Incremental Preference Elicitation in Multi-Attribute Domains for Choice and Ranking with the Borda Count

International audienceIn this paper, we propose an interactive version of the Borda method for collective decision-making (social choice) when the alternatives are described with respect to multiple attributes and the individual preferences are unknown. More precisely, assuming that individual preferences are representable by linear multi-attribute utility functions, we propose an incremental elicitation method aiming to determine the Borda winner while minimizing the communication effort with the agents. This approach follows the recent work of Lu and Boutilier [8] relying on the minimax regret as a criterion for dealing with uncertainty in the preferences. We show that, when preferences are expressed on a multi-attribute domain and are additively separable over attributes, regret-based incremental elic-itation methods can be made more efficient to determine or approximate the Borda winner. Our approach relies on the representation of incomplete preferences using convex polyhedra of possible utilities and is based on linear programming both for minimizing regrets and selecting informative preference queries. It enables to incrementally collect preference judgements from the agents until the Borda winner can be identified. Moreover, we provide an incremental technique for eliciting a collective ranking instead of a single winner

La prevenzione delle polmoniti da ventilazione (VAP). Uno studio quasi-sperimentale sull'efficacia di un intervento formativo per migliorare l'adesione del personale al protocollo aziendale.

Obiettivo. Lo scopo della presente ricerca \ue8 di valutare l\u2019efficacia di un intervento formativo per migliorare l\u2019adesione al protocollo per la prevenzione delle polmoniti da ventilazione (VAP), da parte del personale medico e infermieristico di un reparto di terapia intensiva. Materiali e metodi. \uc8 stata svolta un\u2019indagine che ha previsto 3 diversi momenti: il pre-test, caratterizzato dalla rilevazione dell\u2019adesione al protocollo da parte del personale di reparto; la partecipazione ad un corso di formazione sull\u2019applicazione del protocollo; un post-test in cui il personale \ue8 stato sottoposto nuovamente alla verifica dell\u2019applicazione del protocollo. Il campione era rappresentato da tutto il personale del reparto. Risultati. Dei 14 item valutati, 5 sono risultati essere meno precisi e, quindi, non presi in considerazione per l\u2019elaborazione delle conclusioni. Dei 9 item restanti, 6 hanno riportato un aumento delle percentuali di comportamenti aderenti alle norme del protocollo nel post-test, seppure in maniera meno incisiva di quanto ci si aspettasse, mentre 3 hanno riportato una diminuzione dei comportamenti aderenti. Conclusioni. Il corso di formazione a cui ha partecipato tutto il personale del reparto non \ue8 risultato sufficientemente efficace. Lo studio conferma quanto riportato dalla letteratura, ossia che per aumentare il livello di aderenza alle best practice, gli interventi debbono essere molteplici e supportati da complesse strategie di implementazione

Oxygen and Nitric Oxide Rebinding Kinetics in Nonsymbiotic Hemoglobin AHb1 from Arabidopsis thaliana

Type 1 nonsymbiotic hemoglobin from Arabidopsis thaliana (AHb1) shows a partial bis-histidyl hexacoordination but can reversibly bind diatomic ligands. The physiological function is still unclear, but the high oxygen affinity rules out a function related to O2 sensing, carrying, or storing. To gain insight into its possible functional roles, we have investigated its O2 and NO rebinding kinetics after laser flash photolysis. The rate constants of the rebinding from the primary docking site for both O2 and NO are higher than CO, with lower photolysis yields. Moreover, the amplitude of the geminate phase increases and, as for CO, the numerical analysis of the experimental curves suggests the existence of an internal pathway leading, with high rate, to an additional docking site. However, the accessibility to this site seems to be strongly ligand-dependent, being lower for O2 and higher for NO

Ligand migration through the internal hydrophobic cavities in human neuroglobin

Neuroglobin (Ngb), a member of the globin superfamily, was found in the brain of vertebrates and is suggested to play a neuroprotective function under hypoxic conditions by scavenging nitrogen monoxide (NO) through a dioxygenase activity. In order for such a reaction to efficiently take place and to minimize the release of reactive intermediates in the cytosol, the cosubstrates O2 and NO and other unstable reaction intermediates should bind sequentially to docking sites in the protein matrix. We have characterized the accessibility of these sites by analyzing the geminate CO rebinding kinetics to the heme moiety observed upon nanosecond flash photolysis of the Ngb-CO complex encapsulated in silica gels. The geminate rebinding phase showed a remarkable complexity, revealing the presence of a system of secondary docking sites where ligands are stored for hundreds of microseconds. Most kinetics steps display little temperature dependence, demonstrating that ligands can easily migrate through the cavities, except for the slowest reaction intermediate, possibly reflecting a structural conformational change reshaping the system of cavities. This conformational change is unrelated with distal His E7 binding to the heme, as it persists for the HE7L mutant. Overall, data are consistent with the presence of a discrete system of docking sites, possibly acting as reservoirs for the putative cosubstrates and for other reactive species involved in the physiologically relevant reaction

Histidine E7 Dynamics Modulates Ligand Exchange between Distal Pocket and Solvent in AHb1 from Arabidopsis thaliana

The distal His residue in type 1 nonsymbiotic hemoglobin AHb1 from Arabidopsis thaliana plays a fundamental role in stabilizing the bound ligand. This residue might also be important in regulating the accessibility to the distal cavity. The feasibility of this functional role has been examined using a combination of experimental and computational methods. We show that the exchange of CO between the solvent and the reaction site is modulated by a swinging motion of the distal His, which opens a channel that connects directly the distal heme pocket with the solvent. The nearby PheB10 aids the distal His in the stabilization of the bound ligand by providing additional protection against solvation. Overall, these findings provide evidence supporting the functional implications of the conformational rearrangement found for the distal His in AHb1, which mimics the gating role proposed for the same residue in myoglobin

Mother-to-Infant Microbial Transmission from Different Body Sites Shapes the Developing Infant Gut Microbiome

The acquisition and development of the infant microbiome are key to establishing a healthy host-microbiome symbiosis. The maternal microbial reservoir is thought to play a crucial role in this process. However, the source and transmission routes of the infant pioneering microbes are poorly understood. To address this, we longitudinally sampled the microbiome of 25 mother-infant pairs across multiple body sites from birth up to 4 months postpartum. Strain-level metagenomic profiling showed a rapid influx of microbes at birth followed by strong selection during the first few days of life. Maternal skin and vaginal strains colonize only transiently, and the infant continues to acquire microbes from distinct maternal sources after birth. Maternal gut strains proved more persistent in the infant gut and ecologically better adapted than those acquired from other sources. Together, these data describe the mother-to-infant microbiome transmission routes that are integral in the development of the infant microbiome