Is biodegradability a desirable attribute for discarded solid waste? Perspectives from a national landfill greenhouse gas inventory model

There is increasing interest in the use of biodegradable materials because they are believed to be "greener". In a landfill, these materials degrade anaerobically to form methane and carbon dioxide. The fraction of the methane that is collected can be utilized as an energy source and the fraction of the biogenic carbon that does not decompose is stored in the landfill. A landfill life-cycle model was developed to represent the behavior of MSW components and new materials disposed in a landfill representative of the U.S. average with respect to gas collection and utilization over a range of environmental conditions (i.e., arid, moderate wet, and bioreactor). The behavior of materials that biodegrade at relatively fast (food waste), medium (biodegradable polymer) and slow (newsprint and office paper) rates was studied. Poly(3-hydroxybutyrate-co-3-hydroxyoctanoate) (PHBO) was selected as illustrative for an emerging biodegradable polymer. Global warming potentials (GWP) of 26, 720, -1000, 990, and 1300 kg CO(2)e wet Mg(-1) were estimated for MSW, food waste, newsprint, office paper, and PHBO, respectively in a national average landfill. In a state-of-the-art landfill with gas collection and electricity generation, GWP's of -250, 330, -1400, -96, and -420 kg CO(2)e wet Mg(-1) were estimated for MSW, food waste, newsprint, office paper and PHBO, respectively. Additional simulations showed that for a hypothetical material, a slower biodegradation rate and a lower extent of biodegradation improve the environmental performance of a material in a landfill representative of national average conditions.     

Isolation and partial characterization of the neutral glycosphingolipids and gangliosides of the human heart

The glycosphingolipids (GLS) of the human heart muscle have been isolated from total lipids by column and thin layer chromatography and their sugars and fatty acids analyzed by gas liquid chromatography. Hearts from traffic victims were obtained at autopsy between 12 and 16 hr after death and dissected into parts (left and right ventricular walls, intraventricular septum and papillary muscle). The neutral GSL content for those parts of the hearts of two males aged 22 and one female aged 14 ranged from about 90 to 160 nmoles/g wet weight. Trihexosyl ceramide and globoside were the most abundant neutral GSL. Total ganglioside content was about 50 nmoles/g wet weight, and the most abundant gangliosides were partially characterized as GM₃ and GM₁; other mono-, di- and trisialogangliosides were also present. Differences in the content and composition of neutral GSL and gangliosides between the heart and other human tissues are discussed. It is concluded that the patterns of these two GSL fractions of the heart are more complex than those of most of the extraneural human tissues.     

Distributing and Load Balancing Sparse Fluid Simulations

This paper describes a general algorithm and a system for load balancing sparse fluid simulations. Automatically distributing sparse fluid simulations efficiently is challenging because the computational load varies across the simulation domain and time. A key challenge with load balancing is that optimal decision making requires knowing the fluid distribution across partitions for future time steps, but computing this state for an arbitrary simulation requires running the simulation itself. The key insight of this paper is that it is possible to predict future load by running a speculative low resolution simulation in parallel. We mathematically formulate the problem of load balancing over multiple time steps and present a polynomial time algorithm to compute an approximate solution to it. Our experimental results show that distributing and speculatively load balancing sparse FLIP simulations over 8 nodes speeds them up by 5.3× to 7.9×, and that speculative load balancing generates assignments that perform within 20% of optimal.     

Mass analysis of biological macromolecules at atmospheric pressure using nonresonant femtosecond laser vaporization and electrospray ionization

A nonresonant femtosecond laser pulse, with an intensity of 10(13) Wcm(-2), vaporizes proteins and biomolecules intact, regardless of molecular structure, size or electronic structure for subsequent electrospray ionization and transfer into a mass spectrometer. Rapid, direct analysis from dried sample, aqueous solution and cellular material is demonstrated at atmospheric pressure using laser electrospray mass spectrometry (LEMS). Measurements are presented for lysozyme (14.3 kDa), hemoglobin from human blood, ovalbumin (45 kDa) from hen egg white and phospholipids from hen egg yolk. Mass analysis of biological material is performed without dilution, extraction or sample preparation, other than placing the biological material onto the sample plate.     

On generating distributed intelligence systems architectures usinggenetic algorithms

A methodology for generating large scale distributed intelligence systems (DIS's) using genetic algorithms is presented. An organizational structure (chromosome) is characterized by generic interactions (genes) among the individual nodes comprising it. The objective function evaluates each structure in the generated population against a set of structural constraints and some user defined criteria. The structures satisfying these constraints are feasible solutions to the design problem     

Optimal stochastic enforcement of parking regulations

Effective enforcement of no parking regulations, an essential operation in urban areas, is labor intensive and thus costly. Efficient, implementable enforcement strategies that can raise and keep compliance at a desired high level are needed. It is the objective of this work to determine such strategies. First a model relating enforcement (input) to compliance (output) was obtained on the basis of experimental data; its form is that of a homogeneous bilinear Markov process. Then several optimization problems that reflect different operating conditions were formulated and the corresponding enforcement strategies were derived via dynamic programming. Finally, simulations were used to analyze the practical implications of the results.     

Site diversity for satellite earth terminals and measurements at 28GHz

This work reviews site diversity concepts and models and presents the results of a site diversity experiment, in which radiometers were used to measure attenuation on Earth-space paths, performed at Columbus, Ohio, for a period of one year. Attenuation statistics are presented first in the form of the joint probability density function of attenuation at the two sites. From these are derived the cumulative two-dimensional distribution of attenuation at both sites, the cumulative distribution of attenuation at each site, the effective cumulative distribution of attenuation for a diversity system that always switches to the better of two signals, and the effective cumulative distribution of attenuation for a system with maximal-ratio signal combining. The switched-system diversity gain is compared with D.B. Hodge's (1982) predictive model, and the diversity improvement is compared with L. Boithias' (Radiowave Propagation, McGraw-Hill, 1987) model. Fade-duration and interfade-interval statistics are presented for each site and for systems that use switching and maximal-ratio combining. Rain-rate and interrainfall interval statistics are included