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See detailExtracting a common high frequency signal from Northern Quebec black spruce tree-rings with a Bayesian hierarchical model
Boreux, Jean-Jacques ULg; Naveau, P.; Guin, O. et al

in Climate of the Past (2009), 5

One basic premise of dendroclimatology is that tree rings can be viewed as climate proxies, i.e. rings are assumed to contain some hidden information about past climate. From a statistical perspective ... [more ▼]

One basic premise of dendroclimatology is that tree rings can be viewed as climate proxies, i.e. rings are assumed to contain some hidden information about past climate. From a statistical perspective, this extraction problem can be understood as the search of a hidden variable which represents the common signal within a collection of tree-ring width series. Classical average-based techniques used in dendrochronology have been applied to estimate the mean behavior of this latent variable. Still, depending on tree species, regional factors and statistical methods, a precise quantification of uncertainties associated to the hidden variable distribution is difficult to assess. To model the error propagation throughout the extraction procedure, we propose and study a Bayesian hierarchical model that focuses on extracting an inter-annual high frequency signal. Our method is applied to black spruce (Picea mariana) tree-rings recorded in Northern Quebec and compared to a classical average-based techniques used by dendrochronologists. [less ▲]

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See detailLe climat du Québec : un passé pour quel avenir ?
Boreux, Jean-Jacques ULg; Bernier, J.; Perreault, L.

Conference (2006)

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See detailLe rôle pivot des variables latentes pourle raisonnement statistique conditionnel. Exemples d'applications environnementales des processus ponctuels marqués.
Parent, E.; Bernier, J.; Boreux, Jean-Jacques ULg

in Revue de Statistique Appliquée (2006), 54(4), 85-111

En statistique bayésienne, le raisonnement conditionnel probabiliste fonde la solidarité étroite entre modélisation et inférence. Dans le cadre de ce raisonnement, un rôle pivot est joué par les variables ... [more ▼]

En statistique bayésienne, le raisonnement conditionnel probabiliste fonde la solidarité étroite entre modélisation et inférence. Dans le cadre de ce raisonnement, un rôle pivot est joué par les variables latentes. Ce mode de raisonnement peut s’avérer utile aussi en statistique fréquentiste. On présente trois séries hydrométéorologiques décrites par des modèles de processus ponctuels marqués de complexité croissante. Sur ces exemples, on montre comment récolter les fruits de la souplesse de modélisation et des facilités de calcul apportées par les variables latentes. Ces variables améliorent la conceptualisation de variables de structure dans les modèles statistiques et permettent aux calculs d’inférence de bénéficier des algorithmes MCMC en relation avec les techniques «d’augmentation de données». [less ▲]

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See detailT92-0045: Interlaboratory quality control on Tpot measurements
Coucke, Philippe ULg; Beer, K.; Bernier, J. et al

in International Journal of Radiation, Oncology, Biology, Physics (1996), 36(1(supp1)), 384

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See detailPrognosis of human chorionic gonadotropin-producing seminoma treated by postoperative radiotherapy
Mirimanoff, R-O; Sinzig, M; Krüger, M et al

in International Journal of Radiation, Oncology, Biology, Physics (1993), 27(1), 17-24

To clarify the controversy about the management and prognosis of human chorionic gonadotropin-producing seminoma, the records of 132 patients with abnormal human chorionic gonadotropin values treated with ... [more ▼]

To clarify the controversy about the management and prognosis of human chorionic gonadotropin-producing seminoma, the records of 132 patients with abnormal human chorionic gonadotropin values treated with radiotherapy were analyzed. METHODS AND MATERIALS: The records of 1169 patients with pure seminoma treated in 10 institutions were screened for serum or urinary human chorionic gonadotropin. One hundred and thirty two patients with elevated human chorionic gonadotropin were found: 96 Stage I, 20 IIA, 7 IIB, 8 III and 1 IV. Median age was 34 y., mean follow-up was 5.0 years [range 1-12 y]. All received infradiaphragmatic radiotherapy (median dose 30 Gy), 25 (2 Stage I, 11 IIA, 5 IIB and 7 III) supradiaphragmatic radiotherapy (median dose: 28.5 Gy) and 10 had also initial chemotherapy (3 Stage IIB 6 III and 1 IV). Patients were allocated to three groups according to human chorionic gonadotropin values: (a) moderate elevation: up to 10 times (104 pts), (b) high elevation: 10 to 100 times (20 pts), (c) very high elevation: over 100 times the upper limit of normal value (8 pts). RESULTS: The proportion of Stage I, II and III was 76%, 19%, 5% in the ME group versus 50%, 35%, 15% in the high elevation group (p < 0.05). In the very high elevation group there were 7 Stage I and 1 Stage IV. Of 132 patients, six died (three dead of disease, two suicides, one acquired immunodeficiency syndrome). The 5 years overall survival probability was 94%. There were seven recurrences (initial stage: 1 Stage I, 2 IIB, 3 III and 1 IV). Of these, there were one in-field recurrence, 3 out of field and 3 in both sites. In 5 of 7, the human chorionic gonadotrophin level was again elevated at recurrence. The 5 years recurrence-free-survival probability was 94% (98% for Stage I, 100% for Stage IIA and 65% for Stage IIB and III [p < 0.001 between I and IIB + III, p < 0.05 between IIA and IIB + III]). Four of the 7 recurrences were salvaged by chimiotherapy +/- radiotherapy. In the high elevation and very high elevation groups, the 5 years recurrence-free-survival was 88%, vs. 96% for the moderate elevation group (p = 0.10). CONCLUSION: Based on this series of patients, human chorionic gonadotropin production is not an unfavorable prognostic factor in pure seminoma. Even in the subgroups with high or very high human chorionic gonadotropin levels (who had a higher proportion of advanced stages), the prognosis remained excellent. In Stage I and IIA seminoma with abnormal human chorionic gonadotropin levels, recurrence rate after post-operative radiotherapy alone is extremely low. [less ▲]

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See detailProduction of interferon gamma by peripheral blood mononuclear cells from normal subjects and from patients with rheumatoid arthritis
Reuter, A.; Bernier, J.; Vrindts-Gevaert, Y. et al

in Clinical and Experimental Rheumatology (1988), 6(4, Oct-Dec), 347-354

A radioimmunoassay for human interferon gamma (IFN-gamma) has been carried out using a recombinant glycosylated interferon (Hu IFN-gamma) as tracer, the N.I.H. reference preparation (Gg 23-901-530) and a ... [more ▼]

A radioimmunoassay for human interferon gamma (IFN-gamma) has been carried out using a recombinant glycosylated interferon (Hu IFN-gamma) as tracer, the N.I.H. reference preparation (Gg 23-901-530) and a polyclonal rabbit antiserum. The assay is highly specific for IFN-gamma: there is no cross-reaction either with interferons alpha and beta, Interleukins 1 and 2, tumor necrosis factor alpha and beta or with various brain peptides. The sequential saturation procedure allowed a sensitivity of 0.4 U/ml with intra and between assay coefficients of variation less than 8 and 12%, respectively. The in-vitro production of IFN-gamma by peripheral blood mononuclear cells (P.B.M.C.) was also measured. In unstimulated cultures, IFN-gamma production remained undetectable, i.e. below the 0.4 U/ml sensitivity level. After stimulation of P.B.M.C. from normal subjects with increasing amounts of PHA, both the 3H-thymidine incorporation and IFN-gamma release followed bell-shaped curves. There was no significant difference of 3H-thymidine incorporation between PHA stimulated cultures (0.2 and 2.5 ug/ml) from normal subjects (36 cases) and those with active (16 cases) or non-active (14 cases) rheumatoid arthritis. At two PHA concentrations of 0.2 and 2.5 ug/ml, mononuclear cells from patients with active disease produced significantly less IFN-gamma than those from either controls or cases with non-active disease. [less ▲]

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See detailA RIA for tumor necrosis factor (TNF a) and interleukin 1 a (IL-Ia) and their direct determination in serum
Reuter, A.; Bernier, J.; Gysen, P. et al

in Progress in Leukocyte Biology (1988)

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See detailIn vitro effects of thymopentin on the gamma-interferon production by peripheral blood mononuclear cells from normal subjects and from patients with rheumatoid arthritis
Malaise, Michel ULg; Bastings, M.; Reuter, A. M. et al

in Immunology Letters (1987), 15(4), 323-327

The in vitro production of gamma-interferon (gamma-IFN) by peripheral blood mononuclear cells (MNC) was measured using a specific radioimmunoassay in 16 patients presenting with active rheumatoid ... [more ▼]

The in vitro production of gamma-interferon (gamma-IFN) by peripheral blood mononuclear cells (MNC) was measured using a specific radioimmunoassay in 16 patients presenting with active rheumatoid arthritis (RA), in 14 patients with inactive disease, and in 36 control subjects (CS). Unstimulated cultures produced undetectable levels of gamma-IFN and did not incorporate tritiated thymidine. In response to phytohemagglutinin (PHA) 0.2 microgram/ml, MNC from active RA produced 9 times less, and under PHA 2.5 micrograms/ml, 4 times less gamma-IFN than did MNC from inactive RA or from CS. The uptake of tritiated thymidine was, however, similar in the 3 groups. In unstimulated cultures of the 3 groups, thymopentin (TP-5), at all concentrations tested, did not influence either the levels of gamma-IFN or the uptake of tritiated thymidine. In the presence of PHA 0.2 microgram/ml and TP-5, lambda-IFN levels were increased in CS, unchanged in inactive RA and reduced in active RA, whereas no changes were observed in the uptake of tritiated thymidine. Our results show that under our experimental conditions, TP-5 was able to increase the levels of gamma-IFN produced by normal MNC in vitro, but could not reverse the profound defect observed in active RA. [less ▲]

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