Robust stability and stabilization for singular systems with state delay and parameter uncertainty

This note considers the problems of robust stability and stabilization for uncertain continuous singular systems with state delay. The parametric uncertainty is assumed to be norm bounded. The purpose of the robust stability problem is to give conditions such that the uncertain singular system is regular, impulse free, and stable for all admissible uncertainties, while the purpose of robust stabilization is to design a state feedback control law such that the resulting closed-loop system is robustly stable. These problems are solved via the notions of generalized quadratic stability and generalized quadratic stabilization, respectively. Necessary and sufficient conditions for generalized quadratic stability and generalized quadratic stabilization are derived. A strict linear matrix inequality (LMI) design approach is developed. An explicit expression for the desired robust state feedback control law is also given. Finally, a numerical example is provided to demonstrate the application of the proposed method.published_or_final_versio

Trait evolution and historical biogeography shape assemblages of annual killifish

International audienceAim: Different species assemblages of annual killifish possess replicated body size distributions yet have unique sets of species in each area of endemism. Here, we use models of trait evolution and historical biogeography to discover how size variation originated and has been restructured.Location: South America.Taxon: Austrolebias (Cyprinodontiformes).Methods: We sampled 63 individuals from 26 Austrolebias species. Using phylogenetic trees (BEAST2), data on environmental variables at sampling locations and size data, we compare different models for trait evolution (SURFACE, l1OU) of body size and niche traits. We model the historical biogeography of the areas of endemism (BioGeoBEARS) and use both analyses in combination to reconstruct the history of four species assemblages.Results: We present new phylogenetic trees for Austrolebias and use them to show that large size principally arose within a single area driven by a shifted selection optimum for a subset of the species in that area. We suggest that ecological interactions triggered size divergence and that this large‐bodied lineage subsequently spread to two other areas. A second assemblage may have been shaped by adaptation to a new environment without an associated increase in size divergence. A third assemblage, which has the smallest size range and the most recent origin, is phylogenetically clustered, and we found no evidence of environmental filtering.Main conclusions: Assemblage similarity in Austrolebias is the result of contrasting ecological, evolutionary and historical processes. Modelling trait evolution together with historical biogeography can help to disentangle the complex histories of multispecies assemblages. This approach provides context to commonly used tests investigating the role of ecological processes from phylogenetic data and generates new testable hypotheses on the processes that generated trait diversity and assemblage similarit

Skin-stringer separation in post-buckling of butt-joint stiffened thermoplastic composite panels

Two aeronautical thermoplastic composite stiffened panels are analysed and tested to investigate the buckling behaviour, the skin-stringer separation and the final failure mode. The panels are made of fast crystallising polyetherketoneketone carbon composite, have three stringers with an angled cap on one side, and are joined to the skin by a short-fibre reinforced butt-joint. The panels contain an initial damage in the middle skin-stringer interface representing barely visible impact damage. Finite element analysis using the virtual crack closure technique are conducted before the test to predict the structural behaviour. During the tests, the deformation of the panels is measured by digital image correlation, the damage propagation is recorded by GoPro cameras and the final failure is captured by high speed cameras. The panels show an initial three half-wave buckling shape in each bay, with damage propagation starting shortly after buckling. A combination of relatively stable and unstable damage propagation is observed until final failure, when the middle stringer separates completely and the panels fail in an unstable manner. The test results are compared to the numerical prediction, which shows great agreement for both the buckling and failure behaviour

Effect van het Aeromix systeem op ammoniakemissie in een melkveestal : verkennend onderzoek op Dairy Campus

During a case-control trial with Aeromix manure mixing system a sharp reduction of the ammonia emission from the dairy barn was established. In comparison to the reference barn the reduction was on average 50 %. No increase in laughing gas (N2O) was found

Loudly sing cuckoo : More-than-human seasonalities in Britain

This research was funded by a grant from the Arts and Humanities Research Council, grant number AH/E009573/1.Peer reviewedPostprin

Molecular Epidemiology of Endemic Human T-Lymphotropic Virus Type 1 in a Rural Community in Guinea-Bissau

Human T-Lymphotropic Virus type 1 (HTLV-1) affects millions of people worldwide. It is very similar to Simian T-Lymphotropic Virus, a virus that circulates in monkeys. HTLV-1 causes a lethal form of leukemia (Adult T-cell Leukemia) and a debilitating neurological syndrome (HTLV-associated myelopathy/tropical spastic paraparesis) in approximately 5% of infected people. Based on sequence variation, HTLV-1 can be divided into 7 subtypes (1a–1g) with the Cosmopolitan subtype 1a further subdivided into subgroups (A–E). We examined HTLV-1 diversity in a rural area in Guinea-Bissau, a country in West Africa with a high HTLV-1 prevalence (5%). We found that most viruses belong to the Cosmopolitan subtype 1a, subgroup D, but 2 viruses belonged to subtype 1g. This subtype had thus far only been found in monkey hunters in Cameroon, who were probably recently infected by monkeys. Our findings indicate that this subtype has spread beyond Central Africa. An important, unresolved question is whether persons with this subtype were infected by monkeys or through human-to-human transmission

Innovaties in huisvesting van melkvee : (inter)nationale inspiraties : bouwstenen uit de workshop op 7 en 8 december 2006

Innovaties in huisvesting van melkvee staat om verschillende redenen sterk in de belangstelling. Er is een maatschappelijke druk om dieren op een meer welzijns- en milieuvriendelijke manier te huisvesten en op een wijze die past in het landschap. Veel melkveehouders zijn bezig met renovatie of nieuwbouw omdat de stal verouderd is of omdat men het bedrijf wil uitbreiden. De kosten hiervan zijn vaak hoog. Daarom is het belangrijk dat er goede afwegingen gemaakt worden die rekening houden met de behoeftes van de koe, de boer en de omgeving. Vanuit twee projecten kwam het initiatief een workshop te organiseren over bouwstenen en bedrijfsconcepten voor innovatief huisvesten van melkvee. In het netwerkproject “Koecomfortabel bouwen” (onderdeel van het onderzoeksprogramma Netwerken in de Veehouderij) is in het najaar van 2006 veel inspiratie opgedaan door boeren onderling en met deskundigen. De workshop is gehouden op 7 en 8 december 2006. De centrale vraag tijdens de tweedaagse was: ”Hoe hou ik een koe in een omgeving waar zowel de koe, in alle fasen van haar leven, en de veehouder goed functioneren. Goed in de betekenis van: plezier voor de veehouder, een lang, productief en efficiënt leven voor de koe en een houderijsysteem die maatschappelijk gewaardeerd wordt. Via een proces van inventariseren, verrijken en prioriteren zijn uiteindelijk 13 ideeën geselecteerd. Deze zijn beschreven als innovatiekaarten. Op iedere innovatiekaart is het belang en de ontwikkelpunten aangeven. Deze innovatiekaarten zijn bedoeld als inspiratie voor vernieuwende boeren en nader onderzoe

Cationic amino acid transporters play key roles in the survival and transmission of apicomplexan parasites

© 2017 The Author(s). Apicomplexans are obligate intracellular parasites that scavenge essential nutrients from their hosts via transporter proteins on their plasma membrane. The identities of the transporters that mediate amino acid uptake into apicomplexans are unknown. Here we demonstrate that members of an apicomplexan-specific protein family-the Novel Putative Transporters (NPTs)-play key roles in the uptake of cationic amino acids. We show that an NPT from Toxoplasma gondii (TgNPT1) is a selective arginine transporter that is essential for parasite survival and virulence. We also demonstrate that a homologue of TgNPT1 from the malaria parasite Plasmodium berghei (PbNPT1), shown previously to be essential for the sexual gametocyte stage of the parasite, is a cationic amino acid transporter. This reveals a role for cationic amino acid scavenging in gametocyte biology. Our study demonstrates a critical role for amino acid transporters in the survival, virulence and life cycle progression of these parasites