The Formation and Erosion History of Mt. Sharp

The Curiosity rover is exploring 155 km diameter Gale crater and Mt. Sharp, Gale's 5 km high central mound (Fig. 1). This study addresses the formation and erosion history of Mt. Sharp. Gale lies on the topographic dichotomy between the southern highlands and the northern plains - a drop of over 2 km [1,2]. Altitude differences between the north and south rim reflect this regional slope, as do altitude differences between the deep annulus north of Mt. Sharp and the southern crater floor. Orbiter and rover images demonstrate that most exposed areas on Mt. Sharp consist of thin, sub-parallel units interpreted as sedimentary layers [3]. Gale is typical of the 50 large martian craters that have been totally or partially filled with such layers [4,5]. In many craters these sediments have been deeply eroded. Central Peak and Peak Ring: The highest point on Mt. Sharp, near the crater's center, is interpreted as a central peak [6]. The peak has a massive lower portion and a thin, smooth capping deposit (Fig. 2). Gale's size is transitional between martian craters with single central peaks and craters with peak rings approximately half the crater's diameter [2,6]. The boundaries of Mt. Sharp, as well as an arc of hills to the southeast of the mountain, closely match a circle approximately 80 km in diameter (Fig. 3). This morphology suggests that the Gale impact may have formed both a central peak and a partial peak ring, which is covered by the sediments of Mt. Sharp in the north and possibly exposed in the arc of eroded hills in the southeast quadrant (Figs. 3,4)

The Complex, Multi-Stage History of Mt. Sharp

The Curiosity rover is exploring 155 km diameter Gale crater and Mt. Sharp, Gale's 5 km high central mound. This study addresses the formation and erosion history of Mt. Shar

Effect of an oxygen pressure injection (OPI) device on the oxygen saturation of patients during dermatological methyl aminolevulinate photodynamic therapy

Journal Article“The final publication is available at Springer via http://dx.doi.org/10.1007/s10103-012-1188-y"Methyl aminolevulinate photodynamic therapy (MAL-PDT) (a topical treatment used for a number of precancerous skin conditions) utilizes the combined interaction of a photosensitizer (protoporphyrin IX (PpIX)), light of the appropriate wavelength, and molecular oxygen to produce singlet oxygen and other reactive oxygen species which induce cell death. During treatment, localized oxygen depletion occurs and is thought to contribute to decreased efficacy. The aim of this study was to investigate whether an oxygen pressure injection (OPI) device had an effect on localized oxygen saturation levels and/or PpIX fluorescence of skin lesions during MAL-PDT. This study employed an OPI device to apply oxygen under pressure to the skin lesions of patients undergoing standard MAL-PDT. Optical reflectance spectrometry and fluorescence imaging were used to noninvasively monitor the localized oxygen saturation and PpIX fluorescence of the treatment area, respectively. No significant changes in oxygen saturation were observed when these data were combined for the group with OPI and compared to the group that received standard MAL-PDT without OPI. Additionally, no significant difference in PpIX photobleaching or clinical outcome at 3 months between the groups of patients was observed, although the group that received standard MAL-PDT demonstrated a significant increase (p < 0.05) in PpIX fluorescence initially and both groups produced a significant decrease (p < 0.05) after light irradiation. In conclusion, with this sample size, this OPI device was not found to be an effective method with which to improve tissue oxygenation during MAL-PDT. Further investigation is therefore required to find a more effective method of MAL-PDT enhancement. © 2012 Springer-Verlag London Ltd

Optimized media and workflow for the expansion of human pluripotent stem cells as aggregates in suspension

3D suspension culture enables the efficient and cost-effective scale-up of human pluripotent stem cell (hPSCs) manufacturing. However, media optimized for 2D adherent cultures can lead to low volumetric productivity and inefficient workflow. To overcome these limitations we developed mTeSRTM3D, a defined medium based on mTeSRTM1, and novel protocols for fed-batch culture of hPSC aggregates. Human embryonic stem cell (hESC) lines (H1 or H9) or human induced pluripotent stem cell (hiPSC) lines (WLS-1C or STiPS-M001) that were previously maintained in 2D mTeSRTM1 culture were seeded into multiple suspension culture vessels containing mTeSRTM3D Seed Medium plus 10 μM Y-27632 ROCK inhibitor. 3D cultures were maintained using either daily 50% mTeSRTM1 medium exchanges (control) or using a fed-batch protocol whereby the culture medium was supplemented daily with mTeSRTM3D Feed Medium. After 3 or 4 days in suspension culture, aggregates were harvested, dissociated into small clumps with Gentle Cell Dissociation Reagent (GCDR) or single cell suspensions enzymatically, and re-seeded in mTeSRTM3D Seed Medium plus 10 μM Y-27632. Passaging and feeding cycles were repeated for at least 5 passages. 3D cultures were assessed for growth, viability, hPSC marker expression, in vitro differentiation potential, and karyotype. In addition, media was analyzed for molar glucose to lactate yield to characterize metabolism. By day 4, aggregates cultured in mTeSRTM3D typically grew to a mean diameter of 350 μm, with a 5-fold increase in cell number. Using mTeSRTM3D up to 109 cells can be produced from a single plate within 2-3 weeks representing a greater than 500-fold expansion. hPSC cultures maintained in mTeSRTM3D differentiated into all 3 germ layers with high efficiency. The average volumetric productivities were 0.7, 3.1 and 6.9 (x105) viable cells / mL in 2D, daily 50% media exchange, and mTeSRTM3D cultures, respectively. Using the GCDR clump passaging protocol, mTeSRTM3D cultured hPSCs retained normal karyotypes. Culture performance was evaluated in shaker bottles, spinner flasks and bioreactors. Performance in each culture system was comparable confirming straightforward scale-up and wide applicability. Typical growth rates were on the order of 1.5-fold expansion per day. Metabolic activity as assessed by the moles lactate produced to glucose consumed was 1.7, consistent with a primarily glycolytic metabolism. Image analysis was performed to estimate aggregate size during growth. Adaptation times for cells moving from 2D to 3D aggregate culture varied with different cell lines; typically one passage in 3D was required before consistent expansion passage over passage was obtained. Additionally, protocols were developed for use on a Hamilton® robotic platform for reproducible, matrix-free, high-throughput hPSC suspension culture at a small scale. mTeSRTM3D enables efficient scale-up and scale-down of hPSC cultures with greatly simplified workflow