Soil mechanical properties at the Apollo 14 site

The Apollo 14 lunar landing provided a greater amount of information on the mechanical properties of the lunar soil than previous missions because of the greater area around the landing site that was explored and because a simple penetrometer device, a special soil mechanics trench, and the modularized equipment transporter (Met) provided data of a type not previously available. The characteristics of the soil at shallow depths varied more than anticipated in both lateral and vertical directions. While blowing dust caused less visibility impairment during landing than on previous missions, analysis shows that eroded particles were distributed over a large area around the final touchdown point. Measurements on core-tube samples and the results of transporter track analyses indicate that the average density of the soil in the Fra Mauro region is in the range of 1.45 to 1.60 g/cm^3. The soil strength appears to be higher in the vicinity of the site of the Apollo 14 lunar surface experiments package, and trench data suggest that strength increases with depth. Lower-bound estimates of soil cohesion give values of 0.03 to 0.10 kN/m^2, which are lower than values of 0.35 to 0.70 kN/m^2 estimated for soils encountered in previous missions. The in situ modulus of elasticity, deduced from the measured seismic-wave velocity, is compatible with that to be expected for a terrestrial silty fine sand in the lunar gravitational field

Exploring Entrepreneurial Cognition in Franchisees: A Knowledge-Structure Approach

Franchisees participate in new business creation uniquely, because, in many respects, the development of their ventures is under the direction of franchisors. In this study, using entrepreneurial scripts, we compare the extent to which franchisee venturing is similar to and/or distinct from individual-based entrepreneurship in nonfranchise new ventures. We therefore examined the entrepreneurial scripts of individuals in a purposeful sample of 54 franchisees compared to two counterpart groups: 54 independent entrepreneurs and 94 managers (neither franchisee nor entrepreneur). Using MANCOVA and follow-up tests we find that franchisees are less like entrepreneurs and more similar to nonentrepreneur managers

Exploring Entrepreneurial Cognition in Franchisees: A Knowledge-Structure Approach

ABSTRACT Franchisees participate in new business creation uniquely, because, in many respects, the development of their ventures is under the direction of franchisors. In this study, using entrepreneurial scripts, we compare the extent to which franchisee venturing is similar to and/ or distinct from individual-based entrepreneurship in non-franchise new ventures. We therefore examined the entrepreneurial scripts of individuals in a purposeful sample of 54 franchisees compared to two counterpart groups: 54 independent entrepreneurs and 94 managers (neither franchisee nor entrepreneur). Using MANCOVA and follow-up tests we find that franchisees are less like entrepreneurs and more similar to non-entrepreneur managers

Picture-Hanging Puzzles

We show how to hang a picture by wrapping rope around n nails, making a polynomial number of twists, such that the picture falls whenever any k out of the n nails get removed, and the picture remains hanging when fewer than k nails get removed. This construction makes for some fun mathematical magic performances. More generally, we characterize the possible Boolean functions characterizing when the picture falls in terms of which nails get removed as all monotone Boolean functions. This construction requires an exponential number of twists in the worst case, but exponential complexity is almost always necessary for general functions.Comment: 18 pages, 8 figures, 11 puzzles. Journal version of FUN 2012 pape

Aortic valve replacement in neonates and infants: An analysis of the Society of Thoracic Surgeons Congenital Heart Surgery Database

ObjectiveWe sought to describe early outcomes of aortic valve replacement in neonates and infants across a large multicenter cohort.MethodsNeonates and infants in the Society of Thoracic Surgeons Congenital Heart Surgery Database undergoing nontruncal aortic valve replacement with the Ross-Konno procedure, Ross procedure, or homograft replacement from 2000 to 2009 were included. Preoperative characteristics, operative data, and early outcomes are described.ResultsA total of 160 patients (43 neonates, 117 infants) from 47 centers were included. Society of Thoracic Surgeons–defined preoperative risk factors were present in 76 patients (48%) and were most prevalent in neonates (67%) and patients undergoing homograft aortic valve replacement (93%). Concomitant arch repair or mitral valve surgery was performed in 30 patients (19%) and 19 patients (12%), respectively. Postoperative mechanical circulatory support was used in 17 patients (11%). Overall in-hospital mortality was 18% and was highest for neonates (28%) and patients undergoing homograft aortic valve replacement (40%). Concomitant arch repair was associated with higher in-hospital mortality (33% vs 15%, P = .02), whereas concurrent mitral valve surgery was not (21% vs 18%, P = .73). Postoperative mechanical circulatory support was also associated with increased in-hospital mortality (65% vs 13%, P < .0001).ConclusionsNeonates and infants undergoing aortic valve replacement are a high-risk group, with hospital mortality comparable with some of the highest risk procedures in this age group. The requirement for arch repair or postoperative mechanical circulatory support was associated with an increased risk of death in this cohort

The putative proteinase maturation protein A of Streptococcus pneumoniae is a conserved surface protein with potential to elicit protective immune responses

Surface-exposed proteins often play an important role in the interaction between pathogenic bacteria and their host. We isolated a pool of hydrophobic, surface-associated proteins of Streptococcus pneumoniae. The opsonophagocytic activity of hyperimmune serum raised against this protein fraction was high and species specific. Moreover, the opsonophagocytic activity was independent of the capsular type and chromosomal genotype of the pneumococcus. Since the opsonophagocytic activity is presumed to correlate with in vivo protection, these data indicate that the protein fraction has the potential to elicit species-specific immune protection with cross-protection against various pneumococcal strains. Individual proteins in the extract were purified by two-dimensional gel electrophoresis. Antibodies raised against three distinct proteins contributed to the opsonophagocytic activity of the serum. The proteins were identified by mass spectrometry and N-terminal amino acid sequencing. Two proteins were the previously characterized pneumococcal surface protein A and oligopeptide-binding lipoprotein AmiA. The third protein was the recently identified putative proteinase maturation protein A (PpmA), which showed homology to members of the family of peptidyl-prolyl cis/trans isomerases. Immunoelectron microscopy demonstrated that PpmA was associated with the pneumococcal surface. In addition, PpmA was shown to elicit species-specific opsonophagocytic antibodies that were cross-reactive with various pneumococcal strains. This antibody cross-reactivity was in line with the limited sequence variation of ppmA. The importance of PpmA in pneumococcal pathogenesis was demonstrated in a mouse pneumonia model. Pneumococcal ppmA-deficient mutants showed reduced virulence. The properties of PpmA reported here indicate its potential for inclusion in multicomponent protein vaccines