A GPS-based Mobility Power Model for Military Vehicle Applications

In recent years, military vehicles have been equipped with hybrid, diesel-electric drives to improve fuel efficiency and stealth capabilities. These vehicles require an accurate estimate of the power duty cycles during distinct operating conditions. To meet this demand, a GPS-based mobility power and duty cycle analysis is one approach to predict the power requirements of on-road and off-road vehicles. The dynamic vehicle parameters needed to estimate the forces developed during locomotion are determined from the GPS tracking data, and these forces include the following: the motion resistance, gravitational, linear inertia, rotational inertia, and aerodynamic drag. The motion resistance force generated at the wheel and soil interface is quantified via the U.S. military\u27s Vehicle Terrain Interaction (VTI) model. On-road controlled tests were performed to validate the motion resistance, grade, and inertia components of the model. Uncontrolled tests were performed to validate the model in a scenario that simulated a U.S. military reconnaissance mission. GPS data was collected from Trimble 132 and Garmin 18 GPS receivers. The predicted mobility power values from the GPS data were compared to the measured drivewheel power estimated from engine data transmitted on the vehicle\u27s Controller Area Network (CAN). The results from the validation tests indicated that the model accurately predicted the average power requirements of the vehicle while the model had a moderate level of variability when estimating the power requirements at discrete points in time during testing. The motion resistance tests conducted at slow speeds provided for reasonable estimates of the required mobility power. The absolute average percent error of the average positive power requirements during the grade and inertia tests was 6 and 21% respectively from the Trimble 132 GPS receiver. The absolute average percent error during the uncontrolled test was 20% from the Trimble 132 GPS receiver. The model was applied to GPS tracking data collected for the U.S. Army\u27s 8-wheeled Stryker vehicle conducting reconnaissance missions at Fort Lewis, Washington and Pohakuloa Training Area (PTA), Hawaii. The mission-specific power duty cycle characteristics were quantified, and the average positive power requirement at Fort Lewis and PTA was 65.4 and 43.6 kW respectively

Antioxidant defense in Plasmodium falciparum – data mining of the transcriptome

The intraerythrocytic malaria parasite is under constant oxidative stress originating both from endogenous and exogenous processes. The parasite is endowed with a complete network of enzymes and proteins that protect it from those threats, but also uses redox activities to regulate enzyme activities. In the present analysis, the transcription of the genes coding for the antioxidant defense elements are viewed in the time-frame of the intraerythrocytic cycle. Time-dependent transcription data were taken from the transcriptome of the human malaria parasite Plasmodium falciparum. Whereas for several processes the transcription of the many participating genes is coordinated, in the present case there are some outstanding deviations where gene products that utilize glutathione or thioredoxin are transcribed before the genes coding for elements that control the levels of those substrates are transcribed. Such insights may hint to novel, non-classical pathways that necessitate further investigations

Data mining of the transcriptome of Plasmodium falciparum: the pentose phosphate pathway and ancillary processes

The general paradigm that emerges from the analysis of the transcriptome of the malaria parasite Plasmodium falciparum is that the expression clusters of genes that code for enzymes engaged in the same cellular function is coordinated. Here the consistency of this perception is examined by analysing specific pathways that metabolically-linked. The pentose phosphate pathway (PPP) is a fundamental element of cell biochemistry since it is the major pathway for the recycling of NADP(+ )to NADPH and for the production of ribose-5-phosphate that is needed for the synthesis of nucleotides. The function of PPP depends on the synthesis of NADP(+ )and thiamine pyrophosphate, a co-enzyme of the PPP enzyme transketolase. In this essay, the transcription of gene coding for enzymes involved in the PPP, thiamine and NAD(P)(+ )syntheses are analysed. The genes coding for two essential enzymes in these pathways, transaldolase and NAD(+ )kinase could not be found in the genome of P. falciparum. It is found that the transcription of the genes of each pathway is not always coordinated and there is usually a gene whose transcription sets the latest time for the full deployment of the pathway's activity. The activity of PPP seems to involve only the oxidative arm of PPP that is geared for maximal NADP(+ )reduction and ribose-5-phosphate production during the early stages of parasite development. The synthesis of thiamine diphosphate is predicted to occur much later than the expression of transketolase. Later in the parasite cycle, the non-oxidative arm of PPP that can use fructose-6-phosphate and glyceraldehyde-3-phosphate supplied by glycolysis, becomes fully deployed allowing to maximize the production of ribose-5-phosphate. These discrepancies require direct biochemical investigations to test the activities of the various enzymes in the developing parasite. Notably, several transcripts of PPP enzyme-coding genes display biphasic pattern of transcription unlike most transcripts that peak only once during the parasite cycle. The physiological meaning of this pattern requires further investigation

Opening Access to Cell Biology

PLoS Biology is pleased to present a collection of articles focused on cell biology

Interaction of CO and O₂ with Pt Studied by Field Ion Appearance Energy Spectroscopy

Using field ion appearance energy spectroscopy we have examined the interaction of CO and 02 with stepped platinum surfaces in the presence of electrostatic fields ranging between 10 and 20 V/nm. Mass-to-charge resolved retarding potential analyses have been carried out for single sites of [001] and [111]-oriented Pt field emitter exposed to a continuous flow of CO and 02. Applying a thermionic cycle, binding energies of molecularly adsorbed CO and O2, were derived from the appearance energies of field desorbed CO+ and O+2 . The data reveal an effect of the high field on the molecule-surface interaction, which is most pronounced for COPt(111) steps. Implications for FIM studies of catalytic CO and H2, oxidation reactions are discussed

Defining species specific genome differences in malaria parasites

<p>Abstract</p> <p>Background</p> <p>In recent years a number of genome sequences for different <it>plasmodium </it>species have become available. This has allowed the identification of numerous conserved genes across the different species and has significantly enhanced our understanding of parasite biology. In contrast little is known about species specific differences between the different genomes partly due to the lower sequence coverage and therefore relatively poor annotation of some of the draft genomes particularly the rodent malarias parasite species.</p> <p>Results</p> <p>To improve the current annotation and gene identification status of the draft genomes of <it>P. berghei</it>, <it>P. chabaudi </it>and <it>P. yoelii</it>, we performed genome-wide comparisons between these three species. Through analyses via comparative genome hybridizations using a newly designed pan-rodent array as well as in depth bioinformatics analysis, we were able to improve on the coverage of the draft rodent parasite genomes by detecting orthologous genes between these related rodent parasite species. More than 1,000 orthologs for <it>P. yoelii </it>were now newly associated with a <it>P. falciparum </it>gene. In addition to extending the current core gene set for all plasmodium species this analysis also for the first time identifies a relatively small number of genes that are unique to the primate malaria parasites while a larger gene set is uniquely conserved amongst the rodent malaria parasites.</p> <p>Conclusions</p> <p>These findings allow a more thorough investigation of the genes that are important for host specificity in malaria.</p

Selection of long oligonucleotides for gene expression microarrays using weighted rank-sum strategy

<p>Abstract</p> <p>Background</p> <p>The design of long oligonucleotides for spotted DNA microarrays requires detailed attention to ensure their optimal performance in the hybridization process. The main challenge is to select an optimal oligonucleotide element that represents each genetic locus/gene in the genome and is unique, devoid of internal structures and repetitive sequences and its Tm is uniform with all other elements on the microarray. Currently, all of the publicly available programs for DNA long oligonucleotide microarray selection utilize various combinations of cutoffs in which each parameter (uniqueness, Tm, and secondary structure) is evaluated and filtered individually. The use of the cutoffs can, however, lead to information loss and to selection of suboptimal oligonucleotides, especially for genomes with extreme distribution of the GC content, a large proportion of repetitive sequences or the presence of large gene families with highly homologous members.</p> <p>Results</p> <p>Here we present the program OligoRankPick which is using a weighted rank-based strategy to select microarray oligonucleotide elements via an integer weighted linear function. This approach optimizes the selection criteria (weight score) for each gene individually, accommodating variable properties of the DNA sequence along the genome. The designed algorithm was tested using three microbial genomes <it>Escherichia coli</it>, <it>Saccharomyces cerevisiae </it>and the human malaria parasite species <it>Plasmodium falciparum</it>. In comparison to other published algorithms OligoRankPick provides significant improvements in oligonucleotide design for all three genomes with the most significant improvements observed in the microarray design for <it>P. falciparum </it>whose genome is characterized by large fluctuations of GC content, and abundant gene duplications.</p> <p>Conclusion</p> <p>OligoRankPick is an efficient tool for the design of long oligonucleotide DNA microarrays which does not rely on direct oligonucleotide exclusion by parameter cutoffs but instead optimizes all parameters in context of each other. The weighted rank-sum strategy utilized by this algorithm provides high flexibility of oligonucleotide selection which accommodates extreme variability of DNA sequence properties along genomes of many organisms.</p

Comparative whole genome transcriptome analysis of three Plasmodium falciparum strains

Gene expression patterns have been demonstrated to be highly variable between similar cell types, for example lab strains and wild strains of Saccharomyces cerevisiae cultured under identical growth conditions exhibit a wide range of expression differences. We have used a genome-wide approach to characterize transcriptional differences between strains of Plasmodium falciparum by characterizing the transcriptome of the 48 h intraerythrocytic developmental cycle (IDC) for two strains, 3D7 and Dd2 and compared these results to our prior work using the HB3 strain. These three strains originate from geographically diverse locations and possess distinct drug sensitivity phenotypes. Our goal was to identify transcriptional differences related to phenotypic properties of these strains including immune evasion and drug sensitivity. We find that the highly streamlined transcriptome is remarkably well conserved among all three strains, and differences in gene expression occur mainly in genes coding for surface antigens involved in parasite–host interactions. Our analysis also detects several transcripts that are unique to individual strains as well as identifying large chromosomal deletions and highly polymorphic regions across strains. The majority of these genes are uncharacterized and have no homology to other species. These tractable transcriptional differences provide important phenotypes for these otherwise highly related strains of Plasmodium

Quantitative protein expression profiling reveals extensive post-transcriptional regulation and post-translational modifications in schizont-stage malaria parasites

A quantitative time-course analysis of protein abundance for Plasmodium falciparum schizonts using two-dimensional differential gel electrophoresis reveals significant post-transcriptional regulation