PubMed Health⌕ Search

PubMed · 11315001

Modeling a Poisson forest in variable elevations: a nonparametric Bayesian approach.

Abstract

A nonparametric Bayesian formulation is given to the problem of modeling nonhomogeneous spatial point patterns influenced by concomitant variables. Only incomplete information on the concomitant variables is assumed, consisting of a relatively small number of point measurements. Residual variation, caused by other unmeasured influential factors, is modeled in terms of a spatially varying baseline intensity function. A Markov chain Monte Carlo scheme is proposed for the simultaneous nonparametric estimation of each unknown function in the model. The suggested method is illustrated by reanalysing a data set in Rathbun (1996, Biometrics 52, 226-242), and the estimated models are compared with those obtained by Rathbun.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

J Heikkinen, E Arjas. 1999. Modeling a Poisson forest in variable elevations: a nonparametric Bayesian approach.. https://doi.org/10.1111/j.0006-341x.1999.00738.x

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

Cloudwater studies at a high elevation site in the Vosges Mountains (France).

Cloud and rainwater samples have been collected at a high elevation site in the Vosges Mountains. An automated collection system has been used to collect bulk cloudwater and small cloudwater droplets. Bulk cloudwater concentrations were up to 10 times more concentrated than rainwater concentrations. Small clouddroplets showed generally higher concentrations than bulk cloudwater. Nevertheless, the enrichment factors depend on the compounds under study and appear to be related to the composition of the cloud condensation nuclei forming small or large clouddroplets. Principal component analysis and factor analysis were applied to the collected datasets and confirmed the influence of the cloud condensation nuclei on the composition difference between small and large cloudwater droplets.

Altitude↗

Temporal increase in the reactivity of pulmonary vasculature to substance P in chronically hypoxic rats.

We previously demonstrated that the pulmonary vascular response to substance P (SP) increased in chronically hypoxic rats. This study explored the temporal increase in reactivity of the pulmonary vascular response to SP and its underlying mechanisms. First, young female Wistar rats were exposed to sea level (SL) or simulated high altitude (HA) for 15 h/day for 3 days, 1 wk, 2 wk, and 4 wk. Lungs were isolated and perfused with 4% bovine serum albumin in Krebs-Henseleit buffer solution. SP (1.5 x 10(-4) M) induced significant increases in pulmonary arterial pressure (P(pa)), venous pressure (P(v)), capillary pressure (P(c)), arterial resistance (R(a)), and filtration coefficient (K(fc)) in SL lungs. Increases in P(pa) and R(a) were significantly augmented in HA lungs, with a temporal increase trend peaking at 2 wk of HA exposure. The selective neurokinin (NK) type 1 (NK1) receptor antagonist SR-14033 significantly attenuated SP-induced increases in P(pa), P(v), P(c), R(a), and K(fc) in SL lungs. In lungs exposed to HA for 2 wk, SR-14033 suppressed the effect of SP on P(pa). Also, chronic hypoxia induced significant increases in NK1 receptors and NK1 receptor mRNA, with a temporal trend. We conclude that chronic hypoxia temporally augments SP-induced vascular responses, which are closely associated with increases in NK1 receptors and gene expression.

Altitude↗

[The new frontiers of blood doping].

Blood oxygenation and peripheral perfusion are pivotal factors to optimize intensity and length of the muscular activity. Enhancement and optimization of oxygen delivery to peripheral tissues is associated with a substantial improvement of the athletic performances, especially in endurance sports. Remarkable progresses in medical research promoted the introduction and commercialization of novel methods and molecules for the therapy of severe systemic pathologies, characterized by detrimental peripheral oxygenation. Unfortunately, the evident benefits of some promising classes of molecules propitiated the gradual diffusion to some sport disciplines, in form of doping. Aim of this review is to give further insights into new techniques of blood doping, chiefly focusing on blood transfusion, oxygen-carrying blood substitutes, synthetic haemoglobin allosteric modulators and administration of substances promoting synthesis and maturation of erythrocytes.

Altitude↗