Phospholipides containing amino acids other than serine. I. Detection

In view of the widespread occurrence of the amino acid-containing lipides and the unique course of their metabolism during development of Drosophila, we have carried out extensive investigations concerned with their isolation and chemical nature. The present report is concerned primarily with techniques and procedures developed to insure removal of non-lipide contaminants from preparations of these lipides

Nuclear magnetic resonance cryoporometry

Nuclear Magnetic Resonance (NMR) cryoporometry is a technique for non-destructively determining pore size distributions in porous media through the observation of the depressed melting point of a confined liquid. It is suitable for measuring pore diameters in the range 2 nm-1 mu m, depending on the absorbate. Whilst NMR cryoporometry is a perturbative measurement, the results are independent of spin interactions at the pore surface and so can offer direct measurements of pore volume as a function of pore diameter. Pore size distributions obtained with NMR cryoporometry have been shown to compare favourably with those from other methods such as gas adsorption, DSC thermoporosimetry, and SANS. The applications of NMR cryoporometry include studies of silica gels, bones, cements, rocks and many other porous materials. It is also possible to adapt the basic experiment to provide structural resolution in spatially-dependent pore size distributions, or behavioural information about the confined liquid

Privacy-Preserving Shortest Path Computation

Navigation is one of the most popular cloud computing services. But in virtually all cloud-based navigation systems, the client must reveal her location and destination to the cloud service provider in order to learn the fastest route. In this work, we present a cryptographic protocol for navigation on city streets that provides privacy for both the client's location and the service provider's routing data. Our key ingredient is a novel method for compressing the next-hop routing matrices in networks such as city street maps. Applying our compression method to the map of Los Angeles, for example, we achieve over tenfold reduction in the representation size. In conjunction with other cryptographic techniques, this compressed representation results in an efficient protocol suitable for fully-private real-time navigation on city streets. We demonstrate the practicality of our protocol by benchmarking it on real street map data for major cities such as San Francisco and Washington, D.C.Comment: Extended version of NDSS 2016 pape

Worklife Determinants of Retirement Income Differentials Between Men and Women

Women enter retirement having spent fewer years in market work, earned less over their lifetimes, and worked in different jobs than men of the same age. This study examines whether these differences in work-life experiences help explain why many women end up with lower levels of retirement income in old age. We use the Health and Retirement Study (HRS), which provides information on labor market histories along with the ability to predict retirement income from employer pensions, social security benefits, and investment returns. We document differences in anticipated retirement income by sex that exist largely between nonmarried men and women. Multivariate models show that 85 percent of this retirement income gap can be attributed to differences in lifetime labor market earnings, years worked, and occupational segregation by sex. Our results suggest that as women's work-life experiences become more congruent with men's over time, the gap in retirement income between men and women may shrink.

Cross-Cohort Differences in Health on the Verge of Retirement

Baby Boomers have left a unique imprint on US culture and society in the last 60 years, and it might be anticipated that they will also put their own stamp on retirement, the last phase of the life cycle. Yet because Boomers have not all fully retired, we cannot yet judge how they will fare as retirees. Instead, we focus on how this group compares with prior groups on the verge of retirement, that is, at ages 51-56. Accordingly, this chapter evaluates the stock of health which Early Boomers bring to retirement and compare these to the circumstances of two prior cohorts at the same point in their life cycles. Using three sets of responses from the Health and Retirement Study, we find some interesting patterns. Overall, the raw evidence indicates that Boomers on the verge of retirement are in poorer health their counterparts 12 years ago. Using a summary health index designed for this study, we find that those born 1948 to 1953 share health risks with the War Baby cohort. This suggests that most of the health decline instead began before the late 1940's. A more complex set of health conclusions emerges from the specific self-reported health measures. Boomers indicate they have relatively more difficulty with a range of everyday physical tasks, but they also report having more pain, more chronic conditions, more drinking and psychiatric problems, than their HRS earlier counterparts. This trend portends poorly for the future health of Boomers as they age and incur increasing costs associated with health care and medications. Using our health index, only those at the 75th percentile or higher are likely to be characterized as having good or better health.

Invariant manifolds and the geometry of front propagation in fluid flows

Recent theoretical and experimental work has demonstrated the existence of one-sided, invariant barriers to the propagation of reaction-diffusion fronts in quasi-two-dimensional periodically-driven fluid flows. These barriers were called burning invariant manifolds (BIMs). We provide a detailed theoretical analysis of BIMs, providing criteria for their existence, a classification of their stability, a formalization of their barrier property, and mechanisms by which the barriers can be circumvented. This analysis assumes the sharp front limit and negligible feedback of the front on the fluid velocity. A low-dimensional dynamical systems analysis provides the core of our results.Comment: 14 pages, 11 figures. To appear in Chaos Focus Issue: Chemo-Hydrodynamic Patterns and Instabilities (2012

Improving Agricultural Irrigation on the Balkhab River, Afghanistan

In Afghanistan, where 80% of the population is rural, irrigated agriculture is important for satisfying subsistence needs. While most of the irrigated agriculture is fed by diversion canal systems which tap surface flows, legal and physical water infrastructure in the region is generally poor. A math programming model is used to optimize irrigation strategies under different water-availability and policy scenarios. It is found that the construction of a reservoir could increase net revenues to a representative farming community by up to 30%. However, even greater benefits may result from increasing distribution efficiencies, depending on the initial level of conveyance losses. Further, property rights schemes may be implemented to distribute wealth more evenly through various zones at minimal cost to the agricultural community as a whole. These results may prove useful to policymakers or water authorities in reestablishing water rights.linear programming, irrigation, Afghanistan, Agricultural and Food Policy, Community/Rural/Urban Development, International Development,