Fault diagnosis for discrete events systems described by partially observed Petri nets.

Fault diagnosis problem is discussed for discrete events systems described by partially observed Petri nets. Our goal is to detect and identify faults that may have occurred in both transitions and places assuming that we can measure some of them. The proposed approach is based on two mains steps (i) designing an algebraic observer for estimating the markings and the transitions of a partially observed Petri nets and (ii) presenting algorithms to detect and identify faults based on comparing the estimation of both the transitions and markings of the faulty system provided by an algebraic observer with those of the normal system. The effectiveness of the proposed approach is illustrated through a simple and a manufacturing example.

In vivo XCT bone characterization of lattice structured implants fabricated by additive manufacturing.

Several cylindrical specimens and dental implants, presenting diagonal lattice structures with different cell sizes (600, 900 and 1200 µm) were additively manufactured by selective laser melting process. Then they were implanted for two months in a sheep. After removal, they were studied by Archimedes' method as well as X-ray computed tomography in order to assess the penetration of bone into the lattice. We observed that the additive manufactured parts were geometrically conformed to the theoretical specifications. However, several particles were left adhering to the surface of the lattice, thereby partly or entirely obstructing the cells. Nevertheless, bone penetration was clearly visible. We conclude that the 900 µm lattice cell size is more favourable to bone penetration than the 1200 µm lattice cell size, as the bone penetration is 84% for 900 µm against 54% for 1200 µm cell structures. The lower bone penetration value for the 1200 µm lattice cell could possibly be attributed to the short residence time in the sheep. Our results lead to the conclusion that lattice implants additively manufactured by selective laser melting enable better bone integration.

Census and analysis of persistent false-negative results in serological diagnosis of human immunodeficiency virus type 1 group O infections.

Human immunodeficiency viruses (HIV) have a high level of genetic diversity. The outlier variants of HIV type 1 (HIV-1) group O are distantly related to HIV-1 group M. Their divergence has an impact on serological diagnosis, with a risk of false-negative results. In this study, we report 20 failure cases, involving patients with primary or chronic infection, in France and Cameroon between 2001 and 2008. Our results indicate that some assays detected group O infection much less efficiently than others. Two major reasons for these false-negative results were identified: the presence or absence of a group O-specific antigen (and the designed sequence) for the detection of antibodies and the greater envelope variability of group O than of group M strains. This study highlights the complexity of screening for these divergent variants and the need to evaluate test performance with a large panel of strains, due to the extensive diversity of group O variants.

[Mild Cognitive Impairment: potential therapeutics]. / Le déclin cognitif modéré ou le mild cognitive impairment (MCI): perspectives thérapeutiques.

Mild Cognitive Impairment (MCI) is an emerging concept used to describe memory decline and probably attention disturbances in otherwise intellectually intact individuals. MCI may be considered in 12 to 15 p. 100 of the cases as announcing an Alzheimer's Disease (AD). Although still speculative, the debate concerning the drugs susceptible to normalize symptoms of MCI or to stop conversion to AD must be raised. For that purpose, several long term clinical trials are running (antioxidants, nootropics, anticholinesterasics.) and new molecules in the pipe-line should be assessed in patients with the diagnosis of MCI.

Comparative effects of pharmacotherapy on the maintenance of cognitive function.

The quality of human cognitive performance appears today as one of the main components of quality of life, whatever the age. Ageing by itself and most of the diseases affecting the central nervous system alter higher brain functions such as memory, vigilance and attention. Dementia is the most acute example, with a cascade of behavioral and psychological consequences (BPSD), which are the main cause of the caregiver's burden and need specific pharmacotherapy. In this respect, the problem will be the choice of the best drug in situations such as wandering, agitation, violence, and screaming. The psychotropics, however, should not deteriorate the already disturbed cognition of the patients. This is the reason why we propose to establish for each drug, and notably for the antipsychotics, a precise and exact "cognitive mapping"; in other words, to measure the effects of drugs on the different components of cognition. The results of such studies will be predictive of the future phase III clinical trials and therapeutic responses. As an illustration of this approach we shall relate two studies, TIATEM (phase I) and TIAGE (phase III/IV), leading to the determination of a good cognitive safety profile of an atypical neuroleptic drug, tiapride.