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See detailFeed restriction and IGFBP in bulls: effects of increasing starving period lengths.
Massart, Serge; Van Eenaeme, Christian ULg; Renaville, Robert ULg et al

in Journal of Animal Science (1995), 73(suppl 1), 225

Detailed reference viewed: 9 (4 ULg)
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See detailFeed restriction in young bulls alters the onset of puberty in relationship with plasma insulin-like growth factor-I (IGF-I) and IGF-binding proteins
Portetelle, Daniel ULg; Massart, Serge; Van Eenaeme, Christian ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (1998), 2(special issue), 70

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See detailFeed restriction in young bulls alters the onset of puberty in relationship with plasma insulin-like growth factor-I (IGF-I) and IGF-binding proteins.
Renaville, Robert ULg; Van Eenaeme, Christian ULg; Breier, B. H. et al

in Domestic Animal Endocrinology (2000), 18(2), 165-76

The objectives of this study were to evaluate the effect of feed restriction and re-alimentation on the onset of puberty and IGF status in peripubertal male calves and to compare the radioimmunoassay (RIA ... [more ▼]

The objectives of this study were to evaluate the effect of feed restriction and re-alimentation on the onset of puberty and IGF status in peripubertal male calves and to compare the radioimmunoassay (RIA) and western ligand blotting (WLB) methods for bovine IGFBP-2. Twelve prepubertal 290 d-old Belgian Blue bulls (mean weight: +/- 290 kg) were randomly assigned in three groups: a control group (NG; n = 4) receiving a classic fattening diet to induce "normal" growth (1.48 kg/d), a feed restricted group (RG; n = 4) to obtain reduced growth (0.50 kg/d) and, a severely restricted group (SG; n = 4) to nearly stop growth (0.08 kg/d). The feed restriction period was maintained over a period of 114 d. After the period of differential feeding, all animals received the control feed regime over a period of 100 d. Blood samples were collected at fortnightly intervals. Circulating IGF-I was measured by RIA whereas plasma IGFBPs was evaluated by WLB; IGFBP-2 was additionally quantified by RIA procedure. At the beginning of the trial, IGF-I levels were low (<100 ng/ml) and similar in the three groups in accordance with prepubertal status. In the NG group, a progressive rise in IGF-I was observed from Day 42 to Day 142 whereas in the RG and SG groups, IGF-I levels did not change until the experimental restriction period ended. The delay of the rise in plasma IGF-I was longer for the SG group, IGF-I remained low until 2 wk after the end of the period of restricted feeding. Surprisingly, although differences were detected for IGF-I levels between the three groups, the IGFBP-2 and -3 data, evaluated by WLB could only discriminate between NG and SG group and not between NG and RG. However, by using a RIA method, an IGFBP-2 decrease was observed in the NG group coincident with increasing IGF-I levels. For both RG and SG groups, IGFBP-2 levels remained high throughout the feed restriction period whereas plasma IGFBP-2 levels declined upon feeding in both groups. During this feed restriction period, IGFBP-2 was significantly lower in NG than in RG or SG groups. Moreover, SG group animals had higher levels in plasma IGFBP-2 than RG animals. In conclusion, puberty is characterized by developmental changes in plasma IGF-I and IGFBPs that were altered by feed restriction. Moreover, RIA evaluation of plasma IGFBP-2 is able to better reflect group differences than WLB. [less ▲]

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See detailFeedback Control of Impact Dynamics: the Bouncing Ball Revisited
Ronsse, Renaud; Sepulchre, Rodolphe ULg

in Proceedings of the 45th IEEE Conference on Decision and Control (2006, December)

We study the the design of a tracking controller for the popular bouncing ball model: the continuous-time actuation of a table is used to control the impacts of the table with a bouncing ball. The ... [more ▼]

We study the the design of a tracking controller for the popular bouncing ball model: the continuous-time actuation of a table is used to control the impacts of the table with a bouncing ball. The proposed control law uses the impact times as the sole feedback information. We show that the acceleration of the table at impact plays no role in the stability analysis but is an important parameter for the robustness of the feedback system to model uncertainty, in particular to the uncertainty on the coefficient of restitution. [less ▲]

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See detailA feedback control perspective on models of apoptosis signal transduction
Readman, Mark C.; Schliemann, Monica; Kalamatianos, Dimitrios et al

in Chaos, Solitons & Fractals (2013)

Apoptosis is a key regulator for replacing unused, old and damaged cells. Here we analyse three models of apoptosis. We deconstruct these models by linearising the models about the life steady state and ... [more ▼]

Apoptosis is a key regulator for replacing unused, old and damaged cells. Here we analyse three models of apoptosis. We deconstruct these models by linearising the models about the life steady state and applying methods from linear control theory. This control viewpoint uncovers a decentralised control scheme with a clear separation of plant and controller and reveals that the caspase inhibitors act as decentralised phase lead controllers. © 2013 Elsevier Ltd. All rights reserved. [less ▲]

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See detailFeedback control strategies for spatial navigation revealed by dynamic modelling of learning in the Morris water maze
Fey, Dirk ULg; Commins, Sean; Bullinger, Eric ULg

in Journal of Computational Neuroscience (2011), 30(2), 447-454

The Morris water maze is an experimental procedure in which animals learn to escape swimming in a pool using environmental cues. Despite its success in neuroscience and psychology for studying spatial ... [more ▼]

The Morris water maze is an experimental procedure in which animals learn to escape swimming in a pool using environmental cues. Despite its success in neuroscience and psychology for studying spatial learning and memory, the exact mnemonic and navigational demands of the task are not well understood. Here, we provide a mathematical model of rat swimming dynamics on a behavioural level. The model consists of a random walk, a heading change and a feedback control component in which learning is reflected in parameter changes of the feedback mechanism. The simplicity of the model renders it accessible and useful for analysis of experiments in which swimming paths are recorded. Here, we used the model to analyse an experiment in which rats were trained to find the platform with either three or one extramaze cue. Results indicate that the 3-cues group employs stronger feedback relying only on the actual visual input, whereas the 1-cue group employs weaker feedback relying to some extent on memory. Because the model parameters are linked to neurological processes, identifying different parameter values suggests the activation of different neuronal pathways. [less ▲]

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See detailFeedback from reservoir sedimentation on the flow pattern in rectangular basins
Camnasio, Erica; Erpicum, Sébastien ULg; Orsi, Enrico et al

in 6th International Conference on Scour and Erosion (ICSE) (2012, August)

Despite simple geometries, flow in shallow rectangular reservoirs show complex recirculation patterns, which strongly influence the sediment deposits and, in practice, affect the operation and maintenance ... [more ▼]

Despite simple geometries, flow in shallow rectangular reservoirs show complex recirculation patterns, which strongly influence the sediment deposits and, in practice, affect the operation and maintenance costs of such facilities. Based on composite modelling, this research characterizes flow and sedimentation patterns in geometric conditions which have not been investigated so far. Velocity fields developing in rectangular shallow reservoirs (h = 0.2 m) with different asymmetric locations of the inlet and the outlet channels were experimentally investigated. Tests were performed in a reservoir geometry (4.5 m x 4 m) characterized by a stable symmetric flow pattern in the basic symmetric configuration, at constant hydraulic conditions; the aim was to evaluate exclusively the effect of channels displacing on the flow patterns and on the sedimentation of suspended solids. Horizontal velocity components were measured by ultrasound velocity profilers in the entire reservoir and maps of velocity vectors were obtained. Velocity measurements were performed both with clear water and with an inflowing suspended load. At the end of the experiments sediments deposits thickness on the entire reservoir bottom was measured by a laser light method, and maps of sediments deposits thickness were produced. Reservoir trapping efficiency was evaluated, but no significant influence of inlet and outlet channels location on trapping efficiency was observed. Numerical simulations were performed with the depth-averaged model WOLF 2D, in order to assess the ability of the model to reproduce the different types of flow patterns found in the experiments. In particular, a sensitivity analysis on bottom roughness as well as on the turbulence closure model and parameter was performed, in order to analyze a possible feedback effect of sediment deposits and/or suspended load on the type of flow pattern. [less ▲]

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See detailA feedback loop between the liver-enriched transcription factor network and mir-122 controls hepatocyte differentiation.
Laudadio, Ilaria; Manfroid, Isabelle ULg; Achouri, Younes et al

in Gastroenterology (2012), 142(1), 119-29

BACKGROUND & AIMS: Hepatocyte differentiation is controlled by liver-enriched transcription factors (LETFs). We investigated whether LETFs control microRNA expression during development and whether this ... [more ▼]

BACKGROUND & AIMS: Hepatocyte differentiation is controlled by liver-enriched transcription factors (LETFs). We investigated whether LETFs control microRNA expression during development and whether this control is required for hepatocyte differentiation. METHODS: Using in vivo DNA binding assays, we identified miR-122 as a direct target of the LETF hepatocyte nuclear factor (HNF) 6. The role and mechanisms of the HNF6-miR-122 gene cascade in hepatocyte differentiation were studied in vivo and in vitro by gain-of-function and loss-of-function experiments, using developing mice and zebrafish as model organisms. RESULTS: HNF6 and its paralog Onecut2 are strong transcriptional stimulators of miR-122 expression. Specific levels of miR-122 were required for proper progression of hepatocyte differentiation; miR-122 stimulated the expression of hepatocyte-specific genes and most LETFs, including HNF6. This indicates that HNF6 and miR-122 form a positive feedback loop. Stimulation of hepatocyte differentiation by miR-122 was lost in HNF6-null mice, revealing that a transcription factor can mediate microRNA function. All hepatocyte-specific genes whose expression was stimulated by miR-122 bound HNF6 in vivo, confirming their direct regulation by this factor. CONCLUSIONS: Hepatocyte differentiation is directed by a positive feedback loop that includes a transcription factor (HNF6) and a microRNA (miR-122) that are specifically expressed in liver. These findings could lead to methods to induce differentiation of hepatocytes in vitro and improve our understanding of liver cell dedifferentiation in pathologic conditions. [less ▲]

Detailed reference viewed: 95 (26 ULg)
See detailFeedback loops: From cellular to network principles
Dethier, Julie ULg

Scientific conference (2015, January 12)

Biological rhythms play a major role in the functioning of the brain. However, the generation mechanisms and functions of these rhythms are still under debate and the question of which cellular details ... [more ▼]

Biological rhythms play a major role in the functioning of the brain. However, the generation mechanisms and functions of these rhythms are still under debate and the question of which cellular details must be retained at the network level is largely open. In this presentation, I will highlight that cellular properties have a major impact at the network level, especially in the study of modulation and robustness. I will focus on a particular cellular property, a positive feedback loop in a specific timescale, and illustrate its network level impact with two simple examples: the modulation and robustness of an half-center oscillator, a very simple central pattern generator composed of two reciprocal-inhibitory populations, and the control of transient beta-band oscillations in the basal ganglia, a group of subcortical nuclei that act as a cohesive functional unit, in relation to motor movements. [less ▲]

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See detailFeedback mechanisms for global oscillations in Lure systems
Sepulchre, Rodolphe ULg; Stan, G. B.

in Systems & Control Letters (2005), 54(8), 809-818

The paper presents two mechanisms for global oscillations in feedback systems, based on bifurcations in absolutely stable systems. The external characterization of the oscillators provides the basis for a ... [more ▼]

The paper presents two mechanisms for global oscillations in feedback systems, based on bifurcations in absolutely stable systems. The external characterization of the oscillators provides the basis for a (energy-based) dissipativity theory for oscillators, thereby opening new possibilities for rigorous stability analysis of high-dimensional systems and interconnected oscillators. (C) 2004 Elsevier B.V. All rights reserved. [less ▲]

Detailed reference viewed: 36 (4 ULg)
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See detailFeedback Mechanisms in Intra-Cellular Dynamics
Conzelmann, H.; Sauter, T.; Bullinger, Eric ULg et al

Conference (2003, May 29)

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See detailThe feedback of massive stars on interstellar astrochemical processes
De Becker, Michaël ULg

in Astrophysics & Space Science (2014), 350(1), 237-243

Astrochemistry is a discipline that studies physico-chemical processes in astrophysical environments. Such environments are characterized by conditions that are substantially different from those existing ... [more ▼]

Astrochemistry is a discipline that studies physico-chemical processes in astrophysical environments. Such environments are characterized by conditions that are substantially different from those existing in usual chemical laboratories. Models which aim to explain the formation of molecular species in interstellar environments must take into account various factors, including many that are directly, or indirectly related to the populations of massive stars in galaxies. The aim of this paper is to review the influence of massive stars, whatever their evolution stage, on the physico-chemical processes at work in interstellar environments. These influences include the ultraviolet radiation field, the production of high energy particles, the synthesis of radionuclides and the formation of shocks that permeate the interstellar medium. [less ▲]

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See detailFeedbacks correctifs écrits en anglais langue étrangère et attentes des élèves du secondaire
Noiroux, Kevin ULg

Conference (2013, November)

Grâce à des recherches qui montrent que l’élève ne s’améliore pas après avoir été corrigé, certains chercheurs pensent que la correction des erreurs écrites n’a pas sa place dans l’enseignement d’une ... [more ▼]

Grâce à des recherches qui montrent que l’élève ne s’améliore pas après avoir été corrigé, certains chercheurs pensent que la correction des erreurs écrites n’a pas sa place dans l’enseignement d’une langue étrangère. Cet article a pour but d’analyser les attentes des élèves pour voir s’ils sont demandeurs ou pas de corrections. Nos résultats montrent que les élèves du secondaire de Fédération Wallonie-Bruxelles veulent non seulement être corrigés, mais qu’ils s’intéressent de très près à la compréhension de leurs erreurs. Il faut cependant noter que les erreurs semblent être corrigées dans le cadre d’évaluations certificatives, ce qui est potentiellement inéquitable. [less ▲]

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See detailLes feedbacks des check-up Mohican aux étudiants et aux enseignants
Leclercq, Dieudonné ULg; Gilles, Jean-Luc ULg; Pirson, Marc ULg et al

in Leclercq, Dieudonné (Ed.) Diagnostic cognitif et métacognitif au seuil de l'université : le projet Mohican menée par les 9 universités de la Communauté française Wallonie-Bruxelles (2003)

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See detailFeedbacks Via Internet (FVI)
Gilles, Jean-Luc ULg; Pirson, Marc ULg

Software (2002)

Detailed reference viewed: 43 (8 ULg)
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See detailFeeding and ranging behavior of northern pigtailed macaques (Macaca leonina): impact on their seed dispersal effectiveness and ecological contribution in a tropical rainforest at Khao Yai National Park, Thailand
Albert, Aurélie ULg

Doctoral thesis (2012)

Southeast Asia experiences an exceptional loss of natural habitat due to a deforestation rate that strongly increased during the last decades. The first consequence is the loss of many animal and plant ... [more ▼]

Southeast Asia experiences an exceptional loss of natural habitat due to a deforestation rate that strongly increased during the last decades. The first consequence is the loss of many animal and plant species, threatened by their habitat degradation and by the loss of interactions necessary to the survival of the whole ecosystem. Large mammals and birds populations, the principal dispersal agent of some plant species, already collapsed massively due to hunting and habitat fragmentation and now threaten to die out. Among the large frugivorous species, primates are particularly vulnerable. Only few species, such as macaques, are able to survive in some man-made habitats, due to their opportunistic life-style. But, in the long term, habitat destruction, hunting and capture for local trade threaten their survival. The extinction of primates in Southeast Asian forests would be disastrous for many plant species as primates are among the major seed-dispersal agents. The study of Macaca, the only Cercopithecinae genus in Southeast Asia, could provide a better understanding of the role of cheek-pouched monkeys in tropical rainforest maintenance and restoration. In this study, we chose to focus on northern pigtailed macaques (Macaca leonina) as few studies were carried out on this species, making data concerning its ecology and behavior highly limited. Their seed dispersal capacity, although unknown, is potentially high and pigtailed macaques could be as good seed dispersers as sympatric frugivores. They seem to eat a large number of fruits of many plant species, process seeds with care, and range daily over large areas. Moreover they could have a role in forest maintenance and regeneration given that they seem to eat species with all seed sizes, belonging to all plant life forms present in the forest, and they are able to cross various habitat types (primary as well as secondary forests). After providing an outline of our current knowledge on seed dispersal by Cercopithecinae species and their specific role in forest regeneration, our aim was to highlight the importance of northern pigtailed macaques on seed dispersal and thus on forest regeneration by studying (1) how their eco-ethological characteristics can make them effective dispersers, from a quantitative and a qualitative point of view, (2) how the influence of biotic factors, such as resources and predation, on their activities and movements may impact their seed dispersal effectiveness, and (3) what role Macaca spp. can have in a seed dispersal assemblage. While following a troop of northern pigtailed macaques habituated to humans in Khao Yai National Park, Thailand, we recorded their behavior, travels, and consumed items, from dawn to dusk. Moreover, we studied the spatio-temporal distribution of fruits included in their diet, and the characteristics of their sleeping sites. Finally, we performed germination and viability tests on ingested seeds. Results showed that northern pigtailed macaques could disperse thousands of seeds, up to 58 mm in length, coming from the 126 fruit species they eat. Especially, they could disperse them from primary to secondary forest, thanks to handling techniques such as swallowing, spitting and dropping. Finally, the seed passage through their digestive tract mostly had a neutral or positive effect on seed germination and viability. Macaques observed in this study satisfied therefore most requirements defining effective seed dispersers in both quantitative and qualitative terms and we can conclude to the potential importance of Macaca leonina in the tropical rainforest regeneration. To confirm the seed dispersal effectiveness of M. leonina, we needed to make sure that its ranging behavior did not negatively affect dispersed seeds. Moreover, given the importance of human food in their diet, we wondered if this resource had a negative impact on seed dispersal. Our results showed that northern pigtailed macaques adapted their ranging pattern according to fruit availability. Moreover, during fruit scarcity, they shifted their diet from frugivorous to omnivorous with an important part of human food. However, human food did not seem to have an impact on seed dispersal in high fruit abundance periods where macaques had a large home range, traveled long distances and ate mainly fruits. However, in low fruit abundance periods, macaques decreased their home range size, traveled shorter distances and ate mainly human food. This latter could have a negative impact on the seed dispersal of some rare fructifying species. However, these species were eaten by many other animal species able to provide good dispersal services. Then, we showed that sleeping sites characteristics and pre-sleep behavior in M. leonina were influenced by the proximity of resources and the risk of predation. Given that macaques used few sleeping sites, defecated when they woke up and that all troop members slept concentrated in a small area, we think that they created a high seed density below the sleeping trees. This may be harmful for some seed species but may be beneficial for the ecosystem. Moreover, this pattern may be shown in other effective seed dispersers in the park. So as harmful for seeds it may be, it does not make pigtailed macaques less effective than other frugivores. Finally, we demonstrated that Macaca species are important associates in the seed dispersal assemblage found in Southeast Asian forests. Indeed they may disperse most plant species, usually more efficiently dispersed by other frugivores, and thus provide a significant complement in term of dispersal quantity. Moreover, they are sometimes the only frugivores able to disperse the seeds of some species, mainly large-seeded and/or protected ones, and may thus bring them a vital dispersal service. [less ▲]

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See detailFeeding behaviour of weaned pigs fed either pellets or meal: effects of the number of aniamls per feeding place
Laitat, Martine ULg; Vandenheede, Marc ULg; Desiron, Alain et al

in Ferrante, V. (Ed.) Proceedings of the 37th International Congress of the International Society for Applied Ethology (2003)

Detailed reference viewed: 38 (8 ULg)
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See detailFeeding Cyprinus carpio with infectious materials mediates cyprinid herpesvirus 3 entry through infection of pharyngeal periodontal mucosa
Fournier, Guillaume ULg; Boutier, Maxime ULg; Victor, Stalin Raj et al

in Veterinary Research (2012), 43(6),

Cyprinid herpesvirus 3 (CyHV-3), also known as Koi herpesvirus, is the etiological agent of a mortal disease in common and koi carp. Recently, we investigated the entry of CyHV-3 in carp using ... [more ▼]

Cyprinid herpesvirus 3 (CyHV-3), also known as Koi herpesvirus, is the etiological agent of a mortal disease in common and koi carp. Recently, we investigated the entry of CyHV-3 in carp using bioluminescence imaging and a CyHV-3 recombinant strain expressing luciferase (LUC). We demonstrated that the skin is the major portal of entry after inoculation of carp by immersion in water containing CyHV-3. While this model of infection mimics some natural conditions in which infection takes place, other epidemiological conditions could favour entry of virus through the digestive tract. Here, we investigated whether ingestion of infectious materials mediates CyHV-3 entry through the digestive tract. Carp were fed with materials contaminated with the CyHV-3 LUC recombinant (oral contamination) or immersed in water containing the virus (contamination by immersion). Bioluminescence imaging analyses performed at different times post-infection led to the following observations: (i) the pharyngeal periodontal mucosa is the major portal of entry after oral contamination, while the skin is the major portal of entry after contamination by immersion. (ii) Both modes of inoculation led to the spreading of the infection to the various organs tested. However, the timing and the sequence in which some of the organs turned positive were different between the two modes of inoculation. Finally, we compared the disease induced by the two inoculation modes. They led to comparable clinical signs and mortality rate. The results of the present study suggest that, based on epidemiological conditions, CyHV-3 can enter carp either by skin or periodontal pharyngeal mucosal infection. [less ▲]

Detailed reference viewed: 43 (10 ULg)