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See detailPerformance of leaf wetness sensor used in winter wheat disease management
Mahtour, Abdeslam ULg; El Jarroudi, Moussa ULg; Hoffmann, Lucien et al

Poster (2011, May 26)

Wetness on crop leaves has particular epidemiological significance because many fungal diseases affect plants only when free moisture is present on leaves. The leaf wetness sensor detects the presence of ... [more ▼]

Wetness on crop leaves has particular epidemiological significance because many fungal diseases affect plants only when free moisture is present on leaves. The leaf wetness sensor detects the presence of wetness on a leaf’s surface, enabling researchers and producers to forecast disease and protect plant canopies, and consequently to optimize fungicide application and often reduce environmental load. This research project aimed at better understanding the leaf wetness duration and its influence in winter wheat disease. Measurement of surface wetness duration by three electronic flat-plate sensors (Model 237-Campbell Scientific, Inc) in wheat fields were compared with tactile and visual observations in replicated field experiments at the site of Arlon (Belgium) during the period May-July 2006 and April-July 2007. Performances of the sensor were evaluated against SWEB model outputs and visual observations of disease symptoms. On the field, dew-onset and dry-off of wetness on leaves were observed visually (with a flash light for dew-onset) at 15-minute intervals. Each sensor was placed close the flag leaf. For the three sensors, the two dew-onset and dry-off times measured in both 2006 and 2007 crop seasons gave a leaf wetness duration (LWD) which was on average one hour less than visual observations. In order to establish a relationship between the surface wetness periods and wheat foliar diseases, LWD was compared with the Septoria leaf blotch (SLB) development risk (main winter wheat disease). A minimal surface wetness duration favourable to infection for SLB was established. [less ▲]

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See detailPerformance of Least Squares and Kalman Filter Algorithms for Orbit Determination Using Single- and Multi-Station Tracking of Geostationary Satellites (AAS 98-368)
Halain, Jean-Philippe ULg; Welter, T.; Francken, P. et al

in Spaceflight Dynamics 1998, Volume 100 Part 1, Advances in Astronautical Sciences (1998)

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See detailPerformance of lung recruitment model in healthy anesthetised pigs
Chiew, YS; LAMBERMONT, Bernard ULg; JANSSEN, Nathalie ULg et al

in Proceedings of the World Congress on Medical Physics and Biomedical Engineering 2012 (2012)

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See detailThe performance of mobile devices' inertial measurement unit for the detection of cattle's behaviors on pasture
Andriamandroso, Andriamasinoro ULg; Dumont, Benjamin ULg; Lebeau, Frédéric ULg et al

Conference (2014, July 21)

Over the past decade, the Precision Livestock Farming (PLF) concept has taken a considerable place in the development of accurate methods for a better management of farm animals, as Precision Agriculture ... [more ▼]

Over the past decade, the Precision Livestock Farming (PLF) concept has taken a considerable place in the development of accurate methods for a better management of farm animals, as Precision Agriculture has done for crop production. Mass consumption mobile devices have nowadays the possibility to record accurately user movements with their Inertial Measurement Unit (IMU). We used iPhone 4S to detect accurately cattle behaviors such as grazing and ruminating with the aim of performing a precision grazing management on the near future. Results showed accuracies ranging between 84% and 100% when detecting these two major behaviors by analyzing recorded raw signals in the time-domain. Ongoing research tries to link these behaviors to different pasture characteristics and performs a refined signal processing analysis for a better monitoring of some possible behavioral changes. [less ▲]

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See detailPerformance of osteoporosis risk assessment tools in postmenopausal women aged 45-64 years
Gourlay, M. L.; Miller, W. C.; Richy, F. et al

in Osteoporosis International (2005), 16(8), 921-927

Osteoporosis risk factor assessment is of uncertain utility in women under 65 years of age. Previous comparative studies of osteoporosis risk assessment tools were not stratified by age. We compared the ... [more ▼]

Osteoporosis risk factor assessment is of uncertain utility in women under 65 years of age. Previous comparative studies of osteoporosis risk assessment tools were not stratified by age. We compared the discriminatory ability of three previously validated osteoporosis risk assessment tools in a referral population of postmenopausal women aged 45-64 years (n=2539) and aged 65-96 years (n=1496) seen at a university-based outpatient osteoporosis center in Belgium. Risk scores for the Osteoporosis Self-assessment Tool, Osteoporosis Risk Assessment Instrument, and Simple Calculated Osteoporosis Risk Estimation were calculated for each patient. The reference standard was osteoporosis at the femoral neck, defined as a T-score <=-2.5 based on bone mineral density measured by dual energy X-ray absorptiometry. Osteoporosis was present in 139 of 2539 (5.5%) women aged 45-64 years and 241 of 1496 (16.1%) women aged 65 years or older. The tools had similar overall discriminatory ability to identify women with osteoporosis [area under the ROC curve 0.750-0.768, P=0.23 for women aged 45-64 years; area under the ROC curve 0.745-0.762, P=0.06 for women aged 65 years or older (P > 0.05 indicates no difference among tools)]. The likelihood ratios for the high-risk score categories ranged from 3.60 to 6.73 for the younger women and 3.45 to 6.99 for the older women when different score thresholds were set to maximize the performance of each tool in each age group. We conclude that the diagnostic accuracy of three osteoporosis risk assessment tools was similar in postmenopausal women aged 45-64 years and women aged 65 years or older. Use of structured risk assessment tools to identify women at high risk of osteoporosis in the early postmenopausal period warrants further study. Of the three tools evaluated, the OST is the simplest and has the best potential for use in clinical practice. [less ▲]

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See detailThe performance of public enterprises: a comparative efficiency study of railways and postal services
Pestieau, Pierre ULg; Perelman, Sergio ULg

in Neumann, M.; Roskamp, W. (Eds.) Public Finance and Performance of enterprises (1987)

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See detailPerformance of Solmacs, a High PV Solar Concentrator With Efficient Optics
Thibert, Tanguy ULg; Hellin, Marie-Laure ULg; Loicq, Jerôme ULg et al

in AIP Conference Proceedings, , Volume 1477 (2012, October 05)

A new solar panel with high concentration photovoltaic technology (x700) has been designed, prototyped and tested in the SOLMACS project. The quality of concentrating optics is a key factor for high ... [more ▼]

A new solar panel with high concentration photovoltaic technology (x700) has been designed, prototyped and tested in the SOLMACS project. The quality of concentrating optics is a key factor for high module efficiency. Therefore new dedicated PMMA Fresnel lenses were studied and produced by injection molding. Lens design, material and production process were optimized to achieve a high optical yield of 86%. Thorough lens performance assessment in optical laboratory was completed with lifetime UV aging tests. Another important aspect is the thermal control of the hot spot created under the solar cell that receives the concentrated flux of 700 Suns. A dedicated heat spreader was developed to achieve passive thermal control with minimum mass and cost. This was supported by thermal models and tests at both cell and module level. 35% triple junction cells were implemented in the module. Micro-assembly technologies were used for the cell packaging and electrical connections. In support to the research, a continuous solar simulator was designed and built to assess the system performance, both at component and module level. The concentrator developments were integrated in a prototype and tested both indoor with the simulator and outdoor on the CSL solar test platform. The overall efficiency of the PV concentrator module is 28.5%. [less ▲]

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See detailPerformance of the IDS-iSYS 1,25-dihydroxy vitamin D assay
GADISSEUR, Romy ULg; LUKAS, Pierre ULg; CARLISI, Ignazia ULg et al

Poster (2013, July)

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See detailPerformance of the VERSANT (R) HIV-1 Resistance Assays (LiPA) for detecting drug resistance in therapy-naive patients infected with different HIV-1 subtypes
Derdelinckx, Inge; Van Laethem, Kristel; Maes, Baert et al

in FEMS Immunology & Medical Microbiology (2003), 39(2), 119-124

In this study we evaluated the performance of the VERSANT((R)) HIV-1 Resistance Assays (LiPA) in detecting drug resistance in therapy-naive HIV-infected patients diagnosed in Belgium in 2000. We compared ... [more ▼]

In this study we evaluated the performance of the VERSANT((R)) HIV-1 Resistance Assays (LiPA) in detecting drug resistance in therapy-naive HIV-infected patients diagnosed in Belgium in 2000. We compared the results with population sequencing and found concordance to be in line with previous studies in treatment-experienced patients (86.87% for reverse transcriptase (RT); 92.77% for protease (PRO)). Discordance was mainly due to indeterminate reactions on LiPA (8.45% for RT; 6.85% for PRO) and minor discordances (4.13% for RT; 0.25% for PRO). Major discordances were rare (0.46% for RT; 0.12% for PRO). Indeterminate reactions were significantly associated with strains belonging to non-B subtypes. (C) 2003 Federation of European Microbiological Societies. Published by Elsevier B.V.. All rights reserved. [less ▲]

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See detailPerformance of three HIV-1 DNA real-time PCRs for early diagnosis in infants and adults
Iserentant, G.; Masquelier, C.; Lambert, C. et al

Poster (2011, March)

Background Early pediatric HIV-1 diagnosis is a challenge in resource limited countries to identify HIV-infected newborns to provide early ART treatment. HIV DNA PCR testing is an accurate method for ... [more ▼]

Background Early pediatric HIV-1 diagnosis is a challenge in resource limited countries to identify HIV-infected newborns to provide early ART treatment. HIV DNA PCR testing is an accurate method for diagnosis in newborns and could be valuable for monitoring HIV infection in adults. We have evaluated the analytical, clinical performances and genotype inclusivity of 3 real-time Taqman PCRs targeting the ltr, int and env genes. Material and methods Total DNA was extracted from whole blood and Dried Blood Spots (DBS) using the NucleoSpin Blood kit (Macherey Nagel) and the Chelex resin. DNA amplification was performed using the Qiagen Multiplex PCR kit and detected on a 7300 Real time PCR system (Applied Biosystems). Method validation was realized as required by ISO 15189 standard. The accuracy profile methodology was applied. HIV-1 DNA of ACH2 cells (0, 25, 50, 100, 1000 and 5000 copies/PCR) mixed in whole blood were measured in 4 different series (2 PCR kits and 2 operators) of 5 independent DNA extraction of each standard. Linear and quadratic weighted and non weighted regression models were tested. Trueness, precision, limit of quantifications of the method and accuracy of the results were obtained for each model and compared. 93 whole blood samples of ART treated-patients with undetectable or low viraemia of 16 B and 77 non-B subtypes were assessed. Clinical evaluation of the assay was performed on 26 whole blood samples and 238 DBS from infants of Guinea Conakry determined HIV+ using the rapid Bioline HIV test Results The calibration model providing the most accurate results was the linear regression with an r² equal to 0.92 for ltr, 0.88 for int and 0.95 for env. Trueness, precision and accuracy were highly acceptable for the 3 sets of primers/probe not exceeding -0.23 log(copies/PCR) for bias and 0.5 log(copies) for intermediate precision standard deviation, respectively. The estimated lower limit of quantification was 41, 475 and 25 copies/PCR for ltr, int and env respectively. The accuracy profile of each gene showed that each future measurement using this assay has 80% probability to be within a limit of 0.5 log (copies/PCR) around the reference or true value of copies of each gene. 52/93 whole blood samples of ART-treated patients had 3 positive genes (Ct<40 cycles), 38/93 had two positive genes and 4/93 had only one positive gene (ltr). Among these patients, 3 were assigned as long term progressors and one was a subtype C strain. Clinical evaluation of the assay identified 1 HIV-1 infected newborn and 3 adults (at least 2 positive genes) for which HIV-1 infection was confirmed either by serology or viral load techniques as well as 96 HIV-1 infected infants using DBS. Conclusions This assay is suitable for detection of proviral HIV-1 DNA in infants and adults on whole blood and DBS samples. Despite an estimated lower limit of quantification higher than ltr and env, the int PCR was required to achieve a good genotype inclusivity. The method was fully validated as required by ISO 15189 and showed to provide sufficiently reliable results. [less ▲]

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See detailPerformance of vapor compression systems with compressor oil flooding and regeneration
Bell, Ian ULg; Groll, Eckhard; Braun, James

in International Journal of Refrigeration (2011), 34(1), 225233

Vapor compression refrigeration technology has seen great improvement over the last several decades in terms of cycle efficiency through a concerted effort of manufacturers, regulators, and research ... [more ▼]

Vapor compression refrigeration technology has seen great improvement over the last several decades in terms of cycle efficiency through a concerted effort of manufacturers, regulators, and research engineers. As the standard vapor compression systems approach practical limits, cycle modifications should be investigated to increase system efficiency and capacity. One possible means of increasing cycle efficiency is to flood the compressor with a large quantity of oil to achieve a quasi-isothermal compression process, in addition to using a regenerator to increase refrigerant subcooling. In theory, compressor flooding and regeneration can provide a significant increase in system efficiency over the standard vapor compression system. The effectiveness of compressor flooding and regeneration increases as the temperature lift of the system increases. Therefore, this technology is particularly well suited towards lower evaporating temperatures and high ambient temperatures as seen in supermarket refrigeration applications. While predicted increases in cycle efficiency are over 40% for supermarket refrigeration applications, this technology is still very beneficial for typical air-conditioning applications, for which improvements in cycle efficiency greater than 5% are predicted. It has to be noted though that the beneficial effects of compressor flooding can only be realized if a regenerator is used to exchange heat between the refrigerant vapor exiting the evaporator and the liquid exiting the condenser. [less ▲]

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See detailPerformance on a Computerized Shopping Task in Bipolar Disorder and Alcohol Dependency
Laloyaux, Julien ULg; Michel, Céline; Pellegrini, Nadia et al

Poster (2014, August 10)

Persons diagnosed with bipolar disorder and alcohol dependency are frequently subject to cognitive impairments and encounter difficulties during everyday life activities. However, little is known how ... [more ▼]

Persons diagnosed with bipolar disorder and alcohol dependency are frequently subject to cognitive impairments and encounter difficulties during everyday life activities. However, little is known how these deficits interact in real life. Moreover, previous studies have primarily used questionnaires or observational methods to assess everyday life functioning, both of which contain a number of limits. In order to address some of these limits, we developed a computerized real-life activity task, in particular, a shopping task where participants are required to shop for a list of 8 grocery store items in a virtual supermarket. Twenty individuals diagnosed with alcoholic dependence and 21 patients diagnosed with bipolar disorder were compared with healthy controls (20 and 21, respectively), matched for age, sex and educational level. All participants completed the shopping task, and both clinical groups were evaluated with an extensive battery of cognitive tests (assessing executive functioning, attention, processing speed and memory), clinical scales and a measure of real world functioning. Results showed that, for both clinical groups, performance on the computerized shopping task significantly differentiated patients and healthy controls for a number of variables, especially total time to complete the shopping task. Performances on shopping task variables, in both clinical groups, were also significantly correlated with cognitive tests measuring processing speed, episodic memory, cognitive flexibility and inhibition. Finally, performances on the computerized shopping task were significantly correlated with real world functioning in both patient groups. These findings suggest that the computerized task used in the present study provides a valid indication of the level of real world functioning for these clinical populations, and therefore may be viewed as a valuable instrument in both an evaluation and remediation context. [less ▲]

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See detailPerformance on a computerized shopping task significantly predicts real world functioning in persons diagnosed with bipolar disorder.
Laloyaux, Julien ULg; Pellegrini, Nadia; Mourad, Haitham et al

in Psychiatry Research (2013), 210(2), 465-471

Persons diagnosed with bipolar disorder often suffer from cognitive impairments. However, little is known concerning how these cognitive deficits impact their real world functioning. We developed a ... [more ▼]

Persons diagnosed with bipolar disorder often suffer from cognitive impairments. However, little is known concerning how these cognitive deficits impact their real world functioning. We developed a computerized real-life activity task, where participants are required to shop for a list of grocery store items. Twenty one individuals diagnosed with bipolar disorder and 21 matched healthy controls were administered the computerized shopping task. Moreover, the patient group was assessed with a battery of cognitive tests and clinical scales. Performance on the shopping task significantly differentiated patients and healthy controls for two variables: Total time to complete the shopping task and Mean time spent to consult the shopping list. Moreover, in the patient group, performance on these variables from the shopping task correlated significantly with cognitive functioning (i.e. processing speed, verbal episodic memory, planning, cognitive flexibility, and inhibition) and with clinical variables including duration of illness and real world functioning. Finally, variables from the shopping task were found to significantly explain 41% of real world functioning of patients diagnosed with bipolar disorder. These findings suggest that the shopping task provides a good indication of real world functioning and cognitive functioning of persons diagnosed with bipolar disorder. [less ▲]

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See detailPerformance on an everyday life activity in persons diagnosed with alcohol dependency compared to healthy controls: Relations between a computerized shopping task and cognitive and clinical variables.
Laloyaux, Julien ULg; Michel, Céline; Mourad, Haitham et al

in Alcohol & Alcoholism (2012), 47(3), 240-247

Aim: Persons diagnosed with alcohol dependency often suffer from cognitive impairments. Little is known, however, concerning how these cognitive deficits impact complex, everyday life activities. By this ... [more ▼]

Aim: Persons diagnosed with alcohol dependency often suffer from cognitive impairments. Little is known, however, concerning how these cognitive deficits impact complex, everyday life activities. By this experiment, we wished to contribute to a better characterization of the nature of everyday life difficulties in patients with alcohol dependency using a computerized shopping task. Methods: We developed a computerized real-life activity task (shopping task), where participants are required to shop for a list of 8 grocery store items. Twenty individuals diagnosed with alcohol dependency and 20 healthy controls were administered a battery of cognitive tests, clinical scales and the computerized shopping task. Results: Performance on the computerized shopping task significantly differentiated patients and healthy controls for several variables and in particular for Total time. Moreover, Total time to complete the task correlated significantly with several cognitive measures. In particular, poor performance on measures of processing speed, verbal episodic memory, cognitive flexibility and inhibition were significantly correlated with longer Total time. Finally, longer Total time was significantly correlated with poorer everyday life functioning and longer duration of illness. Conclusions: These findings suggest that the computerized task used in the present study is a good proxy measure of the level of everyday life and cognitive functioning of persons diagnosed with alcohol dependency. [less ▲]

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See detailPerformance relative des règles linéaire, quadratique et logistique en analyse discriminante
Glele Kakaï, R.; Palm, Rodolphe ULg

in XXXVIèmes Journées de Statistique (2004, May)

Monte Carlo study is achieved to compare linear, quadratic and logistic classification rules for two groups, in 480 situations related to the type of distribution, the overlap of the populations, the ... [more ▼]

Monte Carlo study is achieved to compare linear, quadratic and logistic classification rules for two groups, in 480 situations related to the type of distribution, the overlap of the populations, the number of variables, the sample size and the heteroscedasticity degree of the model, which is measured by a parameter gamma defined in the study. The results of this study show that the quadratic rule is the best only for severe heteroscedastic normal or moderate non-normal models with high overlap. The linear rule is the best for homoscedastic normal or moderate non-normal models with low overlap. The logistic rule is the best for severe non-normal models except when homoscedasticity occurs. In the order situations linear and logistic rules have almost the same performance. By considering the parameters computed on the data samples, the linear rule gives the best performance for high values of r whereas logistic rule performs is best for low or moderate values of the same parameter. [less ▲]

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