time difference. We found significant pretest–posttest differences in students’ readiness for interprofessional learning (teamwork and collaboration, positive professional identity, roles, and responsibilities). We also found a significant decrease in students’ social interaction anxiety after the IPE simulation. Conclusions The narrative of our experiences described in this manuscript could be considered by higher education institutions seeking to forge meaningful external partnerships in their effort to establish interprofessional global health education

Study of sphingomyelin and ceramide model membrane phase behavior using deuterium nuclear magnetic resonance spectroscopy

Sphingomyelin is a major constituent of most eukaryotic cell plasma membranes. During apoptosis, sphingomyelin is converted into ceramide. It is hypothesized that this conversion induces a structural change in membranes that leads to downstream signaling. Deuterium nuclear magnetic resonance spectroscopy is used to create a partial phase diagram of multilamellar aqueous dispersions of palmitoyl sphingomyelin and ceramide in excess water to characterize the structural changes associated with increased ceramide content (0--40 mol$$ ceramide) and varying temperature (25--80degD). The two lipids are fully miscible at high temperatures and at 40 mol$$ ceramide. A variety of solid-liquid coexistence phase behavior is observed at lower concentrations. A gel phase is observed at progessively higher temperatures in the sphingomyelin:ceramide membranes as ceramide content increase. This implies that at physiological temperatures, ceramide may increase the gel phase propensity of cell membranes

Can localized impurities exert global effects on lipid model membranes?

The currently accepted model for cell membrane organization involves "lipid rafts"\u27, which differ in composition from the surrounding lipid sea. The existence of these nano-scale heterogeneities is supported by observation of coexisting ordered and disordered lipid phases in lipid model membranes. Fluorescence is a popular family of techniques that can provide dynamic and structural information about membranes. With any probe method, characterization of the effects of fluorescent probe addition on the systems they are used to study is important for the interpretation of experimental data. Comparison can be made between labelled and unlabelled samples using a non-perturbing method, such as deuterium nuclear magnetic resonance spectroscopy (2H NMR). This thesis used 2H NMR to study the effects of an equipartitioning probe, Laurdan, and a non-equipartitioning probe, naphthopyrene, on a well-studied three-component lipid membrane system (35:35:30 dioleoyl-sn-glycero-3-phosphocholine (DOPC)/dipalmitoyl-sn-glycero-3-phosphocholine-D62 (DPPC-D62)/cholesterol) with a miscibility phase transition. In phase-separated membranes, 0.03-0.6% naphthopyrene disordered lipid chains of DPPC-D62 in the liquid-disordered phase, but not of those in the liquid-ordered phase. 0.1-2% Laurdan did not affect the DPPC-D62 in either phase in these membranes. Above the miscibility transition temperature (22 degrees Celsius), there is a single homogeneous liquid phase that is not perturbed by the addition of either probe. Laurdan is particularly well suited to the study of phase separation in lipid membranes. It partitions equally well into ordered and disordered lipid phases and displays a polarity-dependent emission spectral shift. Laurdan general polarization (GP) parameter, which characterizes said spectral shift, has been used to characterize membrane fluidity. Two-photon excitation microscopy Laurdan GP images were acquired for membranes with 0.2-2% Laurdan, and Laurdan GP values were found to be strongly correlated with dnmr methylene order parameters of DPPC-D62 in the liquid-ordered phase. Finally, photo-induced phase separation is known to occur in fluorescence microscopy experiments; however, our 2H NMR experiments showed that naphthopyrene can alter membrane properties in the absence of light. The fact that trace amounts of probe (e.g., 0.03-0.6% naphthopyrene) affect lipid molecular order has biological implications: biomolecules present in very small amounts are known to have important functions in cells

Measuring molecular order for lipid membrane phase studies: Linear relationship between Laurdan generalized polarization and deuterium NMR order parameter

Two dimensional phase separation in lipid membranes and cell membranes is of interest to biology because of the idea of membrane rafts — compositionally heterogeneous liquid crystal domains with cellular functions. Few quantitative tools exist for characterizing and differentiating coexisting phases on a molecular scale. Lipid acyl chain order can be measured directly using deuterium nuclear magnetic resonance spectroscopy (2H NMR), or inferred using fluorescence microscopy along with the environment-sensitive probe Laurdan. We found a linear relationship between the 2H NMR order parameter and Laurdan generalized polarization. This observed correlation supports the idea that lipid chain order is tightly associated with the amount and dynamics of water molecules at the glycerol backbone level of the membrane.Fil: Leung, Sherry See Wai. University Fraser Simon. Faculty Of Applied Sciences; CanadáFil: Brewer, Jonathan. University Of Southern Denmark; DinamarcaFil: Bagatolli, Luis Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra. Universidad Nacional de Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra; ArgentinaFil: Thewalt, Jenifer L.. University Fraser Simon. Faculty Of Applied Sciences; Canad

Regulation of G₂/M cell cycle DNA damage checkpoints

Deregulation of the cell cycle checkpoints is a key step in tumorigenesis. we present evidence that apart from CDC25, WEE1 may also be important for the G₂/M DNA damage checkpoints. ING1 is a candidate tumor suppressor that cooperates with p53 to inhibit cell proliferation. We show that ING1 can regulate the cell cycle and the DNA damage responses at G₂/M phase independent of p53 functions. ING1b enhanced the p53-independent G₂/M DNA damage checkpoint induced by adriamycin, but did not affect the G₁ DNA damage checkpoint. No significant transactivation of p21^CIP1/WAF1 and MDM2 by ING1 in the absence of p53 was observed, suggesting that mechanisms involving activation of p53-related proteins are unlikely to contribute to the G₂/M cell cycle arrest caused by ING1b. These data provide evidence of the involvement of WEE1 and ING1 in the G₂/M DNA damage checkpoint. Understanding precisely how these proteins regulate the cell cycle and checkpoints may shed light on the mechanism of tumorigenesis