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PubMed2001

Potential effect of Anoplophora glabripennis (Coleoptera: Cerambycidae) on urban trees in the United States.

Anoplophora glabripennis Motschulsky, a wood borer native to Asia, was recently found in New York City and Chicago. In an attempt to eradicate these beetle populations, thousands of infested city trees have been removed. Field data from nine U.S. cities and national tree cover data were used to estimate the potential effects of A. glabripennis on urban resources through time. For the cities analyzed, the potential tree resources at risk to A. glabripennis attack based on host preferences, ranges from 12 to 61% of the city tree population, with an estimated value of $72 million-$2.3 billion per city. The corresponding canopy cover loss that would occur if all preferred host trees were killed ranges from 13-68%. The estimated maximum potential national urban impact of A. glabripennis is a loss of 34.9% of total canopy cover, 30.3% tree mortality (1.2 billion trees) and value loss of $669 billion.

Animals↗

PubMed2006

Tropical forest restoration: tree islands as recruitment foci in degraded lands of Honduras.

Tropical forest recovery in pastures is slowed by a number of biotic and abiotic factors, including a lack of adequate seed dispersal and harsh microclimatic extremes. Accordingly, methods to accelerate forest recovery must address multiple impediments. Here, we evaluated the ability of "tree islands" to serve as "recruitment foci" in a two-year study at three sites in northern Honduras. Islands of three sizes (64, 16, and 4 m2) and at two distances to secondary forest (20 and 50 m) were created by planting 2 m tall vegetative stakes of two native species: Gliricidia sepium (Fabaceae) and Bursera simaruba (Burseraceae), each in monoculture. Open-pasture "islands" of equal sizes served as controls. Tree islands reduced temperature and light (PAR) extremes as compared to open pasture, creating a microenvironment more favorable to seedling establishment. Seed-dispersing birds (quantified at one site only) showed an overwhelming preference for islands; 160 visits were recorded to islands compared with one visit to open pasture. Additionally, frugivores visited large islands more often, and for longer time periods, than small islands, thereby increasing the likelihood of a dispersal event there. In total, 144 140 seeds belonging to 186 species were collected in islands; more than 80% were grasses. Tree islands increased zoochorous tree seed rain; seed density and species richness were greater in tree islands than in open pasture, and large islands had greater seed density than smaller islands (Gliricidia only), suggesting that they are more effective for restoration. Distance to forest did not affect seed rain. A total of 543 seedlings and 41 species established in islands; > 85% were zoochorous. Seedling density did not differ among treatments (mean 0.2 seedlings/m2 for islands vs. 0.1 seedlings/m2 for pasture), although an increasing trend in tree islands over the course of two years suggests that seedling recruitment is accelerated there. Lastly, similar seedling densities were censused in the 1 m perimeter surrounding islands, suggesting that islands can expand outward into pasture. Planting vegetative stakes to create tree islands in pastures accelerates forest recovery by overcoming a number of impediments, and presents a simple, broadly applicable alternative for facilitating forest regeneration in abandoned pastures.

Animals↗

PubMed2006

Multi-model analysis of tree competition along environmental gradients in southern New England forests.

Robust predictions of competitive interactions among canopy trees and variation in tree growth along environmental gradients represent key challenges for the management of mixed-species, uneven-aged forests. We analyzed the effects of competition on tree growth along environmental gradients for eight of the most common tree species in southern New England and southeastern New York using forest inventory and analysis (FIA) data, information theoretic decision criteria, and multi-model inference to evaluate models. The suite of models estimated growth of individual trees as a species-specific function of average potential diameter growth, tree diameter at breast height, local environmental conditions, and crowding by neighboring trees. We used ordination based on the relative basal area of species to generate a measure of site conditions in each plot. Two ordination axes were consistent with variation in species abundance along moisture and fertility gradients. Estimated potential growth varied along at least one of these axes for six of the eight species; peak relative abundance of less shade-tolerant species was in all cases displaced away from sites where they showed maximum potential growth. Our crowding functions estimate the strength of competitive effects of neighbors; only one species showed support for the hypothesis that all species of competitors have equivalent effects on growth. The relative weight of evidence (Akaike weights) for the best models varied from a low of 0.207 for Fraxinus americana to 0.747 for Quercus rubra. In such cases, model averaging provides a more robust platform for prediction than that based solely on the best model. We show that predictions based on the selected best models dramatically overestimated differences between species relative to predictions based on the averaged set of models.

Computer Simulation↗

PubMed1998

Tree-type algorithm for statistical analysis in chronic toxicity studies.

An appropriate statistical methodology in toxicity studies has been discussed over the last two decades and many statistical methods have already been proposed. Many practical problems, however, still remain unresolved and most pharmaceutical industries have been using a tree-type algorithm routinely to analyze repeated-dose toxicity study data. In considering routine use of statistical analysis in toxicological studies, standardization of statistical methodology is necessary and the decision tree has an important role. In this article, the problems, relating to tree-type algorithms are summarized. Then we propose a new tree-type algorithm, which targets quantitative data in repeated-dose studies in rodents, usually sample size per group between 10 to 20, based on the following two important principles: "using a parametric method" and "suitable for intuition of toxicologists". An example of its application to actual toxicity study data is demonstrated. The performance of this new method is also evaluated using historical data. However, it should be noted that the intention of this paper is not to make a definite solution of the decision tree. Several other alternatives can be considered. Since there is no single theoretically correct solution of tree-type algorithms, too formal a use of the decision tree is not recommended. We must not forget the exploratory nature of evaluating repeated toxicity data.

Algorithms↗

PubMed2000

[Antimicrobial effects of tea tree oil (Melaleuca alternifolia) on oral microorganisms].

The essential oil of Melaleuca alternifolia (tea tree oil) exhibits antimicrobial activity against a wide range of Gram-positive and Gram-negative bacteria, yeasts and fungi. In this study the bacteriostatic and bacteriocidal/fungicidal activity of a tea tree oil solution, of a new tea tree oil (Tebodont) and the respective placebo-gel, of a chlorhexidindigluconate-solution and of PlakOut was tested in vitro against ten different oral microorganisms. Minimum inhibitory concentrations were in the range from 0.0293% to 1.25% for the tea tree oil solution and from 0.0082% to 1.25% for the tea tree oil gel. The values for minimum bacteriocidal/fungicidal concentrations were in the range from 0.0521% to 2.5% for the tea tree oil solution and from <0.0098% to 3.33% for the tea tree oil gel. The most susceptible microorganisms were Actinobacillus actinomycetemcomitans, Fusobacterium nucleatum, and Porphyromonas gingivalis, whereas Streptococcus mutans and Prevotella intermedia were the least susceptible ones. Both for the chlorhexidindigluconate solution and for PlakOut the values for the minimal inhibitory concentration and for the minimal cidal concentration were between <0.0002% and 0.0125%.

Anti-Infective Agents, Local↗

PubMed2005

[Resources utilization of main tree populations in Pinus armandii mixed forest after controlled burning and aerial-sowing afforestation].

In Hongchiba region of Wuxi County, the controlled burning and aerial sowing in 1972 rehabilitated degraded forest vegetations, and various types of Pinus armandii mixed communities were formed. By employing Petraitis' general and specific overlap indices, this paper analyzed the resources utilization of 10 main tree populations in Pinus armandii mixed forest. The results showed that Pinus armandii and most native trees had a wide niche breadth, and the interspecies general overlap value was 0.728, indicating that there was a fully and effective habitat resources utilization in the communities. The interspecies specific overlap value of Pinus armandii overlapping other native trees was very low, while that of native trees overlapping Pinus armandii was quite high, which demonstrated that the resources utilization and competition capability of Pinus armandii were weaker than those of native trees, and Pinus armandii population was at its inferior state during the process of their competitions. The interspecies specific overlap value between native trees was very low, generally because of their sound niche differentiation on resources utilization. As a result, the niche characteristics of native trees should be regarded as a favorable sample for the application of ecological rehabilitation and reconstruction. The advantages and disadvantages of Petraitis' overlap indices were discussed in this paper preliminarily.

Conservation of Natural Resources↗

PubMed2006

[Progress in research on forest tree genomics].

This is a review on forest tree genomics. In structural genomics, genetic maps have been constructed for up to 40 forest tree species, more than 30 commercially important QTLs have been detected, comparative mapping has been done for a few of forest tree taxa, and whole genome sequencing was completed for Populus and is under way for Eucalyptus. For functional genomics, huge EST databases from multiple tissues of a number of tree species have been rapidly accumulated, and molecular analyses on secondary growth and wood formation, flowering, and cold hardiness have given some insights into the metabolic pathways of those tree-specific development processes. The prospects of development in tree genomics are discussed, which may be implicative for accelerating forest tree genomics studies in China.

Genome, Plant↗

PubMed1990

Habitat pH characteristics of tree hole Culicoides (Diptera: Ceratopogonidae).

Ten species of Culicoides were collected from 166 tree holes at 20 widely separated geographic locations to assess relationships with habitat pH. Wet tree holes (containing standing water) had a mean pH of 7.46 while dry tree holes (no standing water) had a mean pH of 8.60. Culicoides arboricola, C. guttipennis and C. villosipennis occurred in wet tree holes that had mean pH values of 7.66, 7.95 and 7.31, respectively. Dry tree holes, where C. hinmani, C. elemae, C. paraensis, C. nanus, C. snowi and C. footei occurred, had pH values ranging from 8.13 to 9.08. Culicoides lahillei, a dry tree hole species, was collected from habitats with a pH range similar to the wet tree hole species.

Animals↗

PubMed1987

Occurrence and ovitrap site preference of tree hole mosquitoes: Aedes triseriatus and Aedes hendersoni in eastern Kentucky.

This ovitrap study examined the effects of altitude above sea level, tree species, and tree trunk diameter on the distribution of eggs of the 2 tree hole mosquitoes, Aedes hendersoni and Ae. triseriatus. Only tree species and trunk diameter affected the distribution significantly. Aedes hendersoni eggs were found more frequently associated with trees of border and sunny habitat, while Ae. triseriatus eggs were more frequently found in association with trees of mesic habitat. Oviposition of Ae. hendersoni occurred more often at trees with smaller diameter at breast height than did Ae. triseriatus. These differences in ovipositing frequency appear to be related to the microhabitat associated with different sample sites.

Aedes↗

PubMed1996

Decision tree sensitivity analysis for cost-effectiveness of FDG-PET in the staging and management of non-small-cell lung carcinoma.

UNLABELLED: Preliminary studies have shown that PET is more accurate than CT for the staging of non-small-cell lung carcinoma (NSCLC). However, the potential effect of PET on the management of these patients and its cost-effectiveness has not been rigorously studied. Thus, we have used decision tree sensitivity analysis to assess the cost-effectiveness of a PET based strategy for staging of NSCLC. METHODS: Two decision strategies for selection of potential surgical candidates were compared; thoracic CT alone or thoracic CT and thoracic PET. The first decision tree was conservatively constructed by requiring mediastinoscopy (biopsy) to confirm imaging results so that no patient with surgically curable disease would miss the opportunity for surgery in either strategy. A second less conservative tree in which only nonconcordant results are biopsied was also tested. The various paths of each strategy are dependent on numerous parameters which were determined from a review of the medical literature. Life expectancy was calculated using the declining exponential approximation of life expectancy and reduced based on procedural mortality. Costs were based on mean costs at our institution. For all possible outcomes of each strategy, the expected cost and projected life expectancy were determined. The effect of changing one or more parameters on the expected cost and life expectancy were studied using a sensitivity analysis. RESULTS: The CT + PET strategy in the conservative decision tree showed a saving of $1154 per patient without a loss of life expectancy (increase of 2.96 days) as compared to the alternate strategy of CT alone. Both these effects were the result of improved staging of lung carcinoma prior to the decision for surgery. The CT + PET strategy in the less conservative decision tree showed a savings of $2267 per patient but misses 1.7% of potentially operable patients. CONCLUSION: These results show through rigorous decision tree analysis, the potential cost-effectiveness of using FDG PET in the management of NSCLC. These results form a basis for detailed study of the results obtained from multicenter trials on the accuracy of PET in NSCLC management. Furthermore, the techniques utilized for decision tree analysis have broad range of applicability to the entire field of nuclear medicine.

Carcinoma, Non-Small-Cell Lung↗

PubMed1998

Impact of a decision tree on chronic wound care.

OBJECTIVE: To examine the use of a decision tree and its impact on the accuracy of decision making for chronic wound care. DESIGN: Descriptive comparative design; replication study. SETTINGS AND SUBJECTS: Data were collected from 2 groups of home care nurses in large urban centers. One group was measured after initial contact with the decision tree, and the other group was measured 2 years after implementation of the decision tree. INSTRUMENTS: The chronic wound management decision tree (CWMDT) designed by Knight was used, in combination with pictorial case studies developed by Willey and Swords. METHODS: Edmonton Home Care Program nurses, having used a decision tree for 2 years, completed 3 pictorial case studies without the aid of a written copy of the CWMDT. Current accuracy of wound care staging and treatment was compared with the Melchior-MacDougall and Lander results. After this procedure, Calgary Health Services home care nurses completed 3 pictorial case studies to assess the accuracy of wound care staging and treatment between 2 groups: with the CWMDT and without the CWMDT. A questionnaire was completed on factors identified to influence decision making in wound care. MAIN OUTCOME MEASURE: Accuracy and confidence of decision making in wound care staging and treatment. RESULTS: Accuracy of decision making with use of the CWMDT improved over time, as did accuracy of decision making after initial contact with the decision tree. Age, experience in nursing and home care, number of in-services attended, and number of chronic wounds treated, were not found to correlate with accuracy of decision making. CONCLUSION: A decision tree can assist with decision making by guiding the nurse through assessment and treatment options.

Adult↗

PubMed1980

Representation of the body surface in somatosensory area I of tree shrews, Tupaia glis.

Microelectrode mapping methods were used to determine the organization of the first somatosensory area, S-I, of tree shrews. Tree shrews were chosen for study because of their generalized body form, phylogenetic relationship to primates, and smooth, easily mapped cortex. A systematic representation of the contralateral body surface was found in an architectonically distinct zone identified as somatic koniocortex. Overall features of somatotopic organization were similar to S-I of other mammals, S-I of prosimian primates, and the Area 3b "S-I proper" representation of monkeys. Like Area 3b in monkeys and the somatic koniocortex in galagos, S-I in tree shrews is bordered caudally by cortex also responsive to somatosensory stimuli. Several aspects of S-I organization in tree shrews appear to be primitive and generalized. These include the representation of the trunk with the ventrum at the caudal margin of S-I, the restriction of the glabrous digits of the hand and foot to the rostral half of the representation and pointed rostralward, the representation of an anterior strip of the forelimb lateral to the hand, and a posterior strip of hindlimb medial to the foot representation. As in a number of other mammals, a large portion of S-I in tree shrews is devoted to the head. However, the proportion of S-I activated from the glabrous nose is greater in tree shrews than iun any previously studied mammal. We conclude that S-I of tree shrews has both specialized and generalized features, and that the generalized features importantly relate to an understanding of the evolution of the primate somatosensory system.

Animals↗

PubMed1997

Effect of pruning on dendritic tree topology.

The variability in topological shapes of observed neuronal branching patterns can accurately be described by a simple model for random sequential growth. This finding is remarkable in view of the fact that the actual neuritic growth process can vary, and includes phases of regression and removal of branches which were not considered in the model. The aim of the present study is to investigate the influence of removal of branches on the topological structure of branching patterns as well as the effect of variable growth rules. A tree asymmetry index is used for the characterization of the topological structure of a tree. The mean value of the asymmetry index for a set of dendritic trees is sensitive to the mode of growth. The effect of removal of branches ("pruning") on the topological structure of dendritic trees has been studied for several random pruning schemes, namely (i) removal of uniform randomly chosen subtrees, (ii) removal of uniform randomly chosen terminal segments, (iii) uniform random pruning during the growth process itself, and (iv) non-uniform random pruning schemes. It was found that the effect of pruning depends on both the mode of pruning and the mode of growth. Uniform random (terminal) pruning had no effect on the mean and standard deviation of the asymmetry index of trees grown with an order-independent mode of branching. Changes in the mean of the asymmetry index could occur either with non-uniform random pruning or when trees are grown according to an order-dependent mode of branching. The effect of variable growth rules was studied for several specific schemes, and it could be shown that they all result in a substantial increase in the variation in the asymmetry index of the trees.

Animals↗

PubMed1997

Anatomical variability and functional ability of vascular trees modeled by constrained constructive optimization.

The aim of this study was to investigate the extent that functional capability of vascular trees is related to anatomical variability. To these ends we used the method of Constrained Constructive Optimization (CCO) to generate optimized computer models of coronary arterial trees. All these model trees were optimized according to the same principle under equal boundary conditions of pressures and flows. However, by stochastically casting the locations of the terminal segments, different tree structures were generated, each of which conformed to the same boundary conditions. The structural variability of these models was interpreted as the correlate of the anatomical variability found in real arterial trees. The advantage that computer model trees are known in numerical detail was exploited to perform comprehensive and exact classifications of all segments into bifurcation levels, STRAHLER orders and composite vessels, and to compute the area expansion ratio. The unexpected result was that, despite striking visual differences in anatomical structure, the model trees were almost identical with regard to functional performance. We conclude that models optimized on the computer for a given perfusion task show little differences in their morphometric parameters even if they differ considerably regarding the course of the large vessels.

Computer Simulation↗

PubMed1996

Analysis of the distribution of bootstrap tree lengths using the maximum parsimony method.

The bootstrap is an important tool for estimating the confidence interval of monophyletic groups within phylogenies. Although bootstrap analyses are used in most evolutionary studies, there is no clear consensus as how best to interpret bootstrap probability values. To study further the bootstrap method, nine small subunit ribosomal DNA (SSU rDNA) data sets were submitted to bootstrapped maximum parsimony (MP) analyses using unweighted and weighted sequence positions. Analyses of the lengths (i.e., parsimony steps) of the bootstrap trees show that the shape and mean of the bootstrap tree distribution may provide important insights into the evolutionary signal within the sequence data. With complex phylogenies containing nodes defined by short internal branches (multifurcations), the mean of the bootstrap tree distribution may differ by 2 standard deviations from the length of the best tree found from the original data set. Weighting sequence positions significantly increases the bootstrap values at internal nodes. There may, however, be strong bootstrap support for conflicting species groupings among different data sets. This phenomenon appears to result from a correlation between the topology of the tree used to create the weights and the topology of the bootstrap consensus tree inferred from the MP analysis of these weighted data. The analyses also show that characteristics of the bootstrap tree distribution (e.g., skewness) may be used to choose between alternative weighting schemes for phylogenetic analyses.

Animals↗

PubMed1996

On the analytic solution of electrotonic spread in branched passive dendritic trees.

From the classical work of Rall it is known that the spread of electric potential in a passive dendritic tree may be obtained by expressing the initial conditions as a linear combination of a set of trigonometric eigenfunctions, each decaying with the associated time constant. It is shown here that in order to evaluate the permissible parameters in these eigenfunctions one may formulate the boundary conditions at all the junctions and endings of the dendritic tree as a set of homogeneous linear equations in which the parameters in the eigenfunctions are the unknowns. These equations have a nontrivial solution if the relevant determinant vanishes, a condition that permits the evaluation of the various parameters, thus providing an analytic approach to the expression of the eigenfunctions as well as the decay time constants. The above approach is illustrated by application to a dendritic tree that has a parent segments and two generations of offspring segments, without any restrictions as to the relative diameters or lengths of the various segments in the tree. General properties of the tree may be readily derived, like the variation of the eigenvalues on scaling of the lengths or diameters of all the segments. A few special cases with specified dimensions of the various segments are derived from the general case. In the case of a dendritic tree that fulfills the "equivalent cylinder" conditions, all of the eigenvalues and eigenfunctions of the tree may be determined by the proposed method, including those that do not apply to the equivalent cylinder. The orthogonality properties of the eigenfunctions are discussed.

Animals↗

PubMed1993

Unilateral cervical vagotomy decreases the magnitude of neurogenic inflammation induced by capsaicin in the ipsilateral bronchial tree of rats.

Electrical stimulation of a single cervical vagus nerve produces neurogenic inflammation on the stimulated side of the bronchial tree, including the first (main) to the 4th order bronchi. In the contralateral bronchial tree, in contrast, only the proximal part of the main bronchus exhibits inflammatory changes, suggesting that vagal sensory axons present in the bronchi largely originate from the ipsilateral vagus nerve. Intravenous administration of capsaicin can evoke neurogenic inflammation in bilateral bronchial trees. Sensory axons from various sources are thought to be stimulated by this irritant. The extent to which neurogenic inflammation in both bronchial trees might be reduced by unilateral vagotomy is not known. In the present study, we sought to characterize the effect of unilateral cervical vagotomy on capsaicin-induced changes in plasma extravasation and secretory activity of goblet cells in the bronchial trees of both sides. To quantify the magnitude of neurogenic plasma extravasation, Evans blue was used as a tracer dye to measure spectrophotometrically its amount in the bronchial wall. Another tracer dye, Monastral blue, was used to localize the distribution of leaky blood vessels and to measure morphometrically their area density in the whole mounts. To investigate cell and tissue responses of the mucosa, histological methods were employed. After 2 or 4 postoperative weeks, the rats were intravenously administered with a single dose of capsaicin, 150 micrograms/kg. This resulted in different magnitudes of Evans blue extravasation in the bronchi of the two sides in vagotomized rats. Extravasation of Evans blue dye in the bronchial tree ipsilateral to vagotomy was one-half to two-thirds of that of the contralateral bronchial tree.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1979

A graph theoretic approach to the development of minimal phylogenetic trees.

The problem of determining the minimal phylogenetic tree is discussed in relation to graph theory. It is shown that this problem is an example of the Steiner problem in graphs which is to connect a set of points by a minimal length network where new points can be added. There is no reported method of solving realistically-sized Steiner problems in reasonable computing time. A heuristic method of approaching the phylogenetic problem is presented, together with a worked example with 7 mammalian cytochrome c sequences. It is shown in this case that the method develops a phylogenetic tree that has the smallest possible number of amino acid replacements. The potential and limitations of the method are discussed. It is stressed that objective methods must be used for comparing different trees. In particular it should be determined how close a given tree is to a mathematically determined lower bound. A theorem is proved which is used to establish a lower bound on the lenghtof any tree and if a tree is found with a length equal to the lower bound, then no shorter tree can exist.

Mathematics↗