Adaptive clustering for time series: Application for identifying cell cycle expressed genes

The biological problem of identifying the active genes during the cell division process is addressed. The cell division ensures the proliferation of cells, which is drastically aberrant in cancer cells. The studied genes are described by their expression profiles during the cell division cycle. Commonly, the identification process is a supervised approach based on an a priori set of reference genes, assumed as well-characterizing the cell cycle phases. Each studied gene is then classified by its peak similarity to one pre-specified reference gene. This classical approach suffers from two limitations. On the one hand, there is no consensus between biologists about the set of reference genes to consider for the identification process. On the other hand, the proximity measures used for genes expression profiles are unjustified and mainly based on the expression values regardless of the genes expression behavior. To identify genes expression profiles, a new adaptive clustering approach is proposed which consists of two main points. First, it allows in an unsupervised way the selection of a well-justified set of reference genes, to be compared with the pre-specified ones. Secondly, it enables the users to learn the appropriate proximity measure to use for genes expression data, a measure which will cover both proximity on values and on behavior. The adaptive clustering method is compared to a correlation-based approach through public and simulated genes expression data.     

Pseudotumoral hyperplasia of Brunner's glands

Hyperplasia of Brünner's glands is a dysembryoplastic or hyperplasic lesion with an elective location of the proximal duodenum. Symptoms are often non-specific but severe manifestations can occur (haemorrhage, duodenal obstruction). Two cases of hyperplasia of Brünner's glands were reported due to their particularly large size and a misguiding clinical appearance. Difficulties in diagnosis due to this rare benign entity were discussed.     

First evidence of natural vertical transmission of yellow fever virus in Aedes aegypti, its epidemic vector

Entomological investigations were conducted in 1995 in Senegal, following a yellow fever (YF) outbreak. A total of 1125 mosquitoes collected in the field, including males, females and 12-48 h old newly emerged adults reared from wild-caught larvae, were tested for YF virus. Among the 22 species captured, Aedes aegypti was the most common. 'Wild' vectors of YF were also captured, including A. furcifer, A. metallicus and A. luteocephalus. In all, 28 YF virus isolations were made: 19 from A. aegypti females, including 2 from newly emerged specimens; 5 were obtained from A. aegypti males, including one from a pool of newly emerged specimens, 2 from A. furcifer females, and one each from a female A. metallicus and a female A. luteocephalus. The true infection rates (TIRs) were much higher in adult A. aegypti than in specimens reared from larvae--8.2% and 31.4% for female and male A. aegypti captured on human volunteers, respectively (P < 0.0001). The TIRs for A. aegypti reared from larvae were 1.4% and 0.5% for females and males, respectively (P > 0.05). This outbreak was an intermediate YF epidemic, involving 4 vector species. Our data provide the first evidence of vertical transmission of YF virus in nature by A. aegypti, its main vector to humans, and strongly suggest that vertical transmission played a major role in the spread of the epidemic.     

Parent-offspring relationships in apomictic guayule

The genetic base of guayule (Parthenium argentatum Gray) germ plasm that is available is narrow; yet, significant variability has been described within this germ plasm. This variability is surprising because guayule reproduces by facultative apomixis (asexual reproduction by seed), but evidence suggests that progress through selection is feasible. It has been hypothesized that this variation has arisen through periodic sexual reproduction; however, this has not been quantified. This study was designed to describe and compare eight components of yield and the expression of two isozyme systems in twenty parent plants and half-sib, open-pollinated families from each parent. Extensive variation for all characters was found among both the parents and the progeny, with fresh and dry weights being highly correlated to rubber yield. Parent-offspring regressions were not significantly different from zero. This implies low heritabilities for the major components of yield in guayule, and we believe that family selection, rather than single-plant selection, may generate higher-yielding and more genetically uniform lines at an escalated rate than single-plant selection. Periodic sexuality resulting in genetic variation was estimated by differences in isozyme expression within the half-sib families. Fifteen of the twenty progeny families were polymorphic for either esterase or peroxidase or both isozymes. This amount of sexuality is significant, and guayule must be considered an open-pollinated crop. We conclude from this study that we should rethink our breeding procedures to include controlled pollination and family selection.     

Analytical quantification of airflows from soil through building substructures

Soil gas pollutants (VOCs, radon, …) have long been known to intrude into buildings through various openings, e.g., cracks and gaps in the foundations. As yet no model has been developed which can quantify this rate of flow whilst taking into account various substructure configurations. This is due to the complex phenomena that need to be consider and particularly to the difficulty in estimating pollutant flows at soil-building interfaces. In this paper analytical models have been developed to quantify these flows. The models have been developed for some typical substructure configurations: slab-on-grade, basement and crawlspace. The inputs of these models include particularly the foundation wall depth and the slab permeability. The analytical models have been compared to existing analytical models for one of the configurations. Moreover a 2-D finite element model has been used for numerical comparison. The models are presented as pressure-flow relationships and can be integrated into risk assessment tools in order to study the impact of soil gas pollutants on indoor air quality.     

Dendritic Molecular Nanobatteries and the Contribution of Click Chemistry

This article is a mini-review mostly based on the work of the authors’ laboratory on the redox chemistry of metallodendrimers and gold nanoparticles, with emphasis on “click” chemistry. Late transition-metal sandwich complexes possess a rather unique ability to withstand two or three oxidation states without breakdown, especially with permethylated π-cyclopentadienyl or arene ligands. When they are linked to dendritic cores, the assembled nano-systems undergo chemically and electrochemically reversible transfer of a large number of electrons (up to 14,000). These multiple redox processes are useful for nanodevices behaving as nanobatteries for redox sensing, modified electrode surfaces and redox catalysis. Click chemistry was recently disclosed as one of the most powerful means to form such assemblies including both arene-cored and gold nanoparticle-cored dendrimers.     

Modeling, Analysis, and Neural Network Control of an EV Electrical Differential

This paper presents system modeling, analysis, and simulation of an electric vehicle (EV) with two independent rear wheel drives. The traction control system is designed to guarantee the EV dynamics and stability when there are no differential gears. Using two in-wheel electric motors makes it possible to have torque and speed control in each wheel. This control level improves EV stability and safety. The proposed traction control system uses the vehicle speed, which is different from wheel speed characterized by a slip in the driving mode, as an input. In this case, a generalized neural network algorithm is proposed to estimate the vehicle speed. The analysis and simulations lead to the conclusion that the proposed system is feasible. Simulation results on a test vehicle propelled by two 37-kW induction motors showed that the proposed control approach operates satisfactorily.     

Integrated production quality and condition-based maintenance optimisation for a stochastically deteriorating manufacturing system

This paper investigates the problem of optimally integrating production quality and condition-based maintenance in a stochastically deteriorating single- product, single-machine production system. Inspections are periodically performed on the system to assess its actual degradation status. The system is considered to be in ‘fail mode’ whenever its degradation level exceeds a predetermined threshold. The proportion of non-conforming items, those that are produced during the time interval where the degradation is beyond the specification threshold, are replaced either via overtime production or spot market purchases. To optimise preventive maintenance costs and at the same time reduce production of non-conforming items, the degradation of the system must be optimally monitored so that preventive maintenance is carried out at appropriate time intervals. In this paper, an integrated optimisation model is developed to determine the optimal inspection cycle and the degradation threshold level, beyond which preventive maintenance should be carried out, while minimising the sum of inspection and maintenance costs, in addition to the production of non-conforming items and inventory costs. An expression for the total expected cost rate over an infinite time horizon is developed and solution method for the resulting model is discussed. Numerical experiments are provided to illustrate the proposed approach.     

Influence of pressure cycling on damage evolution in an unfilled EPDM exposed to high-pressure hydrogen

This study aims to reveal the internal damage evolution process in a transparent ethylene propylene diene rubber (EPDM) under high-pressure hydrogen cycles (9 and 15 MPa). Damage accumulation of EPDM was tracked from in-situ pictures during cycling. Several dedicated image processing routines allowed the discrimination of mechanisms (separated cavities, clusters and cracks) and sometimes the qualification of their morphology (size distribution, number, ratio of cavities reappearing at any cycle). Numerous small cavities were observed at any cycle, some of them being clustered under the highest pressure. Only part of them systematically appeared again. Some of these cavities inflated and “absorbed” small cavities around them when clustered. Finally, a few cracks were nucleated from some large cavities and grew, following a “stop and grow” process.     

Production planning in the presence of remanufactured spare components: an application in the airline industry

The process of remanufacturing is attractive economically and environmentally for both manufacturers and customers. This paper addresses a problem in the repairable spare parts remanufacturing industry to find the cost-optimal production strategy incorporating reconditioned components. New and reconditioned components are used to carry out replacements in order to honor warranty commitments. Key production decisions, such as when remanufacturing should commence, how long the warranty period should be, and how many returned components should be reconditioned are considered. The availability of reconditioned components and their discounted costs are also incorporated in the mathematical model. The goal is to investigate the interaction between these decisions and their impacts on the manufacturing system and the customer. An application to the remanufacturing of rotable spare parts in the airline industry is presented.