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See detailMeta-learning of Exploration/Exploitation Strategies: The Multi-Armed Bandit Case
Maes, Francis; Wehenkel, Louis ULg; Ernst, Damien ULg

in Filipe, Joaquim; Fred, Ana (Eds.) Agents and Artificial Intelligence: 4th International Conference, ICAART 2012, Vilamoura, Portugal, February 6-8, 2012. Revised Selected Papers (2013)

The exploration/exploitation (E/E) dilemma arises naturally in many subfields of Science. Multi-armed bandit problems formalize this dilemma in its canonical form. Most current research in this field ... [more ▼]

The exploration/exploitation (E/E) dilemma arises naturally in many subfields of Science. Multi-armed bandit problems formalize this dilemma in its canonical form. Most current research in this field focuses on generic solutions that can be applied to a wide range of problems. However, in practice, it is often the case that a form of prior information is available about the specific class of target problems. Prior knowledge is rarely used in current solutions due to the lack of a systematic approach to incorporate it into the E/E strategy. To address a specific class of E/E problems, we propose to proceed in three steps: (i) model prior knowledge in the form of a probability distribution over the target class of E/E problems; (ii) choose a large hypothesis space of candidate E/E strategies; and (iii), solve an optimization problem to find a candidate E/E strategy of maximal average performance over a sample of problems drawn from the prior distribution. We illustrate this meta-learning approach with two different hypothesis spaces: one where E/E strategies are numerically parameterized and another where E/E strategies are represented as small symbolic formulas. We propose appropriate optimization algorithms for both cases. Our experiments, with two-armed “Bernoulli” bandit problems and various playing budgets, show that the metalearnt E/E strategies outperform generic strategies of the literature (UCB1, UCB1-T UNED, UCB-V, KL-UCB and epsilon-GREEDY); they also evaluate the robustness of the learnt E/E strategies, by tests carried out on arms whose rewards follow a truncated Gaussian distribution. [less ▲]

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See detailLe méta-projet de restauration des tourbières de Haute-Ardenne
Dufrêne, Marc ULg; Frankard, Philippe; Plunus, Julie et al

in Hautes Fagnes (2015), 300

Ce méta-projet synthétise les 6 projets de restauration des tourbières et des milieux associés (landes sèches, landes humides, bas-marais, prairies alluviales, aulnaies rivulaires, ...) qui ont été lancés ... [more ▼]

Ce méta-projet synthétise les 6 projets de restauration des tourbières et des milieux associés (landes sèches, landes humides, bas-marais, prairies alluviales, aulnaies rivulaires, ...) qui ont été lancés depuis 2003 en Wallonie. Ces projets se répartissent sur les différents hauts-plateaux ardennais, de la Croix-Scaille aux Hautes-Fagnes, en passant par les plateaux de Libin et de Recogne, de Saint-Hubert, des Tailles et de Spa-Malchamps. Les 5 projets (presque) terminés ont déjà permis de restaurer plus de 4.500 ha de zones tourbeuses et humides sur les Hauts-Plateaux ardennais et d'assurer la protection de plus de 2.700 ha de nouveaux territoires. [less ▲]

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See detailMetabolic Acidosis during Intracranial Surgery under Propofol or Sevoflurane Anesthesia
Schaub, Isabelle; Bonhomme, Vincent; Demoitie, Jeannick et al

in Anesthesiology (2008), 109(A475), 475

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See detailMetabolic acidosis during the first 2 weeks of life in VLBW infants receiving high protein intakes
SENTERRE, Thibault ULg; Rigo, J

in Intensive Care Medicine (2011), 37(S2), 397

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See detailMetabolic activity in external and internal awareness networks in severely brain-damaged patients.
Thibaut, Aurore ULg; Bruno, Marie-Aurélie ULg; Chatelle, Camille ULg et al

in Journal of Rehabilitation Medicine (2012), 44(6), 487-94

OBJECTIVE: An extrinsic cerebral network (encompassing lateral frontoparietal cortices) related to external/sensory awareness and an intrinsic midline network related to internal/self-awareness have been ... [more ▼]

OBJECTIVE: An extrinsic cerebral network (encompassing lateral frontoparietal cortices) related to external/sensory awareness and an intrinsic midline network related to internal/self-awareness have been identified recently. This study measured brain metabolism in both networks in patients with severe brain damage. DESIGN: Prospective [18F]-fluorodeoxyglucose-positron emission tomography and Coma Recovery Scale-Revised assessments in a university hospital setting. SUBJECTS: Healthy volunteers and patients in vegetative state/unresponsive wakefulness syndrome (VS/UWS), minimally conscious state (MCS), emergence from MCS (EMCS), and locked-in syndrome (LIS). RESULTS: A total of 70 patients were included in the study: 24 VS/UWS, 28 MCS, 10 EMCS, 8 LIS and 39 age-matched controls. VS/UWS showed metabolic dysfunction in extrinsic and intrinsic networks and thalami. MCS showed dysfunction mostly in intrinsic network and thalami. EMCS showed impairment in posterior cingulate/retrosplenial cortices. LIS showed dysfunction only in infratentorial regions. Coma Recovery Scale-Revised total scores correlated with metabolic activity in both extrinsic and part of the intrinsic network and thalami. CONCLUSION: Progressive recovery of extrinsic and intrinsic awareness network activity was observed in severely brain-damaged patients, ranging from VS/UWS, MCS, EMCS to LIS. The predominance of intrinsic network impairment in MCS could reflect altered internal/self-awareness in these patients, which is difficult to quantify at the bedside. [less ▲]

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See detailMetabolic adaptation to prolonged exercise in severely obese subjects.
Scheen, André ULg; Pirnay, Freddy ULg; Luyckx, A. S. et al

in International Journal of Obesity & Related Metabolic Disorders (1983), 7(3), 221-9

In investigating the metabolic adaptation to prolonged exercise in markedly obese subjects, we compared blood glucose, plasma lactate, free fatty acids, insulin and glucagon concentrations during 3 h of ... [more ▼]

In investigating the metabolic adaptation to prolonged exercise in markedly obese subjects, we compared blood glucose, plasma lactate, free fatty acids, insulin and glucagon concentrations during 3 h of treadmill exercise in nine severely obese male patients (OB) (weight excess 84 +/- 7 per cent of their ideal body weight) and in nine healthy controls (C). Speed and slope of treadmill were selected to give a similar oxygen consumption in both groups (OB: 1.61 +/- 0.08 1/min; C: 1.72 +/- 0.07 1/min). Under these conditions, heart rate was similar in both groups, whereas ventilation was significantly lower in overweight subjects. In obese patients, plasma free fatty acid (FFA) levels were higher in the basal state (OB: 740 +/- 43 mumol/l; C: 602 +/- 40 mumol/l, 2 P less than 0.05) but showed a lower increase during the exercise period (OB: + 576 +/- 135 mumol/l; C: + 1071 +/- 100 mumol/l, 2 P less than 0.02). This impaired FFA mobilization was related to significantly higher insulin (IRI) levels throughout the exercise period as shown by the regression line of exercise-induced FFA increase (y, mumol/l) vs mean plasma IRI during exercise (x, microU/ml): y = 1238 - 60 x, r = -0.709, 2 P less than 0.001. Lack of glucagon increase could also contribute to the lower rise of FFA in obese subjects. A correspondingly increased contribution of carbohydrates to the energy supply is suggested by a significant decline in blood glucose and higher lactate plasma concentrations during the second half of the exercise period in overweight patients. These abnormalities could represent a metabolic limitation for performing prolonged exercise in markedly obese patients. [less ▲]

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See detailMetabolic alterations after a two-hour nocturnal interruption of a continuous subcutaneous insulin infusion.
Scheen, André ULg; Castillo, M.; Jandrain, Bernard ULg et al

in Diabetes Care (1984), 7(4), 338-42

In order to evaluate the metabolic consequences of a 2-h nocturnal interruption of continuous subcutaneous insulin infusion (CSII), seven insulin-dependent diabetic patients without residual insulin ... [more ▼]

In order to evaluate the metabolic consequences of a 2-h nocturnal interruption of continuous subcutaneous insulin infusion (CSII), seven insulin-dependent diabetic patients without residual insulin secretion were investigated. The changes in blood glucose, plasma free insulin, glucagon, free fatty acids, and 3-hydroxybutyrate (3 OH-B) concentrations have been compared during two randomized tests carried out either during the normal functioning of a Mill-Hill pump from 10 p.m. to 8 a.m. (1.00 +/- 0.06 U insulin/h, keeping adequate metabolic control) or during the same conditions but with a deliberate arrest of the pump between 11 p.m. and 1 a.m. Considering the value recorded at 11 p.m. as reference, interruption of the insulin infusion resulted in: (1) a rapid (already significant after 1 h) and sustained (maximal fall: --12.5 +/- 2.5 mU/L at 3 a.m.) decrease in plasma free insulin; (2) a delayed (significant after 4 h) and linear rise in blood glucose (maximal increase: + 4.0 +/- 1.3 mmol/L at 5 a.m.); (3) an early (significant at midnight) and prolonged rise in plasma free fatty acids (+ 387 +/- 148 mumol/L at 3 a.m.); (4) a delayed (significant after 3 h) and sustained increase in plasma 3 OH-B (+ 347 +/- 88 mumol/L at 3 a.m.); and (5) no significant changes in plasma glucagon. Thus, a 2-h interruption of CSII in resting nocturnal conditions is sufficient to induce significant, delayed, and sustained metabolic alterations in C-peptide-negative patients despite good baseline blood glucose control. Resetting the pump at its basal rate is insufficient to quickly restore adequate circulating insulin levels and effectively counteract the metabolic disturbances. The efficacy of a bolus insulin injection in these conditions should be evaluated. [less ▲]

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See detailMetabolic and cardiovascular consequences of strenuous concentric versus eccentric isokinetic exercise
Lehance, Cédric ULg; Bury, Thierry ULg; Maquet, Didier ULg et al

in Abstract Book “Exercise and muscle physiology” de l’Ecole Doctorale en Sciences de la Motricité (2006)

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See detailMetabolic and endocrine profiles in sick neonatal foals are related to survival.
Armengou, L.; Jose-Cunilleras, E.; Rios, J. et al

in Journal of veterinary internal medicine / American College of Veterinary Internal Medicine (2013), 27(3), 567-75

BACKGROUND: Sick neonatal foals suffer from a variety of endocrine and metabolic derangements that may be related to outcome. There are several hepatic and lipid metabolism blood markers that have never ... [more ▼]

BACKGROUND: Sick neonatal foals suffer from a variety of endocrine and metabolic derangements that may be related to outcome. There are several hepatic and lipid metabolism blood markers that have never been assessed in neonatal foals. OBJECTIVES: Assess panel of endocrine and metabolic variables in group of sick and healthy neonatal foals in order to describe their relationship with diagnosis and survival. ANIMALS: All neonatal foals referred to Unitat Equina-Fundacio Hospital Clinic Veterinari during 3 consecutive foaling seasons and a group of healthy foals. METHODS: Observational prospective study. Blood samples were obtained on admission and, when possible, after 24-48 h of hospitalization and immediately before discharge or death. Measured variables were triglycerides, nonsterified fatty acids, glucose, creatinine, urea, gamma-glutamyltransferase, glutamate dehydrogenase (GLDH), insulin, cortisol, bile acids, and adrenocorticotropic hormone (ACTH). ACTH/cortisol and glucose/insulin ratios were calculated. RESULTS: Urea, creatinine, and cortisol had median concentrations in septic and nonseptic foals 2- to 8-fold higher than in the control group (P < .001). Median ACTH concentration in the septic group was approximately 4 times higher than in nonseptic and control foals (P < .001). ACTH/cortisol ratio was significantly lower in sick foals compared to control foals (P < .001). A score was designed including creatinine, GLDH, and cortisol. When >/= 2 of these variables were altered (P < .001), the foal had 32 times more risk of dying (OR, 31.7; 95% CI, 7.7-130.3). CONCLUSIONS AND CLINICAL IMPORTANCE: Plasma creatinine, GLDH, and cortisol should be determined in sick newborn foals on admission because of their association with survival. [less ▲]

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See detailMetabolic and hormonal effects of intra-nasal administation of insulin in normal man
PAQUOT, Nicolas ULg; SCHEEN, André ULg; Franchimont, P. et al

Poster (1987, November 20)

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See detailMetabolic and respiratory changes after cholecystectomy performed via laparotomy or laparoscopy.
Joris, Jean ULg; Cigarini, I.; Legrand, Marc ULg et al

in British Journal of Anaesthesia (1992), 69(4), 341-5

We have compared metabolic and respiratory changes after laparoscopic cholecystectomy (n = 15) with those after open cholecystectomy (n = 15). The durations of postoperative i.v. therapy, fasting and ... [more ▼]

We have compared metabolic and respiratory changes after laparoscopic cholecystectomy (n = 15) with those after open cholecystectomy (n = 15). The durations of postoperative i.v. therapy, fasting and hospital stay were significantly shorter in the laparoscopy group. During the first and second days after operation, analgesic consumption but not pain scores (visual analogue scale) were significantly smaller after laparoscopy, while vital capacity, forced expiratory volume in 1 s, and PaO2 were significantly greater. The metabolic and acute phase responses (glucose, leucocytosis, C-reactive protein) were less after laparoscopy compared with laparotomy. Although plasma cortisol and catecholamine concentrations were not significantly different between the two groups, after surgery interleukin-6 concentrations were less in the laparoscopy group. [less ▲]

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See detailMetabolic and Structural Abnormalities in Dogs with Early Left Ventricular Dysfunction Induced by Incessant Tachycardia
Mc Entee, Kathleen ULg; Flandre, Thierry; Doizé, Cécile ULg et al

in American Journal of Veterinary Research (2001), 62(6), 889-94

OBJECTIVE: To assess morphologic and metabolic abnormalities in dogs with early left ventricular dysfunction (ELVD) induced by rapid right ventricular pacing (RRVP). ANIMALS: 7 Beagles. PROCEDURE: Plasma ... [more ▼]

OBJECTIVE: To assess morphologic and metabolic abnormalities in dogs with early left ventricular dysfunction (ELVD) induced by rapid right ventricular pacing (RRVP). ANIMALS: 7 Beagles. PROCEDURE: Plasma carnitine concentrations were measured before and after development of ELVD induced by RRVP. At the same times, transvenous endomyocardial biopsy was performed, and specimens were submitted for determination of myocardial carnitine concentrations and histologic, morphometric, and ultrastructural examination. RESULTS: In 4 dogs in which baseline plasma total carnitine concentration was normal, RRVP induced a decrease in myocardial total and free carnitine concentrations and an increase in myocardial esterified carnitine concentration. In 3 dogs in which baseline plasma total carnitine concentration was low, plasma and myocardial carnitine concentrations were unchanged after pacing. Structural changes associated with pacing included perinuclear vacuolization in 3 dogs. Morphometric analyses indicated there was a decrease in myofiber cross-sectional diameter and area following pacing. Electron microscopy revealed changes in myofibrils and mitochondria following pacing. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that moderate to severe alterations in myocyte cytoarchitecture are present in dogs with ELVD induced by RRVP and that in dogs with normal plasma carnitine concentrations, myocardial carnitine deficiency may be a biochemical marker of ELVD. Results also indicated that transvenous endomyocardial biopsy can be used to evaluate biochemical and structural myocardial changes in dogs with cardiac disease. [less ▲]

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See detailMetabolic and structural connectivity within the default mode network relates to working memory performance in young healthy adults
Yakushev, Igor; Chételat, Gael; Fischer F.U. et al

in NeuroImage (2013), 79

Studies of functional connectivity suggest that the default mode network (DMN) might be relevant for cognitive functions. Here, we examined metabolic and structural connectivity between major DMN nodes ... [more ▼]

Studies of functional connectivity suggest that the default mode network (DMN) might be relevant for cognitive functions. Here, we examined metabolic and structural connectivity between major DMN nodes, the posterior cingulate (PCC) and medial prefrontal cortex (MPFC), in relation to normal working memory (WM). DMN was captured using independent component analysis of [18F]fluorodeoxyglucose positron emission tomography (FDG-PET) data from 35 young healthy adults (27.1±5.1 years). Metabolic connectivity, a correlation between FDG uptake in PCC and MPFC, was examined in groups of subjects with (relative to median) low (n=18) and high (n=17) performance on digit span backward test as an index of verbal WM. In addition, fiber tractography based on PCC and MPFC nodes as way points was performed in a subset of subjects. FDG uptake in the DMN nodes did not differ between high and low performers. However, significantly (p=0.01) lower metabolic connectivity was found in the group of low performers. Furthermore, as compared to high performers, low performers showed lower density of the left superior cingulate bundle. Verbal WM performance is related to metabolic and structural connectivity within the DMN in young healthy adults. Metabolic connectivity as quantified with FDG-PET might be a sensitive marker of the normal variability in some cognitive functions. [less ▲]

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See detailMetabolic cerebral correlates of conjunctive and relational memory in Alzheimer's disease
Bastin, Christine ULg; Bahri, Mohamed Ali ULg; Collette, Fabienne ULg et al

Poster (2014)

Introduction. Memory deficits are the clinical hallmark of typical Alzheimer’s disease. The precise nature of these deficits however remains to be fully characterized. In this study, we investigated ... [more ▼]

Introduction. Memory deficits are the clinical hallmark of typical Alzheimer’s disease. The precise nature of these deficits however remains to be fully characterized. In this study, we investigated binding in long-term episodic memory. Relational binding processes in memory create an associative link between independent items or between items and context into episodic memories (Cohen et al., 1999). An alternative process, conjunctive binding, allows associations to be encoded as a united representation of features into a single entity (O'Reilly and Rudy, 2001; Mayes et al., 2007). The current study (1) assessed whether Alzheimer’s disease disrupt both conjunctive and relational memory, and (2) related patients’ memory performance to cerebral metabolism. Methods. Thirty patients with mild Alzheimer’s disease and 24 healthy older adults performed a source memory task where items were associated to a background color (Diana et al., 2008, 2010). In one condition, relational binding was promoted by the instruction to associate the item with another object of the same color as the background. In the other condition, color had to be integrated as an item feature (conjunctive binding). Patients’ brain metabolic activity at rest (FDG-PET) was analysed with spatio-temporal Partial Least Squares (McIntosh et al., 1996) in order to assess the relation of behavioral performance and activity in functional cerebral networks. Results. Alzheimer’s disease patients had an impaired capacity to remember item-color associations, with deficits in both relational and conjunctive memory. However, performance in the two kinds of associative memory varied independently across patients. Partial least square analyses revealed a significant pattern of metabolic activity that correlated specifically with each condition (accounting for 76.48 % of the covariance in the data; p< .05). More specifically, poor conjunctive memory was related to hypometabolism in an anterior temporal-posterior fusiform brain network, whereas relational memory correlated with metabolism in regions of the default mode network. Conclusions. These findings support the hypothesis of distinct neural systems specialized in different types of associative memory and point to heterogeneous profiles of memory alteration in Alzheimer’s disease as a function of damage to the respective neural networks. [less ▲]

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See detailMETABOLIC CHANGES IN THE MIGRAINE BRAIN IN RELATION TO AGEING AND DISEASE LOAD
D'Ostilio, Kevin ULg; Lisicki Martinez, Marco ULg; NONIS, Romain ULg et al

in Cephalalgia : An International Journal of Headache (2016), 36(1S), 59

Introduction: Migraine prevalence tends to decrease with advancing age. Morphological and functional brain changes occuring in migraine could be secondary to repeated attacks and/or to abnormal sensory ... [more ▼]

Introduction: Migraine prevalence tends to decrease with advancing age. Morphological and functional brain changes occuring in migraine could be secondary to repeated attacks and/or to abnormal sensory processing. In normal ageing, brain modifications could traduce a progressive refinement to cope with the environment, associated with a reduction in the complexity of brain connections. We hypothesized that metabolism in various brain regions might be differentially modified by age in migraine patients. Materials and methods: Forty-one subjects underwent a FDG-PET scan: 21 patients with interictal episodic migraine without aura (MO, age range: 20–63 years, 5M) and 20 healthy controls (HV, 21–59 years, 5 M). Results: In MO vs. HV, the overall FDG uptake was reduced in the left visual cortex, left medial frontal gyrus and bilaterally in the insula, somatosensory and motor cortices. Metabolisms of the posterior thalamus, brainstem including the periaqueductal gray (PAG), visual cortex, and (para)hippocampus, strongly increased with age in MO patients but not in HV. Disease duration positively correlated with PAG, (para)hippocampus and rostral anterior cingulate cortex (rACC) metabolisms in MO. Conclusion: Migraine patients, compared to HV, have a decreased resting metabolism in several areas belonging to the ‘‘pain/salience matrix’’, which is in line with previous neuroimaging studies. Metabolism of the rACC is specifically related to disease load whereas metabolism of other sensory processing regions is more affected by age. Whether these functional changes are due to repeated stereotyped attack-related stimulations and to a learning process with complexity reduction of neuronal connections and/or compensatory age-related hyperactivity, remains to be demonstrated [less ▲]

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See detailMetabolic Changes in the Spinal Cord After Brachial Plexus Root Re-implantation
Kachramanoglou, C; De Vita, E; Thomas, D et al

in Neurorehabilitation & Neural Repair (2013), 27(2), 118-124

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