Construction d'un tarif de cubage à l'aide d'un micro-ordinateur

peer reviewedNous avons abordé la construction "informatisée" d'un tarif de cubage d'une manière relativement simple, mais qui nous paraît largement satisfaisante pour l'objectif que nous poursuivions : mettre à la disposition des gestionnaires forestiers une technique rapide de construction. Les tarifs de cubage sont des outils fondamentaux en matière de gestion et des auxiliaires indispensables pour le cubage d'arbres sur pied. Leur construction et leur utilisation constituent un remarquable champ d'activités pour la micro-informatique "forestière". La méthodologie et le système de traitement que nous proposons doivent être considérés comme un moyen d'envisager et de promouvoir la construction de tarifs de cubage appelés à répondre à des objectifs bien déterminés et conçus sur des bases comparables, ce qui constituerait, selon nous, un progrès considérable par rapport à ce qui se fait encore très souvent actuellement. Ils permettent d'accélérer considérablement la détermination de volumes dans le cadre d'inventaires complets ou par échantillonnage faisant eux-mêmes l'objet d'approches informatisées pour ce qui regarde la collecte et le traitement des données

Estimation of oak productivity in uneven aged stands of the Belgian Ardenne Quercus sessilis, site index.

A pilot study has been carried out in order to assess the productivity of various sites for oak (Quercus sessilis) growth in belgian Ardenne. Site quality is evaluated by the measurement of top height at a kay dominant girth of 160 cm. Such a site index seems to be well suited to unevenaged forest structures. Some other calcultations concern relationships between the index and various site factors as aspect, soils and species of plants naturally occuring on the studied areas. Estimations of stands volumes are also made with particular stand volume equations.Une étude pilote destinée à chiffrer localement la productivité des milieux de croissance du chêne rouvre en Ardenne (région de Wellin) a permis de mettre en évidence un critère dendrométrique basé sur la hauteur dominante atteinte à la circonférence dominante de référence de 160 cm. Cet indice, à première vue bien adapté aux structures inéquiennes, peut être estimé de manière satisfaisante, à l'aide d'équations de régression multiples prenant en considération un nombre réduit de variables stationnelles, plus précisément l'exposition et diverses espèces végétales indicatrices. Associé à d'autres variables dendrométriques, il sert également de base à l'estimation du volume des peuplements sur pied dans divers milieux de productivité

Meta-analysis and indirect comparisons of levetiracetam with other second-generation antiepileptic drugs in partial epilepsy

Few comparative clinical trials of newer antiepileptic drugs (AEDs) in patients with refractory partial epilepsy are available. Therefore, meta-analysis is a widely used and useful method for comparing them. Despite the limitations of indirect comparisons, and recognizing that these drugs were tested at different doses, such comparisons can be helpful to physicians making practical treatment decisions. The purposes of this study were to present newer meta-analysis results for add-on levetiracetam compared with placebo and to estimate its efficacy and tolerability compared with other new AEDs (gabapentin, lamotrigine, oxcarbazepine, tiagabine, topiramate, and zonisamide) in a meta-analysis using methods for making indirect comparisons. Randomized placebo-controlled clinical trials of add-on therapy with levetiracetam, gabapentin, lamotrigine, oxcarbazepine, tiagabine, topiramate, and zonisamide in patients with refractory partial epilepsy were identified in the Cochrane Library 2002. A fixed effects model was used to estimate Mantel-Haenszel odds ratios for the responder rate (efficacy measure) and withdrawal rate (mainly tolerability measure) of levetiracetam and other new AEDs versus placebo. Because no head-to-head clinical trials comparing these new AEDs exist, adjusted indirect comparisons were then made between levetiracetam and each other AED using the meta-analysis results. At the doses tested, levetiracetam was more effective in terms of responder rate than gabapentin (odds ratio 2.64 with 95% CI 1.514.63) and lamotrigine (odds ratio 1.86 with 95% CI 1.04-3.34) and equally well tolerated. Levetiracetam had a significantly lower withdrawal rate than topiramate (odds ratio 0.52 with 95% CI 0.290.93) and oxcarbazepine (odds ratio 0.55 with 95% CI 0.33-0.92), with comparable efficacy. Although levetiracetam did not differ significantly from the other AEDs, numerical trends favoring levetiracetam were obtained in response rate and in withdrawal rate (tiagabine, zonisamide). Indirect comparisons based on meta-analysis suggest that add-on therapy with levetiracetam has a favorable responder and/or withdrawal rate relative to several AEDs in patients with partial epilepsy with doses used in clinical trials. These meta-analyses give only short-term efficacy and safety data. Comparative clinical trials and long-term studies of these agents are needed to confirm these findings

Population pharmacokinetic and pharmacodynamic analysis in allergic diseases

In this chapter, we introduce the concepts and methodologies of population analysis as applied to analyzing pharmacokinetic and pharmacodynamic data. One of the key determining characteristics of the population approach is that through it, one seeks not only to characterize deterministic trends in the data, but also to identify and estimate the magnitudes of the important sources of variability within the data. The first section of this chapter provides an introduction to the primary concepts of, and motivation for, population modeling by way of a hypothetical case study. Then, the various methodologies that have been employed throughout the history of population analysis are described in further detail. Of these, the most commonly employed today is nonlinear mixed-effects (NLME) modeling. Finally, notable examples of the application of population PK and PK/PD modeling to treatments for allergies and asthma are discussed. Population PK models have frequently been used to extrapolate exposures to special populations, such as pediatrics, as well as to optimize treatment regimens and trial designs for these populations. Population PK/PD models have most frequently been applied to analyzing and interpreting data from wheal and flare trials, but are also becoming increasingly important in the analysis of PD data from monoclonal antibodies

Geometric mean time profile for total lymphocyte count by administered treatment (per protocol population).

<p>bid = twice daily; qd = once daily.</p

Subject baseline characteristics.

a<p>Determined by Cockroft formula: males = [(140 − age)×body weight]/[72×serum creatinine (mg/dL)]; females = [(140 − age)×body weight]/[72×serum creatinine (mg/dL)]×0.85.</p>b<p>Although 12 subjects had not experienced a relapse in the previous 12 months (4 in the 1000-mg bid group, 3 in each of the 100-mg bid and 500-mg bid groups, and 1 in each of the 1000-mg qd and placebo groups), they all fulfilled the inclusion criteria of having had at least one relapse in the previous 24 months.</p><p>bid = twice daily; BMI = body mass index; EDSS = Expanded Disability Status Scale; qd = once daily; SD = standard deviation.</p

Summary statistics on absolute counts of lymphocytes subsets at baseline, day 1, and day 28 after treatment.

a<p>Mean value over 24 hours.</p><p>bid = twice a day; NK = natural killer; qd = once daily; SD = standard deviation.</p

Percentage change from baseline in absolute lymphocyte counts at day 28 following treatment with CDP323 for 28 days (per protocol population).

a<p>n<i> = </i>14 per group except for CD34+ cells, where n = 5 for placebo and CDP323 1000 mg bid and n = 4 for CDP323 100 mg bid, CDP323 500 mg bid, and CDP323 1000 mg qd.</p>b<p>Least squares mean from analysis of variance (ANOVA).</p>c<p>Statistical comparisons were made using univariate ANOVA.</p><p>bid = twice daily; CI = confidence interval; NK = natural killer; NR = not reported (linear trend test for dose-response relationship was not statistically significant); qd = once daily.</p><p>Note: For all lymphocyte types, differences between the 500-mg bid and 1000-mg qd dosages were not statistically significant and are not displayed in this table.</p