Assessment of the probability of contaminating Mars

New methodology is proposed to assess the probability that the planet Mars will by biologically contaminated by terrestrial microorganisms aboard a spacecraft. Present NASA methods are based on the Sagan-Coleman formula, which states that the probability of contamination is the product of the expected microbial release and a probability of growth. The proposed new methodology extends the Sagan-Coleman approach to permit utilization of detailed information on microbial characteristics, the lethality of release and transport mechanisms, and of other information about the Martian environment. Three different types of microbial release are distinguished in the model for assessing the probability of contamination. The number of viable microbes released by each mechanism depends on the bio-burden in various locations on the spacecraft and on whether the spacecraft landing is accomplished according to plan. For each of the three release mechanisms a probability of growth is computed, using a model for transport into an environment suited to microbial growth

New methodology for assessing the probability of contaminating Mars

Methodology is proposed to assess the probability that the planet Mars will be contaminated by terrestrial microorganisms aboard a spacecraft. The present NASA methods are extended to permit utilization of detailed information on microbial characteristics, the lethality of release and transport mechanisms, and of other information about the Martian environment. Different types of microbial release are distinguished, and for each release mechanism a probability of growth is computed. Using this new methodology, an assessment was carried out for the 1975 Viking landings on Mars. The resulting probability of contamination for each Viking lander is 6 x 10 to the -6 power, and is amenable to revision as additional information becomes available

Institutional investors and corporate governance

We provide a comprehensive overview of the role of institutional investors in corporate governance with three main components. First, we establish new stylized facts documenting the evolution and importance of institutional ownership. Second, we provide a detailed characterization of key aspects of the legal and regulatory setting within which institutional investors govern portfolio firms. Third, we synthesize the evolving response of the recent theoretical and empirical academic literature in finance to the emergence of institutional investors in corporate governance. We highlight how the defining aspect of institutional investors – the fact that they are financial intermediaries – differentiates them in their governance role from standard principal blockholders. Further, not all institutional investors are identical, and we pay close attention to heterogeneity amongst institutional investors as blockholders

NiTiBOND, eine optimierte Steigbügelprothese zur chirurgischen Behandlung der Otosklerose

Compared to traditional stapes prostheses, self-crimping prostheses have been shown to result in similar, if not better, closure of the air bone gap in patients undergoing stapedotomy for otosclerosis. To achieve self-crimping, nitinol, a shape memory alloy, has been used for several years but concerns have been raised regarding possible damage to the incus and its muco-periosteum. We investigate these concerns with regard to the newer NiTiBOND stapes prosthesis in an observational multi-centre study.In a multicentre, prospective observational study, 76 patients undergoing stapedotomy with the NiTiBond prosthesis across 4 centres were compared to 75 -retrospectively selected control SMart patients. Complications, intra-operative user-friendliness and audiological results at 3 months were documented.Audiological improvement and the rate of complications were similar in both groups. Non inferiority was shown at all frequencies and in the pure-tone average. The NiTiBOND prosthesis was described as very user-friendly.By eliminating manual crimping, stapedotomy using the NiTiBOND prosthesis can be facilitated and standardized. Furthermore, intraoperative handling characteristics of the prosthesis are very good which may further reduce operative risk. Importantly, we show that these benefits are not to the detriment of audiological outcome. Larger and longer-term studies are required to further evaluate results

Time interval between primary radiotherapy and salvage laryngectomy: a predictor of pharyngocutaneous fistula formation

Salvage laryngectomy (SL) is associated with high levels of morbidity. Rates of pharyngocutaneous fistulae (PCF) are as high as 35 % in some series. Patients at highest risk of such complications may be candidates for altered surgical management in terms of additional tissue transfer, or delayed tracheoesophageal puncture. This study investigates the relationship between the time from primary radiotherapy (RT) to salvage surgery and the development of PCF. 26 consecutive patients who underwent SL between 2000 and 2010 were identified from our institutional database. Demographic, staging, treatment and complication data were collected. Subgroup analysis was performed using the Student's t test or Mann-Whitney U test for continuous variables and either Chi-squared test or Fisher's Exact test for categorical variables. 26 patients underwent SL between October 2003 and July 2010. Of these, 15 (58 %) developed a PCF. On analysis of the time between pre-operative RT and surgery, a significant difference was seen, with a mean time of 19.5 months in those who developed a PCF versus 47.0 months in those who did not (p = 0.02). Patient characteristics, treatment, and pathology results were comparable between the two groups. There was no significant difference in distribution of the other covariates between the PCF and non-PCF groups. We reported a high rate of PCF and identified an association between PCF and a short time from primary treatment to salvage surgery. Identifying factors associated with higher rates of post-operative morbidity allows surgeons to adapt surgical planning in an attempt to minimize rates of PCF

Characterization of an antennal carboxylesterase from the pest moth Spodoptera littoralis degrading a host plant odorant.

Background: Carboxyl/cholinesterases (CCEs) are highly diversified in insects. These enzymes have a broad range of proposed functions, in neuro/developmental processes, dietary detoxification, insecticide resistance or hormone/pheromone degradation. As few functional data are available on purified or recombinant CCEs, the physiological role of most of these enzymes is unknown. Concerning their role in olfaction, only two CCEs able to metabolize sex pheromones have been functionally characterized in insects. These enzymes are only expressed in the male antennae, and secreted into the lumen of the pheromone-sensitive sensilla. CCEs able to hydrolyze other odorants than sex pheromones, such as plant volatiles, have not been identified. Methodology: In Spodoptera littoralis, a major crop pest, a diversity of antennal CCEs has been previously identified. We have employed here a combination of molecular biology, biochemistry and electrophysiology approaches to functionally characterize an intracellular CCE, SlCXE10, whose predominant expression in the olfactory sensilla suggested a role in olfaction. A recombinant protein was produced using the baculovirus system and we tested its catabolic properties towards a plant volatile and the sex pheromone components. Conclusion: We showed that SlCXE10 could efficiently hydrolyze a green leaf volatile and to a lesser extent the sex pheromone components. The transcript level in male antennae was also strongly induced by exposure to this plant odorant. In antennae, SlCXE10 expression was associated with sensilla responding to the sex pheromones and to plant odours. These results suggest that a CCE-based intracellular metabolism of odorants could occur in insect antennae, in addition to the extracellular metabolism occurring within the sensillar lumen. This is the first functional characterization of an Odorant- Degrading Enzyme active towards a host plant volatile