76,700 research outputs found
How Should Leaf Area, Sapwood Area and Stomatal Conductance Vary with Tree Height to Maximize Growth?
No full textPublished by and copyright by Heron Publishing.Conventional wisdom holds that the ratio of leaf\ud
area to sapwood area (L/S) should decline during height (H)\ud
growth to maintain hydraulic homeostasis and prevent stomatal\ud
conductance (gs) from declining. We contend that L/S\ud
should increase with H based on a numerical simulation, a\ud
mathematical analysis and a conceptual argument: (1) numerical\ud
simulation???a tree growth model, DESPOT (Deducing\ud
Emergent Structure and Physiology Of Trees), in which carbon\ud
(C) allocation is regulated to maximize C gain, predicts L/S\ud
should increase during most of H growth; (2) mathematical\ud
analysis???the formal criterion for optimal C allocation, applied\ud
to a simplified analytical model of whole tree carbon???\ud
water balance, predicts L/S should increase with H if leaf-level\ud
gas exchange parameters including gs are conserved; and (3)\ud
conceptual argument???photosynthesis is limited by several\ud
substitutable resources (chiefly nitrogen (N), water and light)\ud
and H growth increases the C cost of water transport but not\ud
necessarily of N and light capture, so if the goal is to maximize\ud
C gain or growth, allocation should shift in favor of increasing\ud
photosynthetic capacity and irradiance, rather than sustaining\ud
gs. Although many data are consistent with the prediction that\ud
L/S should decline with H, many others are not, and we discuss\ud
possible reasons for these discrepancies.This work was supported by the Cooperative Research Centre for Greenhouse Accounting,\ud
hosted by the Research School of Biological Sciences of The Australian\ud
National University
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A Technique for Examining Non-Climatic Variation in Widths of Annual Tree Rings with Special Reference to Air Pollution
No full textA new technique is developed for examining non-climatic variations in widths of annual tree rings. For each tree core, the technique involves making an adjustment for regional climate as inferred from a regional chronology based on surrounding sites. The technique is applied to two stands in Gila County, Arizona, where air pollution is potentially a limiting factor on tree-ring growth. For the stand closer to the pollution sources, a marked decrease in tree-ring widths minus climate is evident during the period 1908 to 1920. Although this decrease coincides with a period when two smelters were operating nearby, air pollution cannot be definitively identified as the cause of the decrease in ring widths.This item is part of the Tree-Ring Research (formerly Tree-Ring Bulletin) archive. It was digitized from a physical copy provided by the Laboratory of Tree-Ring research at The University of Arizona. For more information about this peer-reviewed scholarly journal, please email the Editor of Tree-Ring Research at [email protected]
Members of the Darwin Tree of Life Barcoding author list
No full textThis document holds a record of the individuals from the Darwin Tree of Life Barcoding team who should be considered coauthors of publications arising from the work of the Darwin Tree of Life project (https://www.darwintreeoflife.org)
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Tests of the RCS Method for Preserving Low-Frequency Variability in Long Tree-Ring Chronologies
No full textTo preserve multi-centennial length variability in annual tree-ring chronologies, the Regional Curve Standardization (RCS) method calculates anomalies from a regionally common, non-climatic age-trend function. The influence of various factors on the estimation of the regional curve (RC) and resulting RCS- chronology is discussed. These factors are: the method of calculating anomalies from the age-trend function, estimation of the true pith offset, the number of series used, species composition, and site characteristics. By applying RCS to a collection of millennium-length tree-ring data sets, the potential and limitations of the RCS method are investigated. RCS is found to be reasonably robust with respect to tested factors, suggesting the method is a suitable tool for preserving low-frequency variance in long tree-ring chronologies.This item is part of the Tree-Ring Research (formerly Tree-Ring Bulletin) archive. It was digitized from a physical copy provided by the Laboratory of Tree-Ring Research at The University of Arizona. For more information about this peer-reviewed scholarly journal, please email the Editor of Tree-Ring Research at [email protected]
H-Y-H-Y-H/fully_body_VSM: publication
No full text<p><strong>Full Changelog</strong>: https://github.com/H-Y-H-Y-H/fully_body_VSM/commits/publication</p>
No advantageous merging in minimum cost spanning tree problems
Get PDFIn the context of cost sharing in minimum cost spanning tree problems, we introduce a property called No Advantageous Merging. This property implies that no group of agents can be better off claiming to be a single node. We show that the sharing rule that assigns to each agent his own connection cost (the Bird rule) satisfies this property. Moreover, we provide a characterization of the Bird rule using No Advantageous Merging.Minimum cost spanning tree problems; cost sharing; Bird rule; No Advantageous Merging
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Dendrochronology in Oaxaca, Mexico: A Preliminary Study
No full textDendrochronological research in the Mexican state of Oaxaca in 1970 proved negative due to complacent ring series. It is suggested that this is caused by a flexible growing season triggered only by the onset of the rains. Pine and fir were sampled from eleven sites. No old age trees were located and crossdating could not be accomplished.This item is part of the Tree-Ring Research (formerly Tree-Ring Bulletin) archive. It was digitized from a physical copy provided by the Laboratory of Tree-Ring research at The University of Arizona. For more information about this peer-reviewed scholarly journal, please email the Editor of Tree-Ring Research at [email protected]
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
On the probabilistic min spanning tree Problem
Get PDFInternational audienceWe study a probabilistic optimization model for min spanning tree, where any vertex v i of the input-graph G(V, E) has some presence probability p i in the final instance G′ ⊂ G that will effectively be optimized. Suppose that when this “real” instance G′ becomes known, a spanning tree T, called anticipatory or a priori spanning tree, has already been computed in G and one can run a quick algorithm (quicker than one that recomputes from scratch), called modification strategy, that modifies the anticipatory tree T in order to fit G′. The goal is to compute an anticipatory spanning tree of G such that, its modification for any GG is optimal for G′. This is what we call probabilistic min spanning tree problem. In this paper we study complexity and approximation of probabilistic min spanning tree in complete graphs under two distinct modification strategies leading to different complexity results for the problem. For the first of the strategies developed, we also study two natural subproblems of probabilistic min spanning tree, namely, the probabilistic metric min spanning tree and the probabilistic min spanning tree 1,2 that deal with metric complete graphs and complete graphs with edge-weights either 1, or 2, respectively
From Fault Tree to Credit Risk Assessment: A Case Study
Get PDFReliability has been largely applied to industrial systems in order to study the various possibilities of systems’ failure. The goal is to establish the chain of events leading to any system’s failure, namely the top event. Looking for the minimal paths leading to any system’s fault allows for a better control of systems’ safety. To this end, reliability is composed of a static approach (see Ngom et al. [1999] for example) as well as a dynamic approach (see Reory & Andrews [2003] for example). In this paper, we extend the framework stated by Gatfaoui (2003) allowing for the application of fault tree theory to credit risk assessment. The author explains that fault tree is one alternative approach of reliability, which matches default risk analysis in a simple framework. Our extension includes other distributions of probability to model the lifetimes of French firms while studying the related empirical default probabilities. We use mainly, but not exclusively, continuous distributions for which the exponential law used by Gatfaoui (2003) constitutes a particular case. Our results exhibit both the exponential nature of French .rms. lifetimes as well as strong convex and fast decreasing time varying failure rates. Such a feature has some non- negligible impact insofar as it characterizes corresponding credit spreads’ Term structure.credit risk, default probability, failure rate, fault tree, reliability, survival probability
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