993 resultados para Active tracking
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Several methods and approaches for measuring parameters to determine fecal sources of pollution in water have been developed in recent years. No single microbial or chemical parameter has proved sufficient to determine the source of fecal pollution. Combinations of parameters involving at least one discriminating indicator and one universal fecal indicator offer the most promising solutions for qualitative and quantitative analyses. The universal (nondiscriminating) fecal indicator provides quantitative information regarding the fecal load. The discriminating indicator contributes to the identification of a specific source. The relative values of the parameters derived from both kinds of indicators could provide information regarding the contribution to the total fecal load from each origin. It is also essential that both parameters characteristically persist in the environment for similar periods. Numerical analysis, such as inductive learning methods, could be used to select the most suitable and the lowest number of parameters to develop predictive models. These combinations of parameters provide information on factors affecting the models, such as dilution, specific types of animal source, persistence of microbial tracers, and complex mixtures from different sources. The combined use of the enumeration of somatic coliphages and the enumeration of Bacteroides-phages using different host specific strains (one from humans and another from pigs), both selected using the suggested approach, provides a feasible model for quantitative and qualitative analyses of fecal source identification.
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Twenty Audouin´s gulls, Larus audouinii, breeding in the Ebro Delta (NW Mediterranean) were radio-tracked in 1998 to study their foraging behaviour and activity patterns. Some detrimental effects of tagging on the breeding success of the birds were detected, especially when both members of the pair were tagged. The results were actually constrained by the low number of locations due to natural breeding failure and failure in tag emission, as well as the adverse effect of tagging. However, through a combination of aircraft surveys at sea and a fixed station for automatic tracking of the presence of the birds at the colony, novel individual-based information of home ranges and activity patterns was obtained. Trawler fishing activity seemed to influence both the foraging range and habitat use: while trawlers operated, gulls overlapped their fishing grounds with vessels, probably to scavenge on discards. Very few locations were obtained during a trawling moratorium period, although they were all recorded in coastal bays and terrestrial habitats. During the trawling activity period, gulls ranged over a minimum convex polygon area of 2900 km2. Gulls were tracked up to 40 km from the colony, but some individuals were observed beyond 150 km while still breeding. Arrivals and departures from the colony were in accordance with the trawling timetable. However, most birds also showed some nocturnal foraging activity, probably linked to active fishing of clupeoids (following diel migrations) or to the exploitation of purse-seine fishing activity. Foraging trips lasted on average 15 hours: males performed significantly shorter trips than females, which spent more time outside the colony. The proportion of nocturnal time involved in the foraging trips was the same for males and females, but whilst all males initiated their trips both during the day and at night, some females only initiated their trips during the day. Hatching success was found to be related to foraging effort by males. Gulls spent on average ca. 38% of their time budget outside the nesting territory, representing the time devoted mainly to flying, foraging and other activities.
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The design of therapeutic cancer vaccines is aimed at inducing high numbers and potent T cells that are able to target and eradicate malignant cells. This calls for close collaboration between cells of the innate immune system, in particular dendritic cells (DCs), and cells of the adaptive immune system, notably CD4+ helper T cells and CD8+ cytotoxic T cells. Therapeutic vaccines are aided by adjuvants, which can be, for example, Toll¬like Receptor agonists or agents promoting the cytosolic delivery of antigens, among others. Vaccination with long synthetic peptides (LSPs) is a promising strategy, as the requirement for their intracellular processing will mainly target LSPs to professional antigen presenting cells (APCs), hence avoiding the immune tolerance elicited by the presentation of antigens by non-professional APCs. The unique property of antigen cross-processing and cross-presentation activity by DCs plays an important role in eliciting antitumour immunity given that antigens from engulfed dead tumour cells require this distinct biological process to be processed and presented to CD8+T cells in the context of MHC class I molecules. DCs expressing the XCR1 chemokine receptor are characterised by their superior capability of antigen cross- presentation and priming of highly cytotoxic T lymphocyte (CTL) responses. Recently, XCR1 was found to be also expressed in tissue-residents DCs in humans, with a simitar transcriptional profile to that of cross- presenting murine DCs. This shed light into the value of harnessing this subtype of XCR1+ cross-presenting DCs for therapeutic vaccination of cancer. In this study, we explored ways of adjuvanting and optimising LSP therapeutic vaccinations by the use, in Part I, of the XCLl chemokine that selectively binds to the XCR1 receptor, as a mean to target antigen to the cross-presenting XCR1+ DCs; and in Part II, by the inclusion of Q.S21 in the LSP vaccine formulation, a saponin with adjuvant activity, as well as the ability to promote cytosolic delivery of LSP antigens due to its intrinsic cell membrane insertion activity. In Part I, we designed and produced XCLl-(OVA LSP)-Fc fusion proteins, and showed that their binding to XCR1+ DCs mediate their chemoattraction. In addition, therapeutic vaccinations adjuvanted with XCLl-(OVA LSP)-Fc fusion proteins significantly enhanced the OVA-specific CD8+ T cell response, and led to complete tumour regression in the EL4-OVA model, and significant control of tumour growth in the B16.0VA tumour model. With the aim to optimise the co-delivery of LSP antigen and XCLl to skin-draining lymph nodes we also tested immunisations using nanoparticle (NP)-conjugated OVA LSP in the presence or absence of XCLl chemokine. The NP-mediated delivery of LSP potentiated the CTL response seen in the blood of vaccinated mice, and NP-OVA LSP vaccine in the presence of XCLl led to higher blood frequencies of OVA-specific memory-precursor effector cells. Nevertheless, in these settings, the addition XCLl to NP-OVA LSP vaccine formulation did not increase its antitumour therapeutic effect. In the Part II, we assessed in HLA-A2/DR1 mice the immunogenicity of the Melan-AA27L LSP or the Melan-A26. 35 AA27l short synthetic peptide (SSP) used in conjunction with the saponin adjuvant QS21, aiming to identify a potent adjuvant formulation that elicits a quantitatively and qualitatively strong immune response to tumour antigens. We showed a high CTL immune response elicited by the use of Melan-A LSP or SSP with QS21, which both exerted similar killing capacity upon in vivo transfer of target cells expressing the Melan-A peptide in the context of HLA-A2 molecules. However, the response generated by the LSP immunisation comprised higher percentages of CD8+T cells of the central memory phenotype (CD44hl CD62L+ and CCR7+ CD62L+) than those of SSP immunisation, and most importantly, the strong LSP+QS21 response was strictly CD4+T cell-dependent, as shown upon CD4 T cell depletion. Altogether, these results suggest that both XCLl and QS21 may enhance the ability of LSP to prime CD8 specific T cell responses, and promote a long-term memory response. Therefore, these observations may have important implications for the design of protein or LSP-based cancer vaccines for specific immunotherapy of cancer -- Les vacans thérapeutiques contre le cancer visent à induire une forte et durable réponse immunitaire contre des cellules cancéreuses résiduelles. Cette réponse requiert la collaboration entre le système immunitaire inné, en particulier les cellules dendrites (DCs), et le système immunitaire adaptatif, en l'occurrence les lymphocytes TCD4 hdper et CD8 cytotoxiques. La mise au point d'adjuvants et de molécules mimant un agent pathogène tels les ligands TLRs ou d'autres agents facilitant l'internalisation d'antigènes, est essentielle pour casser la tolérance du système immunitaire contre les cellules cancéreuses afin de générer une réponse effectrice et mémoire contre la tumeur. L'utilisation de longs peptides synthétiques (LSPs) est une approche prometteuse du fait que leur présentation en tant qu'antigénes requiert leur internalisation et leur transformation par les cellules dendrites (DCs, qui sont les mieux à même d'éviter la tolérance immunitaire. Récemment une sous-population de DCs exprimant le récepteur XCR1 a été décrite comme ayant une capacité supérieure dans la cross-présentation d'antigènes, d'où un intérêt à développer des vaccins ciblant les DCs exprimant le XCR1. Durant ma thèse de doctorat, j'ai exploré différentes approches pour optimiser les vaccins avec LSPs. La première partie visait à cibler les XCR1-DCs à l'aide de la chemokine XCL1 spécifique du récepteur XCR1, soit sou s la forme de protéine de fusion XCL1-OVA LSP-Fc, soit associée à des nanoparticules. La deuxième partie a consisté à tester l'association des LSPs avec I adjuvant QS21 dérivant d'une saponine dans le but d'optimiser l'internalisation cytosolique des longs peptides. Les protéines de fusion XCLl-OVA-Fc développées dans la première partie de mon travail, ont démontré leur capacité de liaison spécifique sur les XCRl-DCs associée à leur capacité de chemo-attractio. Lorsque inclues dans une mmunisation de souris porteuse de tumeurs établies, ces protéines de fusion XCL1-0VA LSP-Fc et XCLl-Fc plus OVA LSP ont induites une forte réponse CDS OVA spécifique permettant la complète régression des tumeurs de modèle EL4- 0VA et un retard de croissance significatif de tumeurs de type B16-0VA. Dans le but d'optimiser le drainage des LSPs vers es noyaux lymphatiques, nous avons également testé les LSPs fixés de manière covalente à des nanoparticules co- injectees ou non avec la chemokine XCL1. Cette formulation a également permis une forte réponse CD8 accompagnée d'un effet thérapeutique significatif, mais l'addition de la chemokine XCL1 n'a pas ajouté d'effet anti-tumeur supplémentaire. Dans la deuxième partie de ma thèse, j'ai comparé l'immunogénicité de l'antigène humain Melan A soit sous la forme d un LSP incluant un épitope CD4 et CD8 ou sous la forme d'un peptide ne contenant que l'épitope CD8 (SSP) Les peptides ont été formulés avec l'adjuvant QS21 et testés dans un modèle de souris transgéniques pour les MHC let II humains, respectivement le HLA-A2 et DR1. Les deux peptides LSP et SSP ont généré une forte réponse CD8 similaire assoc.ee a une capacité cytotoxique équivalente lors du transfert in vivo de cellules cibles présentant le peptide SSP' Cependant les souris immunisées avec le Melan A LSP présentaient un pourcentage plus élevé de CD8 ayant un Phénotype «centra, memory» (CD44h' CD62L+ and CCR7+ CD62L+) que les souris immunisées avec le SSP, même dix mois après I'immunisation. Par ailleurs, la réponse CD8 au Melan A LSP était strictement dépendante des lymphocytes CD4, contrairement à l'immunisation par le Melan A SSP qui n'était pas affectée. Dans l'ensemble ces résultats suggèrent que la chemokine XCL1 et l'adjuvant QS21 améliorent la réponse CD8 à un long peptide synthétique, favorisant ainsi le développement d'une réponse anti-tumeur mémoire durable. Ces observations pourraient être utiles au développement de nouveau vaccins thérapeutiques contre les tumeurs.
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Markets, in the real world, are not efficient zero-sum games where hypotheses of the CAPM are fulfilled. Then, it is easy to conclude the market portfolio is not located on Markowitz"s efficient frontier, and passive investments (and indexing) are not optimal but biased. In this paper, we define and analyze biases suffered by passive investors: the sample, construction, efficiency and active biases and tracking error are presented. We propose Minimum Risk Indices (MRI) as an alternative to deal with to market index biases, and to provide investors with portfolios closer to the efficient frontier, that is, more optimal investment possibilities. MRI (using a Parametric Value-at-Risk Minimization approach) are calculated for three stock markets achieving interesting results. Our indices are less risky and more profitable than current Market Indices in the Argentinean and Spanish markets, facing that way the Efficient Market Hypothesis. Two innovations must be outlined: an error dimension has been included in the backtesting and the Sharpe"s Ratio has been used to select the"best" MRI
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In this paper we show how a nonlinear preprocessing of speech signal -with high noise- based on morphological filters improves the performance of robust algorithms for pitch tracking (RAPT). This result happens for a very simple morphological filter. More sophisticated ones could even improve such results. Mathematical morphology is widely used in image processing and has a great amount of applications. Almost all its formulations derived in the two-dimensional framework are easily reformulated to be adapted to one-dimensional context
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Strain BCT-7112, previously identified as Bacillus cereus var. toyoi, is the type strain of the species Bacillus toyonensis, a novel species of the B. cereus group. The complete genome of this strain, which is the active ingredient of the feed additive preparation Toyocerin, has been sequenced and annotated to reveal the genetic properties of this probiotic organism with a long history of safe use in animal nutrition.
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PURPOSE: Signal detection on 3D medical images depends on many factors, such as foveal and peripheral vision, the type of signal, and background complexity, and the speed at which the frames are displayed. In this paper, the authors focus on the speed with which radiologists and naïve observers search through medical images. Prior to the study, the authors asked the radiologists to estimate the speed at which they scrolled through CT sets. They gave a subjective estimate of 5 frames per second (fps). The aim of this paper is to measure and analyze the speed with which humans scroll through image stacks, showing a method to visually display the behavior of observers as the search is made as well as measuring the accuracy of the decisions. This information will be useful in the development of model observers, mathematical algorithms that can be used to evaluate diagnostic imaging systems. METHODS: The authors performed a series of 3D 4-alternative forced-choice lung nodule detection tasks on volumetric stacks of chest CT images iteratively reconstructed in lung algorithm. The strategy used by three radiologists and three naïve observers was assessed using an eye-tracker in order to establish where their gaze was fixed during the experiment and to verify that when a decision was made, a correct answer was not due only to chance. In a first set of experiments, the observers were restricted to read the images at three fixed speeds of image scrolling and were allowed to see each alternative once. In the second set of experiments, the subjects were allowed to scroll through the image stacks at will with no time or gaze limits. In both static-speed and free-scrolling conditions, the four image stacks were displayed simultaneously. All trials were shown at two different image contrasts. RESULTS: The authors were able to determine a histogram of scrolling speeds in frames per second. The scrolling speed of the naïve observers and the radiologists at the moment the signal was detected was measured at 25-30 fps. For the task chosen, the performance of the observers was not affected by the contrast or experience of the observer. However, the naïve observers exhibited a different pattern of scrolling than the radiologists, which included a tendency toward higher number of direction changes and number of slices viewed. CONCLUSIONS: The authors have determined a distribution of speeds for volumetric detection tasks. The speed at detection was higher than that subjectively estimated by the radiologists before the experiment. The speed information that was measured will be useful in the development of 3D model observers, especially anthropomorphic model observers which try to mimic human behavior.
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This study aims at understanding the evolutionary processes at work in specialized species interactions. Prom the macroevolutionary perspective, coevolution among specialized taxa was proposed to be one of the major processes generating biodiversity. We challenge this idea from the theoretical and practical perspective and through a literature review and show that the major hypotheses linking coevolutionary process with macroevolutionary patterns do not necessarily predict lineage co diversification and parallel speciation, limit¬ing the utility of the comparative phylogenenetic approach for investigating coevolution¬ary processes. We also point to the rarity of observed long-term coevolutionary dynamics among lineages and propose that coevolution rather occurs in shorter timescales, followed by ecological fitting. Prom the empirical point, we focus on the nursery pollination interaction between the European globeflower Trollius europaeus (Ranunculaceae) and its associated Chiastocheta flies (Anthomyiidae; Diptera) as a model system of evolution and maintenance of special¬ized interactions. The flies are obligate parasites of the seeds, but also pollinate the plant - it was thus proposed that both species are mutually dependent. Contrasting with the paradigm used for two decades of research on this system, we show that the female fitness component of the plant is similar in the populations with and without Chiastocheta. The plant is thus not exclusively dependent on the flies for reproduction. We discuss this result in the context of the factors responsible for the evolution of mutualistic systems. Understanding the evolution of a biological system requires understanding of its phylo- genetic context. Previous studies showed large mismatch between mtDNA phylogeny and morphological taxonomy in Chiastocheta. By using a large set of RAD-sequencing loci, we delineate the species limits that are congruent with morphology, and show that the discordance is best explained by the scenario of mitochondrial capture among fly species. Finally, we examine this system from a phylogeographic perspective, and identify the lack of congruence in spatial genetic structures of the plant and associated insects across their whole geographic range. The flies show lower numbers of spatial genetic groups than the plant, indicating that not all of the plant réfugia were shared by all the fly species or that the migration dynamics homogenized some of the groups. The incongruence in spatial genetic patterns indicates that fly migrations were largely independent from the genetic background of the plant, following rather a scenario of resource tracking, without the signature of coevolutionary process at this scale. Indeed, while the flies require the plant to survive climatic oscillations, the opposite is not true. Eventually, we show that there is no phylogenetic signal of spatial genetic structures, meaning that neither histories nor life- history traits are shared among closely related species and that species are characterized by unique trajectories of their genes. -- Cette étude vise à comprendre les processus évolutifs à l'oeuvre au sein d'interactions en¬tre espèces spécialisées. Du point de vue macroévolutif, la coévolution entre les taxons spécialisée a été considérée comme l'un des principaux processus générateur de biodiversité. Nous contestons cette idée du point de vue théorique et pratique à travers une revue de la littérature. Nous montrons que les hypothèses majeures reliant les processus coévolutifs avec les patterns de diversité au niveau macroévolutif ne prédisent pas nécessairement la co- diversification des lignées et leur spéciation parallèle, ce qui limite l'utilité de l'approche de phylogénie comparative pour étudier les processus coévolutifs . Nous rappelons également le peu d'exemples de dynamique coévolutive à long terme et proposons que la coévolution se produit plutôt dans des intervalles courts, suivis d'ajustements écologiques. Du point empirique, nous nous concentrons sur l'interaction de pollinisation entre le Trolle d'Europe Trollius europaeus (Ranunculaceae) et ses pollinisateurs associés, du genre Chiastocheta (Anthomyiidae; Diptera) en tant que système-modèle pour étudier l'évolution et le maintien des interactions spécialisées. Les mouches sont des parasites obligatoires des semences, mais pollinisent également la plante. Il a donc été proposé que les deux espèces soient mutuellement dépendantes. Contrastant avec le paradigme utilisé pendant deux décennies de recherche sur ce système, nous montrons, que la composante de fitness femelle de la plante est similaire dans les populations avec et sans Chiastocheta. La plante ne dépend donc pas exclusivement de son interaction avec les mouches pour la reproduction. Nous discutons de ce résultat dans le contexte des facteurs responsables de l'évolution des systèmes mutualistes. Comprendre l'évolution d'un système biologique nécessite la compréhension de son con- texte phylogénétique. Des études antérieures ont montré, chez Chiastocheta, de grandes disparités entre les phylogénies obtenues à partir d'ADN mitochondrial et la taxonomie basée sur les critères morphologiques. En utilisant un grand nombre de loci obtenus par RAD-sequencing, nous traçons les limites des espèces, qui concordent avec les car¬actéristiques morphologies, et montrons que la discordance s'explique en fait par un scénario de capture mitochondriale entre espèces de mouches. Enfin, nous examinons le système d'un point de vue phylogéographique, et identi¬fions les incohérences entre structurations génétiques spatiales de la plante et des insectes associés dans toute leur aire de distribution géographique. Les mouches présentent un nombre de groupes génétiques inférieur à la plante, indiquant que tous les refuges de la plante n'étaient pas partagés par toutes les espèces de mouches ou que les dynamiques migratoires ont homogénéisés certains des groupes chez les mouches. Les différences ob¬servées dans les patrons de structuration génétique spatiale indique que les migrations et dispersions des mouches ont été indépendantes du contexte génétique de la plante, et ces dernières ont été uniquement tributaires de la disponibilité des ressources, sans qu'il n'y ait de signature du processus de coévolution à cette échelle. En effet, tandis que les mouches ont besoin de la plante pour survivre aux oscillations climatiques, le contraire n'est pas exact. Finalement, nous montrons qu'il n'y a pas de signal phylogénétique des structurations génétiques spatiales chez les mouches, ce qui signifie que ni l'histoire, ni les traits d'histoire de vie ne sont partagés entre les espèces phylogénétiquement proches et que les espèces sont caractérisées par des trajectoires uniques de leurs gènes.
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Through an interplay between scanning tunneling microscopy experiments and density functional theory calculations, we determine unambiguously the active surface site responsible for the dissociation of water molecules adsorbed on rutile TiO2(110). Oxygen vacancies in the surface layer are shown to dissociate H2O through the transfer of one proton to a nearby oxygen atom, forming two hydroxyl groups for every vacancy. The amount of water dissociation is limited by the density of oxygen vacancies present on the clean surface exclusively. The dissociation process sets in as soon as molecular water is able to diffuse to the active site.
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BACKGROUND: To study the 'metabolic profile' of different surgical procedures and correlate it with pertinent surgical details and postoperative complications. METHODS: We conducted a prospective pilot study of 70 patients, ten for each of the seven following groups: (1) laparoscopic cholecystectomy, (2) incisional hernia repair, (3) laparoscopic and (4) open colon surgery, (5) upper gastrointestinal, (6) hepatic, and (7) pancreatic resections. Biochemical assessment included white blood cell count (WBC), C-reactive protein (CRP), glucose, triglycerides (TG), albumin (Alb), and pre-albumin (Pre-Alb), from the day before surgery until 5 days thereafter. Biological markers were compared for major versus minor surgery groups, which were defined on a clinical basis. Univariable analysis was used to identify risk factors for postoperative complications and p < 0.05 was the significance threshold. RESULTS: Common findings in all surgery groups were the acute inflammatory response (↑: WBC, CRP, ↓: TG, Alb, pre-Alb). Using cut-off values of 240 min operative (OR) time and 300 ml estimated blood loss (EBL), laparoscopic cholecystectomy, incisional hernia repair, and laparoscopic colectomy could be distinguished from open colectomy, upper gastrointestinal, liver, and pancreas resections. In a biochemical level, increased CRP and reduced postoperative Alb levels were highly discriminative of all types of 'major surgery.' Significant risk factors for postoperative complications were age, male gender, malignancy, longer OR time, higher blood loss, high CRP, and low Alb levels. CONCLUSIONS: Biochemically, CRP and Alb levels can help quantify the magnitude of the surgical trauma, which is correlated with adverse outcomes.
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Adolescence is an important time for acquiring high peak bone mass. Physical activity is known to be beneficial to bone development. The effect of estrogen-progestin contraceptives (EPC) is still controversial. Altogether 142 (52 gymnasts, 46 runners, and 42 controls) adolescent women participated in this study, which is based on two 7-year (n =142), one 6-year (n =140) and one 4-year (n =122) follow-ups. Information on physical activity, menstrual history, sexual maturation, nutrition, living habits and health status was obtained through questionnaires and interviews. The bone mineral density (BMD) and content (BMC) of lumbar spine (LS) and femoral neck (FN) were measured by dual- energy X-ray absoptiometry. Calcaneal sonographic measurements were also made. The physical activity of the athletes participating in this study decreased after 3-year follow-up. High-impact exercise was beneficial to bones. LS and FN BMC was higher in gymnasts than in controls during the follow-up. Reduction in physical activity had negative effects on bone mass. LS and FN BMC increased less in the group having reduced their physical activity more than 50%, compared with those continuing at the previous level (1.69 g, p=0.021; 0.14 g, p=0.015, respectively). The amount of physical activity was the only significant parameter accounting for the calcaneal sonography measurements at 6-year follow-up (11.3%) and reduced activity level was associated with lower sonographic values. Long-term low-dose EPC use seemed to prevent normal bone mass acquisition. There was a significant trend towards a smaller increase in LS and FN BMC among long-term EPC users. In conclusion, this study confirms that high-impact exercise is beneficial to bones and that the benefits are partly maintained even after a clear reduction in training level at least for 4 years. Continued exercise is needed to retain all acquired benefits. The bone mass gained and maintained can possibly be maximized in adolescence by implementing high-impact exercise for youngsters. The peak bone mass of the young women participating in the study may be reached before the age of 20. Use of low-dose EPCs seems to suppress normal bone mass acquisition.
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The aim of the study is to obtain a mathematical description for an alternative variant of controlling a hydraulic circuit with an electrical drive. The electrical and hydraulic systems are described by basic mathematical equations. The flexibilities of the load and boom is modeled with assumed mode method. The model is achieved and proven with simulations. The controller is constructed and proven to decrease oscillations and improve the dynamic response of the system.
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The aim of this work was to make an active front end from IGBTs for a multilevel inverter. The work was done for Mosart II, a long term still ongoing Vacon Oyj project. The purpose of the AFE is to balance the DC-voltage and to put the returning power back to the grid instead of the breaking chopper and the capacitor. With a diode rectifier the bridge only allows power to pass in one direction and the switching times are not controllable. That means the rectifier always takes the highest phase and the phases are always conducting the same 120◦. With an AFE it is possible to actively change the rectifiers switching pattern. A diode bridge also generates much greater losses than an IGBT bridge. With these arguments it is rational to start researching the possibility of an AFE in a multilevel inverter.
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BACKGROUND: Antiretroviral regimens containing tenofovir disoproxil fumarate have been associated with renal toxicity and reduced bone mineral density. Tenofovir alafenamide is a novel tenofovir prodrug that reduces tenofovir plasma concentrations by 90%, thereby decreasing off-target side-effects. We aimed to assess whether efficacy, safety, and tolerability were non-inferior in patients switched to a regimen containing tenofovir alafenamide versus in those remaining on one containing tenofovir disoproxil fumarate. METHODS: In this randomised, actively controlled, multicentre, open-label, non-inferiority trial, we recruited HIV-1-infected adults from Gilead clinical studies at 168 sites in 19 countries. Patients were virologically suppressed (HIV-1 RNA <50 copies per mL) with an estimated glomerular filtration rate of 50 mL per min or greater, and were taking one of four tenofovir disoproxil fumarate-containing regimens for at least 96 weeks before enrolment. With use of a third-party computer-generated sequence, patients were randomly assigned (2:1) to receive a once-a-day single-tablet containing elvitegravir 150 mg, cobicistat 150 mg, emtricitabine 200 mg, and tenofovir alafenamide 10 mg (tenofovir alafenamide group) or to carry on taking one of four previous tenofovir disoproxil fumarate-containing regimens (tenofovir disoproxil fumarate group) for 96 weeks. Randomisation was stratified by previous treatment regimen in blocks of six. Patients and treating physicians were not masked to the assigned study regimen; outcome assessors were masked until database lock. The primary endpoint was the proportion of patients who received at least one dose of study drug who had undetectable viral load (HIV-1 RNA <50 copies per mL) at week 48. The non-inferiority margin was 12%. This study was registered with ClinicalTrials.gov, number NCT01815736. FINDINGS: Between April 12, 2013 and April 3, 2014, we enrolled 1443 patients. 959 patients were randomly assigned to the tenofovir alafenamide group and 477 to the tenofovir disoproxil fumarate group. Viral suppression at week 48 was noted in 932 (97%) patients assigned to the tenofovir alafenamide group and in 444 (93%) assigned to the tenofovir disoproxil fumarate group (adjusted difference 4·1%, 95% CI 1·6-6·7), with virological failure noted in ten and six patients, respectively. The number of adverse events was similar between the two groups, but study drug-related adverse events were more common in the tenofovir alafenamide group (204 patients [21%] vs 76 [16%]). Hip and spine bone mineral density and glomerular filtration were each significantly improved in patients in the tenofovir alafenamide group compared with those in the tenofovir disoproxil fumarate group. INTERPRETATION: Switching to a tenofovir alafenamide-containing regimen from one containing tenofovir disoproxil fumarate was non-inferior for maintenance of viral suppression and led to improved bone mineral density and renal function. Longer term follow-up is needed to better understand the clinical impact of these changes. FUNDING: Gilead Sciences.