Browsing
     by title


0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

or enter first few letters:   
OK
Peer Reviewed
See detailEstimation of temporal lags for the inference of gene regulatory networks from time series (inproceedings) Author
Lopes, Miguel; Meyer, Patrick ULg; Bontempi, Gianluca

in In proceedings of BENELEARN'12 (2012)

Detailed reference viewed: 17 (3 ULg)
Full Text
Peer Reviewed
See detailEstimation of test-day model (co)variance components across breeds using New Zealand dairy cattle data
Vanderick, Sylvie ULg; Harris, Bevin; Pryce, Jenny et al

in Journal of Dairy Science (2009), 92(3), 1240-1252

In New Zealand, a large proportion of cows are currently crossbreds, mostly Holstein-Friesians (HF) x Jersey (JE). The genetic evaluation system for milk yields is considering the same additive genetic ... [more ▼]

In New Zealand, a large proportion of cows are currently crossbreds, mostly Holstein-Friesians (HF) x Jersey (JE). The genetic evaluation system for milk yields is considering the same additive genetic effects for all breeds. The objective was to model different additive effects according to parental breeds to obtain first estimates of correlations among breed-specific effects and to study the usefulness of this type of random regression test-day model. Estimates of (co) variance components for purebred HF and JE cattle in purebred herds were computed by using a single-breed model. This analysis showed differences between the 2 breeds, with a greater variability in the HF breed. (Co) variance components for purebred HF and JE and crossbred HF x JE cattle were then estimated by using a complete multibreed model in which computations of complete across-breed (co)variances were simplified by correlating only eigenvectors for HF and JE random regressions of the same order as obtained from the single-breed analysis. Parameter estimates differed more strongly than expected between the single-breed and multibreed analyses, especially for JE. This could be due to differences between animals and management in purebred and nonpurebred herds. In addition, the model used only partially accounted for heterosis. The multibreed analysis showed additive genetic differences between the HF and JE breeds, expressed as genetic correlations of additive effects in both breeds, especially in linear and quadratic Legendre polynomials (respectively, 0.807 and 0.604). The differences were small for overall milk production (0.926). Results showed that permanent environmental lactation curves were highly correlated across breeds; however, intraherd lactation curves were also affected by the breed-environment interaction. This result may indicate the existence of breed-specific competition effects that vary through the different lactation stages. In conclusion, a multibreed model similar to the one presented could optimally use the environmental and genetic parameters and provide breed-dependent additive breeding values. This model could also be a useful tool to evaluate crossbred dairy cattle populations like those in New Zealand. However, a routine evaluation would still require the development of an improved methodology. It would also be computationally very challenging because of the simultaneous presence of a large number of breeds. [less ▲]

Detailed reference viewed: 55 (15 ULg)
Full Text
Peer Reviewed
See detailEstimation of the 1900-2100 Greenland ice sheet surface mass balance
Fettweis, Xavier ULg

Conference (2008, April 15)

Results from a 37-year simulation (1970-2006) over the Greenland ice sheet (GrIS) with the regional climate model MAR reveals that more than 97% of the interannual variability of the modelled Surface Mass ... [more ▼]

Results from a 37-year simulation (1970-2006) over the Greenland ice sheet (GrIS) with the regional climate model MAR reveals that more than 97% of the interannual variability of the modelled Surface Mass Balance (SMB) is explained by the GrIS summer temperature anomaly and the GrIS annual precipitation anomaly. This dependence is also fully confirmed by another model using the ECMWF (re)analysis. This multiple regression is then used to empirically estimate the GrIS SMB since 1900 from climatological time series and reanalysises. The projected SMB changes in the 21st century are investigated with the set of simulations performed with AOGCM's for the IPCC Fourth Assessment Report. These estimations show that the high surface mass loss rates of these last years (1998, 2003, 2006) are not unprecedented in the GrIS history of the last hundred years. The minimum SMB rate seems to be occurred in the 1930's due to a combination of dryer and warmer years than now although the effect of the man-induced global warming was not perceptible at that time. The AOGCM's project that the SMB rate of the 1930s would be common at the end of this century. The temperature would be higher than in the 1930s but the increase of accumulation would partly offset the acceleration of surface melt due to the temperature increase. If no change will occur in the iceberg discharge rate, such negative SMB rates would be not large enough to significantly increase in the future the fresh meltwater flux from the GrIS into the ocean. However, these assumptions are based on an empirical multiple regression only currently validated and the accuracy and time homogeneity of the data sets and AOGCM results used in these estimations constitute a large uncertainty. [less ▲]

Detailed reference viewed: 23 (2 ULg)
Full Text
Peer Reviewed
See detailEstimation of the 1900-2100 Greenland ice sheet surface mass balance
Fettweis, Xavier ULg; Hanna, E.; Gallée, H. et al

Conference (2008, April)

Detailed reference viewed: 17 (3 ULg)
Full Text
Peer Reviewed
See detailEstimation of the charge carrier localization length from Gaussian fluctuations in the magneto-thermopower of La0.6Y0.1Ca0.3MnO3
Sergeenkov, S.; Bougrine, Hassan ULg; Ausloos, Marcel ULg et al

in Physical Review. B : Condensed Matter (1999), 60(17), 12322-12328

The magneto-thermoelectric power (TEP) Delta S(T,H) of perovskite-type manganese oxide La0.6Y0.1Ca0.3MnO3 is found to exhibit a sharp peak at some temperature T*=170 K. By approximating the true shape of ... [more ▼]

The magneto-thermoelectric power (TEP) Delta S(T,H) of perovskite-type manganese oxide La0.6Y0.1Ca0.3MnO3 is found to exhibit a sharp peak at some temperature T*=170 K. By approximating the true shape of the measured magneto-TEP in the vicinity of T* by a linear triangle of the form Delta S(T,H) similar or equal to S-p(H)+/-B+/-(H)(T* - T), we observe that B-(H)similar or equal to 2B(+)(H). We adopt the electron localization scenario and introduce a Ginzburg-Landau (GL)-type theory which incorporates the two concurrent phase transitions, viz., the paramagnetic-ferromagnetic transition at the Curie point T-C and the "metal-insulator'' (M-I) transition at T-MI. The latter is characterized by the divergence of the field-dependent charge carrier localization length xi(T,H) at some characteristic field H-o. Calculating the average and fluctuation contributions to the total magnetization and the transport entropy related magneto-TEP Delta S(T,H) within the GL theory, we obtain a simple relationship between T* and the above two critical temperatures (T-C and T-MI). The observed slope ratio B-(H)/B+(H) is found to be governed by the competition between the electron-spin exchange JS and the induced magnetic energy MsHo. The comparison of our data with the model predictions produce T-C = 195 K, JS = 40 meV, M-o = 0.4M(s), and xi(o) = 5 Angstrom for the estimates of the Curie temperature, the exchange coupling constant, the critical magnetization, and the localization length, respectively. The magneto-TEP data obtained by other authors are discussed and Found to be consistent with the model predictions as well. [[S0163-1829(99)00734-1]. [less ▲]

Detailed reference viewed: 21 (1 ULg)
Full Text
Peer Reviewed
See detailEstimation of the comparative therapeutic superiority of QD and BID dosing regimens, based on integrated analysis of dosing history data and pharmacokinetics
Comté, Laetitia ULg; Vrijens, Bernard ULg; Tousset, Eric et al

in Journal of Pharmacokinetics and Pharmacodynamics (2007), 34(4), 549-558

Once-daily dosing almost invariably shows a slightly higher percentage of prescribed doses taken than does twice-daily dosing. Many pharmaceutical scientists, regulators, and prescribers have considered ... [more ▼]

Once-daily dosing almost invariably shows a slightly higher percentage of prescribed doses taken than does twice-daily dosing. Many pharmaceutical scientists, regulators, and prescribers have considered this finding to signify the therapeutic superiority of once-daily dosing. The therapeutically more relevant question, however, is not the percentage of prescribed doses taken but the comparative impact of missed doses on the pharmacologic effects of a drug under the two dosing regimens. A key point in this regard is that the pharmacokinetic equivalent of a single missed once-daily dose is 2-3 sequentially omitted twice-daily doses. Thus, an important parameter in comparing the two regimens is the probability of two or three twice-daily doses being sequentially omitted, versus the probability of missing a single once-daily dose. Our data indicate that the probability of sequential omission of 2-3 twice daily doses is half the probability of omission of a single once-daily dose. For that reason, a twice-daily regimen could prove to be superior to a once-daily regimen in maintaining drug concentrations within a therapeutically desirable range. A more important consideration, however, is to maintain not just the concentration of drug in plasma, but the drug's therapeutic action. The duration of therapeutic drug action following a last-taken dose is not only drug-specific, but also, for some drug, dependent on the pharmacodynamic properties. Judging the comparative superiority of one dosing regimen over another requires knowledge of the drug's duration action after a last-taken dose, plus knowledge of the comparative probabilities of the various patterns of dose omission. When applied to HIV protease inhibitors, a twice-daily regimen appears to be better than an once-daily regimen in maintaining therapeutically effective drug actions. [less ▲]

Detailed reference viewed: 65 (2 ULg)
Peer Reviewed
See detailEstimation of the dominance variance for postweaning gain in the US Limousin population
Gengler, Nicolas ULg; Misztal, I.; Bertrand, J. K. et al

in Journal of Animal Science (1998), 76(10), 2515-2520

The objective of this study was to estimate the dominance variance for postweaning gain in Limousin cattle. Data included 215,326 records of postweaning gain from 205 to 365 d, provided by the North ... [more ▼]

The objective of this study was to estimate the dominance variance for postweaning gain in Limousin cattle. Data included 215,326 records of postweaning gain from 205 to 365 d, provided by the North American Limousin Foundation. Parental dominance subclasses were formed and related using the method of Hoeschele and VanRaden. Variance components were estimated using Method R based on six samples of 50%. Fixed effects in the model included contemporary group apd covariates for inbreeding and breed composition (percentage Limousin). Heterozygosity was negatively correlated with breed composition (< -.99) and was therefore not included in the model. Two types of contemporary groups used as original groups from the National Cattle Evaluation were partially based on breed composition. Original contemporary groups that were too homogeneous for breed composition were replaced by herd-year-sex classes. Two models were used with the two data sets. Model 1 contained the fixed effects described above and an additive genetic effect. Model 2 Included a dominance effect in addition to the effects contained in Model 1. In total, four combinations of contemporary group x model were used. Dominance variance was computed as being four times the estimated parental subclass variance. Estimates for inbreeding depression and breed composition (percentage Limousin) were all small and not greatly affected by inclusion of dominance effects or changes in contemporary groups. Estimates of the additive variance (expressed as percentage of the phenotypic variance) were only slightly affected, with values between 20 and 21%. Dominance estimates were highly affected when passing from original (10%) and to alternative contemporary groups (18%). Such large values may indicate that dominance is important for postweaning gain. Results showed the advantage of an individual dominance approach based on sire-dam combinations; therefore, expected gains through the use of specific combination ability as a part of the mating selection criteria for growth might be high. [less ▲]

Detailed reference viewed: 10 (2 ULg)
Peer Reviewed
See detailAn estimation of the endogenous secretion of calcitonin in normal and pre and postmenopausal osteoporotic women
Reginster, Jean-Yves ULg; DEROISY, Rita ULg; Denis, D et al

in Gynecological Endocrinology : The Official Journal of the International Society of Gynecological Endocrinology (1988), 2

Detailed reference viewed: 11 (2 ULg)
Full Text
Peer Reviewed
See detailAn estimation of the endogenous secretion of calcitonin in normal and pre and postmenopausal osteoporotic women
Reginster, Jean-Yves ULg; DEROISY, Rita ULg; Franchimont, P

in Journal of Bone and Mineral Research (1988), 3(S1), 159

Detailed reference viewed: 10 (2 ULg)
See detailEstimation of the error density in a semi-parametric transformation model.
Samb, Rawane; Heuchenne, Cédric ULg; Van Keilegom, Ingrid

E-print/Working paper (2011)

Detailed reference viewed: 15 (0 ULg)
Full Text
Peer Reviewed
See detailEstimation of the error density in a semiparametric transformation model
Colling, Benjamin; Heuchenne, Cédric ULg; Samb, Rawane et al

in Annals of the Institute of Statistical Mathematics (2014)

Detailed reference viewed: 24 (5 ULg)
Full Text
See detailEstimation of the Error Distribution in a Semiparametric Transformation Model
Heuchenne, Cédric ULg; Samb, Rawane; Van Keilegom, Ingrid

Scientific conference (2011, November 15)

Detailed reference viewed: 23 (1 ULg)
Full Text
See detailEstimation of the error distribution in nonparametric regression with cross-sectional data
Heuchenne, Cédric ULg; Laurent, Géraldine ULg

E-print/Working paper (2014)

In this article, we study the nonparametric regression model Y=m(X)+varepsilon where m(x)=E[Y|X=x] and sigma²(x)=Var[varepsilon|X=x] are unknown smooth functions, and the error varepsilon has zero mean ... [more ▼]

In this article, we study the nonparametric regression model Y=m(X)+varepsilon where m(x)=E[Y|X=x] and sigma²(x)=Var[varepsilon|X=x] are unknown smooth functions, and the error varepsilon has zero mean and finite variance conditionally on X=x. The problem consists in estimating the cumulative distribution function of the error in a nonparametric way when the couple (X,Y) is obtained by cross-sectional sampling while the positive response Y can be right-censored. We propose a new estimator for the error distribution function based on the estimators of m(.) and sigma²(.) described in Heuchenne and Laurent 2014. A bootstrap procedure is developed to solve the critical problem of the smoothing parameter choice. We assess the performance of the proposed estimator through simulations. Finally, a data set based on the mortality of diabetics is analyzed. (Heuchenne Cédric and Laurent Géraldine, Nonparametric regression with cross-sectional data: an alternative to conditional product-limit estimators, 2014) [less ▲]

Detailed reference viewed: 11 (3 ULg)
Full Text
See detailEstimation of the error distribution in right censored and selection biased regression models
Laurent, Géraldine ULg; Heuchenne, Cédric ULg

Conference (2009, October 15)

Consider the location-scale regression model Y=m(X) + σ(X) Ɛ where the error Ɛ is independent of the covariate X and where m and σ are unknown smooth functions. The pair (X; Y ) is subject to generalized ... [more ▼]

Consider the location-scale regression model Y=m(X) + σ(X) Ɛ where the error Ɛ is independent of the covariate X and where m and σ are unknown smooth functions. The pair (X; Y ) is subject to generalized bias selection and the response to right censoring. We construct an estimator for the cumulative distribution function of the error Ɛ, and develop a bootstrap procedure to select the smoothing parameter involved in the procedure. This method is studied via extension simulations and applied to real unemployment data. [less ▲]

Detailed reference viewed: 21 (11 ULg)
Full Text
Peer Reviewed
See detailEstimation of the error on the mean velocity and on the Reynolds stress due to a misoriented ADV probe in the horizontal plane: case of experiments in a compound open-channel
Peltier, Yann ULg; Rivière, Nicolas; Proust, Sébastien et al

in Flow Measurement & Instrumentation (2013), 34(C), 34-41

Detailed reference viewed: 6 (1 ULg)
Full Text
Peer Reviewed
See detailEstimation of the fascine efficiency in terms of runoff infiltration and sediments deposition
Degré, Aurore ULg; Pineux, Nathalie ULg; Cantreul, Vincent ULg et al

in Geophysical Research Abstracts (2013), 15

Runoff inundations and mudflows are more and more frequent phenomena. In 2011, Belgium had a lot of its municipalities affected by this problematic. Since then, mitigation measures are more and more set ... [more ▼]

Runoff inundations and mudflows are more and more frequent phenomena. In 2011, Belgium had a lot of its municipalities affected by this problematic. Since then, mitigation measures are more and more set up in agricultural watersheds. The fascines are one of these measures which allow to protect the public and private infrastructures and in the same way, which don’t reduce the famers productivity. They consist in branches faggots piled up between two rows of stakes. These linear constructions are mainly put in place across concentrated runoff axis in order to slow down the water and to filter the mud. Only few quantifications of their effectiveness (in terms of flow and concentration water reduction) exist and are however needed to better recommend these types of mitigation measures. Our experiment aims at measuring discharge and mud concentration reduction due to the fascines in a completely defined context. The tests were realised through fascines planted in field border. A watertight surface of 2,45m to 0,80m carries the water to the fascines. Three types of fascines were tested (willow wood fascine, straw fascine, straw compacted fascine), three different water flows were applied (0,5L/s, 3L/s and 6L/s) and three water concentration in dry soil (13g/L, 26g/L, 38g/L) were used. The different factor combinations were tested. The results show that we can expect a reduction of 60% of the flow for the biggest water flows (proportional efficiency with the water flow). The factor interaction study doesn’t allow to see a difference between the type. About the sediment water concentration, the filtration can reach 50%, the fascine with wood faggots showing a better efficiency. Finally, the difference between the fascine type show that straw fascine can support a biggest watershed (25 hectares) than the wood faggot fascine can (5-10 hectares) but during a smaller return period (one year against five years). [less ▲]

Detailed reference viewed: 44 (20 ULg)
Full Text
See detailEstimation of the Greenland ice sheet surface mass balance contribution to future sea level rise using the regional climate model MAR
Fettweis, Xavier ULg; Gallée, H.; van den Broeke, M. et al

Conference (2013, April 10)

With the aim of estimating the sea level rise (SLR) coming from Surface Mass Balance (SMB) changes over the Greenland ice sheet (GrIS), we report future projections obtained with the regional climate ... [more ▼]

With the aim of estimating the sea level rise (SLR) coming from Surface Mass Balance (SMB) changes over the Greenland ice sheet (GrIS), we report future projections obtained with the regional climate model MAR, forced by outputs of three CMIP5 General Circulation Models (GCMs). Our results indicate that in warmer climates, the mass gained due to increased winter snowfall over GrIS does not compensate the mass lost through increased meltwater run-off in summer. All the MAR projections shows similar non-linear melt increases with rising temperatures as a result of the positive surface albedo feedback, because no change is projected in the general atmospheric circulation over Greenland. Nevertheless, MAR exhibits a large range in its future projections. By coarsely estimating the GrIS SMB changes from CMIP5 GCMs outputs, we show that the uncertainty coming from the GCM-based forcing represents about half of projected SMB changes. In 2100, the CMIP5 ensemble mean projects a SLR, resulting from a GrIS SMB decrease, estimated to be 4 2 cm and 9 4 cm for the RCP 4.5 and RCP 8.5 scenarios, respectively. However, these future projections do not consider the positive melt-elevation feedback. Sensitivity MAR experiments using perturbed ice sheet topographies consistent with the projected SMB changes highlight the importance of coupling climate models to an ice sheet model. Such a coupling will allow to consider the future response of both surface processes and ice-dynamic changes, and their mutual feedbacks to rising temperatures. [less ▲]

Detailed reference viewed: 40 (5 ULg)
Full Text
Peer Reviewed
See detailEstimation of the Greenland ice sheet surface mass balance for the 20th and 21st centuries
Fettweis, Xavier ULg; Hanna, Edward; Gallée, Hubert et al

in The Cryosphere [=TC] (2008), 2

Results from a regional climate simulation (1970–2006) over the Greenland ice sheet (GrIS) reveals that more than 97% of the interannual variability of the modelled Surface Mass Balance (SMB) can be ... [more ▼]

Results from a regional climate simulation (1970–2006) over the Greenland ice sheet (GrIS) reveals that more than 97% of the interannual variability of the modelled Surface Mass Balance (SMB) can be explained by the GrIS summer temperature anomaly and the GrIS annual precipitation anomaly. This multiple regression is then used to empirically estimate the GrIS SMB since 1900 from climatological time series. The projected SMB changes in the 21st century are investigated with the set of simulations performed with atmosphere-ocean general circulation models (AOGCMs) of the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR4). These estimates show that the high surface mass loss rates of recent years are not unprecedented in the GrIS history of the last hundred years. The minimum SMB rate seems to have occurred earlier in the 1930s and corresponds to a zero SMB rate. The AOGCMs project that the SMB rate of the 1930s would be common at the end of 2100. The temperature would be higher than in the 1930s but the increase of accumulation in the 21st century would partly offset the acceleration of surface melt due to the temperature increase. However, these assumptions are based on an empirical multiple regression only validated for recent/current climatic conditions, and the accuracy and time homogeneity of the data sets and AOGCM results used in these estimations constitute a large uncertainty. [less ▲]

Detailed reference viewed: 189 (17 ULg)