Scheduling Space–Ground Communications for the Air Force Satellite Control Network

We present the first coupled formal and empirical analysis of the Satellite Range Scheduling application. We structure our study as a progression; we start by studying a simplified version of the problem in which only one resource is present. We show that the simplified version of the problem is equivalent to a well-known machine scheduling problem and use this result to prove that Satellite Range Scheduling is NP-complete. We also show that for the one-resource version of the problem, algorithms from the machine scheduling domain outperform a genetic algorithm previously identified as one of the best algorithms for Satellite Range Scheduling. Next, we investigate if these performance results generalize for the problem with multiple resources. We exploit two sources of data: actual request data from the U.S. Air Force Satellite Control Network (AFSCN) circa 1992 and data created by our problem generator, which is designed to produce problems similar to the ones currently solved by AFSCN. Three main results emerge from our empirical study of algorithm performance for multiple-resource problems. First, the performance results obtained for the single-resource version of the problem do not generalize: the algorithms from the machine scheduling domain perform poorly for the multiple-resource problems. Second, a simple heuristic is shown to perform well on the old problems from 1992; however it fails to scale to larger, more complex generated problems. Finally, a genetic algorithm is found to yield the best overall performance on the larger, more difficult problems produced by our generator.     

A reuse business model

This paper summarizes the decision framework for forming reuse business models and offers the Expert Services Model as a preferred first application of that framework. The Expert Services Model is only one possible approach, but one that we found is a good starting point. The framework for setting up a reuse plan consists of four major steps: define reuse, populate a library of reusable assets, share reusable assets, and maintain reusable assets.     

LOX-induced lipid peroxidation mechanism responsible for the detrimental effect of marine diatoms on zooplankton grazers

Some marine diatoms negatively affect the reproduction of dominant zooplankton grazers such as copepods, thus compromising the transfer of energy through the marine food chains. In this paper, the metabolic mechanism that leads to diatom-induced toxicity is investigated in three bloom-forming microalgae. We show that copepod dysfunctions can be induced by highly reactive oxygen species (hROS) and a blended mixture of diatom products, including fatty acid hydroperoxides (FAHs); these compounds display teratogenic and proapoptotic properties. The process is triggered by the early onset of lipoxygenase activities that elicit the synthesis of species-specific products, the basic structures of which were established (1-20); these compounds boost oxidative stress by massive lipid peroxidation. Our study might explain past laboratory and field results showing how diatoms damage zooplankton grazers even in the absence of polyunsaturated aldehydes, a class of molecules that has been formerly implicated in mediating the toxic activity of diatoms on copepods.     

Towards a heat- and mass-balanced kinetic model of TATB decomposition

TATB (1,3,5-triamino-2,4,6-trinitrobenzene) was thermally degraded by two small-scale analytical methods – simultaneous differential scanning calorimetry and thermogravimetric analysis (SDT) and a hot-stage microscope with Fourier Transform Infrared (FTIR) analysis capabilities. SDT used ramped heating, isothermal soaking, and thermal pretreatment at various conditions. The heat flow and mass loss were monitored during various treatment conditions to derive chemical decomposition kinetics and Arrhenius parameters. FTIR experiments used isothermal heating, and changes were monitored spectroscopically. Solid samples generated at specific conditions were collected from both methods and were analyzed by DMSO extraction followed by chemical speciation by optical and mass spectrometric methods. Characterization provided the following reaction insights: 1. TATB decreases in a sigmoidal pattern in isothermally heated samples. Other soluble products gradually increase in concentration and then abruptly decline in concentration during the second exotherm, such as diamino-dinitro-benzofurazan and amino-nitro-benzodifurazan. 2. FTIR showed gradual changes in the amino and nitro functionality, shifting positions and decreasing intensity for the first 40 min. Then the solid gradually appeared more like an amorphous C with N incorporated, similar to previous studies on thermally degraded TATB-type materials. 3. Extracted residues (DMSO-soluble components removed) examined by FTIR showed an abrupt change in chemical composition between 40- and 45-min isothermal treatment, indicating early forming solids are different than later forming residues. 4. A reliable mass- and energy-balanced global reaction network must include at least two autocatalytic reactions, either in parallel or series, and at least one must have an explicit initiation reaction having a low activation energy.     

An adaptive visual environment for digital libraries

CDL (Corporate Digital Library) is a prototypical intelligent digital library service that is currently being developed at the University of Bari, as an evolution of a previous project named IDL (Intelligent Digital Library). Among the characterizing features of CDL there are a retrieval engine and several facilities available for the library users. In this paper, we present the web-based visual environment we have developed with the aim of improving user-library interaction. The CDL environment is equipped with some novel visual tools that are primarily intended for inexperienced users, who represent most of the users that usually have access to digital libraries. Machine Learning techniques have been exploited in CDL for document analysis, classification, and understanding, as well as for building a user modeling module, which is the basic component for providing CDL with user interface adaptivity. This feature is also discussed in the paper. Received: 15 December 1997 / Revised: June 1999     

Proteomic Analysis of Methylglyoxal Modifications Reveals Susceptibility of Glycolytic Enzymes to Dicarbonyl Stress

Methylglyoxal (MGO) is a highly reactive cellular metabolite that glycates lysine and arginine residues to form post-translational modifications known as advanced glycation end products. Because of their low abundance and low stoichiometry, few studies have reported their occurrence and site-specific locations in proteins. Proteomic analysis of WIL2-NS B lymphoblastoid cells in the absence and presence of exogenous MGO was conducted to investigate the extent of MGO modifications. We found over 500 MGO modified proteins, revealing an over-representation of these modifications on many glycolytic enzymes, as well as ribosomal and spliceosome proteins. Moreover, MGO modifications were observed on the active site residues of glycolytic enzymes that could alter their activity. We similarly observed modification of glycolytic enzymes across several epithelial cell lines and peripheral blood lymphocytes, with modification of fructose bisphosphate aldolase being observed in all samples. These results indicate that glycolytic proteins could be particularly prone to the formation of MGO adducts.     

Depolymerization of chromophoric natural organic matter

Although the importance of natural organic matter (NOM) in the environment and in drinking water treatment is well-known, its structure is still ill-defined. The fragmentation patterns of NOM treated by irradiation (various wavelengths--185-400 nm), hydroxyl radicals, chlorine, ozone, and breakdown by a white rot fungus were studied to investigate the structure of chromophoric NOM molecules. Size exclusion chromatography was used to monitor the size distributions of NOM in two natural water waters and two NOM isolates. Three distinct fragmentation patterns were observed: ozone attack appeared to be nonsize specific, UV (> or = 254 nm) irradiation preferentially removed higher molecular weight chromophores, while processes involving hydroxyl radical showed intermediate size specificity. For the samples studied, the UV (> or = 254 nm) irradiation-induced fragmentation of NOM followed the patterns suggested by a simple trimer depolymerization model, supporting the viewpoint that NOM has repeating structural units joined by photolabile chemical bonds. The largest molecules reacted most rapidly, progressively fragmenting into slower reacting smaller molecules, which initially accumulated before breaking down to become nonchromophoric. This dependency of rate on molecular size appears to follow from the law of photochemistry which states the rate of reaction is proportional to the rate of light absorption: larger chromophores had higher molar absorptivities, absorbed more photons, and hence reacted faster than smaller chromophores.     

MGMT and Whole-Genome DNA Methylation Impacts on Diagnosis,Prognosis and Therapy of Glioblastoma Multiforme

Epigenetic changes in DNA methylation contribute to the development of many diseases, including cancer. In glioblastoma multiforme, the most prevalent primary brain cancer and an incurable tumor with a median survival time of 15 months, a single epigenetic modification, the methylation of the O⁶-Methylguanine-DNA Methyltransferase (MGMT) gene, is a valid biomarker for predicting response to therapy with alkylating agents and also, independently, prognosis. More recently, the progress from single gene to whole-genome analysis of DNA methylation has allowed a better subclassification of glioblastomas. Here, we review the clinically relevant information that can be obtained by studying MGMT gene and whole-genome DNA methylation changes in glioblastomas, also highlighting benefits, including those of liquid biopsy, and pitfalls of the different detection methods. Finally, we discuss how changes in DNA methylation, especially in glioblastomas bearing mutations in the Isocitrate Dehydrogenase (IDH) 1 and 2 genes, can be exploited as targets for tailoring therapy.