What Does It Cost To Guarantee Returns?

The financial crisis has dramatically demonstrated how a collapse in equity prices can decimate retirement accounts. The crisis highlights the fragility of existing 401(k) plans as the only supplement to Social Security and has sparked proposals to reform the retirement income system. One component of such a system could be a new tier of retirement accounts. Given the declines in the share of earnings Social Security will replace, these accounts would bolster replacement rates for low-wage workers and increase the security of middle- and upper-wage workers who increasingly rely on their 401(k) plans to supplement Social Security. However, these new accounts could face the same risk of collapse in value seen over the past year in 401(k)s. So policymakers may find some form of guaranteed return or risk sharing desirable to prevent huge variations in outcomes. This brief explores the feasible range and the cost of the first option – guarantees...

Epidermal Patterns in Haploid, Diploid and Tetraploid Tomatoes (Abstract)

Beginning with a sterile, dwarf tomato haploid of Lycopericon esculentum, carrying 12 univalent chromosomes, and a completely homozygous diploid strain with 12 pairs of chromosomes and highly fertile was produced by asexual doubling of chromosomes with the decapitation-callus technique. The latter was in turn doubled by the same method producing the relatively sterile homozygous autotetraploid form with 18 chromosomes (12 sets of quadrivalents). This n-2n-4n series of tomatoes provides unique material to test the influence of the very same genes in different dosages. The length of the guard cells along the median line affords a means of distinguishing between haploid, diploid and tetraploid plants. Stomata length averages 15 microns in haploid, 24 microns in diploid, and 3G microns in tetraploid plants. Stomata length in the three classes of plants is roughly in the ratio 5:8:12. Epidermal cells of haploid plants are approximately isodiametric, those of the tetraploid are considerably longer than wide, and those of the diploid are intermediate in proportions

Some Historical Features of Potato Stem Necrosis Associated With Actinomyces Scabies

Certain varieties of potato (Solanum tuberosum L.) are extremely susceptible to the common scab disease caused by Actinomyces scabies (Thaxt.) Güssow, whereas the tubers of others are very resistant. The scab organism is also capable of parasitizing the stems, causing severe necrosis which may result in premature death of the plant. Varieties known to be resistant to tuber scab show considerable resistance to stem necrosis, whereas those susceptible to tuber scab are likewise susceptible to scab on the stems

Atomic resolution scanning tunneling microscopy images of Au(111) surfaces in air and polar organic solvents

Atomic features of a close‐packed metal surface have been observed for the first time by scanning tunneling microscopy in organic polar solvents. Evaporated gold films, exhibiting large reconstructed (111) terraces, have been imaged with a resolution far superior to previous results in aqueous environments

Glass Bubbles Insulation for Liquid Hydrogen Storage Tanks

A full-scale field application of glass bubbles insulation has been demonstrated in a 218,000 L liquid hydrogen storage tank. This work is the evolution of extensive materials testing, laboratory scale testing, and system studies leading to the use of glass bubbles insulation as a cost efficient and high performance alternative in cryogenic storage tanks of any size. The tank utilized is part of a rocket propulsion test complex at the NASA Stennis Space Center and is a 1960's vintage spherical double wall tank with an evacuated annulus. The original perlite that was removed from the annulus was in pristine condition and showed no signs of deterioration or compaction. Test results show a significant reduction in liquid hydrogen boiloff when compared to recent baseline data prior to removal of the perlite insulation. The data also validates the previous laboratory scale testing (1000 L) and full-scale numerical modeling (3,200,000 L) of boiloff in spherical cryogenic storage tanks. The performance of the tank will continue to be monitored during operation of the tank over the coming years. KEYWORDS: Glass bubble, perlite, insulation, liquid hydrogen, storage tank

Large-Scale Cryogenic Testing of Launch Vehicle Ground Systems at the Kennedy Space Center

The development of a new launch vehicle to support NASA's future exploration plans requires significant redesign and upgrade of Kennedy Space Center's (KSC) launch pad and ground support equipment systems. In many cases, specialized test equipment and systems will be required to certify the function of the new system designs under simulated operational conditions, including propellant loading. This paper provides an overview of the cryogenic test infrastructure that is in place at KSC to conduct development and qualification testing that ranges from the component level to the integrated-system level. An overview of the major cryogenic test facilities will be provided, along with a detailed explanation of the technology focus area for each facilit

Cryogenic Thermal Performance Testing of Bulk-Fill and Aerogel Insulation Materials

The research testing and demonstration of new bulk-fill materials for cryogenic thermal insulation systems was performed by the Cryogenics Test Laboratory at NASA Kennedy Space Center. Thermal conductivity testing under actual-use cryogenic conditions is a key to understanding the total system performance encompassing engineering, economics, and materials factors. A number of bulk fill insulation materials, including aerogel beads, glass bubbles, and perlite powder, were tested using a new cylindrical cryostat. Boundary temperatures for the liquid nitrogen boil-off method were 293 K and 78 K. Tests were performed as a function of cold vacuum pressure from high vacuum to no vacuum conditions. Results are compared with other complementary test methods in the range of 300 K to 20 K. Various testing techniques are shown to be required to obtain a complete understanding of the operating performance of a material and to provide data for answers to design engineering questions

Effects of flow alteration on Apple-ring Acacia (Faidherbia albida) stands, Middle Zambezi floodplains, Zimbabwe

The impounding of the Zambezi River by Kariba dam has regulated the river discharge of the Middle Zambezi river. This has been implicated in the failure of regeneration of Faidherbia albida in the downstream flood plain. This study aimed (1) to assess the effect of the altered flow regime of the river on the establishment and growth of F. albida on the Middle Zambezi floodplain and islands and (2) to test the potential of dendrochronology in detecting the age and long-term growth rates of F. albida in response to flow regime. Results indicated an uneven age distribution of F. albida stands on relatively ‘new islands’, dominated by young trees, while the floodplain and the ‘old island’ exhibited an even-aged stand but with a lack of regeneration, and a dying-off of older trees. The lack of F. albida establishment on the floodplain was linked to the decreased occurrence of flooding events, associated with a decrease in alluvial deposits, soil moisture and groundwater recharge. These effects may be enhanced by impact from browsers on regeneration of trees. Tree-ring analyses revealed the presence of distinct annual growth rings in F. albida and the applicability of dendrochronology for estimating F. albida population dynamics. The trees on the ‘new islands’ are younger and grow faster than those on the floodplain. Lack of competition and possible favourable moisture conditions suggest beneficial conditions for establishment and growth of the trees on the islands

Physikalische Parameter extrakorporaler Stoßwellen

Prerequisites for the successful investigation of the mechanism of action of ESWT (extracorporeal shockwave therapy) and the establishment of treatment standards, are the ability to measure, and a knowledge of, the physical parameters involved. The most accurate measurements are obtained with laser hydrophones. Various parameters (amplitude, rise time, pulse width, pressure pulse decay, rarification phase) of a typical shock wave can thus be determined. These can then be used to calculate energy flux density, focal extent, focal volume and as well as focal energy, effective energy in a defined area, and effective biological energy. These parameters can be utilized to work out a theoretical treatment protocol