MAX-consensus in open multi-agent systems with gossip interactions

We study the problem of distributed maximum computation in an open multi-agent system, where agents can leave and arrive during the execution of the algorithm. The main challenge comes from the possibility that the agent holding the largest value leaves the system, which changes the value to be computed. The algorithms must as a result be endowed with mechanisms allowing to forget outdated information. The focus is on systems in which interactions are pairwise gossips between randomly selected agents. We consider situations where leaving agents can send a last message, and situations where they cannot. For both cases, we provide algorithms able to eventually compute the maximum of the values held by agents.Comment: To appear in the proceedings of the 56th IEEE Conference on Decision and Control (CDC 17). 8 pages, 3 figure

Conduction spectroscopy of a proximity induced superconducting topological insulator

The combination of superconductivity and the helical spin-momentum locking at the surface state of a topological insulator (TI) has been predicted to give rise to p-wave superconductivity and Majorana bound states. The superconductivity can be induced by the proximity effect of a an s-wave superconductor (S) into the TI. To probe the superconducting correlations inside the TI, dI/dV spectroscopy has been performed across such S-TI interfaces. Both the alloyed Bi$_{1.5}$Sb$_{0.5}$Te$_{1.7}$Se$_{1.3}$ and the stoichiometric BiSbTeSe$_2$ have been used as three dimensional TI. In the case of Bi$_{1.5}$Sb$_{0.5}$Te$_{1.7}$Se$_{1.3}$, the presence of disorder induced electron-electron interactions can give rise to an additional zero-bias resistance peak. For the stoichiometric BiSbTeSe$_2$ with less disorder, tunnel barriers were employed in order to enhance the signal from the interface. The general observations in the spectra of a large variety of samples are conductance dips at the induced gap voltage, combined with an increased sub-gap conductance, consistent with p-wave predictions. The induced gap voltage is typically smaller than the gap of the Nb superconducting electrode, especially in the presence of an intentional tunnel barrier. Additional uncovered spectroscopic features are oscillations that are linearly spaced in energy, as well as a possible second order parameter component.Comment: Semiconductor Science and Technology; Special Issue on Hybrid Quantum Materials and Device

Anthelmintic tolerance in free-living and facultative parasitic isolates of Halicephalobus (Panagrolaimidae)

Studies on anthelmintic resistance in equine parasites do not include facultative parasites. Halicephalobus gingivalis is a free-living bacteriovorous nematode and a known facultative parasite of horses with a strong indication of some form of tolerance to common anthelmintic drugs. This research presents the results of an in vitro study on the anthelmintic tolerance of several isolates of Halicephalobus to thiabendazole and ivermectin using an adaptation of the Micro-Agar Larval Development Test hereby focusing on egg hatching and larval development. Panagrellus redivivus and Panagrolaimus superbus were included as a positive control. The results generally show that the anthelmintic tolerance of Halicephalobus to both thiabendazole and ivermectin was considerably higher than that of the closely related Panagrolaimidae and, comparing to other studies, than that of obligatory equine parasites. Our results further reveal a remarkable trend of increasing tolerance from fully free-living isolates towards horse-associated isolates. In vitro anthelmintic testing with free-living and facultative parasitic nematodes offers the advantage of observing drug effect on the complete lifecycle as opposed to obligatory parasites which can only be followed until the third larval stage. We therefore propose Halicephalobus gingivalis as an experimental tool to deepen our understanding of the biology of anthelmintic tolerance

Human-Induced Expanded Distribution of Anopheles plumbeus, Experimental Vector of West Nile Virus and a Potential Vector of Human Malaria in Belgium

For the majority of native species, human-created habitats provide a hostile environment that prevents their colonization. However, if the conditions encountered in this novel environment are part of the fundamental niche of a particular species, these low competitive environments may allow strong population expansion of even rare and stenotopic species. If these species are potentially harmful to humans, such anthropogenic habitat alterations may impose strong risks for human health. Here, we report on a recent and severe outbreak of the viciously biting and day-active mosquito Anopheles plumbeus Stephens, 1828, that is caused by a habitat shift toward human-created habitats. Although historic data indicate that the species was previously reported to be rare in Belgium and confined to natural forest habitats, more recent data indicate a strong population expansion all over Belgium and severe nuisance at a local scale. We show that these outbreaks can be explained by a recent larval habitat shift of this species from tree-holes in forests to large manure collecting pits of abandoned and uncleaned pig stables. Further surveys of the colonization and detection of other potential larval breeding places of this mosquito in this artificial environment are of particular importance for human health because the species is known as a experimental vector of West Nile virus and a potential vector of human malari

Impact of g-factors and valleys on spin qubits in a silicon double quantum dot

We define single electron spin qubits in a silicon MOS double quantum dot system. By mapping the qubit resonance frequency as a function of gate-induced electric field, the spectrum reveals an anticrossing that is consistent with an inter-valley spin-orbit coupling. We fit the data from which we extract an inter-valley coupling strength of 43 MHz. In addition, we observe a narrow resonance near the primary qubit resonance when we operate the device in the (1,1) charge configuration. The experimental data is consistent with a simulation involving two weakly exchanged-coupled spins with a g-factor difference of 1 MHz, of the same order as the Rabi frequency. We conclude that the narrow resonance is the result of driven transitions between the T- and T+ triplet states, using an ESR signal of frequency located halfway between the resonance frequencies of the two individual spins. The findings presented here offer an alternative method of implementing two-qubit gates, of relevance to the operation of larger scale spin qubit systems

Amélioration de la surveillance de l’influenza aviaire de type H5N1 - Cartographie du risque d’influenza aviaire de type H5N1 en Afrique: Rapport final et cartes de risqué d’influenza aviaire

Plus de 85% des ménages ruraux en Afrique élèvent la volaille aux fins d’alimentation, de revenu ou les deux, et de nombreuses personnes vivent en contact étroit avec leurs oiseaux. La possibilité d’une épidémie de l’influenza aviaire hautement pathogène (IAHP) de type H5N1 est donc une grande préoccupation. Depuis 2006, la grippe aviaire est apparue dans au moins 11 pays africains et plus de 600 foyers d’épidémie ont été signalés. La vigilance est essentielle en vue de limiter la maladie mais le personnel de santé animale ne peut faire un suivi partout à la fois. Ce projet de cartographie de facteurs de risques a été conçu en vue d’aider à prioriser leurs efforts en indiquant les lieux où il existe un risque très élevé de flambées de la maladie. La cartographie des risques est une image complexe générée par ordinateur qui montre la répartition spatiale des facteurs de risques prévus d’une maladie. Elle est fondée sur la répartition spatiale des « facteurs de risques » associés au risque accru de maladie et à l’importance relative de chacun de ces facteurs. Dans le cas d’une grippe aviaire de type H5N1, les facteurs de risques sont les principales voies de transport, les marchés de volailles et les points d’eau avec possibilité de contact entre les oiseaux domestiques et sauvages. Pour ce projet, les chercheurs ont préparé des cartes de risques de grippe aviaire en Afrique en utilisant la modélisation de décision multicritères (MCDM). De cette façon, ils ont intégré les données et les informations de diverses sources telles que les publications scientifi ques, les cartes disponibles dans le domaine public, les études de terrain et les consultations d’expert

Risk mapping for HPAI H5N1 in Africa - Improving surveillance for virulent bird flu: Final report and maps

More than 85 percent of households in rural Africa raise poultry for food, income, or both, and many people live in close contact with their birds. The possibility of an epidemic of highly pathogenic avian influenza (HPAI) H5N1 is therefore a major concern. Since 2006 bird fl u has been introduced into at least 11 countries in Africa, and over 600 outbreaks reported. Vigilance is key to limiting the disease but animal health personnel cannot monitor everywhere at once. This risk-mapping project was designed to help prioritize their efforts by showing in which places outbreaks are more likely to occur. A risk map is a complex, computer-generated image that shows the spatial distribution of the predicted risk of a disease. It is based on the spatial distribution of “risk factors” associated with an increased risk of disease, and the relative importance of each of these factors. In the case of virulent bird fl u, risk factors include major transport routes, markets where poultry may be traded, and wetlands with the possibility of contact between poultry and wild birds. Researchers in this project have prepared risk maps for bird fl u in Africa using multi-criteria decision modeling (MCDM). In this way they have integrated data and information from such diverse sources as published scientific literature, maps available in the public domain, field surveys and expert consultations