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1

Trace metals in soil and leaves of Jacaranda mimosifolia in Tshwane area, South Africa  

NASA Astrophysics Data System (ADS)

Plant and soil have been identified as major sink of pollutants in the environment. We evaluated the reliability of biomonitoring of heavy metals in Tshwane area with the use of leaves of Jacaranda mimosifolia. The concentrations of heavy metals such as Ca, Mg, Fe, Pb, Zn, Cu, Sb were measured in leaves of J. mimosifolia and soils collected from 10 sites in the city of Tshwane during two sampling periods. The metals were analyzed with the use of ICP-MS. The result shows significant differences in the concentration of trace metals in all the sites ( p < 0.01). The differences between the two sampling periods were statistically significant ( p < 0.01). Concentration of metals from high traffic and industrial sites were significantly higher than in the residential areas ( p < 0.01). Concentration factor suggests that translocation of metals from roots to leaves could be relevant only for some metals such as Ca, Mg and Sb. The study reveals an anthropogenic source for the trace metals. Leaves of J. mimosifolia were found to be a useful biomonitor of the determined trace metals.

Olowoyo, J. O.; van Heerden, E.; Fischer, J. L.; Baker, C.

2010-05-01

2

ATIVIDADE ANTIMICROBIANA DE Jacaranda mimosaefolia D. DON  

Microsoft Academic Search

RESUMO: Foram realizados ensaios microbiológicos para avaliar a atividade antibacteriana e antifúngica do extrato aquoso de folhas de Jacaranda mimosaefolia D. Don, contra quatro diferentes microrganismos. O extrato aquoso apresentou resultados significativos frente a Staphylococcus aureus ATCC 6538P, Staphylococcus epidermidis ATCC 12128, Escherichia coli ATCC 10536 e contra Saccharomyces cerevisiae ATCC 2601. Verificou-se, porém, diâmetros maiores nas zonas de inibição

3

Toward a predictive model for water and carbon fluxes of non-native trees in urban habitats  

NASA Astrophysics Data System (ADS)

There is considerable interest in estimating uptake of water and carbon by urban trees, in order to assess some of the major costs and benefits associated with maintaining or expanding urban tree cover. However, making large-scale estimates of water and carbon fluxes is challenging in urban ecosystems, where community composition and environmental conditions are highly altered and experimental data is sparse. This is particularly true in regions such as southern California, where few trees are native, yet many species can flourish given supplemental irrigation. In such scenarios one practical way to scale water and carbon fluxes may be to identify reliable traits which can be used to predict gas exchange when trees are transplanted to a new environment. To test this approach, leaf level gas exchange measurements were conducted on eight common urban tree species within the Los Angeles basin. The objective was to determine how well gas exchange parameters, including maximum photosynthesis and stomatal conductance, sensitivity of stomatal conductance to vapor pressure deficit (VPD), and water use efficiency (WUE), can be predicted based on the native habitat and climate (temperature and precipitation) of each study species. All of the species studied naturally occur in humid tropical or subtropical climate zones where precipitation varies widely from ~400 - 3000 mm per year. We found Jacaranda (Jacaranda chelonia) and honey locust (Gleditsia triacanthos) to have the highest photosynthesis and reference (at VPD=1 kPa) conductance, and to be most sensitive to VPD. WUE was found to be greatest in Indian laurel fig (Ficus microcarpa), rose gum (Eucalyptus grandis) and Queensland lacebark (Brachychiton discolor). The relative ordering of maximum photosynthesis and conductance across species was not entirely predictable based on our current knowledge of the native habitats of each species: several other species had similar native climates to Jacaranda and honey locust, yet had lower photosynthesis and conductance. However, WUE generally followed the expected trends, with species predicted to have low conductance showing higher WUE. This implies that WUE is strongly genetically controlled and may be predictable with knowledge of imported species' native habitat. Other traits, such as leaf nitrogen and isotopes, are also being investigated as proxies for detailed gas exchange measurements in this ecosystem. Further refinement of predictive factors will facilitate conceptual and quantitative models that can be used for robust scaling of water and carbon fluxes from trees to urban regions.

McCarthy, H. R.; Jenerette, G. D.; Pataki, D. E.

2008-12-01

4

Tree Squirrels  

Microsoft Academic Search

In this chapter tree squirrels are divided into three groups: large tree squirrels, pine squirrels, and flying squirrels. Large tree squirrels include fox (Sciurus niger), eastern gray (Sciurus carolinensis), western gray (Sciurus griseus), and tassel-eared (Sciurus aberti) squirrels. Fox squirrels (Fig. 1) measure 18 to 27 inches (46 to 69 cm) from nose to tip of tail. They weigh about

Jeffrey J. Jackson

1994-01-01

5

Tree frog  

NSDL National Science Digital Library

This tree frog can be found living in jungles and forests. Two reasons why the common frog is considered to be an amphibian are because it lays eggs in water and its spawn goes through metamorphosis to reach adulthood.

Hans Hillewaert (None;)

2008-04-20

6

Christmas Tree  

NSDL National Science Digital Library

Last year, the front page of the Christmas Day New York Times talked about how you could do `finger xmastree@cygnus.com' to find out the current state of the Christmas tree in the offices of Cygnus Support. Well, it's back again this year. But, we wouldn't want you to be bored! "Oh, ho hum, that same boring thing all over again...been there, saw that." So to follow the example of a few million enthusiasts, the increasingly-popular World Wide Web is now toting its very own Christmas tree, which is so interactive it's almost like it's in your home. (Well, not quite. But if you'd like to send some wrapped gifts, I'm sure we wouldn't be upset.) Along with getting to look at a small photo of the tree when you first connect to it, you may: choose to see a full-size version of that picture -- they are updated every two minutes; choose to watch an MPEG movie of the tree which is 20 frames long, so you can watch the lights blink, etc. This is updated every fifteen minutes; vote on the different features of the tree, and every fifteen minutes the system will do the vote count and change the tree accordingly; send any one of ten random cards to a given email address; find out the technical details of how it was done, if you're really that interested. If you have any comments, suggestions, or complaints (come to think of it, you can keep the complaints), write to

7

Trees, Soil and Water  

NSDL National Science Digital Library

Trees, soil and water: Journey to Forever - health care for mountains, trees for deserts, trees for people, forest, forestry, deforestation, erosion, soil conservation, water conservation, desertification.

Addison, Keith

2010-01-01

8

Greenhouse trees  

SciTech Connect

Michigan State University has been conducting research on growth control of woody plants with emphasis on commercial plantations. The objective was to develop the optimum levels for the major factors that affect tree seedling growth and development so that high quality plants can be produced for a specific use. This article describes the accelerated-optimal-growth (AOG) concept, describes precautions to take in its application, and shows ways to maximize the potential of AOG for producing ornamental trees. Factors considered were container growing system; protective culture including light, temperature, mineral nutrients, water, carbon dioxide, growth regulators, mycorrhizae, growing media, competition, and pests; size of seedlings; and acclamation. 1 table. (DP)

Hanover, J.W.; Hart, J.W.

1980-05-09

9

Assessing the extent of "conflict of use" in multipurpose tropical forest trees: a regional view.  

PubMed

In the context of multiple forest management, multipurpose tree species which provide both timber and non-timber forest products (NTFP), present particular challenges as the potential of conflicting use for either product may be high. One key aspect is that the magnitude of conflict of use can be location specific, thus adding complexity to policy development. This paper focuses on the extent to which the potential for conflict of use in multipurpose tree species varies across the Amazonian lowland forests shared by Peru, Bolivia, Colombia, Ecuador and Venezuela, emphasizing the economic dimension of conflict. Based on a review of the current normative and regulatory aspects of timber and NTFP extraction in the five countries, the paper also briefly discusses the opportunities and constraints for harmonization of timber and NTFP management of multipurpose species across the region. It was found that about half of the 336 timber species reviewed across the five countries also have non-timber uses. Eleven timber species are multipurpose in all five countries: Calophyllum brasiliense, Cedrela odorata, Ceiba pentandra, Clarisia racemosa, Ficus insipida, Jacaranda copaia, Schefflera morototoni, Simarouba amara and Terminalia amazonia. Seven other multipurpose species occurred only in either Venezuela (Tabebuia impetiginosa, Spondias mombin, Pentaclethra macroloba, Copaifera officinalis, Chlorophora tinctoria, Carapa guianensis) or Ecuador (Tabebuia chrysantha). Four multipurpose tree species presented the highest potential of conflict of use across the region: Dipteryx odorata, Tabebuia serratifolia, Hymenaea courbaril and Myroxylon balsamum yet these were not evenly distributed across all five countries. None of the five studied countries have specific legislation to promote sustainable use of any of the multipurpose species reported here and thus mitigate potential conflict of use; nor documented management options for integration or else segregation of both their timber and NTFP values. PMID:24061084

Herrero-Jáuregui, Cristina; Guariguata, Manuel R; Cárdenas, Dairon; Vilanova, Emilio; Robles, Marco; Licona, Juan Carlos; Nalvarte, Walter

2013-11-30

10

Reading trees.  

PubMed

Are birds dinosaurs? Answers to this question yield various responses, depending on a particular viewpoint. From the perspective of a common understanding of recent theories of the origin of birds and their potential precursor (ancestral) animals, then, yes, birds are a kind of dinosaur, having evolved from one or another non-avian dinosaur (Bostwick 2003). From the perspective of public understanding of science (how to inform the general public of biology's latest findings), then, yes, birds are dinosaurs, at least they are a kind of dinosaur, one that young children can actually hold in their hands (e.g., Maugh 2012). These two perspectives, largely derived from phylogenetic reasoning, contrast with the perspective from classification, which asks different questions: What are birds; what are dinosaurs; and how are they related to one another? Addressing these questions raises the issue of trees in classification (phylogenetic or otherwise) and how to read them. This is not as easy a task as is often suggested in the recent literature on tree-reading and tree-thinking (first noted long ago by O'Hara 1988, see Baum and Smith 2012 for a first book-length treatment).                      The role of tree-thinking in classification is applied after a tree has been constructed and natural groups established. For instance, it would seem premature to infer phylogenies on poorly classified taxa, such as invertebrates, reptiles and so on, as these groupings are artificial. Doing so would only result in erroneous hypotheses that cannot be substantiated. The role of classification, however, is to make sure that the natural groups are justified, and in order to do this it is vital that those groups are understood. Birds represent a monophyletic group, which has series of unique characteristics that it shares with other theropods (i.e., bipedal saurischian dinosaurs). Dinosaurs, as usually conceived, are a group of non-monophyletic organisms that variously share closer characteristics (i.e., relationships) with other taxa rather than uniquely among themselves. In the case of dinosaurs (as Dinosauria) and classification, what is at stake is a taxonomic name, rather than a unique group of character traits. Below we outline and compare two contrasting ways of reading trees, one way, concerned with classification, yielding the view that, no, birds are not dinosaurs. PMID:24943430

Ebach, Malte C; Williams, David M

2014-01-01

11

The Tree-to-Tree Correction Problem  

Microsoft Academic Search

The tree-to-tree correctmn problem Is to determine, for two labeled ordered trees T and T', the distance from T to T' as measured by the mlmmum cost sequence of edit operaUons needed to transform T into T' The edit operations investigated allow changing one node of a tree into another node, deleting one node from a tree, or inserting a

Kuo-Chung Tai

1979-01-01

12

Tree Troubles  

NSDL National Science Digital Library

This Topic in Depth explores some of the diseases and other threats that certain trees must contend with to remain healthy and vital. The first website (1), from the USDA Forest Service-St. Paul Field Office, contains a collection of archived publications designed to help people diagnose, control, and identify various threats to different types of trees. Examples of these publications include: How to Control Sapstreak Disease of Sugar Maple; How to Differentiate Dutch Elm Disease From Elm Phloem Necrosis; How to Identify and Manage Needlecast Diseases on Balsam Fir; and How to Manage Eastern White Pine to Minimize Damage from Blister Rust and White Pine Weevil, to name few. The second (2) site, Forest & Shade Tree Pathology, is an online textbook that was developed by Dr. James J. Worrall, a plant pathologist for the USDA Forest Service, and former professor at the College of Environmental Science and Forestry, State University of New York. Dr. Worrall's site contains information about rusts, foliage and root diseases, parasitic plants, cankers, abiotic diseases, and wilts as well as disease profiles for Swiss Needle Cast; Oak Wilt, Chestnut Blight, Armillaria Root Disease, and more. The third (3) site, Oak Wilt: A Threat to Red Oaks & White Oaks Species, was created by Dr. David L. Roberts at Michigan State University Extension. Dr. Robert's concise site contains brief sections addressing oak wilt distribution, field diagnosis, management, disease cycle, and more. The fourth (4) site, from the California Oak Mortality Task Force, contains images, publications, maps, and information about Sudden Oak Death-related research, management recommendations, nursery issues, and regulations. The final three websites come from the USDA Forest Service and contain information about different insect threats. The fifth (5) site offers information about the emerald ash borer. The sixth (6) site provides information about the gypsy moth, and the final (7) site contains information about the Asian longhorned beetle.

13

Trees in the Landscape.  

ERIC Educational Resources Information Center

Strategies for using trees in classroom instruction are provided. Includes: (1) activities (such as tree identification, mapping, measuring tree height/width); (2) list of asthetic, architectural, engineering, climate, and wildlife functions of trees; (3) tree discussion questions; and (4) references. (JN)

Webb, Richard; Forbatha, Ann

1982-01-01

14

Trees and Air Quality  

NSDL National Science Digital Library

In this activity, students describe the positive effects that trees have on air quality and determine how to landscape a home with trees to decrease energy use. Students will draw a map of their yard or school site showing the location of trees and check a leaf of each tree for particulates. They will then make observations on several different days to determine which trees save energy and draw on their map where more trees should be planted to save energy.

15

Estimating species trees from unrooted gene trees.  

PubMed

In this study, we develop a distance method for inferring unrooted species trees from a collection of unrooted gene trees. The species tree is estimated by the neighbor joining (NJ) tree built from a distance matrix in which the distance between two species is defined as the average number of internodes between two species across gene trees, that is, average gene-tree internode distance. The distance method is named NJ(st) to distinguish it from the original NJ method. Under the coalescent model, we show that if gene trees are known or estimated correctly, the NJ(st) method is statistically consistent in estimating unrooted species trees. The simulation results suggest that NJ(st) and STAR (another coalescence-based method for inferring species trees) perform almost equally well in estimating topologies of species trees, whereas the Bayesian coalescence-based method, BEST, outperforms both NJ(st) and STAR. Unlike BEST and STAR, the NJ(st) method can take unrooted gene trees to infer species trees without using an outgroup. In addition, the NJ(st) method can handle missing data and is thus useful in phylogenomic studies in which data sets often contain missing loci for some individuals. PMID:21447481

Liu, Liang; Yu, Lili

2011-10-01

16

Categorizing ideas about trees: a tree of trees.  

PubMed

The aim of this study is to explore whether matrices and MP trees used to produce systematic categories of organisms could be useful to produce categories of ideas in history of science. We study the history of the use of trees in systematics to represent the diversity of life from 1766 to 1991. We apply to those ideas a method inspired from coding homologous parts of organisms. We discretize conceptual parts of ideas, writings and drawings about trees contained in 41 main writings; we detect shared parts among authors and code them into a 91-characters matrix and use a tree representation to show who shares what with whom. In other words, we propose a hierarchical representation of the shared ideas about trees among authors: this produces a "tree of trees." Then, we categorize schools of tree-representations. Classical schools like "cladists" and "pheneticists" are recovered but others are not: "gradists" are separated into two blocks, one of them being called here "grade theoreticians." We propose new interesting categories like the "buffonian school," the "metaphoricians," and those using "strictly genealogical classifications." We consider that networks are not useful to represent shared ideas at the present step of the study. A cladogram is made for showing who is sharing what with whom, but also heterobathmy and homoplasy of characters. The present cladogram is not modelling processes of transmission of ideas about trees, and here it is mostly used to test for proximity of ideas of the same age and for categorization. PMID:23950877

Fisler, Marie; Lecointre, Guillaume

2013-01-01

17

Categorizing Ideas about Trees: A Tree of Trees  

PubMed Central

The aim of this study is to explore whether matrices and MP trees used to produce systematic categories of organisms could be useful to produce categories of ideas in history of science. We study the history of the use of trees in systematics to represent the diversity of life from 1766 to 1991. We apply to those ideas a method inspired from coding homologous parts of organisms. We discretize conceptual parts of ideas, writings and drawings about trees contained in 41 main writings; we detect shared parts among authors and code them into a 91-characters matrix and use a tree representation to show who shares what with whom. In other words, we propose a hierarchical representation of the shared ideas about trees among authors: this produces a “tree of trees.” Then, we categorize schools of tree-representations. Classical schools like “cladists” and “pheneticists” are recovered but others are not: “gradists” are separated into two blocks, one of them being called here “grade theoreticians.” We propose new interesting categories like the “buffonian school,” the “metaphoricians,” and those using “strictly genealogical classifications.” We consider that networks are not useful to represent shared ideas at the present step of the study. A cladogram is made for showing who is sharing what with whom, but also heterobathmy and homoplasy of characters. The present cladogram is not modelling processes of transmission of ideas about trees, and here it is mostly used to test for proximity of ideas of the same age and for categorization.

Fisler, Marie; Lecointre, Guillaume

2013-01-01

18

Additive similarity trees  

Microsoft Academic Search

Similarity data can be represented by additive trees. In this model, objects are represented by the external nodes of a tree, and the dissimilarity between objects is the length of the path joining them. The additive tree is less restrictive than the ultrametric tree, commonly known as the hierarchical clustering scheme. The two representations are characterized and compared. A computer

Shmuel Sattath; Amos Tversky

1977-01-01

19

Tree Tectonics  

NASA Astrophysics Data System (ADS)

Nature often replicates her processes at different scales of space and time in differing media. Here a tree-trunk cross section I am preparing for a dendrochronological display at the Battle Creek Cypress Swamp Nature Sanctuary (Calvert County, Maryland) dried and cracked in a way that replicates practically all the planform features found along the Mid-Oceanic Ridge (see Figure 1). The left-lateral offset of saw marks, contrasting with the right-lateral ``rift'' offset, even illustrates the distinction between transcurrent (strike-slip) and transform faults, the latter only recognized as a geologic feature, by J. Tuzo Wilson, in 1965. However, wood cracking is but one of many examples of natural processes that replicate one or several elements of lithospheric plate tectonics. Many of these examples occur in everyday venues and thus make great teaching aids, ``teachable'' from primary school to university levels. Plate tectonics, the dominant process of Earth geology, also occurs in miniature on the surface of some lava lakes, and as ``ice plate tectonics'' on our frozen seas and lakes. Ice tectonics also happens at larger spatial and temporal scales on the Jovian moons Europa and perhaps Ganymede. Tabletop plate tectonics, in which a molten-paraffin ``asthenosphere'' is surfaced by a skin of congealing wax ``plates,'' first replicated Mid-Oceanic Ridge type seafloor spreading more than three decades ago. A seismologist (J. Brune, personal communication, 2004) discovered wax plate tectonics by casually and serendipitously pulling a stick across a container of molten wax his wife and daughters had used in making candles. Brune and his student D. Oldenburg followed up and mirabile dictu published the results in Science (178, 301-304).

Vogt, Peter R.

2004-09-01

20

Visibility Representations of Trees.  

National Technical Information Service (NTIS)

Trees are among the most common structures in computing and many algorithms for drawing trees have been developed in the last years. Such algorithms usually adopt different drawing conventions and attempt to solve several optimization problems. The aim of...

G. Kant G. Liotta R. Tamassia I. G. Tollis

1996-01-01

21

Chem-Is-Tree.  

ERIC Educational Resources Information Center

Provides details on the chemical composition of trees including a definition of wood. Also includes an activity on anthocyanins as well as a discussion of the resistance of wood to solvents and chemicals. Lists interesting products from trees. (DDR)

Barry, Dana M.

1997-01-01

22

Tropical Tree Seed Manual.  

National Technical Information Service (NTIS)

The Tropical Tree Seed Manual is a one-volume reference manual for students, technicians, and scientists that provides comprehensive internationally compiled data about tropical trees. The emphasis is on species of the Americas; however, a number of tropi...

J. A. Vozzo

2002-01-01

23

Evolution of tree nutrition.  

PubMed

Using a broad definition of trees, the evolutionary origins of trees in a nutritional context is considered using data from the fossil record and molecular phylogeny. Trees are first known from the Late Devonian about 380 million years ago, originated polyphyletically at the pteridophyte grade of organization; the earliest gymnosperms were trees, and trees are polyphyletic in the angiosperms. Nutrient transporters, assimilatory pathways, homoiohydry (cuticle, intercellular gas spaces, stomata, endohydric water transport systems including xylem and phloem-like tissue) and arbuscular mycorrhizas preceded the origin of trees. Nutritional innovations that began uniquely in trees were the seed habit and, certainly (but not necessarily uniquely) in trees, ectomycorrhizas, cyanobacterial, actinorhizal and rhizobial (Parasponia, some legumes) diazotrophic symbioses and cluster roots. PMID:20581011

Raven, John A; Andrews, Mitchell

2010-09-01

24

Tea tree oil  

MedlinePLUS

... of the nail (onychomycosis), lice, scabies, athlete’s foot (tinea pedis), and ringworm. It is also used topically as ... TEA TREE OIL are as follows:Athlete’s foot (tinea pedis). Topical application of a 10% tea tree oil ...

25

Pine tree forest  

NSDL National Science Digital Library

The pine tree demonstrates the differences among gymnosperms and bryophytes and seedless vascular plants. Pine trees have separate cones with pollen and ovulates. Wind blows the pollen onto the ovulate cone and seeds are produced.

Katie Hale (California State University, Fullerton;Student, Biological Sciences)

2007-01-13

26

Directed TreeWidth  

Microsoft Academic Search

We generalize the concept of tree-width to directed graphs and prove that every directed graph with no “haven” of large order has small tree-width. Conversely, a digraph with a large haven has large tree-width. We also show that the Hamilton cycle problem and other NP-hard problems can be solved in polynomial time when restricted to digraphs of bounded tree-width.

Thor Johnson; Neil Robertson; Paul D. Seymour; Robin Thomas

2001-01-01

27

Build a Tree  

NSDL National Science Digital Library

This activity (on pages 13-18) has learners build a model tree and then figure out how to make their tree stand up by itself. This illustrates how the tall rain forest trees adapt to support a huge trunk and heavy branches, while also sending their roots out instead of down. Trees built in this activity can be used for the Rain Forest in Your Room activity that is also part of the Wonderwise Rain Forest Ecologist Activity Book.

Museum, University O.; Nebraska Cooperative Extension 4-H Youth Development

2001-01-01

28

Graded Brauer Tree Algebras  

Microsoft Academic Search

In this paper we construct non-negative gradings on a basic Brauer tree algebra $A_{\\\\Gamma}$ corresponding to an arbitrary Brauer tree $\\\\Gamma$ of type $(m,e)$. We do this by transferring gradings via derived equivalence from a basic Brauer tree algebra $A_S$, whose tree is a star with the exceptional vertex in the middle, to $A_{\\\\Gamma}$. The grading on $A_S$ comes from

Dusko Bogdanic

2008-01-01

29

Diary of a Tree.  

ERIC Educational Resources Information Center

Describes an activity to develop students' skills of observation and recordkeeping by studying the growth of a tree's leaves during the spring. Children monitor the growth of 11 tress over a 2-month period, draw pictures of the tree at different stages of growth, and write diaries of the tree's growth. (MDH)

Srulowitz, Frances

1992-01-01

30

Structural Equation Model Trees  

ERIC Educational Resources Information Center

In the behavioral and social sciences, structural equation models (SEMs) have become widely accepted as a modeling tool for the relation between latent and observed variables. SEMs can be seen as a unification of several multivariate analysis techniques. SEM Trees combine the strengths of SEMs and the decision tree paradigm by building tree

Brandmaier, Andreas M.; von Oertzen, Timo; McArdle, John J.; Lindenberger, Ulman

2013-01-01

31

Nectarine tree, "Kam Red"  

US Patent & Trademark Office Database

A new and distinct nectarine tree denominated varietally as "Kam Red" and generally resembling the Flamekist nectarine tree (unpatented) but bearing a freestone fruit which is mature for harvesting and shipment approximately five to six days earlier than that of the Flamekist nectarine tree in the San Joaquin Valley of Central California.

1989-06-20

32

Macro Tree Transducers  

Microsoft Academic Search

Macro tree transducers are a combination of top-down tree transducers and macro grammars. They serve as a model for syntax-directed semantics in which context information can be handled. In this paper the formal model of macro tree transducers is studied by investigating typical automata theoretical topics like composition, decomposition, domains, and ranges of the induced translation classes. The extension with

Joost Engelfriet; Heiko Vogler

1985-01-01

33

RC trees revisited  

Microsoft Academic Search

RC tree approximation is a computationally simple method for calculating the signal delay of MOS circuits with several states of fanout. The author derives a formal solution of RC tree equations. Based on this solution, it is shown that even though waveforms found using RC tree approximation are inaccurate, delays are exact. The author derives the dependence of the delays

Mehinet A. Cirit

1988-01-01

34

STRESS MANAGEMENT FOR TREES1  

Microsoft Academic Search

Excessive stress is a common cause of tree mor- tality in the urban environment. People must take positive steps to minimize and avoid stress on trees if urban shade trees are to survive and grow. Stress kills trees. However, stress is also part of the environment of all trees and a stress-free con- dition for a tree can only exist

Terry A. Tattar

1983-01-01

35

Growth of a Pine Tree  

ERIC Educational Resources Information Center

The growth of a pine tree is examined by preparing "tree cookies" (cross-sectional disks) between whorls of branches. The use of Christmas trees allows the tree cookies to be obtained with inexpensive, commonly available tools. Students use the tree cookies to investigate the annual growth of the tree and how it corresponds to the number of whorls…

Rollinson, Susan Wells

2012-01-01

36

Reversible adaptive trees.  

PubMed

We describe reversible adaptive trees, a class of stochastic algorithms modified from the formerly described adaptive trees. They evolve in time a finite subset of an ambient Euclidean space of any dimension, starting from a seed point and, accreting points to the evolving set, they grow branches towards a target set which can depend on time. In contrast with plain adaptive trees, which were formerly proven to have strong convergence properties to a static target, the points of reversible adaptive trees are removed from the tree when they have not been used recently enough in a path from the root to an accreted point. This, together with a straightening process performed on the branches, permits the tree to follow some moving targets and still remain adapted to it. We then discuss in what way one can see such reversible trees as a model for a qualitative property of resilience, which leads us to discuss qualitative modeling. PMID:23934230

Kergosien, Yannick L

2013-09-01

37

Holiday Factor Trees  

NSDL National Science Digital Library

To review the idea of factor trees and prime factorization I have the students make Holiday Factor Trees. I created a template that looks like a Christmas tree that the students can trace out. We use green paper for the top of the tree and brown paper for the trunk of the tree. Each student then picks a number to find the prime factorization for. It might be helpful to assign each student a number; therefore, they do not all end up doing the same number. I then have the students make a star for the top of their tree which they write their assigned number on. Next, they cut out construction paper bulbs that become the factors on their factor tree. (Pre cut stars and bulbs may be helpful for this as well). You can choose to do any color bulbs, but one thing that I had my student do was to use the same color for the prime numbers at the bottom of the tree therefore prime factors stand out and look unified. On the trunk of the tree the students also wrote the final prime factorization using exponents. Example:1 Yellow Star: 644 multicolored Bulbs: 8, 8,4,46 Red Prime Factors Bulbs: 2,2,2,2,2,2,

2011-12-06

38

Chem-Is-Tree  

NASA Astrophysics Data System (ADS)

Trees are woody plants that contain chemicals and undergo chemical reactions. They consist of cellulose, volatile oils, fatty acids, and more. Wood is obtained from the stems, roots, and branches of trees. It is not a homogeneous material with a uniform structure but instead a tissue of different kinds of cells which perform specific functions in the living plant. Trees are of great importance. They provide oxygen which results from photosynthesis taking place in their leaves. In addition, trees supply us with interesting products such as vanilla flavoring and natural-rubber used in cements, adhesives, vehicle tires and shoes.

Barry, Dana M.

1997-10-01

39

National Register of Big Trees  

NSDL National Science Digital Library

Most trees can outlive us. Even so, it's not unusual for trees to succumb to disease, insects, over development and drought. So it's especially meaningful when a tree reaches a good old age. Here you'll find out all about the oldest trees on earth, as well as have the opportunity to nominate a old tree you might know.

Forests, American

40

Tree Projects for Schools.  

National Technical Information Service (NTIS)

Trees have an enormous educational potential when used as a subject for class projects. This book consists of projects which follow a general theme. The study of a single tree in the school grounds leads on to an examination of basic ecological principles...

R. Webb

1984-01-01

41

Trees From Helicopters  

NSDL National Science Digital Library

This story is aimed at promoting not only inquiry into the germination of tree seeds but seeing trees as typical flowering plants, also known as angiosperms. There is also ample opportunity to take an excursion into fruits and seeds and the germination of

Konicek-Moran, Richard

2008-04-01

42

Trees From Helicopters, Continued  

NSDL National Science Digital Library

Maples are very interesting trees with lots of variation in form. They provide us with a view of diversity in plants as well as a chance to look at natural phenomena that is very common to anyone who has had a maple tree near them. The main purpose is to

Konicek-Moran, Richard

2009-04-01

43

Survival of Trees  

NSDL National Science Digital Library

In this video a scientist explains how DNA extracted from ancient tree remains provides insights about how trees/plants have adapted, over time, to changes in CO2 in the atmosphere. Her lab research investigates changes in plant genotypes under experimental conditions that simulate potential changes in CO2 levels in the future.

Foundation, National S.; Learn, Nbc; Science 360 Network

44

Boosting Lazy Decision Trees  

Microsoft Academic Search

This paper explores the problem of how to construct lazy decision tree ensembles. We present and empirically evaluate a relevance- based boosting-style algorithm that builds a lazy decision tree ensemble customized for each test instance. From the experimental results, we conclude that our boosting-style algorithm signicantly improves the perfor- mance of the base learner. An empirical comparison to boosted regular

Xiaoli Zhang Fern; Carla E. Brodley

2003-01-01

45

Tree Pattern Rewriting Systems  

Microsoft Academic Search

Classical verification often uses abstraction when dealing with data. On the other hand, dynamic XML-based applications have become pervasive, for instance with the ever growing importance of web services. We define here Tree Pattern Rewriting Systems (TPRS) as an abstract model of dynamic XML-based documents. TPRS systems gener- ate infinite transition systems, where states are unranked and unordered trees (hence

Blaise Genest; Anca Muscholl; Olivier Serre; Marc Zeitoun

2008-01-01

46

Biodiversity and Evolutionary Trees  

NSDL National Science Digital Library

In this interactive activity, learners analyze seashells to explore phylogeny and evolution. Learners identify similar and dissimilar seashells to create a phylogenetic tree. The Teacher Guide includes pre-activity video clip suggestions and a pre-activity sorting exercise. The Teacher Guide also includes instructions on how learners can draw a phylogenetic tree instead of using the online interactive.

Institute, Howard H.

2010-01-01

47

Fault tree handbook  

Microsoft Academic Search

This handbook describes a methodology for reliability analysis of complex systems such as those which comprise the engineered safety features of nuclear power generating stations. After an initial overview of the available system analysis approaches, the handbook focuses on a description of the deductive method known as fault tree analysis. The following aspects of fault tree analysis are covered: basic

D. F. Haasl; N. H. Roberts; W. E. Vesely; F. F. Goldberg

1981-01-01

48

The Flame Tree  

ERIC Educational Resources Information Center

Lewis's own experiences living in Indonesia are fertile ground for telling "a ripping good story," one found in "The Flame Tree." He hopes people will enjoy the tale and appreciate the differences of an unfamiliar culture. The excerpt from "The Flame Tree" will reel readers in quickly.

Lewis, Richard

2004-01-01

49

Phylogenetic trees in bioinformatics  

SciTech Connect

Genetic data is often used to infer evolutionary relationships among a collection of viruses, bacteria, animal or plant species, or other operational taxonomic units (OTU). A phylogenetic tree depicts such relationships and provides a visual representation of the estimated branching order of the OTUs. Tree estimation is unique for several reasons, including: the types of data used to represent each OTU; the use ofprobabilistic nucleotide substitution models; the inference goals involving both tree topology and branch length, and the huge number of possible trees for a given sample of a very modest number of OTUs, which implies that fmding the best tree(s) to describe the genetic data for each OTU is computationally demanding. Bioinformatics is too large a field to review here. We focus on that aspect of bioinformatics that includes study of similarities in genetic data from multiple OTUs. Although research questions are diverse, a common underlying challenge is to estimate the evolutionary history of the OTUs. Therefore, this paper reviews the role of phylogenetic tree estimation in bioinformatics, available methods and software, and identifies areas for additional research and development.

Burr, Tom L [Los Alamos National Laboratory

2008-01-01

50

Global Trees Campaign  

NSDL National Science Digital Library

Along with increasing concerns about the extinction of different animal species, there has been increased interest in monitoring the fate of plant species, particularly those of various trees. Drawing on a partnership between Flora & Fauna International and the UNEP World Conservation Monitoring Centre, the Global Trees Campaign Web site serves as an online conduit for information about endangered tree species. First-time visitors will want to read the various tree profiles along the right-hand side of the homepage. Some of the species covered here include the African blackwood, Honduras rosewood, and the monkey puzzle tree, which grows naturally in Chile and Argentina. The resources section of the site is also worth a look, as it contains a database with information on close to 7,300 tree species, and list of suggested readings -- including several that are available as PDF files. For those interested in the projects initiated by the Global Trees Campaign, a section detailing their various initiatives around the globe is also available for consultation.

51

Evolutionary tree reconstruction  

NASA Technical Reports Server (NTRS)

It is described how Minimum Description Length (MDL) can be applied to the problem of DNA and protein evolutionary tree reconstruction. If there is a set of mutations that transform a common ancestor into a set of the known sequences, and this description is shorter than the information to encode the known sequences directly, then strong evidence for an evolutionary relationship has been found. A heuristic algorithm is described that searches for the simplest tree (smallest MDL) that finds close to optimal trees on the test data. Various ways of extending the MDL theory to more complex evolutionary relationships are discussed.

Cheeseman, Peter; Kanefsky, Bob

1990-01-01

52

Learning classification trees  

NASA Technical Reports Server (NTRS)

Algorithms for learning classification trees have had successes in artificial intelligence and statistics over many years. How a tree learning algorithm can be derived from Bayesian decision theory is outlined. This introduces Bayesian techniques for splitting, smoothing, and tree averaging. The splitting rule turns out to be similar to Quinlan's information gain splitting rule, while smoothing and averaging replace pruning. Comparative experiments with reimplementations of a minimum encoding approach, Quinlan's C4 and Breiman et al. Cart show the full Bayesian algorithm is consistently as good, or more accurate than these other approaches though at a computational price.

Buntine, Wray

1991-01-01

53

Trees of trees: an approach to comparing multiple alternative phylogenies.  

PubMed

Phylogenetic analysis very commonly produces several alternative trees for a given fixed set of taxa. For example, different sets of orthologous genes may be analyzed, or the analysis may sample from a distribution of probable trees. This article describes an approach to comparing and visualizing multiple alternative phylogenies via the idea of a "tree of trees" or "meta-tree." A meta-tree clusters phylogenies with similar topologies together in the same way that a phylogeny clusters species with similar DNA sequences. Leaf nodes on a meta-tree correspond to the original set of phylogenies given by some analysis, whereas interior nodes correspond to certain consensus topologies. The construction of meta-trees is motivated by analogy with construction of a most parsimonious tree for DNA data, but instead of using DNA letters, in a meta-tree the characters are partitions or splits of the set of taxa. An efficient algorithm for meta-tree construction is described that makes use of a known relationship between the majority consensus and parsimony in terms of gain and loss of splits. To illustrate these ideas meta-trees are constructed for two datasets: a set of gene trees for species of yeast and trees from a bootstrap analysis of a set of gene trees in ray-finned fish. A software tool for constructing meta-trees and comparing alternative phylogenies is available online, and the source code can be obtained from the author. PMID:18853364

Nye, Tom M W

2008-10-01

54

Generalized constructive tree weights  

NASA Astrophysics Data System (ADS)

The Loop Vertex Expansion (LVE) is a quantum field theory (QFT) method which explicitly computes the Borel sum of Feynman perturbation series. This LVE relies in a crucial way on symmetric tree weights which define a measure on the set of spanning trees of any connected graph. In this paper we generalize this method by defining new tree weights. They depend on the choice of a partition of a set of vertices of the graph, and when the partition is non-trivial, they are no longer symmetric under permutation of vertices. Nevertheless we prove they have the required positivity property to lead to a convergent LVE; in fact we formulate this positivity property precisely for the first time. Our generalized tree weights are inspired by the Brydges-Battle-Federbush work on cluster expansions and could be particularly suited to the computation of connected functions in QFT. Several concrete examples are explicitly given.

Rivasseau, Vincent; Tanasa, Adrian

2014-04-01

55

The Tree of Life  

NSDL National Science Digital Library

This article describes how interdisciplinary, thematic lessons about plants, animals, and the environment were introduced with children's literature. First-grade students created a display of the African baobab tree and its inhabitants, focusing on their interdependence.

Plummer, Donna M.; Macshara, Jeannie; Brown, Skila K.

2003-03-01

56

Encoding Voxel Trees.  

National Technical Information Service (NTIS)

The paper presents an analysis based on geometric probability for obtaining a better understanding of the space efficiency of representing three dimensional pictures using voxel trees. It is shown that asymptotically, as resolution is increased with respe...

W. de Jonge A. Schijf E. Wattel

1991-01-01

57

Trees as energy crops  

SciTech Connect

A report is presented of studies on the energy production of forest trees in California. The volume yield of the fastest growing species (Eucalyptus) was 23 cubic metres per hectare and energy yield 20 million kcal per hectare per annum.

Standiford, R.B.; Donaldson, D.R.

1982-01-01

58

Tea Tree Oil  

MedlinePLUS

... resistant Staphylococcus aureus (MRSA). However, large, well-designed clinical trials on tea tree oil are lacking, and ... strains of bacteria in people. Some smaller-scale clinical studies have had positive results for treating athlete's ...

59

Life of a Tree  

NSDL National Science Digital Library

In this interactive activity adapted from the National Arbor Day Foundation, take a sixty-two-year journey observing the inner layers, rings, and environmental factors that affect a tree's growth and life cycle.

Foundation, Wgbh E.

2007-08-09

60

Tea tree oil.  

PubMed

Tea tree oil is an increasingly popular ingredient in a variety of household and cosmetic products, including shampoos, massage oils, skin and nail creams, and laundry detergents. Known for its potential antiseptic properties, it has been shown to be active against a variety of bacteria, fungi, viruses, and mites. The oil is extracted from the leaves of the tea tree via steam distillation. This essential oil possesses a sharp camphoraceous odor followed by a menthol-like cooling sensation. Most commonly an ingredient in topical products, it is used at a concentration of 5% to 10%. Even at this concentration, it has been reported to induce contact sensitization and allergic contact dermatitis reactions. In 1999, tea tree oil was added to the North American Contact Dermatitis Group screening panel. The latest prevalence rates suggest that 1.4% of patients referred for patch testing had a positive reaction to tea tree oil. PMID:22653070

Larson, David; Jacob, Sharon E

2012-01-01

61

Tree of Hexagons  

NSDL National Science Digital Library

In this activity students use measuring skills and follow directions to make a three-dimensional ornament. Learners construct hexagons of graduated sizes from circles and assemble them into a tree. Complete instructions are provided.

2011-01-01

62

The Average Height of Binary Trees and Other Simple Trees  

Microsoft Academic Search

The average height of a binary tree with n internal nodes is shown to be asymptotic to 2 6. This represents the average stack height of the simplest recursive tree traversal algorithm. The method used in this estimation is also applicable to the analysis of traversal algorithms of unary-binary trees, unbalanced 2-3 trees, t-ary trees for any t, and other

Philippe Flajolet; Andrew M. Odlyzko

1982-01-01

63

TreeVector: Scalable, Interactive, Phylogenetic Trees for the Web  

Microsoft Academic Search

BackgroundPhylogenetic trees are complex data forms that need to be graphically displayed to be human-readable. Traditional techniques of plotting phylogenetic trees focus on rendering a single static image, but increases in the production of biological data and large-scale analyses demand scalable, browsable, and interactive trees.Methodology\\/Principal FindingsWe introduce TreeVector, a Scalable Vector Graphics–and Java-based method that allows trees to be integrated

Ralph Pethica; Gary Barker; Tim Kovacs; Julian Gough; I. King Jordan

2010-01-01

64

TreeVector: Scalable, Interactive, Phylogenetic Trees for the Web  

Microsoft Academic Search

Background: Phylogenetic trees are complex data forms that need to be graphically displayed to be human-readable. Traditional techniques of plotting phylogenetic trees focus on rendering a single static image, but increases in the production of biological data and large-scale analyses demand scalable, browsable, and interactive trees. Methodology\\/Principal Findings: We introduce TreeVector, a Scalable Vector Graphics-and Java-based method that allows trees

Ralph Pethica; Gary Barker; Tim Kovacs; Julian Gough

2010-01-01

65

Partial Alphabetic Trees  

Microsoft Academic Search

In the partial alphabetic tree problem we are given a multiset of nonnegative weights W = w\\u000a 1, . . . , w\\u000a \\u000a n\\u000a , partitioned into k ? n blocks B\\u000a 1, . . . , B\\u000a k. We want to find a binary tree T where the elements of W resides in its leaves such that if we

Arye Barkan; Haim Kaplan

2002-01-01

66

Trees for reclamation  

SciTech Connect

Land reclamation programs sponsored by several state forestry organizations are summarized in these presentations. The use of trees as a preferred specie for revegetation of surface mined lands is addressed. Modern methods of forestry can be used to make land economically and aesthetically acceptable. Tree planting techniques are presented and the role of Mycorrhizae is discussed. There are 30 papers included in this proceedings. States represented include: Alabama, Arkansas, Georgia, Illinois, Kansas, Kentucky, Maryland, Virginia, Iowa, Ohio, Pennsylvania, and West Virginia.

Not Available

1980-01-01

67

Handy Family Tree  

NSDL National Science Digital Library

In this bilingual (English/Spanish) activity, learners create family trees by tracing the hands of their family members. Learners list inherited traits like eye color, freckles, and chin shape on the fingers of the left hands and list learned traits like favorite foods, games, and pets on the fingers of the right hands. Learners assemble the hands to form trees. Use this family activity to help learners distinguish between inherited and learned traits.

Utah, University O.

2006-01-01

68

Tree nut allergy  

Microsoft Academic Search

Tree nuts are clinically associated with severe immunoglobulin E-mediated systemic allergic reactions independent of pollen\\u000a allergy and with reactions that are usually confined to the oral mucosa in patients with immunoglobulin E directed toward\\u000a cross-reacting pollen allergens. The latter reactions can progress to severe and life-threatening episodes in some patients.\\u000a Many patients with severe tree nut allergy are co-sensitized to

Suzanne S. Teuber; Sarah S. Comstock; Shridhar K. Sathe; Kenneth H. Roux

2003-01-01

69

State Trees and Arbor Days.  

ERIC Educational Resources Information Center

Provides information on state trees for each of the 50 states and the District of Columbia. Includes for each state: (1) year in which state tree was chosen; (2) common and scientific names of the tree; (3) arbor day observance; (4) address of state forester; and (5) drawings of the tree, leaf, and fruit or cone. (JN)

Forest Service (USDA), Washington, DC.

70

Image Segmentation with Directed Trees  

Microsoft Academic Search

This correspondence presents a simple algorithm to detect and label homogeneous areas in an image, using directed trees for region labeling. The scheme constructs directed trees with the image points as nodes, guided by an edge value computed at every point. These directed trees segment the image into disjoint regions. Because of a valley seeldng property of the tree construction

P. M. Narendra; M. Goldberg

1980-01-01

71

Carbon Sequestration in Campus Trees  

NSDL National Science Digital Library

In this activity, students use a spreadsheet to calculate the net carbon sequestration in a set of trees; they will utilize an allometric approach based upon parameters measured on the individual trees. They determine the species of trees in the set, measure trunk diameter at a particular height, and use the spreadsheet to calculate carbon content of the tree using forestry research data.

Cole, Robert S.; Spreadsheets Across the Curruculum; Washington Center; Science Education Resource Center (SERC)

72

Quantum computation and decision trees  

Microsoft Academic Search

Many interesting computational problems can be reformulated in terms of decision trees. A natural classical algorithm is to then run a random walk on the tree, starting at the root, to see if the tree contains a node n level from the root. We devise a quantum-mechanical algorithm that evolves a state, initially localized at the root, through the tree.

Edward Farhi; Sam Gutmann

1998-01-01

73

Random Sampling from B+ Trees  

Microsoft Academic Search

We consider the design and analysis of algorithms to retrieve simple random samples from databases. Specifi- cally, we examine simple random sampling from B+ tree files. Existing methods of sampling from B+ trees, re- quire the use of auxiliary rank information in the nodes of the tree. Such modified B+ tree files are called \\

Frank Olken; Doron Rotem

1989-01-01

74

Oscillation damping in trees.  

PubMed

Oscillation damping is of vital importance for trees to withstand strong gusty winds. Tree adaptation to wind loading takes place over a long time and during a storm only passive damping mechanisms can reduce the impact of the wind on trunk and roots. Structural damping, a phenomenon, which is associated with the conspicuous movements of the branches relative to the trunk is of particular importance. Primary and higher order branches can be seen as multiple tuned mass dampers. Moreover, as the frequency bands overlap within branches and between primary branches and the entire tree, resonance energy transfer can distribute mechanical energy over the entire tree, such that it is dissipated more effectively than in a tree with stiff branches and not so much focused on the tree trunk and the roots. Theoretical studies using modal analysis and finite element methods have supported these assertions. Next to "multiple mass damping" and "multiple resonance damping", both characterized by linear coupling between the elements, a third non linear mode, operative at large amplitudes has been identified: "damping by branching". In all these not mutually exclusive concepts frequency tuning between the elements appears to be a fundamental requisite. PMID:23602100

Spatz, Hanns-Christof; Theckes, Benoit

2013-06-01

75

Tree domestication in tropical agroforestry  

Microsoft Academic Search

We execute tree ‘domestication’ as a farmer-driven and market-led process, which matches the intraspecific diversity of locally\\u000a important trees to the needs of subsistence farmers, product markets, and agricultural environments. We propose that the products\\u000a of such domesticated trees are called Agroforestry Tree Products (AFTPs) to distinguish them from the extractive tree resources\\u000a commonly referred to as non-timber forest products

A. J. Simons; R. R. B. Leakey

2004-01-01

76

Extracting Species Trees From Complex Gene Trees: Reconciled Trees And Vertebrate Phylogeny  

Microsoft Academic Search

Paralogy is a pervasive problem in trying to use nuclear gene sequences to infer species phylogenies. One strategy for dealing with this problem is to infer species phylogenies from gene trees using reconciled trees, rather than directly from the sequences themselves. In this approach, the optimal species tree is the tree that requires the fewest gene duplications to be invoked.

Roderic D. M. Page

2000-01-01

77

Gene tree correction for reconciliation and species tree inference  

PubMed Central

Background Reconciliation is the commonly used method for inferring the evolutionary scenario for a gene family. It consists in “embedding” inferred gene trees into a known species tree, revealing the evolution of the gene family by duplications and losses. When a species tree is not known, a natural algorithmic problem is to infer a species tree from a set of gene trees, such that the corresponding reconciliation minimizes the number of duplications and/or losses. The main drawback of reconciliation is that the inferred evolutionary scenario is strongly dependent on the considered gene trees, as few misplaced leaves may lead to a completely different history, with significantly more duplications and losses. Results In this paper, we take advantage of certain gene trees’ properties in order to preprocess them for reconciliation or species tree inference. We flag certain duplication vertices of a gene tree, the “non-apparent duplication” (NAD) vertices, as resulting from the misplacement of leaves. In the case of species tree inference, we develop a polynomial-time heuristic for removing the minimum number of species leading to a set of gene trees that exhibit no NAD vertices with respect to at least one species tree. In the case of reconciliation, we consider the optimization problem of removing the minimum number of leaves or species leading to a tree without any NAD vertex. We develop a polynomial-time algorithm that is exact for two special classes of gene trees, and show a good performance on simulated data sets in the general case.

2012-01-01

78

Tree Rings: Timekeepers of the Past.  

ERIC Educational Resources Information Center

One of a series of general interest publications on science issues, this booklet describes the uses of tree rings in historical and biological recordkeeping. Separate sections cover the following topics: dating of tree rings, dating with tree rings, tree ring formation, tree ring identification, sample collections, tree ring cross dating, tree

Phipps, R. L.; McGowan, J.

79

Tree Impact Study  

NSDL National Science Digital Library

In this field activity, students document examine the role of a tree in its ecosystem and as part of the environment in a human community. Students measure the tree's dimensions, examine co-residing organisms, leaf litter, and soil, and research the tree's history, using interviews or archival resources. A measuring stick, sturdy string, and an outdoor thermometer are required. An art project concludes the exploration. This activity is supported by a textbook chapter, "A History of Forest use in the Pacific Northwest,â part of the unit, A New World View, in Global Systems Science (GSS), an interdisciplinary course for high school students that emphasizes how scientists from a wide variety of fields work together to understand significant problems of global impact.

80

Trees and Carbon  

NSDL National Science Digital Library

The transport and transformation of substances in the environment are known collectively as biogeochemical cycles. These global cycles involve the circulation of elements and nutrients that sustain both the biological and physical aspects of the environment. As an example, this discussion centers around the carbon cycle and how carbon is sequestered in trees. Students will perform an activity that replicates a case study in which the biomass of trees in a 15-acre plot of forest was calculated to determine the amount of carbon sequestered per acre.

Pratte, John

81

VisTree: Generic Decision Tree Inducer and Visualizer  

Microsoft Academic Search

\\u000a Decision tree is one of the most popular and commonly used technique for predictive modeling. Interpretability and understandability\\u000a makes decision trees an attractive option among various classification induction algorithms. There are several freewares available\\u000a for decision tree induction which can be used in data mining education and practice. However, these freewares have limited\\u000a capability to interactively visualize the induced tree

Vasudha Bhatnagar; Eman Zaman; Yayati Rajpal; Manju Bhardwaj

2010-01-01

82

Bkd-Tree: A Dznamic Scalable kd-Tree  

Microsoft Academic Search

Abstract In this paper we propose a new data structure, called the Bkd - tree, for indexing large multi - dimensional point data sets The Bkd - tree is an I\\/O - efficient dynamic data structure based on the kd - tree We present the results of an extensive experimental study showing that unlike previous attempts on making external versions

Octavian Procopiuc; Pankaj K. Agarwal; Lars Arge; Jeffrey Scott Vitter

2003-01-01

83

Flat Tree Oyster (Isognomon alatus)  

USGS Multimedia Gallery

At high tide, the red bark of the Red Mangrove Trees is submerged, creating a brilliant reflection at the water's surface. Flat Tree Oysters (Isognomon alatus) grow on the upper portions of the roots....

2010-05-03

84

An Introduction to Tree Diagrams  

NSDL National Science Digital Library

This brief article describes the use of tree diagrams in calculating probabilities. The author provides examples of how tree diagrams are used to calculate specific probabilities and why the language chosen relates to the operations used to find the probability.

Cork, Stu

2014-01-01

85

Selecting Superior Yellow Birch Trees.  

National Technical Information Service (NTIS)

The report describes procedures to follow and characteristics to consider in selecting superior yellow birch trees. The first selection should be on the basis of tree quality. Characteristics to consider are as follows: for the stem - straightness, roundn...

K. E. Clausen R. M. Godman

1967-01-01

86

Measure a Tree  

NSDL National Science Digital Library

This activity introduces measurement and scale using hands-on activities. In this activity, students use the concept of similar triangles to determine the height of a tree. This activity is one of several available on an educational poster related to NASA's Space Interferometry Mission.

87

Formal Fault Tree Semantics  

Microsoft Academic Search

In train control systems, more and more (electro-)mechanical devices are substituted by software based devices. To sustain the high level safety standards for these embedded systems, we propose the integration of fault tree analysis and formal methods. This combines two important safety analysis methods from the involved domains of engineering and software development. Our approach proposes to build a formal

Gerhard Schellhorn; Andreas Thums; Wolfgang Reif Lehrstuhl

2002-01-01

88

Christmas Tree Category Manual.  

ERIC Educational Resources Information Center

This manual provides information needed to meet the standards for pesticide applicator certification. Pests and diseases of christmas tree plantations are identified and discussed. Section one deals with weeds and woody plants and the application, formulation and effects of herbicides in controlling them. Section two discusses specific diseases…

Bowman, James S.; Turmel, Jon P.

89

Cherry Trees with Cones?  

Microsoft Academic Search

Statistics students and practitioners may think that they can get away with doing individual t tests instead of a simultaneous test provided that the t values look “insignificant” enough. The trees data set from the Minitab Handbook provides a multiple regression example illustrating how this shortcut can lead to trouble.

David Fairley

1986-01-01

90

DRAFT Wrapping of Trees  

Microsoft Academic Search

We explore the descriptive power, in terms of syn- tactic phenomena, of a formalism that extends Tree- Adjoining Grammar (TAG) by adding a fourth level of hierarchical decomposition to the three levels TAG already employs. While extending the descrip- tive power minimally, the additional level of decom- position allows us to obtain a uniform account of a range of phenomena

James Rogers

91

Giant Sequoia Tree  

NSDL National Science Digital Library

The purpose of this assessment probe is to elicit students' ideas about transformation of matter. The probe is designed to reveal whether students recognize that a gas from the air (carbon dioxide) is combined with water and transformed into the new material that makes up most of the matter of the tree.

Eberle, Francis; Tugel, Joyce; Keeley, Page

2007-01-01

92

Digging Deeper with Trees.  

ERIC Educational Resources Information Center

Describes hands-on science areas that focus on trees. A project on leaf pigmentation involves putting crushed leaves in a test tube with solvent acetone to dissolve pigment. In another project, students learn taxonomy by sorting and classifying leaves based on observable characteristics. Includes a language arts connection. (PVD)

Growing Ideas, 2001

2001-01-01

93

Tree Nut Allergens  

Microsoft Academic Search

Allergic reactions to tree nuts can be serious and life threatening. Considerable research has been conducted in recent years in an attempt to characterize those allergens that are most responsible for allergy sensitization and triggering. Both native and recombinant nut allergens have been identified and characterized and, for some, the IgE-reactive epitopes described. Some allergens, such as lipid transfer proteins,

Kenneth H. Roux; Suzanne S. Teuber; Shridhar K. Sathe

2003-01-01

94

Generating functions for generating trees  

Microsoft Academic Search

Certain families of combinatorial objects admit recursive descriptions in terms of gen- erating trees: each node of the tree corresponds to an object, and the branch leading to the node encodes the choices made in the construction of the object. Generating trees lead to a fast computation of enumeration sequences (sometimes, to explicit formulae as well) and provide efficient random

Cyril Banderier; Mireille Bousquet-mélou; Alain Denise; Philippe Flajolet; Danièle Gardy; Dominique Gouyou-beauchamps

2002-01-01

95

New Life From Dead Trees  

ERIC Educational Resources Information Center

There are numerous bird species that will nest only in dead or dying trees. Current forestry practices include clearing forests of these snags, or dead trees. This practice is driving many species out of the forests. An illustrated example of bird succession in and on a tree is given. (MA)

DeGraaf, Richard M.

1978-01-01

96

Bkd-Tree: A Dynamic Scalable kd-Tree  

Microsoft Academic Search

\\u000a In this paper we propose a new index structure, called the Bkd-tree, for indexing large multi-dimensional point data sets.\\u000a The Bkd-tree is an I\\/O-efficient dynamic data structure based on the kd-tree. We present the results of an extensive experimental\\u000a study showing that unlike previous attempts on making external versions of the kd-tree dynamic, the Bkd-tree maintains its\\u000a high space utilization

Octavian Procopiuc; Pankaj K. Agarwal; Lars Arge; Jeffrey Scott Vitter

97

Geometric tree kernels: classification of COPD from airway tree geometry.  

PubMed

Methodological contributions: This paper introduces a family of kernels for analyzing (anatomical) trees endowed with vector valued measurements made along the tree. While state-of-the-art graph and tree kernels use combinatorial tree/graph structure with discrete node and edge labels, the kernels presented in this paper can include geometric information such as branch shape, branch radius or other vector valued properties. In addition to being flexible in their ability to model different types of attributes, the presented kernels are computationally efficient and some of them can easily be computed for large datasets (N - 10.000) of trees with 30 - 600 branches. Combining the kernels with standard machine learning tools enables us to analyze the relation between disease and anatomical tree structure and geometry. Experimental results: The kernels are used to compare airway trees segmented from low-dose CT, endowed with branch shape descriptors and airway wall area percentage measurements made along the tree. Using kernelized hypothesis testing we show that the geometric airway trees are significantly differently distributed in patients with Chronic Obstructive Pulmonary Disease (COPD) than in healthy individuals. The geometric tree kernels also give a significant increase in the classification accuracy of COPD from geometric tree structure endowed with airway wall thickness measurements in comparison with state-of-the-art methods, giving further insight into the relationship between airway wall thickness and COPD. Software: Software for computing kernels and statistical tests is available at http://image.diku.dk/aasa/software.php. PMID:24683967

Feragen, Aasa; Petersen, Jens; Grimm, Dominik; Dirksen, Asger; Pedersen, Jesper Holst; Borgwardt, Karsten; de Bruijne, Marleen

2013-01-01

98

Binary search trees of bounded balance  

Microsoft Academic Search

A new class of binary search trees, called trees of bounded balance, is introduced. These trees are easy to maintain in their form despite insertions and deletions of nodes, and the search time is only moderately longer than in completely balanced trees. Trees of bounded balance differ from other classes of binary search trees in that they contain a parameter

Jürg Nievergelt; Edward M. Reingold

1972-01-01

99

Neuro-fuzzy decision trees.  

PubMed

Fuzzy decision trees are powerful, top-down, hierarchical search methodology to extract human interpretable classification rules. However, they are often criticized to result in poor learning accuracy. In this paper, we propose Neuro-Fuzzy Decision Trees (N-FDTs); a fuzzy decision tree structure with neural like parameter adaptation strategy. In the forward cycle, we construct fuzzy decision trees using any of the standard induction algorithms like fuzzy ID3. In the feedback cycle, parameters of fuzzy decision trees have been adapted using stochastic gradient descent algorithm by traversing back from leaf to root nodes. With this strategy, during the parameter adaptation stage, we keep the hierarchical structure of fuzzy decision trees intact. The proposed approach of applying backpropagation algorithm directly on the structure of fuzzy decision trees improves its learning accuracy without compromising the comprehensibility (interpretability). The proposed methodology has been validated using computational experiments on real-world datasets. PMID:16496439

Bhatt, Rajen B; Gopal, M

2006-02-01

100

Tree of Life  

NSDL National Science Digital Library

Collaboration by biologists worldwide assembles webpages on diversity of organisms on earth, their evolutionary history, phylogenetic relationships, characteristics. Each group described with introduction, photos, map, key references, important links. Start at Kingdom level and move down to individual species by clicking on branches of the Tree diagram. Designed for biologists familiar with Latin names, but useful for others. Treehouse pages, designed for K-16 learners and teachers, complement technical pages presented elsewhere on the site.

101

Insert tree completion system  

SciTech Connect

This paper outlines the overall project for development and installation of a low-profile, caisson-installed subsea Christmas tree. After various design studies and laboratory and field tests of key components, a system for installation inside a 30-in. conductor was ordered in July 1978 from Cameron Iron Works Inc. The system is designed to have all critical-pressure-containing components below the mudline and, with the reduced profile (height) above seabed, provides for improved safety of satellite underwater wells from damage by anchors, trawl boards, and even icebergs. In addition to the innovative nature of the tree design, the completion includes improved 3 1/2-in. through flowline (TFL) pumpdown completion equipment with deep set safety valves and a dual detachable packer head for simplified workover capability. The all-hydraulic control system incorporates a new design of sequencing valve for both Christmas tree control and remote flowline connection. A semisubmersible drilling rig was used to initiate the first end flowline connection at the wellhead for subsequent tie-in to the prelaid, surface-towed, all-welded subsea pipeline bundle.

Brands, K.W.; Ball, I.G.; Cegielski, E.J.; Gresham, J.S.; Saunders, D.N.

1982-09-01

102

TreeFix: statistically informed gene tree error correction using species trees.  

PubMed

Accurate gene tree reconstruction is a fundamental problem in phylogenetics, with many important applications. However, sequence data alone often lack enough information to confidently support one gene tree topology over many competing alternatives. Here, we present a novel framework for combining sequence data and species tree information, and we describe an implementation of this framework in TreeFix, a new phylogenetic program for improving gene tree reconstructions. Given a gene tree (preferably computed using a maximum-likelihood phylogenetic program), TreeFix finds a "statistically equivalent" gene tree that minimizes a species tree-based cost function. We have applied TreeFix to 2 clades of 12 Drosophila and 16 fungal genomes, as well as to simulated phylogenies and show that it dramatically improves reconstructions compared with current state-of-the-art programs. Given its accuracy, speed, and simplicity, TreeFix should be applicable to a wide range of analyses and have many important implications for future investigations of gene evolution. The source code and a sample data set are available at http://compbio.mit.edu/treefix. PMID:22949484

Wu, Yi-Chieh; Rasmussen, Matthew D; Bansal, Mukul S; Kellis, Manolis

2013-01-01

103

A Novel Approach for Compressing Phylogenetic Trees  

NASA Astrophysics Data System (ADS)

Phylogenetic trees are tree structures that depict relationships between organisms. Popular analysis techniques often produce large collections of candidate trees, which are expensive to store. We introduce TreeZip, a novel algorithm to compress phylogenetic trees based on their shared evolutionary relationships. We evaluate TreeZip's performance on fourteen tree collections ranging from 2,505 trees on 328 taxa to 150,000 trees on 525 taxa corresponding to 0.6 MB to 434 MB in storage. Our results show that TreeZip is very effective, typically compressing a tree file to less than 2% of its original size. When coupled with standard compression methods such as 7zip, TreeZip can compress a file to less than 1% of its original size. Our results strongly suggest that TreeZip is very effective at compressing phylogenetic trees, which allows for easier exchange of data with colleagues around the world.

Matthews, Suzanne J.; Sul, Seung-Jin; Williams, Tiffani L.

104

From event-labeled gene trees to species trees  

PubMed Central

Background Tree reconciliation problems have long been studied in phylogenetics. A particular variant of the reconciliation problem for a gene tree T and a species tree S assumes that for each interior vertex x of T it is known whether x represents a speciation or a duplication. This problem appears in the context of analyzing orthology data. Results We show that S is a species tree for T if and only if S displays all rooted triples of T that have three distinct species as their leaves and are rooted in a speciation vertex. A valid reconciliation map can then be found in polynomial time. Simulated data shows that the event-labeled gene trees convey a large amount of information on underlying species trees, even for a large percentage of losses. Conclusions The knowledge of event labels in a gene tree strongly constrains the possible species tree and, for a given species tree, also the possible reconciliation maps. Nevertheless, many degrees of freedom remain in the space of feasible solutions. In order to disambiguate the alternative solutions additional external constraints as well as optimization criteria could be employed.

2012-01-01

105

Alignment of Trees - An Alternative to Tree Edit  

Microsoft Academic Search

In this paper, we propose the alignment of trees as a measure of the similarity between two labeled trees. Both ordered and unordered trees are considered. An algorithm is designed for ordered trees. The time complexity of this algorithm is O(¦T\\u000a1¦· s¦T\\u000a2· (deg(T\\u000a1) + deg(T\\u000a2))2), where ¦T\\u000ai¦ is the number of nodes in T\\u000a\\u000ai

Tao Jiang; Lusheng Wang; Kaizhong Zhang

1994-01-01

106

Exploring Trees and Ponds  

NSDL National Science Digital Library

Trees and Ponds is a collection of activities to be implemented with middle school youth in out-of-school environments. The website provides a rationale and goal of the activities, curriculum activities and resources such as relevant digital photos. Available for free as downloadable PDFs, these activities provide a structure for youth in out-of-school programs to carry out long-term observations of natural objects. This project uses a qualitative approach, where changes over time are studied, recorded (by youth through writing, drawing, and digital photography), and discussed.

107

Redrawing Humanity's Family Tree  

NSDL National Science Digital Library

This New York Times article details two skulls, one from central Africa and the other from the Black Sea republic of Georgia, that "have shaken the human family tree to its roots, sending scientists scrambling to see if their favorite theories are among the fallen fruit." The article discusses how the two skulls have caused scientists to rethink not only how we conceive of human evolution and its chain of events, but even the geography of evolution and migration patterns of very early humans.

Wilford, John N.

1969-12-31

108

Clustering with shallow trees  

NASA Astrophysics Data System (ADS)

We propose a new method for obtaining hierarchical clustering based on the optimization of a cost function over trees of limited depth, and we derive a message-passing method that allows one to use it efficiently. The method and the associated algorithm can be interpreted as a natural interpolation between two well-known approaches, namely that of single linkage and the recently presented affinity propagation. We analyse using this general scheme three biological/medical structured data sets (human population based on genetic information, proteins based on sequences and verbal autopsies) and show that the interpolation technique provides new insight.

Bailly-Bechet, M.; Bradde, S.; Braunstein, A.; Flaxman, A.; Foini, L.; Zecchina, R.

2009-12-01

109

Project Learning Tree  

NSDL National Science Digital Library

Project Learning Tree is a national environmental education program containing a series of learning modules with inquiry-oriented activities for K-12 students and educators that address current environmental topics and issues. These topics range from forests, wildlife and water to community planning, waste management and energy. The materials correlate with the national environmental education performance standards. The curriculum is available for a fee; materials must be ordered or obtained by attending a professional development workshop. The newsletter and an environmental action project guide are free.

110

A Tree of Genetic Traits  

NSDL National Science Digital Library

Learners mark their traits for tongue rolling, PTC tasting (a harmless, bitter chemical), and earlobe attachment on tree leaf cut-outs. They then place their leaves on a large tree with branches, in which each each branch represents a different combination of traits. When completed, the tree forms a visual representation of the frequency of trait combinations within the group. Included are handouts in English and Spanish. This resource also contains information about PTC safety.

Malone, Molly; Starr, Harmony; Mitchell, April

2006-01-01

111

Decision trees: a recent overview  

Microsoft Academic Search

Decision tree techniques have been widely used to build classification models as such models closely resemble human reasoning\\u000a and are easy to understand. This paper describes basic decision tree issues and current research points. Of course, a single\\u000a article cannot be a complete review of all algorithms (also known induction classification trees), yet we hope that the references\\u000a cited will

S. B. Kotsiantis

112

Fault trees and sequence dependencies  

Microsoft Academic Search

One of the frequency cited shortcomings of fault-tree models, their inability to model so-called sequence dependencies, is discussed. Several sources of such sequence dependencies are discussed, and new fault-tree gates to capture this behavior are defined. These complex behaviors can be included in present fault-tree models because they utilize a Markov solution. The utility of the new gates is demonstrated

Joanne Bechta Dugan; Salvatore J. Bavuso; Mark A. Boyd

1990-01-01

113

Compositional Temporal Fault Tree Analysis  

Microsoft Academic Search

HiP-HOPS (Hierarchically-Performed Hazard Origin and Propaga- tion Studies) is a recent technique that partly automates Fault Tree Analysis (FTA) by constructing fault trees from system topologies annotated with component-level failure specifications. HiP-HOPS has hitherto created only classical combinatorial fault trees that fail to capture the often significant temporal ordering of failure events. In this paper, we propose temporal extensions to

Martin Walker; Leonardo Bottaci; Yiannis Papadopoulos

2007-01-01

114

Human decision error (HUMDEE) trees  

SciTech Connect

Graphical presentations of human actions in incident and accident sequences have been used for many years. However, for the most part, human decision making has been underrepresented in these trees. This paper presents a method of incorporating the human decision process into graphical presentations of incident/accident sequences. This presentation is in the form of logic trees. These trees are called Human Decision Error Trees or HUMDEE for short. The primary benefit of HUMDEE trees is that they graphically illustrate what else the individuals involved in the event could have done to prevent either the initiation or continuation of the event. HUMDEE trees also present the alternate paths available at the operator decision points in the incident/accident sequence. This is different from the Technique for Human Error Rate Prediction (THERP) event trees. There are many uses of these trees. They can be used for incident/accident investigations to show what other courses of actions were available and for training operators. The trees also have a consequence component so that not only the decision can be explored, also the consequence of that decision.

Ostrom, L.T.

1993-08-01

115

Semi-Supervised Learning with Trees  

Microsoft Academic Search

We describe a nonparametric Bayesian approach to generalizing from few labeled examples, guided by a larger set of unlabeled objects and the assumption of a latent tree-structure to the domain. The tree (or a distribution over trees) may be inferred using the unlabeled data. A prior over concepts generated by a mutation process on the inferred tree(s) allows efficient computation

Charles Kemp; Thomas L. Griffiths; Sean Stromsten; Joshua B. Tenenbaum

2003-01-01

116

CartograTree: connecting tree genomes, phenotypes and environment.  

PubMed

Today, researchers spend a tremendous amount of time gathering, formatting, filtering and visualizing data collected from disparate sources. Under the umbrella of forest tree biology, we seek to provide a platform and leverage modern technologies to connect biotic and abiotic data. Our goal is to provide an integrated web-based workspace that connects environmental, genomic and phenotypic data via geo-referenced coordinates. Here, we connect the genomic query web-based workspace, DiversiTree and a novel geographical interface called CartograTree to data housed on the TreeGenes database. To accomplish this goal, we implemented Simple Semantic Web Architecture and Protocol to enable the primary genomics database, TreeGenes, to communicate with semantic web services regardless of platform or back-end technologies. The novelty of CartograTree lies in the interactive workspace that allows for geographical visualization and engagement of high performance computing (HPC) resources. The application provides a unique tool set to facilitate research on the ecology, physiology and evolution of forest tree species. CartograTree can be accessed at: http://dendrome.ucdavis.edu/cartogratree. PMID:23433187

Vasquez-Gross, Hans A; Yu, John J; Figueroa, Ben; Gessler, Damian D G; Neale, David B; Wegrzyn, Jill L

2013-05-01

117

Do Invasive Trees have a Hydraulic Advantage over Native Trees?  

Microsoft Academic Search

The hypothesis was tested that invasive trees have hydraulic traits that contribute to their invasive nature. Five pairs of co-occurring invasive and native trees, in mesic habitats, were selected: (1) Tamarix ramosissima and Salix amygdaloides; (2) Robinia pseudoacacia and Alnus rhombifolia (3) Schinus terebinthifolius and Myrica cerifera; (4) Ligustrum sinense and Acer negundo; and (5) Sapium sebiferum and Diospyros virginiana,

R B Pratt; R A Black

2006-01-01

118

Relating phylogenetic trees to transmission trees of infectious disease outbreaks.  

PubMed

Transmission events are the fundamental building blocks of the dynamics of any infectious disease. Much about the epidemiology of a disease can be learned when these individual transmission events are known or can be estimated. Such estimations are difficult and generally feasible only when detailed epidemiological data are available. The genealogy estimated from genetic sequences of sampled pathogens is another rich source of information on transmission history. Optimal inference of transmission events calls for the combination of genetic data and epidemiological data into one joint analysis. A key difficulty is that the transmission tree, which describes the transmission events between infected hosts, differs from the phylogenetic tree, which describes the ancestral relationships between pathogens sampled from these hosts. The trees differ both in timing of the internal nodes and in topology. These differences become more pronounced when a higher fraction of infected hosts is sampled. We show how the phylogenetic tree of sampled pathogens is related to the transmission tree of an outbreak of an infectious disease, by the within-host dynamics of pathogens. We provide a statistical framework to infer key epidemiological and mutational parameters by simultaneously estimating the phylogenetic tree and the transmission tree. We test the approach using simulations and illustrate its use on an outbreak of foot-and-mouth disease. The approach unifies existing methods in the emerging field of phylodynamics with transmission tree reconstruction methods that are used in infectious disease epidemiology. PMID:24037268

Ypma, Rolf J F; van Ballegooijen, W Marijn; Wallinga, Jacco

2013-11-01

119

Two Trees: Migrating Fault Trees to Decision Trees for Real Time Fault Detection on International Space Station  

NASA Technical Reports Server (NTRS)

We started from ISS fault trees example to migrate to decision trees, presented a method to convert fault trees to decision trees. The method shows that the visualizations of root cause of fault are easier and the tree manipulating becomes more programmatic via available decision tree programs. The visualization of decision trees for the diagnostic shows a format of straight forward and easy understands. For ISS real time fault diagnostic, the status of the systems could be shown by mining the signals through the trees and see where it stops at. The other advantage to use decision trees is that the trees can learn the fault patterns and predict the future fault from the historic data. The learning is not only on the static data sets but also can be online, through accumulating the real time data sets, the decision trees can gain and store faults patterns in the trees and recognize them when they come.

Lee, Charles; Alena, Richard L.; Robinson, Peter

2004-01-01

120

Tree Hydraulics: How Sap Rises  

ERIC Educational Resources Information Center

Trees transport water from roots to crown--a height that can exceed 100 m. The physics of tree hydraulics can be conveyed with simple fluid dynamics based upon the Hagen-Poiseuille equation and Murray's law. Here the conduit structure is modelled as conical pipes and as branching pipes. The force required to lift sap is generated mostly by…

Denny, Mark

2012-01-01

121

Mixtures of (Constrained) Ultrametric Trees.  

ERIC Educational Resources Information Center

Presents a method for the estimation of ultrametric trees calibrated on subjects' pairwise proximity judgments of stimuli, capturing subject heterogeneity using a finite mixture formulation. An empirical example from published data shows the ability to deal with external constraints on the tree topology. (Author/SLD)

Wedel, Michel; DeSarbo, Wayne S.

1998-01-01

122

Genome Trees from Conservation Profiles  

PubMed Central

The concept of the genome tree depends on the potential evolutionary significance in the clustering of species according to similarities in the gene content of their genomes. In this respect, genome trees have often been identified with species trees. With the rapid expansion of genome sequence data it becomes of increasing importance to develop accurate methods for grasping global trends for the phylogenetic signals that mutually link the various genomes. We therefore derive here the methodological concept of genome trees based on protein conservation profiles in multiple species. The basic idea in this derivation is that the multi-component “presence-absence” protein conservation profiles permit tracking of common evolutionary histories of genes across multiple genomes. We show that a significant reduction in informational redundancy is achieved by considering only the subset of distinct conservation profiles. Beyond these basic ideas, we point out various pitfalls and limitations associated with the data handling, paving the way for further improvements. As an illustration for the methods, we analyze a genome tree based on the above principles, along with a series of other trees derived from the same data and based on pair-wise comparisons (ancestral duplication-conservation and shared orthologs). In all trees we observe a sharp discrimination between the three primary domains of life: Bacteria, Archaea, and Eukarya. The new genome tree, based on conservation profiles, displays a significant correspondence with classically recognized taxonomical groupings, along with a series of departures from such conventional clusterings.

Tekaia, Fredj; Yeramian, Edouard

2005-01-01

123

Electrical Treeing in Polymer Nanocomposites  

Microsoft Academic Search

This paper presents a study of electrical treeing phenomena in polymer nanocomposites. The polymer nanocomposite studied consists of epoxy resin as the base polymer and silica as the nano filler. Treeing experiments were conducted at a constant ac voltage of 20kV, 50Hz on epoxy samples without any fillers as well as epoxy silica nano composites with 1% by weight of

Sridhar Alapati; M. Joy Thomas

2008-01-01

124

Looking/Learning Drawing: Trees.  

ERIC Educational Resources Information Center

Secondary students are asked to study and compare three reproductions--Van Gogh's "Grove of Cypresses," Da Vinci's "Study of a Tree," and Mondrian's "Tree II." The activity will help students develop their powers of observation and analysis, powers that can be applied to their own drawings. (RM)

Hurwitz, Al; Blume, Sharon

1985-01-01

125

Orderly Spanning Trees with Applications  

Microsoft Academic Search

We introduce and study orderly spanning trees of plane graphs. This algorithmic tool generalizes canonical orderings, which exist only for triconnected plane graphs. Although not every plane graph admits an orderly spanning tree, we provide an algorithm to compute an orderly pair for any connected planar graph G, consisting of an embedded planar graph H isomorphic to G, and an

Yi-Ting Chiang; Ching-Chi Lin; Hsueh-I Lu

2001-01-01

126

Communism in trees goes underground  

NSDL National Science Digital Library

This news article reports that some trees give their neighbors carbon that they have captured from the atmosphere. Scientists discovered that shade enhances a tree's ability to receive and that carbon appears to travel via a subterranean web formed by a common group of fungi. The article concludes with references and sources (with contact information).

Strauss, E.; Online, Science N.

127

Constructing Trees for Region Description.  

National Technical Information Service (NTIS)

A thresholded (binary) image can be represented as a region tree in which each node corresponds to a component of 1's (object) or 0's (background). If regions O and B share a border, then one encloses the other. This enclosure relation defines the tree. T...

D. L. Milgram

1977-01-01

128

Tree preserving embedding  

PubMed Central

The goal of dimensionality reduction is to embed high-dimensional data in a low-dimensional space while preserving structure in the data relevant to exploratory data analysis such as clusters. However, existing dimensionality reduction methods often either fail to separate clusters due to the crowding problem or can only separate clusters at a single resolution. We develop a new approach to dimensionality reduction: tree preserving embedding. Our approach uses the topological notion of connectedness to separate clusters at all resolutions. We provide a formal guarantee of cluster separation for our approach that holds for finite samples. Our approach requires no parameters and can handle general types of data, making it easy to use in practice and suggesting new strategies for robust data visualization.

Shieh, Albert D.; Hashimoto, Tatsunori B.; Airoldi, Edoardo M.

2011-01-01

129

A Cost Benefit Analysis of Urban Trees  

SciTech Connect

Urban shade trees offer significant benefits in reducing building air- conditioning and improving urban air quality by reducing smog. The savings associated with these benefits varies by climate regions and can be up to $200 per tree. The cost of planting trees and maintaining them can vary from $10 to $500 per tree. Tree planting programs can be designed offer savings to communities that plant trees.

Akbari, Hashem

1997-09-01

130

Terrestrial apes and phylogenetic trees  

PubMed Central

The image that best expresses Darwin’s thinking is the tree of life. However, Darwin’s human evolutionary tree lacked almost everything because only the Neanderthals were known at the time and they were considered one extreme expression of our own species. Darwin believed that the root of the human tree was very deep and in Africa. It was not until 1962 that the root was shown to be much more recent in time and definitively in Africa. On the other hand, some neo-Darwinians believed that our family tree was not a tree, because there were no branches, but, rather, a straight stem. The recent years have witnessed spectacular discoveries in Africa that take us close to the origin of the human tree and in Spain at Atapuerca that help us better understand the origin of the Neanderthals as well as our own species. The final form of the tree, and the number of branches, remains an object of passionate debate.

Arsuaga, Juan Luis

2010-01-01

131

Fault trees and sequence dependencies  

NASA Technical Reports Server (NTRS)

One of the frequently cited shortcomings of fault-tree models, their inability to model so-called sequence dependencies, is discussed. Several sources of such sequence dependencies are discussed, and new fault-tree gates to capture this behavior are defined. These complex behaviors can be included in present fault-tree models because they utilize a Markov solution. The utility of the new gates is demonstrated by presenting several models of the fault-tolerant parallel processor, which include both hot and cold spares.

Dugan, Joanne Bechta; Boyd, Mark A.; Bavuso, Salvatore J.

1990-01-01

132

Tree-growth analyses to estimate tree species' drought tolerance.  

PubMed

Climate change is challenging forestry management and practices. Among other things, tree species with the ability to cope with more extreme climate conditions have to be identified. However, while environmental factors may severely limit tree growth or even cause tree death, assessing a tree species' potential for surviving future aggravated environmental conditions is rather demanding. The aim of this study was to find a tree-ring-based method suitable for identifying very drought-tolerant species, particularly potential substitute species for Scots pine (Pinus sylvestris L.) in Valais. In this inner-Alpine valley, Scots pine used to be the dominating species for dry forests, but today it suffers from high drought-induced mortality. We investigate the growth response of two native tree species, Scots pine and European larch (Larix decidua Mill.), and two non-native species, black pine (Pinus nigra Arnold) and Douglas fir (Pseudotsuga menziesii Mirb. var. menziesii), to drought. This involved analysing how the radial increment of these species responded to increasing water shortage (abandonment of irrigation) and to increasingly frequent drought years. Black pine and Douglas fir are able to cope with drought better than Scots pine and larch, as they show relatively high radial growth even after irrigation has been stopped and a plastic growth response to drought years. European larch does not seem to be able to cope with these dry conditions as it lacks the ability to recover from drought years. The analysis of trees' short-term response to extreme climate events seems to be the most promising and suitable method for detecting how tolerant a tree species is towards drought. However, combining all the methods used in this study provides a complete picture of how water shortage could limit species. PMID:22363071

Eilmann, Britta; Rigling, Andreas

2012-02-01

133

Trees, networks and optimality  

NASA Astrophysics Data System (ADS)

Theoretical and observational material on form and function of natural networks appeared in somewhat disparate contexts from physics to biology is critically reviewed. Moving from the exact result that drainage network configurations minimizing total energy dissipation are stationary solutions of the general equation describing landscape evolution, the properties and the dynamic origin of the scale-invariant structure of river patterns are discussed in relation to optimal selection. It is argued that at least in the fluvial landscape Nature works through imperfect searches for dynamically accessible optimal configurations and that purely random or deterministic constructs are clearly unsuitable to properly describe natural network forms. We also show that optimal networks are spanning loopless configurations only under precise physical requirements that arise under the constraints imposed by continuity. In the case of rivers, every spanning tree proves a local minimum of total energy dissipation. This is stated in a theorem form applicable to generic networks, suggesting that other branching structures occurring in nature (e.g., scale-free and looping) may possibly arise through optimality to different selective pressures. It is thus suggested that one recurrent self- organized mechanism for the dynamic origin of fractal forms is the robust strive for imperfect optimality that it is observed in many natural patterns, chief and foremost hydrologic ones.

Rinaldo, A.

2008-12-01

134

Reflecticons: Trees of a City.  

ERIC Educational Resources Information Center

Describes a four week artist-in-residence program called "Reflecticons: Trees of a City." Using handmade paper, the children of Kaukauna (Wisconsin) explored the heritage, development, and growth of their community from the 1700s to the present. (CMK)

Hoglund, Paula Stevenson

1999-01-01

135

Tree of Life Workshop Report  

NSF Publications Database

... Development meets Tree Of Life What are the most exciting questions in the Evolution of Development ... the key questions about the Evolution of Development? How does the community exploit these increased ...

136

Syntactic Structures as Multidimensional Trees  

Microsoft Academic Search

We survey a sequence of results relating model-theoretic and language-theoreticdefinability over an infinite hierarchy of multi-dimensional tree-like structures and explore their applications to a corresponding range of theoriesof syntax. We discuss, in particular, results for Government and Binding Theory(GB), Tree-Adjoining Grammar (TAG) and Generalized Phrase-Structure Grammar(GPSG) along with a generalized version of TAG extending TAG in much the sameway that

James Rogers

2003-01-01

137

On packing R-trees  

Microsoft Academic Search

We propose new R-tree packing techniques for static databases. Given a collection of rectangles, we sort them and build the R-tree bottom-up. There are several ways to sort the rectangles; the innovation of this work is the use of fractals, and specifically the hilbert curve, to achieve better ordering of the rectangles and eventually better pack- ing. We proposed and

Ibrahim Kamel; Christos Faloutsos

1993-01-01

138

Fault Tree Analysis: A Bibliography  

NASA Technical Reports Server (NTRS)

Fault tree analysis is a top-down approach to the identification of process hazards. It is as one of the best methods for systematically identifying an graphically displaying the many ways some things can go wrong. This bibliography references 266 documents in the NASA STI Database that contain the major concepts. fault tree analysis, risk an probability theory, in the basic index or major subject terms. An abstract is included with most citations, followed by the applicable subject terms.

2000-01-01

139

Water in the trunk of a tree  

NSDL National Science Digital Library

Every December, people cut down pine trees and other evergreens and stick them in their houses. The trees start sucking up water right away (unless you wait too long between cutting the tree and putting it in water, of course). A new study helps to explain how the heck water moves up the trunk of cone-making trees called "conifers."

American Association for the Advancement of Science (AAAS;)

2005-12-22

140

Modular approach to fault tree analysis  

Microsoft Academic Search

An analytical method to describe fault tree diagrams in terms of their modular composition is developed. Fault tree structures are characterized by recursively relating the top tree event to all its basic component inputs through a set of equations defining each of the modules for the fault tree. It is shown that such a modular description is an extremely valuable

J. Olmes; L. Wolf

1977-01-01

141

Sensitivity analysis of modular dynamic fault trees  

Microsoft Academic Search

Dynamic fault tree analysis, as currently supported by the Galileo software package, provides an effective means for assessing the reliability of embedded computer-based systems. Dynamic fault trees extend traditional fault trees by defining special gates to capture sequential and functional dependency characteristics. A modular approach to the solution of dynamic fault trees effectively applies Binary Decision Diagram (BOD) and Markov

Yong Ou; Joanne Bechta Dugan

2000-01-01

142

Locating Multiple Gene Duplications through Reconciled Trees  

Microsoft Academic Search

We introduce the first exact and efficient algorithm for Guig´ o et al.'s problem that, given a collection of rooted, binary gene trees and a rooted, binary species tree, determines a minimum number of locations for gene duplication events from the gene trees on the species tree. We examined the performance of our algorithm using a set of 85 gene

J. Gordon Burleigh; Mukul S. Bansal; André Wehe; Oliver Eulenstein

2008-01-01

143

Generic physical protection logic trees  

SciTech Connect

Generic physical protection logic trees, designed for application to nuclear facilities and materials, are presented together with a method of qualitative evaluation of the trees for design and analysis of physical protection systems. One or more defense zones are defined where adversaries interact with the physical protection system. Logic trees that are needed to describe the possible scenarios within a defense zone are selected. Elements of a postulated or existing physical protection system are tagged to the primary events of the logic tree. The likelihood of adversary success in overcoming these elements is evaluated on a binary, yes/no basis. The effect of these evaluations is propagated through the logic of each tree to determine whether the adversary is likely to accomplish the end event of the tree. The physical protection system must be highly likely to overcome the adversary before he accomplishes his objective. The evaluation must be conducted for all significant states of the site. Deficiencies uncovered become inputs to redesign and further analysis, closing the loop on the design/analysis cycle.

Paulus, W.K.

1981-10-01

144

If a Tree Falls in the Forest ...  

NSDL National Science Digital Library

This activity has students explore the role that forests play in their own lives by listing everyday products made from trees. They use the Internet to find as many uses for trees as possible in order to develop a class list that should include foods from trees, products derived from all parts of a tree, environmental benefits of trees, and recreational uses of trees. Students are then asked to imagine a day in their lives without trees and consider how their routine would differ and how their environment would change. This site also contains ideas for assessment and ways of extending the lesson.

145

Hi-trees and their layout.  

PubMed

We introduce hi-trees, a new visual representation for hierarchical data in which, depending on the kind of parent node, the child relationship is represented using either containment or links. We give a drawing convention for hi-trees based on the standard layered drawing convention for rooted trees, then show how to extend standard bottom-up tree layout algorithms to draw hi-trees in this convention. We also explore a number of other more compact layout styles for layout of larger hi-trees and give algorithms for computing these. Finally, we describe two applications of hi-trees: argument mapping and business decision support. PMID:21233514

Marriott, Kim; Sbarski, Peter; van Gelder, Tim; Prager, Daniel; Bulka, Andy

2011-03-01

146

Mechanisms of Resistance in Trees to Defoliators  

Microsoft Academic Search

At least 10 mechanisms are known to be important in resistance of trees to insect defoliators: 1) Phonological asynchrony\\u000a between host trees and insect herbivores; 2) Host tree tolerance of defoliation, which is linked to host tree vigor; 3) Host\\u000a tree compensatory photosynthesis and growth in response to defoliation; 4) Toughness of leaves and needles; 5) Low nutritive\\u000a quality of

Karen M. Clancy

147

On Straightening Low-Diameter Unit Trees  

Microsoft Academic Search

\\u000a A polygonal chain is a sequence of consecutively joined edges embedded in space. A k-chain is a chain of k edges. A polygonal tree is a set of edges joined into a tree structure embedded in space. A unit tree is a tree with only edges of unit length. A chain or a tree is simple if non-adjacent edges do

Sheung-hung Poon

2005-01-01

148

Ray tracing with the BSP tree  

Microsoft Academic Search

One of the most fundamental concepts in computer graphics is binary space subdivision. In its purest form, this concept leads to binary space partitioning trees (BSP trees) with arbitrarily oriented space partitioning planes. In practice, however, most algorithms use kd-trees-a special case of BSP trees that restrict themselves to axis-aligned planes-since BSP trees are believed to be numerically unstable, costly

Thiago Ize; Ingo Wald; S. G. Parker

2008-01-01

149

Sussing Merger Trees: The Merger Trees Comparison Project  

NASA Astrophysics Data System (ADS)

Merger trees follow the growth and merger of dark-matter haloes over cosmic history. As well as giving important insights into the growth of cosmic structure in their own right, they provide an essential backbone to semi-analytic models of galaxy formation. This paper is the first in a series to arise from the Sussing Merger Trees Workshop in which 10 different tree-building algorithms were applied to the same set of halo catalogues and their results compared. Although many of these codes were similar in nature, all algorithms produced distinct results. Our main conclusions are that a useful merger-tree code should possess the following features: (i) the use of particle IDs to match haloes between snapshots; (ii) the ability to skip at least one, and preferably more, snapshots in order to recover subhaloes that are temporarily lost during merging; (iii) the ability to cope with (and ideally smooth out) large, temporary fluctuations in halo mass. Finally, to enable different groups to communicate effectively, we defined a common terminology that we used when discussing merger trees and we encourage others to adopt the same language. We also specified a minimal output format to record the results.

Srisawat, Chaichalit; Knebe, Alexander; Pearce, Frazer R.; Schneider, Aurel; Thomas, Peter A.; Behroozi, Peter; Dolag, Klaus; Elahi, Pascal J.; Han, Jiaxin; Helly, John; Jing, Yipeng; Jung, Intae; Lee, Jaehyun; Mao, Yao-Yuan; Onions, Julian; Rodriguez-Gomez, Vicente; Tweed, Dylan; Yi, Sukyoung K.

2013-11-01

150

Genealogical trees from genetic distances  

NASA Astrophysics Data System (ADS)

In a population with haploid reproduction any individual has a single parent in the previous generation. If all genealogical distances among pairs of individuals (generations from the closest common ancestor) are known it is possible to exactly reconstruct their genealogical tree. Unfortunately, in most cases, genealogical distances are unknown and only genetic distances are available. The genetic distance between two individuals is measurable from differences in mtDNA (mitochondrial DNA) since in the case of humans or other complex organisms mtDNA is transmitted in a haploid manner. An analogous distance can be also computed for languages where it may be measured from lexical differences, in this case, nevertheless, haploid reproduction is only a raw approximation. Assuming a constant rate of mutation, these genetic distances are random and proportional only on average to genealogical ones. The reconstruction of the genealogical tree from the available genetic distances is forceful imprecise. In this paper we try to quantify the error one may commit in the reconstruction of the tree for different degrees of randomness. The errors may concern both topology of the tree (the branching hierarchy) and, in case of correct topology, the proportions of the tree (length of various branches).

Prignano, L.; Serva, M.

2009-06-01

151

Nitrogen nutrition of poplar trees.  

PubMed

Many forest ecosystems have evolved at sites with growth-limiting nitrogen (N) availability, low N input from external sources and high ecosystem internal cycling of N. By contrast, many poplar species are frequent constituents of floodplain forests where they are exposed to a significant ecosystem external supply of N, mainly nitrate, in the moving water table. Therefore, nitrate is much more important for N nutrition of these poplar species than for many other tree species. We summarise current knowledge of nitrate uptake and its regulation by tree internal signals, as well as acquisition of ammonium and organic N from the soil. Unlike herbaceous plants, N nutrition of trees is sustained by seasonal, tree internal cycling. Recent advances in the understanding of seasonal storage and mobilisation in poplar bark and regulation of these processes by temperature and daylength are addressed. To explore consequences of global climate change on N nutrition of poplar trees, responses of N uptake and metabolism to increased atmospheric CO(2) and O(3) concentrations, increased air and soil temperatures, drought and salt stress are highlighted. PMID:20398235

Rennenberg, H; Wildhagen, H; Ehlting, B

2010-03-01

152

Transport of Methane in Trees  

NASA Astrophysics Data System (ADS)

Although overall methane (CH4) emissions for croplands, wetlands, and forests have been measured, the exact dynamics of CH4 transport through trees is not well understood. What roles transport mechanisms play in emission rates has been thoroughly investigated for rice, but is fairly unknown for trees. Better defined plant transport mechanisms yield more accurate determination of greenhouse gas flux and its variations, contributing to a comprehensive theory quantifying greenhouse gas emissions globally. CH4 emissions from the common wetland tree species black cottonwood (Populus trichocarpa) native to the Pacific Northwest have been measured under hydroponic conditions in order to separate plant transport processes from the influence of soil processes. Canopy emissions of CH4 have been measured via canopy enclosure. Measurements of CH4 flux from each of 16 trees have indicated that emissions are normally constant over the half-hour sampling period. Samples for stable carbon isotope composition have been taken during these experiments and measured on a mass spectrometer. Compared to the isotopic composition of root water CH4, canopy CH4 is depleted in 13C; this indicates that CH4 moving through the tree is not following a bulk flow pathway (where no depletion would occur), but instead moves either diffusively or through other cell or tissue barriers. No correlation was found to exist between leaf area and CH4 emission; this is vital to upscaling tree-level emissions to the global scale since leaf area index (LAI) cannot be treated as an appropriate parameter to upscale flux. Correctly informing global-scale CH4 fluxes from plants requires an association between the role plant physiology plays in the production and transport of CH4 and magnitudes of flux. This research was supported by the Office of Science (BER), U. S. Department of Energy, Grant No. DE-FG02-08ER64515. Supported in part through NASA / Oregon Space Grant Consortium, grant NNG05GJ85H.

Kutschera, E.; Khalil, A. K.; Shearer, M. J.; Rosenstiel, T.; Rice, A. L.

2011-12-01

153

Trees, soils, and food security  

PubMed Central

Trees have a different impact on soil properties than annual crops, because of their longer residence time, larger biomass accumulation, and longer-lasting, more extensive root systems. In natural forests nutrients are efficiently cycled with very small inputs and outputs from the system. In most agricultural systems the opposite happens. Agroforestry encompasses the continuum between these extremes, and emerging hard data is showing that successful agroforestry systems increase nutrient inputs, enhance internal flows, decrease nutrient losses and provide environmental benefits: when the competition for growth resources between the tree and the crop component is well managed. The three main determinants for overcoming rural poverty in Africa are (i) reversing soil fertility depletion, (ii) intensifying and diversifying land use with high-value products, and (iii) providing an enabling policy environment for the smallholder farming sector. Agroforestry practices can improve food production in a sustainable way through their contribution to soil fertility replenishment. The use of organic inputs as a source of biologically-fixed nitrogen, together with deep nitrate that is captured by trees, plays a major role in nitrogen replenishment. The combination of commercial phosphorus fertilizers with available organic resources may be the key to increasing and sustaining phosphorus capital. High-value trees, 'Cinderella' species, can fit in specific niches on farms, thereby making the system ecologically stable and more rewarding economically, in addition to diversifying and increasing rural incomes and improving food security. In the most heavily populated areas of East Africa, where farm size is extremely small, the number of trees on farms is increasing as farmers seek to reduce labour demands, compatible with the drift of some members of the family into the towns to earn off-farm income. Contrary to the concept that population pressure promotes deforestation, there is evidence that demonstrates that there are conditions under which increasing tree planting is occurring on farms in the tropics through successful agroforestry as human population density increases.

Sanchez, P. A.; Buresh, R. J.; Leakey, R. R. B.

1997-01-01

154

Interpreting the universal phylogenetic tree.  

PubMed

The universal phylogenetic tree not only spans all extant life, but its root and earliest branchings represent stages in the evolutionary process before modern cell types had come into being. The evolution of the cell is an interplay between vertically derived and horizontally acquired variation. Primitive cellular entities were necessarily simpler and more modular in design than are modern cells. Consequently, horizontal gene transfer early on was pervasive, dominating the evolutionary dynamic. The root of the universal phylogenetic tree represents the first stage in cellular evolution when the evolving cell became sufficiently integrated and stable to the erosive effects of horizontal gene transfer that true organismal lineages could exist. PMID:10900003

Woese, C R

2000-07-18

155

Rhabdomyosarcoma of the biliary tree.  

PubMed

Rhabdomyosarcoma (RMS) of the biliary tree is a rare tumor in children that has a very poor prognosis. Preoperatively, it is often mistaken for a choledochal cyst. We report a case of RMS of the biliary tree in a 4-year-old girl who presented with abdominal pain and obstructive jaundice. The RMS was diagnosed at laparotomy; excision was not possible due to its size and localization. Chemotherapy achieved complete regression of the tumor observed at second-look surgery. Preoperative chemotherapy can now avoid mutilating surgical procedures and improve survival. PMID:9156861

Sanz, N; de Mingo, L; Flórez, F; Rollán, V

1997-02-01

156

Water Transport in Trees--An Artificial Laboratory Tree  

ERIC Educational Resources Information Center

Water transport in tall trees is an everyday phenomenon, seldom noticed and not completely understood even by scientists. As a topic of current research in plant physiology it has several advantages for presentation within school physics lectures: it is interdisciplinary and clearly shows the connection between physics and biology; the…

Susman, K.; Razpet, N.; Cepic, M.

2011-01-01

157

Tree Height Calculator: An Android App for Estimating Tree Height  

NASA Astrophysics Data System (ADS)

Conventionally, measuring tree height requires a collection of different tools - clinometer, transit, pencil, paper, laptop computer. Results are recorded manually and entered into a spreadsheet or database for future calculation and analysis. Tree Height Calculator is a mobile Android app the integrates the various steps in this process thereby improving the accuracy and dramatically reducing the time required to go from taking measurements to analyzing data. Given the user's height and the distance from the base of the tree (which can be downloaded into the app from a server), the app uses the phone's orientation sensor to calculate the angle of elevation. A simple trigonometric formula is then used to calculate and record the tree's height in the phone's database. When the phone has a WiFi connection, the data are transmitted to a server, from where they can be downloaded directly into a spreadsheet. The application was first tested in an Environmental Science laboratory at Trinity College. On the first trial, 103 data samples were collected, stored, and uploaded to the online database with only couple of dropped data points. On the second trial, 98 data samples were gathered with no loss of data. The app combined the individual measurements taken by the students in the lab, reducing the time required to produce a graph of the class's results from days to hours.

Burca, V. S.; Htet, N. M.; Huang, X.; de Lanerolle, T. R.; Morelli, R.; Gourley, J. R.

2011-12-01

158

Alcohol CO-Production from Tree Crops.  

National Technical Information Service (NTIS)

A concept for the sustainable production of alcohol from fermentable substrates produced on an annual basis by the reproductive organs (pods, fruits, nuts, berries, etc.) of tree crops is presented. The advantages of tree-crop systems include suitability ...

M. Seibert G. Folger T. Milne

1982-01-01

159

Decision Trees for Prediction and Data Mining.  

National Technical Information Service (NTIS)

Three tree-structured algorithms are developed: GUIDE, CRUISE, and LOTUS. GUIDE is an algorithm for constructing least-squares, quantile, and Poisson regression trees. It can fit piecewise constant, piecewise polynomial, and piecewise multiple linear mode...

Y. Wei

2005-01-01

160

Generating Functions for Multi-labeled Trees.  

PubMed

Multi-labeled trees are a generalization of phylogenetic trees that are used, for example, in the study of gene versus species evolution and as the basis for phylogenetic network construction. Unlike phylogenetic trees, in a leaf-multi-labeled tree it is possible to label more than one leaf by the same element of the underlying label set. In this paper we derive formulae for generating functions of leaf-multi-labeled trees and use these to derive recursions for counting such trees. In particular, we prove results which generalize previous theorems by Harding on so-called tree-shapes, and by Otter on relating the number of rooted and unrooted phylogenetic trees. PMID:23175592

Czabarka, E; Erd?s, P L; Johnson, V; Moulton, V

2013-01-01

161

The Gift of the Tree  

NSDL National Science Digital Library

A piece of children's literature can be a powerful tool for teaching and learning science; however, it takes more than reading about a topic to qualify as "doing science." Inspired by the book, The Gift of the Tree , the author developed an in-dep

Jones, Marla W.

2009-09-01

162

Fault trees and imperfect coverage  

Microsoft Academic Search

A new algorithm is presented for solving the fault tree. The algorithm includes the dynamic behavior of the fault\\/error handling model but obviates the need for the Markov chain solution. As the state space is expanded in a breadth-first search (the same is done in the conversion to a Markov chain), the state's contribution to each future state is calculated

Joanne Bechta Dugan

1989-01-01

163

Trees of Our National Forests.  

ERIC Educational Resources Information Center

Presented is a description of the creation of the National Forests system, how trees grow, managing the National Forests, types of management systems, and managing for multiple use, including wildlife, water, recreation and other uses. Included are: (1) photographs; (2) line drawings of typical leaves, cones, flowers, and seeds; and (3)…

Forest Service (USDA), Washington, DC.

164

Multiway Iceberg Cubing on Trees  

Microsoft Academic Search

The Star-cubing algorithm performs multiway aggregation on trees but incurs huge memory consumption. We propose a new al- gorithm MG-cubing that achieves maximal multiway aggregation. Our experiments show that MG-cubing achieves similar and very often better time and memory efficiency than Star-cubing.

Pauline Lienhua Chou; Xiuzhen Zhang

2005-01-01

165

The Right Mix of Trees  

NSDL National Science Digital Library

This video describes the work of scientists who are studying the precise combination of trees that would be most effective in reducing the level of greenhouse gases in the air around Syracuse, NY. This is a pilot study that will serve as a model for other urban areas.

Forestry, New Y.; Suny-Esf, Syracuse

166

The Education of Little Tree.  

ERIC Educational Resources Information Center

First published in 1976, this autobiography contains Forrest Carter's--Little Tree's--remembrances of life with his Eastern Cherokee Hill country grandparents in the 1930s. There are 21 chapters, recounting humorous and serious episodes from a 5-year period and dealing with the themes of growing up, Indian life and values, family relationships,…

Carter, Forrest

167

Trees are Terrific...Travels with Pierre  

NSDL National Science Digital Library

This page, from the University of Illinois Extension, has an animated cartoon designed to help young children (5-8 years of age) gain an appreciation of trees, observe trees in their every day lives and develop an interest in learning more about trees. It is intended for adults to work with children to explore the wonders of trees. It meets several of the Illinois statewide learning goals for second grade. The teacher's guide includes a number of suggested activities.

168

Exploring the Secret Life of Trees  

NSDL National Science Digital Library

This page, from the University of Illinois Extension, has an animated cartoon designed to help 3rd through 5th grade students gain an appreciation of trees, observe trees in their everyday lives, and develop an interest in discovering more about trees. It is intended for adults to work with children to explore the secret life of trees. It meets several of the Illinois statewide learning goals for fourth grade. The teacher's guide suggests a number of supporting activities for students.

169

Wavelet tree quantization for copyright protection watermarking  

Microsoft Academic Search

This paper proposes a wavelet-tree-based blind watermarking scheme for copyright protection. The wavelet coefficients of the host image are grouped into so-called super trees. The watermark is embedded by quantizing super trees. The trees are so quantized that they exhibit a large enough statistical difference, which will later be used for watermark extraction. Each watermark bit is embedded in perceptually

Shih-hao Wang; Yuan-pei Lin

2004-01-01

170

Imaging Tree Roots with Borehole Radar  

Microsoft Academic Search

Ground-penetrating radar has been used to de- tect and map tree roots using surface-based antennas in reflection mode. On amenable soils these methods can accurately detect lateral tree roots. In some tree species (e.g. Pinus taeda, Pinus palustris), vertically orientated tap roots directly beneath the tree, comprise most of the root mass. It is difficult if not impossible to vertically

John R. Butnor; Kurt H. Johnsen; Per Wikström; Tomas Lundmark; Sune Linder

2006-01-01

171

Balancing minimum spanning and shortest path trees  

Microsoft Academic Search

This paper give a simple linear-time algorithm that, given a weighted\\u000adigraph, finds a spanning tree that simultaneously approximates a shortest-path\\u000atree and a minimum spanning tree. The algorithm provides a continuous\\u000atrade-off: given the two trees and epsilon > 0, the algorithm returns a\\u000aspanning tree in which the distance between any vertex and the root of the\\u000ashortest-path

Samir Khuller; Balaji Raghavacharit; Neal E. Young

1993-01-01

172

Tree Ring Data and Environmental Variables  

NSDL National Science Digital Library

This activity uses Bristlecone pine tree-ring data to understand how tree growth is related to environmental variables. It can be used to test hypotheses about how tree growth has been increasing with increasing northern hemisphere temperature in the past 100 years. This activity was originally developed by Christine Hallman and Katie Hirschboeck at the Laboratory of Tree-Ring Research at the University of Arizona. This activity is used in a Global Change course for first year non-science majors.

Bigio, Erica

173

Lookahead and Pathology in Decision Tree Induction  

Microsoft Academic Search

The standard approach to decision tree induction is a top-down, greedyalgorithm that makes locally optimal, irrevocable decisions at each nodeof a tree. In this paper, we study an alternative approach, in which thealgorithms use limited lookahead to decide what test to use at a node.We systematically compare, using a very large number of decision trees,the quality of decision trees induced

Sreerama K. Murthy; Steven Salzberg

1995-01-01

174

Isoprene emission from Indian trees  

NASA Astrophysics Data System (ADS)

Isoprene is the most dominant non-methane volatile organic compound (NMVOC) emitted by plants. NMVOCs play an important role in regulating the composition of atmospheric trace gases including global concentration of tropospheric ozone. Our present knowledge about NMVOCs emission is mainly from studies on temperate tree species. So far information on biogenic NMVOCs emission from tropical tree species is limited. In this study, isoprene emission rates from 40 tropical Indian tree species belonging to 33 genera and 17 families were measured for the first time using a dynamic flow through enclosure chamber technique. The isoprene emission rate from plants (30°C and PAR 1000 ?molm-2s-1) ranged from undetectable to 81.5 ?g g-1 h-1 and values were found to be comparable with other studies on tropical tree species. Tree species screened for isoprene emission in the present study may be grouped into the four categories, proposed by [2001], namely, 18 species were negligible or BDL isoprene emitting (<1 ?g g-1 h-1), 6 species were low emitting (1 ? to <10 ?g g-1 h-1), 5 species were moderate emitting (10? to <25 ?g g-1 h-1), and 11 species were high isoprene emitting (?25 ?g g-1 h-1). Maximum isoprene emission rate (81.5 ?g g-1 h-1) was observed in the case of Dalbergia sissoo Linn. It was interesting to find that Citrus limon Linn., Citrus reticulata Linn., Citrus sinensis Linn., Grevillea robusta A. Cunn., and Morus alba Linn., which were earlier reported as BDL or non isoprene emitters in US [, 1998; , 2001] were found to be appreciably high isoprene emitters (0.61-21.60 ?g g-1 h-1) in the present study.

Varshney, C. K.; Singh, Abhai Pratap

2003-12-01

175

Totally Tree-mendous Activities: Projects To Discover the Beauty and Benefits of Trees.  

ERIC Educational Resources Information Center

This teacher's guide supplies information and hands-on activities to teach about trees from several disciplines. Activities are grouped into six areas that cover botany, social studies, arts and literature (aesthetics), and trees as a resource. Sections include: (1) Tree Identification, which defines trees and leaves and presents activities that…

Hollister, Sarah

176

Combining dynamic fault trees and event trees for probabilistic risk assessment  

Microsoft Academic Search

As system analysis methodologies, both event tree analysis (ETA) and fault tree analysis (FTA) are used in probabilistic risk assessment (PRA), especially in identifying system interrelationships due to shared events. Although there are differences between them, ETA and FTA, are so closely linked that fault trees (FT) are often used to quantify system events that are part of event tree

Hong Xu; Joanne Bechta Dugan

2004-01-01

177

Ohio's Shade Tree Evaluation Project. In SEARCH OF A WELL ADAPTED TREE  

Microsoft Academic Search

Ohio's Shade Tree Evaluation Project is an attempt to evaluate trees for a different number of different characteristics. Similar projects are needed to determine those trees which are most suitable or more adaptable to particular locations. Projects of this nature serve not only the green industry, but also maintain a healthy urban tree population.

T Davis Sydnor

1984-01-01

178

Anisotropic branching random walks on homogeneous trees  

Microsoft Academic Search

Symmetric branching random walk on a homogeneous tree exhibits a weak sur- vival phase: For parameter values in a certain interval, the population survives forever with positive probability, but, with probability one, eventually vacates every finite subset of the tree. In this phase, particle trails must converge to the geometric boundaryof the tree. The random subset3 of the boundary consisting

I. Hueter; S. P. Lalley

1999-01-01

179

Anisotropic branching random walks on homogeneous trees  

Microsoft Academic Search

.   Symmetric branching random walk on a homogeneous tree exhibits a weak survival phase: For parameter values in a certain interval, the population survives forever with positive probability, but, with probability\\u000a one, eventually vacates every finite subset of the tree. In this phase, particle trails must converge to the geometric boundary? of the tree. The random subset ? of the

Irene Hueter; Steven P. Lalley

2000-01-01

180

On the topology of multicast trees  

Microsoft Academic Search

The benefit derived from using multicast is seemingly dependent upon the shape of the distribution tree. In this paper, we attempt to accurately model interdomain multicast trees. We measure a number of key parameters, such as depth, degree frequency, and average degree, for a number of real and synthetic data sets. We find that interdomain multicast trees actually do share

Robert C. Chalmers; Kevin C. Almeroth

2003-01-01

181

A construction of almost all Brauer trees  

Microsoft Academic Search

We know that almost all Brauer trees are shaped like a star. Given such a star and an odd prime l, we give an explicit method for constructing inflnitely many groups with this star as the Brauer tree of some l-block. Furthermore we show, that there is an inflnite family of Brauer trees which cannot be realized in the principal

Natalie Naehrig

2008-01-01

182

Foundations of Attack-Defense Trees  

NASA Astrophysics Data System (ADS)

We introduce and give formal definitions of attack-defense trees. We argue that these trees are a simple, yet powerful tool to analyze complex security and privacy problems. Our formalization is generic in the sense that it supports different semantical approaches. We present several semantics for attack-defense trees along with usage scenarios, and we show how to evaluate attributes.

Kordy, Barbara; Mauw, Sjouke; Radomirovi?, Saša; Schweitzer, Patrick

183

On multicast trees: structure and size estimation  

Microsoft Academic Search

This work presents a thorough investigation of the structure of multicast trees cut from the Internet and power-law topologies. Based on both generated topologies and real Internet data, we characterize the structure of such trees and show that they obey the rank-degree power law; that most high degree tree nodes are concentrated in a low diameter neighborhood; and that the

Danny Dolev; Osnat Mokryn; Yuval Shavitt

2006-01-01

184

Source-Tree Routing in Wireless Networks  

Microsoft Academic Search

We present the source-tree adaptive routing (STAR) protocol and analyze its performance in wireless networks with broadcast radio links. Routers in STAR communicate to its neighbors their source routing trees either incrementally or in atomic updates. Source routing trees are specified by stating the link parameters of each link belonging to the paths used to reach every destination. Hence, a

J. J. Garcia-luna-aceves; Marcelo Spohn

1999-01-01

185

TREES AND FOUNDATIONS—A REASSESSMENT  

Microsoft Academic Search

The abstraction of water from the soil by tree roots causes damage tofoundations by shrinking clay soils. The factors determining whether or not damage occurs are the water supply to the ground, the flow of water through the ground to the trees roots, the water demand of the tree, and the shrinkability of the clay. Crude investigation of the extent

Paul F. McCombie

1993-01-01

186

Diagnostic expert systems from dynamic fault trees  

Microsoft Academic Search

A methodology for developing a diagnostic map for systems that can be analyzed via a dynamic fault tree is proposed in this paper. This paper shows how to automatically design a diagnostic decision tree from a dynamic fault tree used for reliability analysis. In particular the methodology makes use of Markov chains since they are mathematical models used for reliability

Tariq Assaf; Joanne Bechta Dugan

2004-01-01

187

The Galileo Fault Tree Analysis Tool  

Microsoft Academic Search

We present Galileo, a dynamic fault tree modeling and analysis tool that combines the innovative DIF- Tree analysis methodology with a rich user interface built using package-oriented programming. DIFTree integrates binary decision diagram and Markov meth- ods under the common notation of dynamic fault trees, allowing the user to exploit the benefits of both tech- niques while avoiding the need

Kevin J. Sullivan; Joanne Bechta Dugan; David Coppit

1999-01-01

188

Formal methodology for fault tree construction  

Microsoft Academic Search

A model is presented for formulating the Boolean failure logic, cailed ; the fault tree, for electrical systems from associated schematic diagrams and ; system-independent component information. The model is developed in detail for ; electrical systems, while its implication and terminology extend to all fault ; tree construction. The methodology is verified as formal by fault trees ; constructed

Fussell

1973-01-01

189

Kinetic Medians and kd-Trees  

Microsoft Academic Search

We propose algorithms for maintaining two variants of -trees of a set of moving points in the plane. A pseudo -tree allows the number of points stored in the two children to differ by a constant factor. An overlapping -tree allows the bounding boxes of two children to overlap. We show that both of them support range search operations in

Pankaj K. Agarwal; Jie Gao; Leonidas J. Guibas

2002-01-01

190

Gene tree correction guided by orthology  

PubMed Central

Background Reconciled gene trees yield orthology and paralogy relationships between genes. This information may however contradict other information on orthology and paralogy provided by other footprints of evolution, such as conserved synteny. Results We explore a way to include external information on orthology in the process of gene tree construction. Given an initial gene tree and a set of orthology constraints on pairs of genes or on clades, we give polynomial-time algorithms for producing a modified gene tree satisfying the set of constraints, that is as close as possible to the original one according to the Robinson-Foulds distance. We assess the validity of the modifications we propose by computing the likelihood ratio between initial and modified trees according to sequence alignments on Ensembl trees, showing that often the two trees are statistically equivalent. Availability Software and data available upon request to the corresponding author.

2013-01-01

191

Hyperdominance in the Amazonian tree flora.  

PubMed

The vast extent of the Amazon Basin has historically restricted the study of its tree communities to the local and regional scales. Here, we provide empirical data on the commonness, rarity, and richness of lowland tree species across the entire Amazon Basin and Guiana Shield (Amazonia), collected in 1170 tree plots in all major forest types. Extrapolations suggest that Amazonia harbors roughly 16,000 tree species, of which just 227 (1.4%) account for half of all trees. Most of these are habitat specialists and only dominant in one or two regions of the basin. We discuss some implications of the finding that a small group of species--less diverse than the North American tree flora--accounts for half of the world's most diverse tree community. PMID:24136971

ter Steege, Hans; Pitman, Nigel C A; Sabatier, Daniel; Baraloto, Christopher; Salomão, Rafael P; Guevara, Juan Ernesto; Phillips, Oliver L; Castilho, Carolina V; Magnusson, William E; Molino, Jean-François; Monteagudo, Abel; Núñez Vargas, Percy; Montero, Juan Carlos; Feldpausch, Ted R; Coronado, Eurídice N Honorio; Killeen, Tim J; Mostacedo, Bonifacio; Vasquez, Rodolfo; Assis, Rafael L; Terborgh, John; Wittmann, Florian; Andrade, Ana; Laurance, William F; Laurance, Susan G W; Marimon, Beatriz S; Marimon, Ben-Hur; Guimarães Vieira, Ima Célia; Amaral, Iêda Leão; Brienen, Roel; Castellanos, Hernán; Cárdenas López, Dairon; Duivenvoorden, Joost F; Mogollón, Hugo F; Matos, Francisca Dionízia de Almeida; Dávila, Nállarett; García-Villacorta, Roosevelt; Stevenson Diaz, Pablo Roberto; Costa, Flávia; Emilio, Thaise; Levis, Carolina; Schietti, Juliana; Souza, Priscila; Alonso, Alfonso; Dallmeier, Francisco; Montoya, Alvaro Javier Duque; Fernandez Piedade, Maria Teresa; Araujo-Murakami, Alejandro; Arroyo, Luzmila; Gribel, Rogerio; Fine, Paul V A; Peres, Carlos A; Toledo, Marisol; Aymard C, Gerardo A; Baker, Tim R; Cerón, Carlos; Engel, Julien; Henkel, Terry W; Maas, Paul; Petronelli, Pascal; Stropp, Juliana; Zartman, Charles Eugene; Daly, Doug; Neill, David; Silveira, Marcos; Paredes, Marcos Ríos; Chave, Jerome; Lima Filho, Diógenes de Andrade; Jørgensen, Peter Møller; Fuentes, Alfredo; Schöngart, Jochen; Cornejo Valverde, Fernando; Di Fiore, Anthony; Jimenez, Eliana M; Peñuela Mora, Maria Cristina; Phillips, Juan Fernando; Rivas, Gonzalo; van Andel, Tinde R; von Hildebrand, Patricio; Hoffman, Bruce; Zent, Eglée L; Malhi, Yadvinder; Prieto, Adriana; Rudas, Agustín; Ruschell, Ademir R; Silva, Natalino; Vos, Vincent; Zent, Stanford; Oliveira, Alexandre A; Schutz, Angela Cano; Gonzales, Therany; Trindade Nascimento, Marcelo; Ramirez-Angulo, Hirma; Sierra, Rodrigo; Tirado, Milton; Umaña Medina, María Natalia; van der Heijden, Geertje; Vela, César I A; Vilanova Torre, Emilio; Vriesendorp, Corine; Wang, Ophelia; Young, Kenneth R; Baider, Claudia; Balslev, Henrik; Ferreira, Cid; Mesones, Italo; Torres-Lezama, Armando; Urrego Giraldo, Ligia Estela; Zagt, Roderick; Alexiades, Miguel N; Hernandez, Lionel; Huamantupa-Chuquimaco, Isau; Milliken, William; Palacios Cuenca, Walter; Pauletto, Daniela; Valderrama Sandoval, Elvis; Valenzuela Gamarra, Luis; Dexter, Kyle G; Feeley, Ken; Lopez-Gonzalez, Gabriela; Silman, Miles R

2013-10-18

192

Zinc Fertilization of Avocado Trees  

Microsoft Academic Search

Methods for Zn fertilization of 'Hass' avocado (Persea americana Mill.) trees were evaluated in a 2-year field experiment on a commercial orchard located on a calcareous soil (pH 7.8) in Ventura County, Calif. The fertilization methods included soil- or irrigation-applied ZnSO4; irrigation-applied Zn chelate (Zn- EDTA); trunk injection of Zn(NO3)2, and foliar applications of ZnSO4, ZnO, or Zn metalosate. Other

David E. Crowley; Woody Smith

193

Organic & Integrated Tree Fruit Production  

NSDL National Science Digital Library

Part of the Washington State University Tree Fruit Research and Extension Center, this website offers various resources for orchardists interested in organic and integrated production methods. The site contains sections on Organic Fruit Production, Soil and Pest Management, Apple Replant Disease, and more. The site also offers links to other Washington State University sites for Horticulture, Entomology, Fruit Pathology, and Postharvest resources. Many of the documents on this site are available for download as PDF files.

2007-08-02

194

Foreign body in tracheobronchial tree  

Microsoft Academic Search

Foreign body inhalation into the tracheobronchial tree can prove to be a life threatening unless timely intervened and appropriate\\u000a steps are being taken towards its management [1]. A review of 32 cases was done at MP Shah Medical College Jamnagar over a\\u000a period of 2 years. Children were most susceptible to aspiration of foreign bodies. All the cases were selected

Vikas Sinha; Viral Chhaya; Dilavar S. Barot; Keyur Mehta; Parin Patel; Swapna Patil; Vishal Parmar; C. D. Pashanth; Niral Modi; Rahul Patel

2010-01-01

195

Cover trees for nearest neighbor  

Microsoft Academic Search

Abstract We present a tree data structure for fast nearest neighbor operations in general n- point metric spaces (where the data set con- sists of n points). The data structure re- quires O(n) space regardless of the met- ric’s structure yet maintains all performance properties of a navigating net [KL04a]. If the point set has a bounded expansion con- stant

Alina Beygelzimer; Sham Kakade; John Langford

2006-01-01

196

Tree climbing and human evolution  

PubMed Central

Paleoanthropologists have long argued—often contentiously—about the climbing abilities of early hominins and whether a foot adapted to terrestrial bipedalism constrained regular access to trees. However, some modern humans climb tall trees routinely in pursuit of honey, fruit, and game, often without the aid of tools or support systems. Mortality and morbidity associated with facultative arboreality is expected to favor behaviors and anatomies that facilitate safe and efficient climbing. Here we show that Twa hunter–gatherers use extraordinary ankle dorsiflexion (>45°) during climbing, similar to the degree observed in wild chimpanzees. Although we did not detect a skeletal signature of dorsiflexion in museum specimens of climbing hunter–gatherers from the Ituri forest, we did find that climbing by the Twa is associated with longer fibers in the gastrocnemius muscle relative to those of neighboring, nonclimbing agriculturalists. This result suggests that a more excursive calf muscle facilitates climbing with a bipedally adapted ankle and foot by positioning the climber closer to the tree, and it might be among the mechanisms that allow hunter–gatherers to access the canopy safely. Given that we did not find a skeletal correlate for this observed behavior, our results imply that derived aspects of the hominin ankle associated with bipedalism remain compatible with vertical climbing and arboreal resource acquisition. Our findings challenge the persistent arboreal–terrestrial dichotomy that has informed behavioral reconstructions of fossil hominins and highlight the value of using modern humans as models for inferring the limits of hominin arboreality.

Venkataraman, Vivek V.; Kraft, Thomas S.; Dominy, Nathaniel J.

2013-01-01

197

Dendrochemistry: Seeing the forest through the trees  

NASA Astrophysics Data System (ADS)

Dendrochemistry is a term used to describe the compositional analysis of tree-rings and its application to biomonitoring of the tree's environment. The central hypothesis of this study is that the concentrations of silver and gold in tree-rings in the Mediterranean region record the history of African dust storms. Although there have been previous studies of tree-ring composition using both NAA and other analytical techniques, to the author's knowledge, this is the first dendrochemical study to consider the effects of dust storms on tree-ring chemistry. However, the results, as with many other dendrochemical studies, are promising at best. The tree-ring concentrations in a single tree in west-central Turkey were highly correlated with the local aerosol index obtained from the Total Ozone Mapping Spectrometer (TOMS). This suggests that silver and gold concentrations in carefully selected trees may serve as a proxy indicator of dust storm activity and indirectly, the phase of the North Atlantic Oscillation. Three other trees from the same forest did not have any silver or gold concentration peaks and possible reasons for this discrepancy are discussed. The correlation with dust storms is still uncertain because it was impossible to gather appropriate information about soil characteristics or additional trees for sampling to prove or disprove the hypothesis. However, the chemistries of silver and gold are discussed to elucidate why they may be uniquely good at recording environmental signals in tree-rings. Some promising results for detecting volcanic eruptions in tree-rings were obtained on tree samples of a shorter duration (20-30 years) from Catacik Turkey that were prepared for irradiation under improved conditions of cleanliness. These tree samples were analyzed later in the project after sample preparation procedures were altered to reduce the possibility of sample contamination. Concentration peaks in the Catacik samples were correlated with the timing of the Pinatubo eruption (1991) and the El Chichon eruption in 1982. However, many of the concentration peaks were in single trees and could not be verified by comparison to other trees that grew nearby. The relative success of correlating concentration peaks in these shorter tree sequences may have been due to the improved sample preparation procedures. Another possible explanation is that concentration peaks do not remain in the tree-rings over time due to diffusion or mobilization by the tree. This would make it more difficult to find or identify possible environmental signals in the older rings of a long tree sequence. Unfortunately, this study contributes to the overwhelming number of feasibility studies that have been performed since the 1950s. There is still no consensus regarding the mechanisms responsible for recording environmental events in tree-rings beyond passive uptake. The feasibility of dendrochemistry will be more firmly established by moving forward with thoughtfully planned control studies. The refined NAA procedures developed here are necessary for future experiments which should strive to understand the actual mechanisms responsible for uptake. There are several different aspects of dendrochemistry that could be tested with control studies and that would be useful for interpreting tree-ring chemistry. For instance, dendrochemical studies could focus on the variation in specific elements between trees and the creation of composite forest chronologies for the appropriate elements. If this was successful, it would indicate that tree-ring compositions faithfully record environmental conditions in some cases and for some elements. A possible correlation was found between the Ag and Au concentration in tree-rings and the intensity and frequency of dust storms. However, the promising results were only found for one tree out of four sampled in the Catacik forest. A future study could be dedicated to verifying the presence of the Ag and Au signals in other trees in the same forest. Future studies could also analyze the ground water near sample sites to mon

Hauck, Danielle K.

198

Enumerating All Rooted Trees Including k Leaves  

NASA Astrophysics Data System (ADS)

This paper presents an efficient algorithm to generate all (unordered) rooted trees with exactly n vertices including exactly k leaves. There are known results on efficient enumerations of some classes of graphs embedded on a plane, for instance, biconnected and triconnected triangulations [3], [6], and floorplans [4]. On the other hand, it is difficult to enumerate a class of graphs without a fixed embedding. The paper is on enumeration of rooted trees without a fixed embedding. We already proposed an algorithm to generate all “ordered” trees with n vertices including k leaves [11], while the algorithm cannot seem to efficiently generate all (unordered) rooted trees with n vertices including k leaves. We design a simple tree structure among such trees, then by traversing the tree structure we generate all such trees in constant time per tree in the worst case. By repeatedly applying the algorithm for each k=1,2,...,n-1, we can also generate all rooted trees with exactly n vertices.

Ishikawa, Masanobu; Yamanaka, Katsuhisa; Otachi, Yota; Nakano, Shin-Ichi

199

Assessment of student conceptions of evolutionary trees  

NASA Astrophysics Data System (ADS)

Biologists use evolutionary trees to depict hypotheses about the relationships among taxa. Trees possess lines that represent lineages, internal nodes that represent where lineages become evolutionarily isolated from one another and terminal nodes that represent the taxa under consideration. Interpreting a tree (i.e., "tree-thinking") is an important skill for biologists yet many students struggle when reading evolutionary trees. Common documented misconceptions include using morphological similarity, internal node counting or terminal node proximity, instead of identifying the internal node that represents a most recent common ancestor (MRCA), to determine relationships among taxa. I developed an instrument to assess whether students were using common ancestry or another, non-scientific, strategy to determine relationships among taxa. The study is the first to explicitly test hypotheses about how students approach reading evolutionary trees. To test the hypotheses an instrument was developed. The instrument is the first reliable and valid assessment testing student understanding of how to use most recent common ancestor to interpret evolutionary relationships in tree diagrams. Instructors can use the instrument as a diagnostic tool enabling them to help students learn this challenging concept. This study shows that, contrary to the assertion that students hold misconceptions about evolutionary trees made in the literature, students do not consistently use erroneous strategies when interpreting trees. This study suggests that a constructivist perspective of cognitive structure describes students' conception of evolutionary trees more closely than a misconception perspective.

Blacquiere, Luke

200

Self-Organizing Tree Using Cluster Validity  

NASA Astrophysics Data System (ADS)

Self-organizing tree (S-TREE) models solve clustering problems by imposing tree-structured constraints on the solution. It has a self-organizing capacity and has better performance than previous tree-structured algorithms. S-TREE carries out pruning to reduce the effect of bad leaf nodes when the tree reaches a predetermined maximum size (U), However, it is difficult to determine U beforehand because it is problem-dependent. U gives the limit of tree growth and can also prevent self-organization of the tree. It may produce an unnatural clustering. In this paper, we propose an algorithm for pruning algorithm that does not require U. This algorithm prunes extra nodes based on a significant level of cluster validity and allows the S-TREE to grow by a self-organization. The performance of the new algorithm was examined by experiments on vector quantization. The results of experiments show that natural leaf nodes are formed by this algorithm without setting the limit for the growth of the S-TREE.

Sasaki, Yasue; Suzuki, Yukinori; Miyamoto, Takayuki; Maeda, Junji

201

Computing the joint distribution of tree shape and tree distance for gene tree inference and recombination detection.  

PubMed

Ancestral recombination events can cause the underlying genealogy of a site to vary along the genome. We consider Bayesian models to simultaneously detect recombination breakpoints in very long sequence alignments and estimate the phylogenetic tree of each block between breakpoints. The models we consider use a dissimilarity measure between trees in their prior distribution to favor similar trees at neighboring loci. We show empirical evidence in Enterobacteria that neighboring genomic regions have similar trees. The main hurdle in using such models is the need to properly calculate the normalizing function for the prior probabilities on trees. In this work, we quantify the impact of approximating this normalizing function as done in biomc2, a hierarchical Bayesian method to detect recombination based on distance between tree topologies. We then derive an algorithm to calculate the normalizing function exactly, for a Gibbs distribution based on the Robinson-Foulds (RF) distance between gene trees at neighboring loci. At the core is the calculation of the joint distribution of the shape of a random tree and its RF distance to a fixed tree. We also propose fast approximations to the normalizing function, which are shown to be very accurate with little impact on the Bayesian inference. PMID:24384712

Chung, Yujin; Perna, Nicole T; Ané, Cécile

2013-01-01

202

TreeNetViz: revealing patterns of networks over tree structures.  

PubMed

Network data often contain important attributes from various dimensions such as social affiliations and areas of expertise in a social network. If such attributes exhibit a tree structure, visualizing a compound graph consisting of tree and network structures becomes complicated. How to visually reveal patterns of a network over a tree has not been fully studied. In this paper, we propose a compound graph model, TreeNet, to support visualization and analysis of a network at multiple levels of aggregation over a tree. We also present a visualization design, TreeNetViz, to offer the multiscale and cross-scale exploration and interaction of a TreeNet graph. TreeNetViz uses a Radial, Space-Filling (RSF) visualization to represent the tree structure, a circle layout with novel optimization to show aggregated networks derived from TreeNet, and an edge bundling technique to reduce visual complexity. Our circular layout algorithm reduces both total edge-crossings and edge length and also considers hierarchical structure constraints and edge weight in a TreeNet graph. These experiments illustrate that the algorithm can reduce visual cluttering in TreeNet graphs. Our case study also shows that TreeNetViz has the potential to support the analysis of a compound graph by revealing multiscale and cross-scale network patterns. PMID:22034366

Gou, Liang; Zhang, Xiaolong Luke

2011-12-01

203

Electrical tree in ethylene based copolymers  

Microsoft Academic Search

The electrical treeing resistance of ethylene-based copolymers is investigated. It is shown that the AC tree initiation voltages of copolymers with small contents (<5~7 wt.%) of polar monomers are higher than that of LDPE (low-density polyethylene). Removal of free oxygen gas by vacuum degassing treatment makes tree initiation voltage 6-7 times higher in LDPE and styrene-graft polyethylene. In EVA (ethylene-vinylacetate)

N. Shimizu; H. Asai; H. Ishihara; K. Uchida; S. Rasikawan

1992-01-01

204

On the ideals of equivariant tree models  

Microsoft Academic Search

We introduce equivariant tree models in algebraic statistics, which unify and generalise existing tree models such as the\\u000a general Markov model, the strand symmetric model, and group-based models such as the Jukes–Cantor and Kimura models. We focus\\u000a on the ideals of such models. We show how the ideals for general trees can be determined from the ideals for stars. A

Jan Draisma; Jochen Kuttler

2009-01-01

205

Signs of Change: Studying Tree Rings  

NSDL National Science Digital Library

In this very hands-on lesson, students will learn about dendrochronology (the study of tree rings to answer ecological questions about the recent past) and come up with conclusions as to what possible climatic conditions might affect tree growth in their region. Students determine the average age of the trees in their schoolyard, investigate any years of poor growth, and draw conclusions about the reasons for the years of poor growth.

2007-01-01

206

Efficient Spectrum Sensing With Dyadic Tree Partitioning  

Microsoft Academic Search

A low-complexity spectrum-sensing method that is based on dyadic (binary) tree partitioning is proposed. For this purpose, first, a representation of the spectrum occupation with a dyadic tree is developed. Then, the accuracy of this representation is evaluated through a rate-distortion criterion. Using this criterion, a pruning algorithm for the dyadic tree that minimizes the number of sensing operations for

Lionel Gueguen; Berna Sayrac

2010-01-01

207

Tutorial: Advanced fault tree applications using HARP  

NASA Technical Reports Server (NTRS)

Reliability analysis of fault tolerant computer systems for critical applications is complicated by several factors. These modeling difficulties are discussed and dynamic fault tree modeling techniques for handling them are described and demonstrated. Several advanced fault tolerant computer systems are described, and fault tree models for their analysis are presented. HARP (Hybrid Automated Reliability Predictor) is a software package developed at Duke University and NASA Langley Research Center that is capable of solving the fault tree models presented.

Dugan, Joanne Bechta; Bavuso, Salvatore J.; Boyd, Mark A.

1993-01-01

208

Tree initiation phenomena in nanostructured epoxy composites  

Microsoft Academic Search

Tree initiation time was evaluated by a pulse detection system to detect a small PD (partial discharge) signal that might take place at first just after a tree was formed. Six kinds of materials were prepared for evaluation, i.e. base epoxy resin, microcomposite, two kinds of nanocomposites, and two kinds of nano-micro-mixed-composites. Lengths of trees detected were around 100 ?m

Yu Chen; Takahiro Imai; Yoshimichi Ohki; Toshikatsu Tanaka

2010-01-01

209

Teaching Through Trade Books: Talking Trees  

NSDL National Science Digital Library

Students love outdoor activities and will love them even more when they build confidence in their tree identification and measurement skills. The activities in this month's Teaching Through Trade Books column help students learn to identify the major characteristics of trees and discover how the pace--a nonstandard measuring unit--can be used to estimate not only distances but also the height of a tree.

Tolman, Marvin

2005-02-01

210

Immunological Analysis of Allergenic Tree Nut Proteins  

Microsoft Academic Search

Allergies are a growing problem in industrialized countries, with food allergies affecting 6% of children and 3-4% of adults. Tree nuts are a common cause of food-induced allergy and include walnut, cashew, almond, hazelnut, pistachio, pecan, chestnut, and Brazil nut. Tree nut allergy, in particular, affects 0.5% of the US population. Unlike other food allergies, tree nut allergy persists throughout

LeAnna N. Willison

2009-01-01

211

SAH KD-tree construction on GPU  

Microsoft Academic Search

KD-tree is one of the most efficient acceleration data structures for ray tracing. In this paper, we present a kd-tree construction algorithm that is precisely SAH-optimized and runs entirely on GPU. We construct the tree nodes in breadth-first order. In order to precisely evaluate the SAH cost, we design a parallel scheme based on the standard parallel scan primitive to

Zhefeng Wu; Fukai Zhao; Xinguo Liu

2011-01-01

212

Horizontal subsea trees allow frequent deepwater workovers  

SciTech Connect

Horizontal subsea wellheads have found application in the Liuhua oil field in the South China Sea. These trees allow installation and retrieval of downhole equipment through the tree without having to disturb the tree or its external connections to flow lines, service lines, or control umbilicals. This access to the well is important because the Liuhua wells will be produced with electrical submersible pumps (ESPs), which may have relatively short intervals between maintenance, leading to frequent well work. The wells will be completed subsea in about 300 m of water. The large bore, horizontal trees allow all downhole equipment to be pulled without removal of the subsea tree. This wellhead configuration also provides well control and vertical access to downhole equipment through a conventional marine drilling riser and subsea blowout preventer (BOP), eliminating the need for costly specialized completion risers. Another benefit of the horizontal tree is its extremely compact profile with a low number of valves for well control. Valve size and spacing are decoupled from the size and bore spacing of the tubing hanger. The tree`s low profile geometry reduces costs of manufacturing the tree and framework and optimize load transfer to the wellhead.

Krenek, M. [FMC Wellhead Equipment Division, Houston, TX (United States); Hall, G. [Amoco Corp., Shekou (China); Sheng, W.Z. [China Offshore Nanhai East Corp., Shekou (China)

1995-05-01

213

Tree ring record chronicles major Mesoamerican droughts  

NASA Astrophysics Data System (ADS)

A new tree ring record chronicles major Mesoamerican droughts in the past millennium that may have contributed to the decline of some pre-Hispanic civilizations. Although there is other evidence of droughts during the past millennium, the paleoclimate record had gaps. Stahle et al. used core samples from Montezuma bald cypress trees found in Barranca de Amealco, Querétaro, Mexico, to develop a 1238-year tree ring chronology. They reconstructed the soil moisture record from the tree ring growth patterns. The new record provides the first dated, annually resolved climate record for Mexico and Central America spanning this time period.(Geophysical Research Letters, doi:10.1029/2010GL046472, 2011)

Tretkoff, Ernie

2011-05-01

214

Minimax Trees in Linear Time with Applications  

NASA Astrophysics Data System (ADS)

A minimax tree is similar to a Huffman tree except that, instead of minimizing the weighted average of the leaves' depths, it minimizes the maximum of any leaf's weight plus its depth. Golumbic (1976) introduced minimax trees and gave a Huffman-like, {O}{n log n}-time algorithm for building them. Drmota and Szpankowski (2002) gave another {O}{n log n}-time algorithm, which takes linear time when the weights are already sorted by their fractional parts. In this paper we give the first linear-time algorithm for building minimax trees for unsorted real weights.

Gawrychowski, Pawe?; Gagie, Travis

215

Tree models for macroevolution and phylogenetic analysis.  

PubMed

It has long been recognized that phylogenetic trees are more unbalanced than those generated by a Yule process. Recently, the degree of this imbalance has been quantified using the large set of phylogenetic trees available in the TreeBASE data set. In this article, a more precise analysis of imbalance is undertaken. Trees simulated under a range of models are compared with trees from TreeBASE and two smaller data sets. Several simple models can match the amount of imbalance measured in real data. Most of them also match the variance of imbalance among empirical trees to a remarkable degree. Statistics are developed to measure balance and to distinguish between trees with the same overall imbalance. The match between models and data for these statistics is investigated. In particular, age-dependent (Bellman-Harris) branching process are studied in detail. It remains difficult to separate the process of macroevolution from biases introduced by sampling. The lessons for phylogenetic analysis are clearer. In particular, the use of the usual proportional to distinguishable arrangements (uniform) prior on tree topologies in Bayesian phylogenetic analysis is not recommended. PMID:21865338

Jones, Graham R

2011-12-01

216

Tree-space statistics and approximations for large-scale analysis of anatomical trees.  

PubMed

Statistical analysis of anatomical trees is hard to perform due to differences in the topological structure of the trees. In this paper we define statistical properties of leaf-labeled anatomical trees with geometric edge attributes by considering the anatomical trees as points in the geometric space of leaf-labeled trees. This tree-space is a geodesic metric space where any two trees are connected by a unique shortest path, which corresponds to a tree deformation. However, tree-space is not a manifold, and the usual strategy of performing statistical analysis in a tangent space and projecting onto tree-space is not available. Using tree-space and its shortest paths, a variety of statistical properties, such as mean, principal component, hypothesis testing and linear discriminant analysis can be defined. For some of these properties it is still an open problem how to compute them; others (like the mean) can be computed, but efficient alternatives are helpful in speeding up algorithms that use means iteratively, like hypothesis testing. In this paper, we take advantage of a very large dataset (N = 8016) to obtain computable approximations, under the assumption that the data trees parametrize the relevant parts of tree-space well. Using the developed approximate statistics, we illustrate how the structure and geometry of airway trees vary across a population and show that airway trees with Chronic Obstructive Pulmonary Disease come from a different distribution in tree-space than healthy ones. Software is available from http://image.diku.dk/aasa/software.php. PMID:24683959

Feragen, Aasa; Owen, Megan; Petersen, Jens; Wille, Mathilde M W; Thomsen, Laura H; Dirksen, Asger; de Bruijne, Marleen

2013-01-01

217

Methodology for system analysis using fault trees, success trees, and importance evaluations  

Microsoft Academic Search

This dissertation describes an investigation of certain methods available for reactor safety analyses. These approaches include fault-tree and success-tree approaches. It then focuses on the application, development, and evaluation of several importance measures for use with fault-tree and success-tree analyses. These developments provide a basis on which to develop a thorough and systematic approach to sensitivity analysis when using fault

Sharirli

1985-01-01

218

Analysis of KDT-Trees: KD-Trees Improved by Local Reogranisations  

Microsoft Academic Search

This paper deals with kd-tree like structures that implement the multidimensional dictionary. It presents the first efficient online reorganisation method that improves the performance of kd-trees. We propose a new variation of kd-trees, to be called kdt-trees, whereby the updating procedures guarantee that any subtree of size greater than 2t, t0, has at least t nodes on each side. Thus,

Walter Cunto; Gustavo Lau; Philippe Flajolet

1989-01-01

219

Sulfur nutrition of deciduous trees  

NASA Astrophysics Data System (ADS)

Sulfur in its reduced form (-II) is an essential nutrient for growth and development, but is mainly available to plants in its oxidised form as sulfate. Deciduous trees take up sulfate by the roots from the soil solution and reduce sulfate to sulfide via assimilatory sulfate reduction in both roots and leaves. For reduction in the leaves, sulfate is loaded into the xylem and transported to the shoot. The surplus of sulfate not reduced in the chloroplast or stored in the vacuole and the surplus of reduced S not used for protein synthesis in the leaves is loaded into the phloem and transported back to the roots. Along the transport path, sulfate and glutathione (GSH) is unloaded from the phloem for storage in xylem and phloem parenchyma as well as in pit and ray cells. Re-mobilised S from storage tissues is loaded into the xylem during spring, but a phloem to xylem exchange does not appear to exist later in the season. As a consequence, a cycling pool of S was only found during the change of the seasons. The sulfate:glutathione ratio in the phloem seems to be involved in the regulation of S nutrition. This picture of S nutrition is discussed in relation to the different growth patterns of deciduous trees from the temperate climate zone, i.e. (1) terminated, (2) periodic and (3) indeterminate growth patterns, and in relation to environmental changes.

Herschbach, Cornelia; Rennenberg, Heinz

2001-01-01

220

Identifying species of individual trees using airborne laser scanner  

Microsoft Academic Search

Individual trees can be detected using high-density airborne laser scanner data. Also, variables characterizing the detected trees such as tree height, crown area, and crown base height can be measured. The Scandinavian boreal forest mainly consists of Norway spruce (Picea abies L. Karst.), Scots pine (Pinus sylvestris L.), and deciduous trees. It is possible to separate coniferous from deciduous trees

Johan Holmgren; Åsa Persson

2004-01-01

221

On the Use of Context Tree for Binary Image Compression  

Microsoft Academic Search

We consider the use of a static context tree for binary image compression. The contexts are stored in the leaves of a variable-depth binary tree. The tree structure itself is fully static and optimized off-line for a training image. The structure of the tree is similar for different images of the same type. The benefit from optimizing the tree for

Pasi Friinti; Eugene I. Ageenko

1999-01-01

222

Disk Tree: A Fat-Tree Based Heterogeneous Multi-tier Storage Architecture  

Microsoft Academic Search

Traditional disk arrays have the internal bus bottleneck and can not scale well. This paper proposes Disk Tree, a novel Fat-tree based heterogeneous multi-tier storage architecture. Disk Tree is built from a collection of storage nodes, small storage appliances containing commodity disks, CPU, RAM and interconnection interfaces. Each node provides moderate levels of reliability, availability, and performance. We examine four

Zhikun Wang; Ke Zhou; Dan Feng; Junping Liu

2007-01-01

223

GIS in management of landscape trees: Determining, monitoring and implementing safety measures on potentially hazardous trees  

Microsoft Academic Search

Trees located in the vicinity public areas such as roadsides, recreation areas, and around building should be monitored regularly for structural weakness. Certain conditions can cause a tree to be structurally weakened so that parts or all of it are likely to collapse Landscape trees do not only contribute to the enhancement of scenery but might also become potential hazards

Masbiha Mat Isa; Noriah Othman; Rosmadi Ghazali

2012-01-01

224

Whole-tree water transport scales with sapwood capacitance in tropical forest canopy trees  

Microsoft Academic Search

The present study examines the manner in which several whole-tree water transport properties scale with species- specific variation in sapwood water storage capacity. The hypothesis that constraints on relationships between sap- wood capacitance and other water relations characteristics lead to predictable scaling relationships between intrinsic capacitance and whole-tree behaviour was investigated. Samples of sapwood from four tropical forest canopy tree

F. C. MEINZER; S. A. JAMES; G. GOLDSTEIN; D. WOODRUFF

2003-01-01

225

Balanced aspect ratio trees: combining the advantages of k -d trees and octrees  

Microsoft Academic Search

Given a set S of n points in lRd, we show, for fixed d, how to construct in O(n log n) time a data structure we call the Balanced Aspect Ratio (BAR) tree. A BAR tree is a binary space partition tree on S that has O(logn) depth and in which every region is convex and \\

Christian A. Duncan; Michael T. Goodrich; Stephen G. Kobourov

1999-01-01

226

Balanced Aspect Ratio Trees: Combining the Advantages of k-d Trees and Octrees  

Microsoft Academic Search

Given a set S of n points on Rd, we show, for fixed d, how to construct in O(nlogn) time a data structure we call the balanced aspect ratio (BAR) tree. A BAR tree is a binary space partition tree on S that has O(logn) depth in which every region is convex and “fat” (that is, has a bounded aspect

Christian A. Duncan; Michael T. Goodrich; Stephen G. Kobourov

2001-01-01

227

Comparative Use of Tree Leaves, Needles, Tree Barks and Lichens for Air Pollution Biomonitoring  

Microsoft Academic Search

The aim of this work is to determine the most suitable bioaccumulators for air pollution survey in Morocco. For this, we compare in this paper heavy metals uptake efficiencies for different types of biomonitors: leaves of oak and eucalyptus trees, needles of coniferous trees, tree-barks and lichens collected at the same site. Instrumental neutron activation analysis using the k0 method

T. El Khoukhi; R. Cherkaoui El Moursli; A. Chouak; Z. Moutia; M. Lferde; A. Senhou; A. Gaudry; S. Ayrault; M. Chakir

2005-01-01

228

New method for counting the number of spanning trees in a two-tree network  

NASA Astrophysics Data System (ADS)

The number of spanning trees is an important quantity characterizing the reliability of a network. Generally, the number of spanning trees in a network can be obtained by directly calculating a related determinant corresponding to the network. However, for a large network, evaluating the relevant determinant is intractable. In this paper, we investigate the number of spanning trees in two-tree networks. We first give a new algorithm which avoids the laborious computation of the determinant for counting the number of spanning trees. Using the algorithm, we can obtain the number of spanning trees of any two-tree network in linear time. The result shows that the computation complexity is O(n), which is better than that of the matrix tree theorem with O(n2), where n is the number of steps. We then characterize two-tree networks with the maximum and minimum numbers of spanning trees. Denote by P(t) and K(t), respectively, the two-tree networks of t+2 vertices with the maximum and minimum numbers of spanning trees. Denote by PA and EN, respectively, the two-tree network of t+2 vertices generated by preferential attachment and by equiprobability attachment. By algorithmic analysis and through simulations, we conjecture that N(K(t))?N(PA)?N(EN)?N(P(t)) as t tends to infinity, where N(G) is the number of spanning trees of G. As an application of the algorithm, we give the formula of the number of spanning trees of a particular small-world network.

Xiao, Yuzhi; Zhao, Haixing

2013-10-01

229

Kinetic KD-trees and longest-side KD-trees  

Microsoft Academic Search

We propose a simple variant of kd-trees, called rank-based kd-trees, for sets of points in Rd. We show that a rank-based kd-tree, like an ordinary kd-tree, supports range search que- ries in O(n1?1\\/d + k) time, where k is the output size. The main advantage of rank-based kd-trees is that they can be efficiently kinetized: the KDS processes O(n2 )e

Mohammad Ali Abam; Mark De Berg; Bettina Speckmann

2007-01-01

230

Millimeter wave backscatter from deciduous trees  

Microsoft Academic Search

Measurements of the millimeter-wave backscatter from deciduous (leafed) trees are explained using a simple scattering model. The backscatter from individual leaves was measured in the laboratory and used to justify the use of an average leaf radar cross section when computing the normalized radar cross section (NRCS) of tree canopies. NRCS measurements of canopies show that the direction in which

Christoph C. Borel; ROBERT E. McINTOSH

1990-01-01

231

Credit scoring with boosted decision trees  

Microsoft Academic Search

The enormous growth experienced by the credit industry has led researchers to develop sophisticated credit scoring models that help lenders decide whether to grant or reject credit to applicants. This paper proposes a credit scoring model based on boosted decision trees, a powerful learning technique that aggregates several deci- sion trees to form a classier given by a weighted majority

A. Bastos

232

Credit scoring with boosted decision trees  

Microsoft Academic Search

The enormous growth experienced by the credit industry has led researchers to develop sophisticated credit scoring models that help lenders decide whether to grant or reject credit to applicants. This paper proposes a credit scoring model based on boosted decision trees, a powerful learning technique that aggregates several decision trees to form a classifier given by a weighted majority vote

Joao Bastos

2008-01-01

233

Global percent tree cover from MODIS data  

Microsoft Academic Search

A global percent tree cover map was created using 500 meter MODIS data. The new map product reveals a detailed depiction of tree cover unprecedented at the global scale. The MODIS data were composited and annual metrics derived describing the phenology of global vegetation. Training data were derived from a global sample of high-resolution imagery which were resampled to the

M. C. Hansen; R. S. DeFries; J. R. Townshend; R. Sohlberg; M. Carroll; C. Dimiceli

2002-01-01

234

Quad Tree Structures for Image Compression Applications.  

ERIC Educational Resources Information Center

Presents a class of distortion controlled vector quantizers that are capable of compressing images so they comply with certain distortion requirements. Highlights include tree-structured vector quantizers; multiresolution vector quantization; error coding vector quantizer; error coding multiresolution algorithm; and Huffman coding of the quad-tree

Markas, Tassos; Reif, John

1992-01-01

235

Employing Linear Regression in Regression Tree Leaves  

Microsoft Academic Search

. The advantage of using linear regressionin the leaves of a regression tree is analysed in thepaper. It is carried out how this modification affectsthe construction, pruning and interpretation of a regressiontree. The modification is tested on artificialand real-life domains. The results show that the modificationis beneficial as it leads to smaller classificationerrors of induced regression trees. Keywords: machinelearning, TDIDT,

Aram Karalic

1992-01-01

236

Computing steiner minimum trees in Hamming metric  

Microsoft Academic Search

Computing Steiner minimum trees in Hamming metric is a well studied problem that has applications in several fields of science such as computational linguistics and computational biology. Among all methods for finding such trees, algorithms using variations of a branch and bound method developed by Penny and Hendy have been the fastest for more than 20 years. In this paper

Ernst Althaus; Rouven Naujoks

2006-01-01

237

Mosses on a tree in forest habitat  

NSDL National Science Digital Library

Mosses require moisture and nutrients to grow (such as moist soil or tree bark). They anchor to tree bark with rhizoids, which are root-like structures lacking phloem and xylem. Mosses are able to lose most of their moisture without dying.

Katie Hale (California State University, Fullerton;Student, Biological Sciences)

2007-01-13

238

Linear Trees and RNA Secondary Structure  

Microsoft Academic Search

The total number of RNA secondary structures of a given length with a fixed number of base pairs is computed, under the assumption that all base pairs can occur. This is done by establishing a one-to-one correspondence between secondary structures and trees. A duality operator on trees is presented, which explains a symmetry in the numbers counting secondary structures.

William R. Schmitt; Michael S. Waterman

1994-01-01

239

Reconstruction of Cell Lineage Trees in Mice  

Microsoft Academic Search

The cell lineage tree of a multicellular organism represents its history of cell divisions from the very first cell, the zygote. A new method for high-resolution reconstruction of parts of such cell lineage trees was recently developed based on phylogenetic analysis of somatic mutations accumulated during normal development of an organism. In this study we apply this method in mice

Adam Wasserstrom; Rivka Adar; Gabi Shefer; Dan Frumkin; Shalev Itzkovitz; Tomer Stern; Irena Shur; Lior Zangi; Shai Kaplan; Alon Harmelin; Yair Reisner; Dafna Benayahu; Eldad Tzahor; Eran Segal; Ehud Shapiro

2008-01-01

240

Water treeing - filled versus unfilled cable insulation  

Microsoft Academic Search

Attempts to make XLPE increasingly resistant to water tree growth have involved additives, which decrease hydrophobicity and make the XLPE more like EPR. EPS are evolving through improved processing, clay compatibilization, etc. to reduce losses while retaining the inherent water tree resistance. Thus in the end, the two technologies appear to be moving toward the \\

Steven Boggs; James Xu

2001-01-01

241

Human Tracking with Mixtures of Trees  

Microsoft Academic Search

Tree-structured probabilistic models admit simple, fast in- ference. However, they are not well suited to phenomena such as occlusion, where multiple components of an object may disappear simultaneously. Mixtures of trees appear to address this problem, at the cost of representing a large mixture. We demonstrate an efficient and compact repre- sentation of this mixture, which admits simple learning and

Sergey Ioffe; David A. Forsyth

2001-01-01

242

The Tree Man: Robert Mazibuko's Story.  

ERIC Educational Resources Information Center

This book for beginning readers highlights Robert Mazibuko, the "Tree Man," who spent his life teaching people how to enrich the soil and plant vegetables and trees. Born in South Africa in 1904, he lived on a farm, learning to work with livestock, raise crops, and share with the community. In college, his professor of agriculture provided a…

Bloch, Joanne, Ed.

243

Adaptive aspects of tree crown geometry  

SciTech Connect

This work attempts to account for the multiplicity of tree crown forms in terms of a biological cost-benefit model in which cost is accounted for in terms of the mass of the wood of the tree and benefit is derived from the crown's efficiency as a solar collector. Methods are developed to describe complex crown shapes, to describe important aspects of complex branching systems, and to describe the three-dimensional distribution of light in forest and open habitats. Data on branching-system geometry was taken from felled trees, and data on overall crown form was taken from photographs of open-grown trees along a latitudinal transect. Computer programs were developed that can iteratively simulate tree growth based on any set of environmental and species-specific parameters. The results of simulations may be produced in printed and graphical form in ways that enable comparison to observed tree crowns. Observed north-south clines in crown form for Juniperus and Pinus are analyzed in terms of the model, and various insights into crown geometry, tree ecology, and tree physiology are won. The cost-benefit model is a powerful tool for understanding crown form and has great potential for future research.

Meiss, M.M.

1983-01-01

244

PCFG models of linguistic tree representations  

Microsoft Academic Search

The kinds of tree representations used in a treebank corpus can have a dramatic effect on performance of a parser based on the PCFG estimated from that corpus, causing the estimated likelihood of a tree to differ substantially from its frequency in the training corpus. This paper points out that the Penn II treebank representations are of the kind predicted

Mark Johnson

1998-01-01

245

BOAT-Optimistic Decision Tree Construction  

Microsoft Academic Search

Classification is an important data mining problem. Given a training databaseof records, each tagged with a class label, the goal of classification is tobuild a concise model that can be used to predict the class label of future,unlabeled records. A very popular class of classifiers are decision trees. Allcurrent algorithms to construct decision trees, including all main-memoryalgorithms, make one scan

Johannes Gehrke; Venkatesh Ganti; Raghu Ramakrishnan; Wei-Yin Loh

1999-01-01

246

Percolation on general trees and HIV modeling  

NASA Astrophysics Data System (ADS)

Percolation on a general tree is studied. A general tree is used to model the transition from HIV infection into AIDS and to explain the large differences of the transition time from one patient to another. HIV has some autoimmune effects due to its low antigenic mutants. Fuzzy mathematics is used to explain these effects.

Ahmed, E.; Agiza, H. N.

1996-12-01

247

Efficiently mining frequent trees in a forest  

Microsoft Academic Search

Mining frequent trees is very useful in domains like bioinformatics, web mining, mining semistructured data, and so on. We formulate the problem of mining (embedded) subtrees in a forest of rooted, labeled, and ordered trees. We present TREEMINER, a novel algorithm to discover all frequent subtrees in a forest, using a new data structure called scope-list. We contrast TREEMINER with

Mohammed Javeed Zaki

2002-01-01

248

Spatiotemporal Relational Probability Trees: An Introduction  

Microsoft Academic Search

We introduce spatiotemporal relational probability trees (SRPTs), probability estimation trees for relational data that can vary in both space and time. The SRPT algo- rithm addresses the exponential increase in search complex- ity through sampling. We validate the SRPT using a sim- ulated data set and we empirically demonstrate the SRPT algorithm on two real-world data sets.

Amy Mcgovern; Nathan C. Hiers; Matthew W. Collier; David J. Gagne II; Rodger A. Brown

2008-01-01

249

Generation of Binary Trees from Ballot Sequences  

Microsoft Academic Search

An efficient algorithm for generating and indexing all shapes of n-noded binary trees is described The algorithm is based on a correspondence between binary trees and the class of stack-sortable permutations. together with a representation of such permutatmns as ballot sequences Justification for the related procedures is given, and their efficiency estabhshed by comparison to other approaches

Doron Rotem; Yaakov L. Varol

1978-01-01

250

Pesticide bioconcentration modelling for fruit trees  

Microsoft Academic Search

The model presented allows simulating the pesticide concentration evolution in fruit trees and estimating the pesticide bioconcentration factor in fruits. Pesticides are non-ionic organic compounds that are degraded in soils cropped with woody species, fruit trees and other perennials. The model allows estimating the pesticide uptake by plants through the water transpiration stream and also the time in which maximum

Lourival Costa Paraíba

2007-01-01

251

Enumeration of End-Labeled Trees.  

National Technical Information Service (NTIS)

Labeled trees with unlabeled end-points were counted previously. Moon enumerated connected labeled graphs with unlabeled end-points. In this note we examine the complementary problem of counting trees in which only the endpoints are labeled, and in so doi...

A. Mowshowitz F. Harary

1975-01-01

252

Regular trees in random regular graphs  

Microsoft Academic Search

We investigate the size of the embedded regular tree rooted at a vertex in a $d$ regular random graph. We show that almost always, the radius of this tree will be ${1\\/2}\\\\log n$, where $n$ is the number of vertices in the graph. And we give an asymptotic estimate for Gauss' Hypergeometric Function.

Eran Makover; Jeffrey McGowan

2006-01-01

253

TAX: A Tree Algebra for XML  

Microsoft Academic Search

Querying XML has been the subject of much recent investigation. A formal bulk algebra is essential for applying database-style optimization to XML queries. We develop such an algebra, called TAX (Tree Algebra for XML), for manipulating XML data, modeled as forests of labeled ordered trees. Motivated both by aesthetic considerations of intuitiveness, and by efficient computability and amenability to optimization,

H. V. Jagadish; Laks V. S. Lakshmanan; Divesh Srivastava; Keith Thompson

2001-01-01

254

FAULT TREE ANALYSIS FOR SYSTEM RELIABILITY  

Microsoft Academic Search

Fault Tree Analysis (FTA) can be used to predict and prevent accidents or as an investigative tool after an event. FTA is an analytical methodology that uses a graphical model to display the analysis process. Visually a fault tree is built by special symbols, some derived from Boolean algebra. Consequently, the resulting model resembles a logic diagram or a flow

Ercüment N. D?ZDAR

255

Algorithmic fault tree synthesis for control loops  

Microsoft Academic Search

Efficient process control is an integral part of the design and operation of a safe and productive chemical plant. It is crucial for fault tree analysis since control systems are designed to prevent process deviations. How to handle control loops is a major concern in the research of computer-aided fault tree synthesis for the chemical process industry (CPI). This paper

Yanjun Wang; William J Rogers; Harry H West; M. Sam Mannan

2003-01-01

256

Symbolic Fault Tree Analysis for Reactive Systems  

Microsoft Academic Search

Fault tree analysis is a traditional and well-established technique for analyzing system design and robustness. Its purpose is to identify sets of basic events, called cut sets, which can cause a given top level event, e.g. a system malfunction, to occur. Generating fault trees is particularly critical in the case of reactive systems, as hazards can be the result of

Marco Bozzano; Alessandro Cimatti; Francesco Tapparo

2007-01-01

257

CRITIQUE OF CARBON BASED TREE GROWTH MODELS  

EPA Science Inventory

Simulation models of the processes that control carbohydrate balance in coniferous trees are reviewed, and their appropriateness for assessing pollution effects is considered. Currently such models are at the forefront of attempts to simulate the growth process of trees, but they...

258

Using Decision Trees for Coreference Resolution  

Microsoft Academic Search

This paper describes RESOLVE, a s>stem that uses decision trees to learn how to classify coref- erent phrases in the domain of business joint ventures An experiment is presented in which the performance of RESOLVE is compared to the performance of a manually engineered set of rules for the same task The results show that decision trees achieve higher performance

Joseph F. Mccarthy; Wendy G. Lehnert

1995-01-01

259

Aboveground Tree Biomass Statistics for Maine: 1982.  

National Technical Information Service (NTIS)

A statistical report based on the third forest survey of Maine conducted in 1980-82. Results of the survey are displayed in 87 tables containing estimates of timberland area, timber volume, numbers of trees, and aboveground tree biomass. These estimates w...

A. M. Malley E. H. Wharton T. S. Frieswyk

1985-01-01

260

A Dichromatic Framework for Balanced Trees  

Microsoft Academic Search

In this paper we present a uniform framework for the implementation and study of balanced tree algorithms. We show how to imbed in this framework the best known balanced tree techniques and then use the framework to develop new algorithms which perform the update and rebalancing in one pass, on the way down towards a leaf. We conclude with a

Leonidas J. Guibas; Robert Sedgewick

1978-01-01

261

Applications of Path Compression on Balanced Trees  

Microsoft Academic Search

Several fast algorithms are presented for computing functions defined on paths in trees under various assumpuons. The algorithms are based on tree mampulatton methods first used to efficiently represent equivalence relations. The algorithms have O((m + n)a(m + n, n)) running tunes, where m and n are measures of the problem size and a Is a functional reverse of Ackermann's

Robert Endre Tarjan

1979-01-01

262

Dynamic Positional Trees for Structural Image Analysis  

Microsoft Academic Search

Dynamic positional trees are a signicant extensionof dynamic trees, incorporating movablenodes. This addition makes sequencetracking viable within the model, but requiresa new formulation to incorporate the priorover positions. The model is implemented usinga structured variational procedure, and isillustrated on synthetic raytraced images andimage sequences.We consider the problem of structural image analysisand in particular the inference of scene propertiesfrom image...

Amos J. Storkey; Christopher K. i. Williams

2000-01-01

263

Combining Classifiers with Meta Decision Trees  

Microsoft Academic Search

The paper introduces meta decision trees (MDTs), a novel method for combining multiple classifiers. Instead of giving a prediction, MDT leaves specify which classifier should be used to obtain a prediction. We present an algorithm for learning MDTs based on the C4.5 algorithm for learning ordinary decision trees (ODTs). An extensive experimental evaluation of the new algorithm is performed on

Robert E. Schapire

264

Enlarging the Margins in Perceptron Decision Trees  

Microsoft Academic Search

Capacity control in perceptron decision trees is typically performed by controlling their size. We prove that other quantities can be as relevant to reduce their flexibility and combat overfitting. In particular, we provide an upper bound on the generalization error which depends both on the size of the tree and on the margin of the decision nodes. So enlarging the

Kristin P. Bennett; Nello Cristianini; John Shawe-taylor; Donghui Wu

2000-01-01

265

How Trees Help the Power Company!  

ERIC Educational Resources Information Center

Proposes the utilization of graph theory to solve optimization problems. Defines the notion of spanning trees and presents two algorithms to determine optimization of a spanning tree. Discusses an example to connect towns by power transmission lines at minimum cost. (MDH)

King, Rik

1992-01-01

266

Bootstrap Confidence Levels for Phylogenetic Trees  

Microsoft Academic Search

Evolutionary trees are often estimated from DNA or RNA sequence data. How much confidence should we have in the estimated trees? In 1985, Felsenstein [Felsenstein, J. (1985) Evolution 39, 783-791] suggested the use of the bootstrap to answer this question. Felsenstein's method, which in concept is a straightforward application of the bootstrap, is widely used, but has been criticized as

Bradley Efron; Elizabeth Halloran; Susan Holmes

1996-01-01

267

Design and Realization of Directory Tree Navigation  

Microsoft Academic Search

There are many Web-based curriculums in which the chapter navigation is designed as directory tree. In most cases, developing the directory tree requires a large quantity of code and the chapter navigation lacks flexibility as well as extensibility. In our method, we rationally integrated EXTJS with WEBWORK in the JAVA platform. The EXTJS code was directly introduced on the JSP

Hexiao Huang; Rener Zheng; Lei Wang; Haijian Chen; Jianhan Peng

2009-01-01

268

Nearest Neighbor Search using Kd-trees  

Microsoft Academic Search

We suggest a simple modification to the kd-tree search algorithm for nearest neighbor search re- sulting in an improved performance. The Kd-tree data structure seems to work well in finding nearest neighbors in low dimensions but its performance degrades even if the number of dimensions increases to more than three. Since the exact nearest neighbor search problem suffers from the

Rina Panigrahy

269

On Improving Kd Tree for Ray Shooting  

Microsoft Academic Search

Efficient ray shooting algorithm is inherently required by many computer graphics algorithms, particularly in image synthesis. Practical ray shooting algorithms aiming at the average-case complexity use some underlying spatial data structure such as -tree. We show the new termi- nation criteria algorithm that improves the space and time complexity of the -tree construction. It provides efficient ray-shooting queries and does

Vlastimil Havran; Jirí Bittner

2002-01-01

270

Alcohol co-production from tree crops  

SciTech Connect

A concept for the sustainable production of alcohol from fermentable substrates produced on an annual basis by the reproductive organs (pods, fruits, nuts, berries, etc.) of tree crops is presented. The advantages of tree-crop systems include suitability for use on marginal land, potential productivity equivalent to row crops, minimal maintenance and energy-input requirements, environmental compatibility, and the possibility of co-product production. Honeylocust, mesquite, and persimmon are examined as potential US tree-crop species. Other species not previously considered, including osage orange and breadfruit, are suggested as tree-crop candidates for North America and the tropical developing world, respectively. Fermentation of tree-crop organs and the economics of tree-crop systems are also discussed. Currently the greatest area of uncertainty lies in actual pod or fruit yields one can expect from large tree farms under real life conditions. However, ballpark ethanol yield estimates of from 880 to 3470 l hectare/sup -1/ (94 to 400 gal acre/sup -1/) justify further consideration of tree crop systems.

Seibert, M.; Folger, G.; Milne, T.

1982-06-01

271

Alternation-free modal mu-calculus for data trees  

Microsoft Academic Search

An alternation-free modal mu-calculus over data trees is introduced and studied. A data tree is an unranked ordered tree whose every node is labelled by a letter from a finite alphabet and an element (\\

Marcin Jurdzinski; Ranko Lazic

2007-01-01

272

Global percent tree cover from MODIS data  

NASA Astrophysics Data System (ADS)

A global percent tree cover map was created using 500 meter MODIS data. The new map product reveals a detailed depiction of tree cover unprecedented at the global scale. The MODIS data were composited and annual metrics derived describing the phenology of global vegetation. Training data were derived from a global sample of high-resolution imagery which were resampled to the 500 meter grid. This continuous training data set was then input to a regression tree algorithm. The regression tree outputs were modified using a stepwise regression model and a bias function. Also generated were layers describing leaf type and leaf morphology of tree cover. Using the same procedure, percent broadleaf and needleleaf and percent evergreen and deciduous layers were created. Results show that the MODIS data offer a much improved depiction of land cover heterogeneity than AVHRR data.

Hansen, M. C.; DeFries, R. S.; Townshend, J. R.; Sohlberg, R.; Carroll, M.; Dimiceli, C.

2002-05-01

273

TreeViewJ: An application for viewing and analyzing phylogenetic trees  

PubMed Central

Background Phylogenetic trees are widely used to visualize evolutionary relationships between different organisms or samples of the same organism. There exists a variety of both free and commercial tree visualization software available, but limitations in these programs often require researchers to use multiple programs for analysis, annotation, and the production of publication-ready images. Results We present TreeViewJ, a Java tool for visualizing, editing and analyzing phylogenetic trees. The software allows researchers to color and change the width of branches that they wish to highlight, and add names to nodes. If collection dates are available for taxa, the software can map them onto a timeline, and sort the tree in ascending or descending date order. Conclusion TreeViewJ is a tool for researchers to visualize, edit, "decorate," and produce publication-ready images of phylogenetic trees. It is open-source, and released under an GPL license, and available at .

Peterson, Matthew W; Colosimo, Marc E

2007-01-01

274

Decision Tree for Optimization Software  

NSDL National Science Digital Library

H.D. Mittelmann from the Department of Math and Statistics at Arizona State University and P. Spellucci from Department of Mathematics at Technical University Darmstadt have posted this guide entitled, Decision Tree for Optimization Software. The guide "aims at helping you identify ready to use solutions for your optimization problem, or at least to find some way to build such a solution using work done by others." The online document is organized into sections covering specific software problems, a collection of test results and performance tests, and example files to use with existing software. The authors also list information on available books and tutorials, some of which are online, as well as various software tools to assist in formulating an optimization problem or simplifying its solution. Those tools listed in the Web-submission section are available to try directly via the Internet.

275

Electrical signals in avocado trees  

PubMed Central

Plant responses to environmental changes are associated with electrical excitability and signaling; automatic and continuous measurements of electrical potential differences (?EP) between plant tissues can be effectively used to study information transport mechanisms and physiological responses that result from external stimuli on plants. The generation and conduction of electrochemical impulses within plant different tissues and organs, resulting from abiotic and biotic changes in environmental conditions is reported. In this work, electrical potential differences are monitored continuously using Ag/AgCl microelectrodes, inserted 5 mm deep into sapwood at two positions in the trunks of several Avocado trees. Electrodes are referenced to a non polarisable Ag/AgCl microelectrode installed 20 cm deep in the soil. Systematic patterns of ?EP during absolute darkness, day-night cycles and different conditions of soil water availability are discussed as alternative tools to assess early plant stress conditions.

Oyarce, Patricio

2010-01-01

276

Tree array quantum cascade laser.  

PubMed

A monolithic coupling scheme for mid-infrared quantum cascade laser arrays is investigated with respect to brightness enhancement. The tree-shaped resonator enables parallel coupling of six laser elements into a single element by means of several Y-junctions. Phase-locking is observed on the basis of far field analysis, and leads to in-phase emission on both sides of the device. The experimental results match calculated far field profiles and demonstrate a high level of modal control when driven far above threshold. Whereas optical power measurements confirm negligible coupling losses, the slope efficiency is below the theoretically expected value, which is attributed to modal competition. Additional evaluation of near fields and spectral characteristics provides background on the modal dynamics of the sophisticated cavity and reveals limitations to coherent beam combining. The findings pave the way to improved coupling efficiency and brightness scaling of a single facet emitting compact quantum cascade laser array. PMID:19158878

Hoffmann, Leonard K; Klinkmüller, Matthias; Mujagi?, Elvis; Semtsiv, Mykhaylo P; Schrenk, Werner; Masselink, William T; Strasser, Gottfried

2009-01-19

277

Fault trees and imperfect coverage  

NASA Technical Reports Server (NTRS)

A new algorithm is presented for solving the fault tree. The algorithm includes the dynamic behavior of the fault/error handling model but obviates the need for the Markov chain solution. As the state space is expanded in a breadth-first search (the same is done in the conversion to a Markov chain), the state's contribution to each future state is calculated exactly. A dynamic state truncation technique is also presented; it produces bounds on the unreliability of the system by considering only part of the state space. Since the model is solved as the state space is generated, the process can be stopped as soon as the desired accuracy is reached.

Dugan, Joanne B.

1989-01-01

278

Pruning a minimum spanning tree  

NASA Astrophysics Data System (ADS)

This work employs various techniques in order to filter random noise from the information provided by minimum spanning trees obtained from the correlation matrices of international stock market indices prior to and during times of crisis. The first technique establishes a threshold above which connections are considered affected by noise, based on the study of random networks with the same probability density distribution of the original data. The second technique is to judge the strength of a connection by its survival rate, which is the amount of time a connection between two stock market indices endures. The idea is that true connections will survive for longer periods of time, and that random connections will not. That information is then combined with the information obtained from the first technique in order to create a smaller network, in which most of the connections are either strong or enduring in time.

Sandoval, Leonidas

2012-04-01

279

Language distance and tree reconstruction  

NASA Astrophysics Data System (ADS)

Languages evolve over time according to a process in which reproduction, mutation and extinction are all possible. This is very similar to haploid evolution for asexual organisms and for the mitochondrial DNA of complex ones. Exploiting this similarity, it is possible, in principle, to verify hypotheses concerning the relationship among languages and to reconstruct their family tree. The key point is the definition of the distances among pairs of languages in analogy with the genetic distances among pairs of organisms. Distances can be evaluated by comparing grammar and/or vocabulary, but while it is difficult, if not impossible, to quantify grammar distance, it is possible to measure a distance from vocabulary differences. The method used by glottochronology computes distances from the percentage of shared 'cognates', which are words with a common historical origin. The weak point of this method is that subjective judgment plays a significant role. Here we define the distance of two languages by considering a renormalized edit distance among words with the same meaning and averaging over the two hundred words contained in a Swadesh list. In our approach the vocabulary of a language is the analogue of DNA for organisms. The advantage is that we avoid subjectivity and, furthermore, reproducibility of results is guaranteed. We apply our method to the Indo-European and the Austronesian groups, considering, in both cases, fifty different languages. The two trees obtained are, in many respects, similar to those found by glottochronologists, with some important differences as regards the positions of a few languages. In order to support these different results we separately analyze the structure of the distances of these languages with respect to all the others.

Petroni, Filippo; Serva, Maurizio

2008-08-01

280

75 FR 51507 - WisdomTree Asset Management, Inc., and WisdomTree Trust; Notice of Application  

Federal Register 2010, 2011, 2012, 2013

...812-13733] WisdomTree Asset Management, Inc., and WisdomTree...Applicants: WisdomTree Asset Management, Inc (``WTAM'' or...providing continuous investment management for each Fund's assets. As compensation for...

2010-08-20

281

Urban Tree Effects on Soil Organic Carbon  

PubMed Central

Urban trees sequester carbon into biomass and provide many ecosystem service benefits aboveground leading to worldwide tree planting schemes. Since soils hold ?75% of ecosystem organic carbon, understanding the effect of urban trees on soil organic carbon (SOC) and soil properties that underpin belowground ecosystem services is vital. We use an observational study to investigate effects of three important tree genera and mixed-species woodlands on soil properties (to 1 m depth) compared to adjacent urban grasslands. Aboveground biomass and belowground ecosystem service provision by urban trees are found not to be directly coupled. Indeed, SOC enhancement relative to urban grasslands is genus-specific being highest under Fraxinus excelsior and Acer spp., but similar to grasslands under Quercus robur and mixed woodland. Tree cover type does not influence soil bulk density or C?N ratio, properties which indicate the ability of soils to provide regulating ecosystem services such as nutrient cycling and flood mitigation. The trends observed in this study suggest that genus selection is important to maximise long-term SOC storage under urban trees, but emerging threats from genus-specific pathogens must also be considered.

Edmondson, Jill L.; O'Sullivan, Odhran S.; Inger, Richard; Potter, Jonathan; McHugh, Nicola; Gaston, Kevin J.; Leake, Jonathan R.

2014-01-01

282

Binary space partitioning trees and their uses  

NASA Technical Reports Server (NTRS)

Binary Space Partitioning (BSP) trees have some qualities that make them useful in solving many graphics related problems. The purpose is to describe what a BSP tree is, and how it can be used to solve the problem of hidden surface removal, and constructive solid geometry. The BSP tree is based on the idea that a plane acting as a divider subdivides space into two parts with one being on the positive side and the other on the negative. A polygonal solid is then represented as the volume defined by the collective interior half spaces of the solid's bounding surfaces. The nature of how the tree is organized lends itself well for sorting polygons relative to an arbitrary point in 3 space. The speed at which the tree can be traversed for depth sorting is fast enough to provide hidden surface removal at interactive speeds. The fact that a BSP tree actually represents a polygonal solid as a bounded volume also makes it quite useful in performing the boolean operations used in constructive solid geometry. Due to the nature of the BSP tree, polygons can be classified as they are subdivided. The ability to classify polygons as they are subdivided can enhance the simplicity of implementing constructive solid geometry.

Bell, Bradley N.

1989-01-01

283

Reconciliation of Gene and Species Trees  

PubMed Central

The first part of the paper briefly overviews the problem of gene and species trees reconciliation with the focus on defining and algorithmic construction of the evolutionary scenario. Basic ideas are discussed for the aspects of mapping definitions, costs of the mapping and evolutionary scenario, imposing time scales on a scenario, incorporating horizontal gene transfers, binarization and reconciliation of polytomous trees, and construction of species trees and scenarios. The review does not intend to cover the vast diversity of literature published on these subjects. Instead, the authors strived to overview the problem of the evolutionary scenario as a central concept in many areas of evolutionary research. The second part provides detailed mathematical proofs for the solutions of two problems: (i) inferring a gene evolution along a species tree accounting for various types of evolutionary events and (ii) trees reconciliation into a single species tree when only gene duplications and losses are allowed. All proposed algorithms have a cubic time complexity and are mathematically proved to find exact solutions. Solving algorithms for problem (ii) can be naturally extended to incorporate horizontal transfers, other evolutionary events, and time scales on the species tree.

Rusin, L. Y.; Lyubetskaya, E. V.; Gorbunov, K. Y.; Lyubetsky, V. A.

2014-01-01

284

Tree-hole breeding mosquitoes in Israel.  

PubMed

A survey was conducted to evaluate the number of tree-hole breeding mosquito species and their distribution in the six principal woodland types in Israel. Out of approximately 3,000 mature trees examined, only 38 contained holes that retained water for extended periods of time, and breeding mosquitoes were observed in 27 of them. Two specialized tree-hole breeders, Aedes pulchritarsis Rondani and Aedes geniculatus Oliver, were found breeding at several sites in northern Israel, always at locations 500 m above sea level (a.s.l) and with high annual precipitation. Aedes albopictus Skuse which, in Israel, is known as an opportunistic container breeder, was found in this study to have adapted remarkably well to breeding in tree holes and was found in most forest types investigated and in most tree species which had adequate tree holes. Two other species, Culiseta annulata Schrank and Culex pipiens Linnaeus instars, were found in one of the tree holes, but did not survive to reach maturity. PMID:22548543

Müller, Günter C; Kravchenko, Vasiliy D; Junnila, Amy; Schlein, Yosef

2012-06-01

285

Looking for trees in the forest: summary tree from posterior samples  

PubMed Central

Background Bayesian phylogenetic analysis generates a set of trees which are often condensed into a single tree representing the whole set. Many methods exist for selecting a representative topology for a set of unrooted trees, few exist for assigning branch lengths to a fixed topology, and even fewer for simultaneously setting the topology and branch lengths. However, there is very little research into locating a good representative for a set of rooted time trees like the ones obtained from a BEAST analysis. Results We empirically compare new and known methods for generating a summary tree. Some new methods are motivated by mathematical constructions such as tree metrics, while the rest employ tree concepts which work well in practice. These use more of the posterior than existing methods, which discard information not directly mapped to the chosen topology. Using results from a large number of simulations we assess the quality of a summary tree, measuring (a) how well it explains the sequence data under the model and (b) how close it is to the “truth”, i.e to the tree used to generate the sequences. Conclusions Our simulations indicate that no single method is “best”. Methods producing good divergence time estimates have poor branch lengths and lower model fit, and vice versa. Using the results presented here, a user can choose the appropriate method based on the purpose of the summary tree.

2013-01-01

286

Mechanical Stimuli Regulate the Allocation of Biomass in Trees: Demonstration with Young Prunus avium Trees  

PubMed Central

Background and Aims Plastic tree-shelters are increasingly used to protect tree seedlings against browsing animals and herbicide drifts. The biomass allocation in young seedlings of deciduous trees is highly disturbed by common plastic tree-shelters, resulting in poor root systems and reduced diameter growth of the trunk. The shelters have been improved by creating chimney-effect ventilation with holes drilled at the bottom, resulting in stimulated trunk diameter growth, but the root deficit has remained unchanged. An experiment was set up to elucidate the mechanisms behind the poor root growth of sheltered Prunus avium trees. Methods Tree seedlings were grown either in natural windy conditions or in tree-shelters. Mechanical wind stimuli were suppressed in ten unsheltered trees by staking. Mechanical stimuli (bending) of the stem were applied in ten sheltered trees using an original mechanical device. Key Results Sheltered trees suffered from poor root growth, but sheltered bent trees largely recovered, showing that mechano-sensing is an important mechanism governing C allocation and the shoot–root balance. The use of a few artificial mechanical stimuli increased the biomass allocation towards the roots, as did natural wind sway. It was demonstrated that there was an acclimation of plants to the imposed strain. Conclusions This study suggests that if mechanical stimuli are used to control plant growth, they should be applied at low frequency in order to be most effective. The impact on the functional equilibrium hypothesis that is used in many tree growth models is discussed. The consequence of the lack of mechanical stimuli should be incorporated in tree growth models when applied to environments protected from the wind (e.g. greenhouses, dense forests).

Coutand, Catherine; Dupraz, Christian; Jaouen, Gaelle; Ploquin, Stephane; Adam, Boris

2008-01-01

287

Comprehensive Decision Tree Models in Bioinformatics  

PubMed Central

Purpose Classification is an important and widely used machine learning technique in bioinformatics. Researchers and other end-users of machine learning software often prefer to work with comprehensible models where knowledge extraction and explanation of reasoning behind the classification model are possible. Methods This paper presents an extension to an existing machine learning environment and a study on visual tuning of decision tree classifiers. The motivation for this research comes from the need to build effective and easily interpretable decision tree models by so called one-button data mining approach where no parameter tuning is needed. To avoid bias in classification, no classification performance measure is used during the tuning of the model that is constrained exclusively by the dimensions of the produced decision tree. Results The proposed visual tuning of decision trees was evaluated on 40 datasets containing classical machine learning problems and 31 datasets from the field of bioinformatics. Although we did not expected significant differences in classification performance, the results demonstrate a significant increase of accuracy in less complex visually tuned decision trees. In contrast to classical machine learning benchmarking datasets, we observe higher accuracy gains in bioinformatics datasets. Additionally, a user study was carried out to confirm the assumption that the tree tuning times are significantly lower for the proposed method in comparison to manual tuning of the decision tree. Conclusions The empirical results demonstrate that by building simple models constrained by predefined visual boundaries, one not only achieves good comprehensibility, but also very good classification performance that does not differ from usually more complex models built using default settings of the classical decision tree algorithm. In addition, our study demonstrates the suitability of visually tuned decision trees for datasets with binary class attributes and a high number of possibly redundant attributes that are very common in bioinformatics.

Stiglic, Gregor; Kocbek, Simon; Pernek, Igor; Kokol, Peter

2012-01-01

288

Tree Edit Distance Problems: Algorithms and Applications to Bioinformatics  

NASA Astrophysics Data System (ADS)

Tree structured data often appear in bioinformatics. For example, glycans, RNA secondary structures and phylogenetic trees usually have tree structures. Comparison of trees is one of fundamental tasks in analysis of these data. Various distance measures have been proposed and utilized for comparison of trees, among which extensive studies have been done on tree edit distance. In this paper, we review key results and our recent results on the tree edit distance problem and related problems. In particular, we review polynomial time exact algorithms and more efficient approximation algorithms for the edit distance problem for ordered trees, and approximation algorithms for the largest common sub-tree problem for unordered trees. We also review applications of tree edit distance and its variants to bioinformatics with focusing on comparison of glycan structures.

Akutsu, Tatsuya

289

The decision tree approach to classification  

NASA Technical Reports Server (NTRS)

A class of multistage decision tree classifiers is proposed and studied relative to the classification of multispectral remotely sensed data. The decision tree classifiers are shown to have the potential for improving both the classification accuracy and the computation efficiency. Dimensionality in pattern recognition is discussed and two theorems on the lower bound of logic computation for multiclass classification are derived. The automatic or optimization approach is emphasized. Experimental results on real data are reported, which clearly demonstrate the usefulness of decision tree classifiers.

Wu, C.; Landgrebe, D. A.; Swain, P. H.

1975-01-01

290

Tree Death Study's Climate Change Connections  

ScienceCinema

What are the exact physiological mechanisms that lead to tree death during prolonged drought and rising temperatures? These are the questions that scientists are trying to answer at a Los Alamos National Laboratory research project called SUMO. SUMO stands for SUrvival/MOrtality study; it's a plot of land on the Lab's southern border that features 18 climate controlled tree study chambers and a large drought structure that limits rain and snowfall. Scientists are taking a wide variety of measurements over a long period of time to determine what happens during drought and warming, and what the connections and feedback loops might be between tree death and climate change.

McDowell, Nate

2014-06-25

291

Tree Rings as Records of the Past  

NSDL National Science Digital Library

In this activity students will examine sections of cut trees. They will observe and describe the difference between early and late wood, make a guess about the age of the tree, determine the actual age by counting the rings, and identify the rings that represent the years the student, the student's parents, and the student's grandparents were born, or years of historical importance. In addition, students may identify the narrowest rings, then check precipitation records to see if these coincide with years of low rainfall. They will discover that trees grow in diameter by producing new wood in the layer just beneath their bark.

Bjornerud, Marcia

292

Photosynthesis, Trees, and the Greenhouse Effect  

NSDL National Science Digital Library

In this lesson plan students will study photosynthesis and then transfer their understanding of this topic to a consideration of how trees can help reduce the negative impacts of the greenhouse effect. They will read a webpage describing the greenhouse effect, the role of carbon dioxide as a greenhouse gas, and the role of humans in exacerbating this effect. Students will also browse the website of an organization that sponsors tree planting programs and consider how these programs might help reduce or slow down the increase of the greenhouse effect. They will conclude by writing paragraphs telling younger kids about the benefits of trees and plants.

293

Tree Death Study's Climate Change Connections  

SciTech Connect

What are the exact physiological mechanisms that lead to tree death during prolonged drought and rising temperatures? These are the questions that scientists are trying to answer at a Los Alamos National Laboratory research project called SUMO. SUMO stands for SUrvival/MOrtality study; it's a plot of land on the Lab's southern border that features 18 climate controlled tree study chambers and a large drought structure that limits rain and snowfall. Scientists are taking a wide variety of measurements over a long period of time to determine what happens during drought and warming, and what the connections and feedback loops might be between tree death and climate change.

McDowell, Nate

2012-09-10

294

Big tree : have you ever seen a tree big enough to drive a car through?  

NSDL National Science Digital Library

In this activity, students are given the girth and height of 10 National Champion giant trees and asked to determine which of the trees is large enough for a car to drive through. The activity, from the Figure This! list of 80 math challenges, also asks students to apply what they have learned to estimate the height of a tree in their neighborhood. It suggests that the student make a table to relate information about tree girth, circumference, and diameter to help determine which giant trees are big enough for a car to drive through. The importance of measurement formulas to careers in biology, construction, and publishing is noted. The page features links to a solution hint, the solution, related math questions, and resources for learning more about trees. Copyright 2005 Eisenhower National Clearinghouse

Engineering, National A.; National Council of Teachers of Mathematics (NCTM); Communications, Widmeyer

2002-01-01

295

Distributed game-tree searching  

SciTech Connect

Conventional parallelizations of the alpha-beta ({alpha}{beta}) algorithm have met with limited success. Implementations suffer primarily from the synchronization and search overheads of parallelization. This paper describes a parallel {alpha}{beta} searching program that achieves high performance through the use of four different types of processes: Controllers, Searchers, Table Managers, and Scouts. Synchronization is reduced by having Controller process reassigning idle processes to help out busy ones. Search overhead is reduced by having two types of parallel table management: global Table Managers and the periodic merging and redistribution of local tables. Experiments show that nine processors can achieve 5.67-fold speedups but beyond that, additional processors provide diminishing returns. Given that additional resources are of little benefit, speculative computing is introduced as a means of extending the effective number of processors that can be utilized. Scout processes speculatively search ahead in the tree looking for interesting features and communicate this information back to the {alpha}{beta} program. In this way, the effective search depth is extended. These ideas have been tested experimentally and empirically as part of the chess program ParaPhoenix.

Schaeffer, J. (Computing Science Dept., Univ. of Alberta, Alberta (CA))

1989-02-01

296

Photosynthetic Action Spectra of Trees  

PubMed Central

Comparative isoenergetic action spectra of net photosynthesis for intact, current year foliage of five tree species were determined from 400 to 710 nm by CO2 exchange analysis. The blue (400 to 500 nm) peak of net photosynthetic activity for the green broadleaves of red alder (Alnus rubra Bong.) was reduced to a plateau for the green needle-leaves of Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) and Sitka spruce (Picea sitchensis [Bong.] Carr.), a shoulder for the blue-green needles of Colorado spruce (Picea pungens Engelm.), and a reduced shoulder for the blue-white needles of Blue spruce (Picea pungens var. hoospii). These differences were attributable neither to a differential blue light stimulation of photorespiration nor to a differential presence of a nonplastid screening pigment. The conifers all had similar carotenoid-chlorophyll ratios, with approximately 50% more carotenoid relative to chlorophyll as compared to red alder. Blue light absorption and low efficiency of energy transfer by the carotenoids probably accounts for the low net photosynthetic activity of the green conifers in blue light as compared to red alder. Leaf form per se (broad versus needle) had no distinguishable influence on these results.

Clark, John B.; Lister, Geoffrey R.

1975-01-01

297

Extended Full Computation-Tree Logic with Sequence Modal Operator: Representing Hierarchical Tree Structures  

NASA Astrophysics Data System (ADS)

An extended full computation-tree logic, CTLS*, is introduced as a Kripke semantics with a sequence modal operator. This logic can appropriately represent hierarchical tree structures where sequence modal operators in CTLS* are applied to tree structures. An embedding theorem of CTLS* into CTL* is proved. The validity, satisfiability and model-checking problems of CTLS* are shown to be decidable. An illustrative example of biological taxonomy is presented using CTLS* formulas.

Kamide, Norihiro; Kaneiwa, Ken

298

Tree mixture effects on aboveground nutrient pools of trees in an experimental plantation in Panama  

Microsoft Academic Search

Mixed plantations might contribute to sustainable land use because of complementary nutrient use. Our objective was to assess\\u000a the nutrient economy of five native tree species and their response to different neighbor trees in an experimental plantation\\u000a in Panama. In our study, H. crepitans was the least nutrient efficient tree species. H. crepitans produced less biomass in mixtures than in

Yvonne Oelmann; Catherine Potvin; Timo Mark; Lisa Werther; Simone Tapernon; Wolfgang Wilcke

2010-01-01

299

Production rates and costs of whole-tree, tree length, and log-length skyline thinning  

Microsoft Academic Search

Production rates and costs were determined for harvesting smallwood by different methods of skyline yarding: whole-tree (yarding with limbs and tops), tree-length (bucking done on the landing), and log-length (limbing, topping, and bucking done on the slope). A rubber-tired skidder was used to swing and sort the variously cut trees from the landing to a site on the haul road

N. E. Putman; L. D. Kellogg; E. D. Olsen

1984-01-01

300

Medical Image Segmentation using a Tree Model.  

National Technical Information Service (NTIS)

A model-driven, multiscale medical image segmentation system is presented. A tree representation is calculated for the image, using a modification of the immersion algorithm used for watersheds calculation. Segmentation is carried out by a matching proces...

V. Grau M. Alcaniz C. Monserrat M. C. Juan J. A. Gil

2001-01-01

301

Circular Drawings of Rooted Trees. Information Systems.  

National Technical Information Service (NTIS)

We describe an algorithm producing circular layouts for trees, that is drawings, where subtrees of a node lie within circles, and these circles are themselves placed on the circumference of a circle. The complexity and methodology of our algorithm compare...

G. Melancon I. Herman

1998-01-01

302

Fruit and Tree Nuts Outlook, June 2012.  

National Technical Information Service (NTIS)

Provides current intelligence and forecasts the effects of changing conditions in the U.S. fruit and tree nuts sector. Topics include production, consumption, shipments, prices received, and more. This seasons Southern Hemisphere blueberry shipments to th...

A. Perez K. Plattner

2012-01-01

303

Repeatability of TREES rotor bore inspection system  

SciTech Connect

The repeatability of near-bore flaw detection and sizing of the Turbine Rotor Examination and Evaluation System (TREES) developed in EPRI RP502 was examined by making many repeat scans of sample blocks containing fatigue cracks and embedded spherical- and disk-shaped flaws of various sizes. Comparison data was also collected manually using the Bore Ultrasonic Characterization System (BUCS). Approximately 1500 measurements were taken with TREES and 1200 were taken with BUCS during the course of this study. The results of this work showed that TREES consistently detected flaws in the near-bore region. TREES determined the radial extent of flaws with associated standard deviations of 18% for fatigue cracks, 30% for embedded spherical beads and 18 to 28% for embedded disk-shaped reflectors. Corresponding BUCS measurements showed larger measurement spreads in each flaw classification.

Ammirato, F.V.

1982-11-01

304

Interaction Trees with Censored Survival Data  

PubMed Central

We propose an interaction tree (IT) procedure to optimize the subgroup analysis in comparative studies that involve censored survival times. The proposed method recursively partitions the data into two subsets that show the greatest interaction with the treatment, which results in a number of objectively defined subgroups: in some of them the treatment effect is prominent while in others the treatment may have a negligible or even negative effect. The resultant tree structure can be used to explore the overall interaction between treatment and other covariates and help identify and describe possible target populations on which an experimental treatment demonstrates desired efficacy. We follow the standard CART (Breiman, et al., 1984) methodology to develop the interaction tree structure. Variable importance information is extracted via random forests of interaction trees. Both simulated experiments and an analysis of the primary billiary cirrhosis (PBC) data are provided for evaluation and illustration of the proposed procedure.

Su, Xiaogang; Zhou, Tianni; Yan, Xin; Fan, Juanjuan; Yang, Song

2008-01-01

305

Asian Longhorned Beetle and Its Host Trees.  

National Technical Information Service (NTIS)

This pictorial guide provides basic information for identifying the Asian longhorned beetle, its injury characteristics, and its common host trees. The guide will help users detect the beetle in both urban and forested settings.

2012-01-01

306

Evolutionary and Ecological Trees and Networks  

NASA Astrophysics Data System (ADS)

Evolutionary relationships between species are usually represented in phylogenies, i.e. evolutionary trees, which are a type of networks. The terminal nodes of these trees represent species, which are made of individuals and populations among which gene flow occurs. This flow can also be represented as a network. In this paper we briefly show some properties of these complex networks of evolutionary and ecological relationships. First, we characterize large scale evolutionary relationships in the Tree of Life by a degree distribution. Second, we represent genetic relationships between individuals of a Mediterranean marine plant, Posidonia oceanica, in terms of a Minimum Spanning Tree. Finally, relationships among plant shoots inside populations are represented as networks of genetic similarity.

Hernández-García, Emilio; Herrada, E. Alejandro; Rozenfeld, Alejandro F.; Tessone, Claudio J.; Eguíluz, Víctor M.; Duarte, Carlos M.; Arnaud-Haond, Sophie; Serra~O, Ester

2007-05-01

307

On the Optimality of Huffman Trees.  

National Technical Information Service (NTIS)

Huffman's well-known algorithm for the construction of optimal search trees is shown to have a more general optimality property than was previously known. A corollary of this general optimality property yields explicitly the optimal policy for the dynamic...

C. R. Glassey R. M. Karp

1974-01-01

308

Worms and Trees: An Exciting Adventure.  

ERIC Educational Resources Information Center

Outlines procedures for using silkworms in elementary science, mathematics, history, ecology, social studies, language arts, art, and physical education. Also focuses on the silkworm's use of the mulberry tree. (DDR)

El Harim, Jean Love

1997-01-01

309

Phloem Exudation Studies in Selected Woody Trees.  

National Technical Information Service (NTIS)

Chelating agents, particularly EDTA, were tested for their effectiveness in enhancing the exudation of phloem sugars from selected woody tree species. Of the species selected, Fraxinus uhdei (Evergreen Ash) proved most useful for exudation studies. Experi...

L. R. Costello

1980-01-01

310

Electrochemical Treeing in Cable. Final Report.  

National Technical Information Service (NTIS)

Results are presented of an investigation of electrochemical treeing in solid dielectric insulated cables performed between May, 1973 and March, 1977 for the Electric Power Research Institute. The purpose of the work was to establish the influence of vari...

N. Nagu inivas H. C. Deopken A. L. McKean M. C. Biskeborn

1978-01-01

311

Optimal parallel evaluation of AND trees  

SciTech Connect

AND-tree evaluation is an important technique in artificial intelligence and operations research. An example is the divide-and-conquer algorithm, which can be considered the evaluation of a precedence graph consisting of two opposing AND trees. In this paper, the optimal degree of parallelism for evaluating any given AND tree is quantitatively analyzed. The efficiency analysis is based on both preemptive and on preemptive critical-path scheduling algorithms. It is found that the optimal degree of parallelism depends on the complexity of the problem to be solved, the shape of the precedence graph, and the task-time distribution along each path. The major results consist of showing the optimality of the preemptive critical-path scheduling algorithm for evaluating any given AND tree on a fixed number of processors, and tight bounds on the number of processors within which the number of processors leading to the optimal processor-time efficiency can be sought efficiently.

Wah, B.W. (Illinois Univ., Urbana, IL (USA). Dept. of Electrical and Computer Engineering); Li, G.J. (Institute of Computing Technology, Academia Sinica, P.O. Box 2704-1, Beijing (CN))

1990-09-01

312

Trees protected villages from tsunami waves  

NSDL National Science Digital Library

In India, trees growing along the coastline helped to protect villages from the "walls of water" or tsunami waves that were triggered by a powerful earthquake that struck beneath the Indian Ocean on 26 December 2004, scientists have discovered.

American Association for the Advancement of Science (AAAS;)

2005-10-27

313

Tree Growth Studies on Uranium Mill Tailings.  

National Technical Information Service (NTIS)

Coniferous trees planted in 1974 and deciduous species, that have volunteered since 1970 on uranium mill tailings that had been stabilized to varying degrees using limestone and vegetation, were evaluated. Their survival and growth rates were compared wit...

D. R. Murray M. Turcotte

1982-01-01

314

Crosstalk Noise Estimation for Generic RC Trees  

Microsoft Academic Search

Absrrmr- We propose an estimation method of crosstalk noise for generic RC trees. The proposed method derives an analytic waveform of crosstalk noise in a 2-7r equivalent circuit. The peak voltage is calculated from the closed-form expression, and the crosstalk induced delay is esti- mated using the derived noise waveform. We also develop a transformation method from generic RC trees

Masao Takahashi; Masanori Hashimoto; Hidetoshi Onodera

2001-01-01

315

Fruit trees in a Malaysian rain forest  

Microsoft Academic Search

An inventory was made of 50 ha of primary lowland rain forest in Peninsular Malaysia, in which ca. 340,000 trees 1 cm dbh\\u000a or larger were measured and identified to species. Out of a total plot tree flora of 820 species, 76 species are known to\\u000a bear edible fruit. Especially diverse were the wild species of mango (Mangifera, Anacardiaceae, 12

L. G. Saw; J. V. LaFrankie; K. M. Kochummen; S. K. Yap

1991-01-01

316

Using invariants for phylogenetic tree construction  

Microsoft Academic Search

Phylogenetic invariants are certain polynomials in the joint probability\\u000adistribution of a Markov model on a phylogenetic tree. Such polynomials are of\\u000atheoretical interest in the field of algebraic statistics and they are also of\\u000apractical interest--they can be used to construct phylogenetic trees. This\\u000apaper is a self-contained introduction to the algebraic, statistical, and\\u000acomputational challenges involved in the

Nicholas Eriksson

2007-01-01

317

Exact Bipartite Crossing Minimization under Tree Constraints  

Microsoft Academic Search

A tanglegram consists of a pair of (not necessarily binary) trees T1, T2 with leaf sets L1, L2. Additional edges, called tangles, may connect nodes in L1 with those in L2. The task is to draw the tanglegram with a minimum number of tangle edge crossings while making sure that no crossing occurs between edges within each tree. This problem

Frank Baumann; Christoph Buchheim; Frauke Liers

2010-01-01

318

Hyphomycetes in the snow from gymnosperm trees.  

PubMed

The presence of 26 hyphomycete species was noted in snow water collected from coniferous trees. Camposporium pellucidum, Monodictys peruviana, Polystratorictus fusarioideus, Sporidesmium moniliforme, Tripospermum acerinum and Veronaea botryosa were recorded for the first time to Poland. Among the 26 species found in snow water from coniferous trees predominance of the socalled aero-aquatic hyphomycetes and only a few species belong to the group of aquatic hyphomycetes. PMID:9972045

Czeczuga, B; Or?owska, M

1998-01-01

319

Alcohol co-production from tree crops  

Microsoft Academic Search

A concept for the sustainable production of alcohol from fermentable substrates produced on an annual basis by the reproductive organs (pods, fruits, nuts, berries, etc.) of tree crops is presented. The advantages of tree-crop systems include suitability for use on marginal land, potential productivity equivalent to row crops, minimal maintenance and energy-input requirements, environmental compatibility, and the possibility of co-product

M. Seibert; G. Folger; T. Milne

1982-01-01

320

The generalized Randic index of trees  

Microsoft Academic Search

The Generalised Randic index R??(T) of a tree T is the sum over the edges uv of T of (d(u)d(v))?? where d(x) is the degree of the vertex x in T. For all ? > 0, we find the minimal constantc = ?c(?) such that for all trees on at least 3 vertices R??(T) ? ?c(n + 1) where n

Paul N. Balister; Béla Bollobás; Stefanie Gerke

2007-01-01

321

Parallel object-oriented decision tree system  

DOEpatents

A data mining decision tree system that uncovers patterns, associations, anomalies, and other statistically significant structures in data by reading and displaying data files, extracting relevant features for each of the objects, and using a method of recognizing patterns among the objects based upon object features through a decision tree that reads the data, sorts the data if necessary, determines the best manner to split the data into subsets according to some criterion, and splits the data.

Kamath; Chandrika (Dublin, CA), Cantu-Paz; Erick (Oakland, CA)

2006-02-28

322

Construction of Decision Trees Using Data Cube  

Microsoft Academic Search

Data classification is an important problem in data mining. The traditional classification algorithms based on decision trees\\u000a have been widely used due to their fast model construction and good model understandability. However, the existing decision\\u000a tree algorithms need to recursively partition dataset into subsets according to some splitting criteria i.e. they still have\\u000a to repeatedly compute the records belonging to

Lixin Fu

2005-01-01

323

Tractable Symmetry Breaking Using Restricted Search Trees  

Microsoft Academic Search

We present a new conceptual abstraction in symmetry breaking - the GE-tree. The construction and traversal of a GE-tree breaks all symmetries in any constraint satisfaction or similar prob- lem. We give a polynomial-time algorithm for this construction in the case of CSPs with arbitrary value symmetries. We have implemented this technique, and supply experimental evidence of its practical ef-

Colva M. Roney-dougal; Ian P. Gent; Tom Kelsey; Steve Linton

2004-01-01

324

Bow-tie-tree in EPR cables after accelerated water treeing test  

SciTech Connect

The paper describes the results of accelerated water treeing test after a period of approximately one year with two recently manufactured (1988) varieties of commercial EPR cables, produced by different manufacturers and possessing different cable structures, as well as water impervious XLPE cable for comparison. In the test, bow-tie trees were found in the EPR insulation which was though to develop no or few bow-tie-trees. Examination results of bow-tie-tree in EPR cables are described in this report.

Uematsu, T.; Iwata, Z.; Irie, S.; Fujii, O. (Furukawa Electric Co. Ltd., Tokyo (Japan))

1992-10-01

325

Variable Selection in Classification Trees Based on Imprecise Probabilities  

Microsoft Academic Search

Classiflcation trees are a popular statistical tool with multiple applications. Recent advancements of tra- ditional classiflcation trees, such as the approach of classiflcation trees based on imprecise probabilities by Abellan and Moral (2005), efiectively address their tendency to overfltting. However, another ?aw in- herent in traditional classiflcation trees is not elim- inated by the imprecise probability approach: Due to a

Carolin Strobl

2005-01-01

326

Water treeing and breakdown strength reduction of XLPE insulation  

Microsoft Academic Search

An effort was made to determine factors influencing initiation and growth of vented water trees and to study the reduction of breakdown strength caused by water treeing. Water treeing experiments were performed on both cable samples and Rogowski-type test objects. The influence of aging time and electric field stress was elucidated. In order to test the hypothesis that water treeing

E. Ildstad; J. Sletbak; H. Faremo

1989-01-01

327

The invasiveness of the African Tulip Tree, Spathodea campanulata Beauv  

Microsoft Academic Search

The African Tulip Tree (Spathodea campanulata Beauv.), originally from East and Southern Africa, is a large upright tree with green, pinnately compound leaves and bright orange-coloured flowers. The tree can grow to more than 20m in height and reproduces through seeds and runners. The plant's uses are very limited; it serves as a shade tree or for making fence posts.

Ricardo Labrada; Alejandro Díaz Medina

2009-01-01

328

Growing Greener Cities: A Tree-Planting Handbook.  

ERIC Educational Resources Information Center

This step-by-step guide, developed by the Global ReLeaf organization, presents tree-planting advice and simple steps to organizing a successful community tree-planting and tree-care program. The text is divided into three parts. Part 1 introduces trees and discusses the role they play as components of the living urban environment. Distinctions are…

Moll, Gary; Young, Stanley

329

A Spring Playscape Project: Building a Tree Circle  

ERIC Educational Resources Information Center

The Tree Circle is a green gathering area for children made by planting trees in a circle. For children, the Tree Circle becomes a magical place for dramatic play, quiet retreat, or lively nature exploration. For teachers and parents it becomes a shady grove for snacks and stories. The trees create a sweet spot that changes during the seasons and…

Keeler, Rusty

2009-01-01

330

The Bayesian Additive Classification Tree applied to credit risk modelling  

Microsoft Academic Search

We propose a new nonlinear classification method based on a Bayesian “sum-of-trees” model, the Bayesian Additive Classification Tree (BACT), which extends the Bayesian Additive Regression Tree (BART) method into the classification context. Like BART, the BACT is a Bayesian nonparametric additive model specified by a prior and a likelihood in which the additive components are trees, and it is fitted

Junni L. Zhang; Wolfgang K. Härdle

2010-01-01

331

Predicting Lumber Grade Yields for Standing Hardwood Trees.  

National Technical Information Service (NTIS)

A method was developed for estimating lumber grade yields for hardwood trees using selected tree stem characteristics. The method was tested on sugar maple trees from four National Forests. When tested on trees from the Ottawa National Forest (near the ar...

C. L. Stayton R. M. Marden G. L. Gammon

1971-01-01

332

Rooting a phylogenetic tree with nonreversible substitution models  

Microsoft Academic Search

BACKGROUND: We compared two methods of rooting a phylogenetic tree: the stationary and the nonstationary substitution processes. These methods do not require an outgroup. METHODS: Given a multiple alignment and an unrooted tree, the maximum likelihood estimates of branch lengths and substitution parameters for each associated rooted tree are found; rooted trees are compared using their likelihood values. Site variation

Von Bing Yap; Terry Speed

2005-01-01

333

Computing the Edit-Distance between Unrooted Ordered Trees  

Microsoft Academic Search

An ordered tree is a tree in which each node's incident edges are cyclically ordered; think of the tree as being embedded in the plane. Let A and B be two ordered trees. The edit distance between A and B is the minimum cost of a sequence of operations (contract an edge, uncontract an edge, modify the label of an

Philip N. Klein

1998-01-01

334

Contribution of agroforestry trees to nutrient requirements of intercropped plants  

Microsoft Academic Search

A major tenet of agroforestry, that trees maintain soil fertility, is based primarily on observations of higher crop yields near trees or where trees were previously grown. Recently objective analyses and controlled experiments have addressed this topic. This paper examines the issues of tree prunings containing sufficient nutrients to meet crop demands, the timing of nutrient transfer from decomposition to

C. A. Palm

1995-01-01

335

``Overturned-Stairs'' Adder Trees and Multiplier Design  

Microsoft Academic Search

Wallace trees are the theoretically fastest multioperand adders. However, their complex interconnections do not permit practical implementations. A family of Overturned-Stairs trees which achieve the same speed performance as equivalent Wallace trees in many cases, but require a simple and regular interconnection scheme is introduced. These trees can be designed in a systematic way and laid out regularly in a

Francis Jutand

1992-01-01

336

Comparative water use by dryland trees in Parklands in Senegal  

Microsoft Academic Search

Despite the clear evidence of competition for water between trees and crops, there have been very few studies comparing simultaneous water use by differing tree species in drylands. Comparative water use by dryland trees was measured in Senegal using heat balance gauges at the end of the wet season and in the dry season. Significant differences between tree species were

J. D. Deans; R. C. Munro

2004-01-01

337

Methodology for Computer-Aided Fault Tree Analysis  

Microsoft Academic Search

Fault tree analysis is a systematic, deductive and probabilistic risk assessment tool which elucidates the causal relations leading to a given undesired event. Quantitative fault tree (failure) analysis requires a fault tree and failure data of basic events. Development of a fault tree and subsequent analysis require a great deal of expertise, which may not be available all the time.

R. Ferdous; F. I. Khan; B. Veitch; P. R. Amyotte

2007-01-01

338

A Dynamic Mechanism for Distributed Optimization of Overlay Multicast Tree  

Microsoft Academic Search

To enhance the performance of overlay multicast networks, the overlay multicast tree should be optimized. This optimization prob- lem is a minimum diameter, degree-limited spanning tree (MDDLST) problem which is known to be NP-Hard. We present a new scheme to optimize an overlay multicast tree dynamically. Our algorithm can adapt the tree structure to the dynamic membership and network situation.

Han Choe; Seongho Cho; Chongkwon Kim

2004-01-01

339

The Hydraulic System of Trees: Theoretical Framework and Numerical Simulation  

Microsoft Academic Search

Empirical studies pose the problem of the physiological integration of the tree organism, which is also important on the scale of ecosystems. Recently, spatially distributed models emerged, which approach this problem by reflecting the close linkage between physiological processes and the structures of trees and tree stands. In the case of water flow, the tree organism can be regarded as

THOMAS FRÜH; WINFRIED KURTH

1999-01-01

340

3D FractaL-Tree  

NSDL National Science Digital Library

3D FractaL-Tree allows scientists to collect data from actual specimens in the field or laboratory, insert these measurements into a spatially explicit L-system package, and then visually compare to the computer generated 3D image with such specimens. The measurements are recorded and analyzed in a series of worksheets in Microsoft Excelî and the results are entered into the graphics engine in a Java applet. 3D FractaL-Tree produces a rotatable three-dimensional image of the tree which is helpful for examining such characters as self-avoidance (entanglement and breakage), penetration of sunlight, distances that small herbivores (such as caterpillars) would have to traverse to go from one tip to another, and Voronoi polyhedra of volume distribution of biomass on different subsections of a tree. These and other factors have been discussed in the Adaptive Geometry of Trees (Horn, 1971). Three different representations are available in 3D FractaL-Tree images: wire frame, solid, and transparent. Easy options for saving and exporting images are included.

John Jungck (Beloit College;Biology); Jennifer Spangenberg (Beloit College;Biology); Noppadon Khiripet (National Electronics and Computer Technology Center, Thailand;Bioinformatics Unit); Rawin Viruchpinta (National Electronics and Computer Technology Center, Thailand;); Jutarat Maneewattanapluk (National Electronics and Computer Technology Center, Thailand;)

2007-07-18

341

A study of tea tree oil ototoxicity.  

PubMed

Tea tree oil shows promise as an effective treatment for a number of micro-organisms commonly associated with otitis externa and otitis media, but its possible ototoxicity has not been previously assessed. The ototoxicity of tea tree oil was examined in the guinea pig by measuring the thresholds of the compound auditory nerve action potential (CAP) to tone bursts before and after instillation of the oil into the middle ear. After 30 min of instillation, 100% tea tree oil caused a partial CAP threshold elevation at 20 kHz. A lower concentration of oil [2% tea tree oil dissolved in saline using 0.5% detergent (Tween-80)] did not cause any significant lasting threshold change after middle ear instillation for the same period of time. The latter concentration of oil is greater than the minimum inhibitory concentration reported for most micro-organisms in the effective spectrum of the oil and this suggests that this concentration may be safe and effective provided only short exposures (about 30 min) are used. The results suggest that high concentrations of tea tree oil applied to the round window for a relatively short time are to some extent ototoxic to the high-frequency region of the cochlea. Hence further study is needed to establish whether tea tree oil can be used with safety in the treatment of external and middle ear infections. PMID:10720822

Zhang, S Y; Robertson, D

2000-01-01

342

A natural history of human tree climbing.  

PubMed

Walking and running have dominated the literature on human locomotor evolution at the expense of other behaviors with positive and negative fitness consequences. For example, although modern hunter-gatherers frequently climb trees to obtain important food resources in the canopy, these behaviors are seldom considered within the existing framework of primate positional behavior. As a result, inferences about the arboreal performance capabilities of fossil hominins based on a resemblance to humans may be more complicated than previously assumed. Here we use ethnographic reports of human tree climbing to critically evaluate hypotheses about the performance capabilities of humans in trees compared with other primates. We do so by reviewing the ecological basis of tree climbing behavior among hunter-gatherers and the diversity of human climbing techniques and styles. Results suggest that the biological and adaptive significance of human climbing has been underestimated, and that some humans are surprisingly competent in trees, particularly during vertical climbing and activities in the central core of trees. We conclude that while hominins evolved enhanced terrestrial locomotor performance through time, such shifts may have imposed only minor costs on vertical climbing abilities. The diversity of the locomotor repertoire of modern humans must therefore be taken into account when making form-function inferences during the behavioral reconstruction of fossil hominins. PMID:24630525

Kraft, Thomas S; Venkataraman, Vivek V; Dominy, Nathaniel J

2014-06-01

343

A global history of Australian trees.  

PubMed

Scholars studying the globalization of Australian trees have previously emphasized the rapid natural propagation of Australian trees outside of their native habitats, believing their success to be a reversal of "ecological imperialism" from the "new world" to the "old world." This article argues that the expansion of Australian trees should not be viewed as a biological phenomenon, but as the result of a long-term attempt by powerful states and state-sponsored scientists to select and breed Australian species that could grow in a variety of climates and ecological conditions. Five non-biological factors largely determined the success of these attempts to grow Australian trees: the abundance or paucity of natural forests, state power, the amount of scientific research directed to planting Australian trees, the cost of labor, and the ability to utilize hardwood timbers and bark. This paper compares the use of Australian trees in Australia, India, and South Africa to demonstrate that biology was not the determining factor in the long-term success of many Australian genera and species. PMID:20665086

Bennett, Brett M

2011-01-01

344

Spectra of generalized Bethe trees attached to a path  

Microsoft Academic Search

A generalized Bethe tree is a rooted tree in which vertices at the same distance from the root have the same degree. Let Pm be a path of m vertices. Let {Bi:1?i?m} be a set of generalized Bethe trees. Let Pm{Bi:1?i?m} be the tree obtained from Pm and the trees B1,B2,…,Bm by identifying the root vertex of Bi with the

Oscar Rojo; Luis Medina

2009-01-01

345

A Neural Tree with Partial Incremental Learning Capability  

Microsoft Academic Search

This paper presents a new approach to constructing a neural tree with partial incremental learning capability. The proposed neural tree, called a quadratic-neuron-based neural tree (QUANT), is a tree structured neural network composed of neurons with quadratic neural-type junctions for pattern classification. The proposed QUANT integrates the advantages of decision trees and neural networks. Via a batch-mode training algorithm, the

Mu-Chun Su; Hsu-Hsun Lo

2007-01-01

346

Efficient Exploration of the Space of Reconciled Gene Trees  

PubMed Central

Gene trees record the combination of gene-level events, such as duplication, transfer and loss (DTL), and species-level events, such as speciation and extinction. Gene tree–species tree reconciliation methods model these processes by drawing gene trees into the species tree using a series of gene and species-level events. The reconstruction of gene trees based on sequence alone almost always involves choosing between statistically equivalent or weakly distinguishable relationships that could be much better resolved based on a putative species tree. To exploit this potential for accurate reconstruction of gene trees, the space of reconciled gene trees must be explored according to a joint model of sequence evolution and gene tree–species tree reconciliation. Here we present amalgamated likelihood estimation (ALE), a probabilistic approach to exhaustively explore all reconciled gene trees that can be amalgamated as a combination of clades observed in a sample of gene trees. We implement the ALE approach in the context of a reconciliation model (Szöll?si et al. 2013), which allows for the DTL of genes. We use ALE to efficiently approximate the sum of the joint likelihood over amalgamations and to find the reconciled gene tree that maximizes the joint likelihood among all such trees. We demonstrate using simulations that gene trees reconstructed using the joint likelihood are substantially more accurate than those reconstructed using sequence alone. Using realistic gene tree topologies, branch lengths, and alignment sizes, we demonstrate that ALE produces more accurate gene trees even if the model of sequence evolution is greatly simplified. Finally, examining 1099 gene families from 36 cyanobacterial genomes we find that joint likelihood-based inference results in a striking reduction in apparent phylogenetic discord, with respectively. 24%, 59%, and 46% reductions in the mean numbers of duplications, transfers, and losses per gene family. The open source implementation of ALE is available from https://github.com/ssolo/ALE.git. [amalgamation; gene tree reconciliation; gene tree reconstruction; lateral gene transfer; phylogeny.

Szollosi, Gergely J.; Rosikiewicz, Wojciech; Boussau, Bastien; Tannier, Eric; Daubin, Vincent

2013-01-01

347

Optimised KD-trees for fast image descriptor matching  

Microsoft Academic Search

In this paper, we look at improving the KD-tree for a spe- cific usage: indexing a large number of SIFTand other types of image descriptors. We have extended priority search, to priority search among multiple trees. By creating multiple KD-trees from the same data set and simultaneously search- ing among these trees, we have improved the KD-tree's search performancesignificantly.We have

Chanop Silpa-anan; Richard Hartley

2008-01-01

348

Real-time KD-tree construction on graphics hardware  

Microsoft Academic Search

We present an algorithm for constructing kd-trees on GPUs. This algorithm achieves real-time performance by exploiting the GPU's streaming architecture at all stages of kd-tree construction. Unlike previous parallel kd-tree algorithms, our method builds tree nodes completely in BFS (breadth-first search) order. We also develop a special strategy for large nodes at upper tree levels so as to further exploit

Kun Zhou; Qiming Hou; Rui Wang; Baining Guo

2008-01-01

349

TreeRipper web application: towards a fully automated optical tree recognition software  

PubMed Central

Background Relationships between species, genes and genomes have been printed as trees for over a century. Whilst this may have been the best format for exchanging and sharing phylogenetic hypotheses during the 20th century, the worldwide web now provides faster and automated ways of transferring and sharing phylogenetic knowledge. However, novel software is needed to defrost these published phylogenies for the 21st century. Results TreeRipper is a simple website for the fully-automated recognition of multifurcating phylogenetic trees (http://linnaeus.zoology.gla.ac.uk/~jhughes/treeripper/). The program accepts a range of input image formats (PNG, JPG/JPEG or GIF). The underlying command line c++ program follows a number of cleaning steps to detect lines, remove node labels, patch-up broken lines and corners and detect line edges. The edge contour is then determined to detect the branch length, tip label positions and the topology of the tree. Optical Character Recognition (OCR) is used to convert the tip labels into text with the freely available tesseract-ocr software. 32% of images meeting the prerequisites for TreeRipper were successfully recognised, the largest tree had 115 leaves. Conclusions Despite the diversity of ways phylogenies have been illustrated making the design of a fully automated tree recognition software difficult, TreeRipper is a step towards automating the digitization of past phylogenies. We also provide a dataset of 100 tree images and associated tree files for training and/or benchmarking future software. TreeRipper is an open source project licensed under the GNU General Public Licence v3.

2011-01-01

350

Estimating divergence times in large phylogenetic trees.  

PubMed

A new method, PATHd8, for estimating ultrametric trees from trees with edge (branch) lengths proportional to the number of substitutions is proposed. The method allows for an arbitrary number of reference nodes for time calibration, each defined either as absolute age, minimum age, or maximum age, and the tree need not be fully resolved. The method is based on estimating node ages by mean path lengths from the node to the leaves but correcting for deviations from a molecular clock suggested by reference nodes. As opposed to most existing methods allowing substitution rate variation, the new method smoothes substitution rates locally, rather than simultaneously over the whole tree, thus allowing for analysis of very large trees. The performance of PATHd8 is compared with other frequently used methods for estimating divergence times. In analyses of three separate data sets, PATHd8 gives similar divergence times to other methods, the largest difference being between crown group ages, where unconstrained nodes get younger ages when analyzed with PATHd8. Overall, chronograms obtained from other methods appear smoother, whereas PATHd8 preserves more of the heterogeneity seen in the original edge lengths. Divergence times are most evenly spread over the chronograms obtained from the Bayesian implementation and the clock-based Langley-Fitch method, and these two methods produce very similar ages for most nodes. Evaluations of PATHd8 using simulated data suggest that PATHd8 is slightly less precise compared with penalized likelihood, but it gives more sensible answers for extreme data sets. A clear advantage with PATHd8 is that it is more or less instantaneous even with trees having several thousand leaves, whereas other programs often run into problems when analyzing trees with hundreds of leaves. PATHd8 is implemented in freely available software. PMID:17886144

Britton, Tom; Anderson, Cajsa Lisa; Jacquet, David; Lundqvist, Samuel; Bremer, Kåre

2007-10-01

351

Temperature histories from tree rings and corals  

SciTech Connect

Recent temperature trends in long tree-ring and coral proxy temperature histories are evaluated and compared in an effort to objectively determine how anomalous twentieth century temperature changes have been. These histories mostly reflect regional variations in summer warmth from the tree rings and annual warmth from the corals. In the Northern Hemisphere. the North American tree-ring temperature histories and those from the north Polar Urals, covering the past 1000 or more years, indicate that the twentieth century has been anomalously warm relative to the past. In contrast, the tree-ring history from northern Fennoscandia indicates that summer temperatures during the {open_quote}Medieval Warm Period{close_quote} were probably warmer on average than those than during this century. In the Southern Hemisphere, the tree-ring temperature histories from South America show no indication of recent warming, which is in accordance with local instrumental records. In contrast, the tree-ring, records from Tasmania and New Zealand indicate that the twentieth century has been unusually warm particularly since 1960. The coral temperature histories from the Galapagos Islands and the Great Barrier Reef are in broad agreement with the tree-ring temperature histories in those sectors, with the former showing recent cooling and the latter showing recent warming that may be unprecedented. Overall, the regional temperature histories evaluated here broadly support the larger-scale evidence for anomalous twentieth century warming based on instrumental records. However, this warming cannot be confirmed as an unprecedented event in all regions. 38 refs., 3 figs., 2 tabs.

Cook, E.R. [Tree-Ring Lab., Palisades, NY (United States)

1995-05-01

352

The tree gangs of Glittertown. [Los Angeles organizations promote tree planting  

Microsoft Academic Search

This article describes the activities of four groups in Los Angeles as part of The Global ReLeaf challenge to plant trees for environmental improvement and to combat global warming. The activities include: training of citizen foresters' in selection of tree species, planting sites, maintenance, and fund-raising; education of school children about recycling, organic gardening, water conservation and composting. By working

Boerner-Ein

2009-01-01

353

Tree-Bole Volume Estimation on Standing Pine Trees Using Cascade Correlation Artificial Neural Network Models  

Microsoft Academic Search

Total tree volume estimation is an integral part of forest growth and yield forecasting. Complex formulae are used to estimate bole volume by section, based on relationships proposed by Huber, Smalian and Newton. All these relationships require many measurements of bole diameters at certain heights that are difficult to obtain on standing trees especially when diameter measurements have to be

M. J. Diamantopoulou

2006-01-01

354

Migrating Fault Trees To Decision Trees For Real Time Fault Detection On International Space Station  

Microsoft Academic Search

Fault Tree Analysis shows the possible causes of a system malfunction by enumerating the suspect components and their respective failure modes that may have induced the problem. Complex systems often use fault trees to analyze the faults. Fault diagnosis, when error occurs, is performed by engineers and analysts performing extensive examination of all data gathered during the mission. International Space

Charles Lee; Richard L. Alena; Peter Robinson

2005-01-01

355

Computer-oriented approach to fault-tree construction. [Computer Automated Tree (CAT) code  

Microsoft Academic Search

A methodology for systematically constructing fault trees for general complex systems is developed and applied, via the Computer Automated Tree (CAT) program, to several systems. A means of representing component behavior by decision tables is presented. The method developed allows the modeling of components with various combinations of electrical, fluid and mechanical inputs and outputs. Each component can have multiple

S. L. Salem; G. E. Apostolakis; D. Okrent

1976-01-01

356

Application of fault tree analysis to the service process: service tree analysis approach  

Microsoft Academic Search

Purpose – This study aims to propose a tree-based analytic tool that may be used in analyzing a large-scale and complex service process. The tenet of this tool is based on the Boolean logic and named service tree analysis (STA). The proposed STA aims to reflect the customer participation perspective and to propose how to analyze the service process and

Youngjung Geum; Hyeonju Seol; Sungjoo Lee

2009-01-01

357

Reconfiguration algorithms for tree architectures using sub-tree oriented fault tolerance  

NASA Technical Reports Server (NTRS)

An approach to reconfiguration in tree architectures has been developed in which redundant processors are allocated at the leaves. The scheme is called sub-tree oriented fault tolerances (SOFT) and is capable of tolerating both link failures as well as multiple processor failures. In this paper, the SOFT scheme is examined from the perspective of reconfigurability. Specific algorithms are presented for reconfiguration.

Lowrie, M. B.; Fuchs, W. K.

1986-01-01

358

Up in the Tree - The Overlooked Richness of Bryophytes and Lichens in Tree Crowns  

PubMed Central

Assessing diversity is among the major tasks in ecology and conservation science. In ecological and conservation studies, epiphytic cryptogams are usually sampled up to accessible heights in forests. Thus, their diversity, especially of canopy specialists, likely is underestimated. If the proportion of those species differs among forest types, plot-based diversity assessments are biased and may result in misleading conservation recommendations. We sampled bryophytes and lichens in 30 forest plots of 20 m × 20 m in three German regions, considering all substrates, and including epiphytic litter fall. First, the sampling of epiphytic species was restricted to the lower 2 m of trees and shrubs. Then, on one representative tree per plot, we additionally recorded epiphytic species in the crown, using tree climbing techniques. Per tree, on average 54% of lichen and 20% of bryophyte species were overlooked if the crown was not been included. After sampling all substrates per plot, including the bark of all shrubs and trees, still 38% of the lichen and 4% of the bryophyte species were overlooked if the tree crown of the sampled tree was not included. The number of overlooked lichen species varied strongly among regions. Furthermore, the number of overlooked bryophyte and lichen species per plot was higher in European beech than in coniferous stands and increased with increasing diameter at breast height of the sampled tree. Thus, our results indicate a bias of comparative studies which might have led to misleading conservation recommendations of plot-based diversity assessments.

Boch, Steffen; Muller, Jorg; Prati, Daniel; Blaser, Stefan; Fischer, Markus

2013-01-01

359

Colorado River Droughts Inferred from Tree Rings  

NASA Astrophysics Data System (ADS)

Tree-ring reconstructions for the Colorado River at Lee Ferry, Arizona, have consistently indicated that the modern gaged flow record is unrepresentative of the past few centuries both in the long-term mean annual flow and the severity of extended hydrologic droughts. Information on past droughts can be considered most reliable for the past 500 years, when tree-ring site coverage is relatively dense. Alternative reconstructions using different modeling methods and basic tree-ring data differ in details but are consistent in the timing of periods of relative drought and wetness, and in identifying the late 1500s as the most severe multi-year drought of the last 500 years. Reconstructions for major tributaries emphasize the spatial coherence of droughts and wet periods over the UCRB. The Lee Ferry record of annual flows can be extended back beyond 500 years, with diminished confidence, by analysis of tree rings from dead standing trees and logs. A new reconstruction covering the period A.D. 762-2005 was generated by a series of reconstruction models with time-varying subsets of 11 recently developed tree-ring chronologies from the Upper Colorado River Basin (UCRB) as predictors. The percentage of variance of annual flow at Lee Ferry accounted for by these models decreases from 77 percent after A. D. 1365 to 60 percent before A. D. 1182, as the number of available tree-ring chronologies drops from eleven to three. Correlation analysis and cross-spectral analysis support the hydrologic interpretation of annual as well as decadal fluctuations in the extended reconstruction. The singular multi-decadal event is a drought in the mid-1100s, when the lowest 25- year mean is estimated to be just 84 percent of the modern observed long-term mean. Absence of high flows rather than presence of record-low flows is characteristic of this drought. Results suggest the mid-1100s drought was more severe in the western part of the UCRB than the well-documented North American mega-drought of the late 1500s. Greater site coverage and sample depth (number of trees) are essential to reducing the uncertainty of assessments of hydrologic drought severity in the early part of the tree-ring record.

Meko, D. M.; Woodhouse, C. A.

2007-05-01

360

Factors affecting the concordance between orthologous gene trees and species tree in bacteria  

PubMed Central

Background As originally defined, orthologous genes implied a reflection of the history of the species. In recent years, many studies have examined the concordance between orthologous gene trees and species trees in bacteria. These studies have produced contradictory results that may have been influenced by orthologous gene misidentification and artefactual phylogenetic reconstructions. Here, using a method that allows the detection and exclusion of false positives during identification of orthologous genes, we address the question of whether putative orthologous genes within bacteria really reflect the history of the species. Results We identified a set of 370 orthologous genes from the bacterial order Rhizobiales. Although manifesting strong vertical signal, almost every orthologous gene had a distinct phylogeny, and the most common topology among the orthologous gene trees did not correspond with the best estimate of the species tree. However, each orthologous gene tree shared an average of 70% of its bipartitions with the best estimate of the species tree. Stochastic error related to gene size affected the concordance between the best estimated of the species tree and the orthologous gene trees, although this effect was weak and distributed unevenly among the functional categories. The nodes showing the greatest discordance were those defined by the shortest internal branches in the best estimated of the species tree. Moreover, a clear bias was evident with respect to the function of the orthologous genes, and the degree of divergence among the orthologous genes appeared to be related to their functional classification. Conclusion Orthologous genes do not reflect the history of the species when taken as individual markers, but they do when taken as a whole. Stochastic error affected the concordance of orthologous genes with the species tree, albeit weakly. We conclude that two important biological causes of discordance among orthologous genes are incomplete lineage sorting and functional restriction.

2008-01-01

361

Untangling tanglegrams: comparing trees by their drawings.  

PubMed

A tanglegram is a pair of trees on the same set of leaves with matching leaves in the two trees joined by an edge. Tanglegrams are widely used in biology--to compare evolutionary histories of host and parasite species and to analyze genes of species in the same geographical area. We consider optimization problems in tanglegram drawings. We show a linear time algorithm to decide if a tanglegram admits a planar embedding by a reduction to the planar graph drawing problem. This problem was also studied by Fernau et al. A similar reduction to a graph crossing problem also helps to solve an open problem they posed, showing a fixed-parameter tractable algorithm for minimizing the number of crossings over all d-ary trees. For the case where one tree is fixed, we show an O(n log n) algorithm to determine the drawing of the second tree that minimizes the number of crossings. This improves the bound from earlier methods. We introduce a new optimization criterion using Spearman's footrule distance and give an O(n²) algorithm. We also show integer programming formulations to quickly obtain tanglegram drawings that minimize the two optimization measures discussed. We prove lower bounds on the maximum gap between the optimal solution and the heuristic of Dwyer and Schreiber to minimize crossings. PMID:20530818

Venkatachalam, Balaji; Apple, Jim; St John, Katherine; Gusfield, Dan

2010-01-01

362

LocTree3 prediction of localization.  

PubMed

The prediction of protein sub-cellular localization is an important step toward elucidating protein function. For each query protein sequence, LocTree2 applies machine learning (profile kernel SVM) to predict the native sub-cellular localization in 18 classes for eukaryotes, in six for bacteria and in three for archaea. The method outputs a score that reflects the reliability of each prediction. LocTree2 has performed on par with or better than any other state-of-the-art method. Here, we report the availability of LocTree3 as a public web server. The server includes the machine learning-based LocTree2 and improves over it through the addition of homology-based inference. Assessed on sequence-unique data, LocTree3 reached an 18-state accuracy Q18 = 80 ± 3% for eukaryotes and a six-state accuracy Q6 = 89 ± 4% for bacteria. The server accepts submissions ranging from single protein sequences to entire proteomes. Response time of the unloaded server is about 90 s for a 300-residue eukaryotic protein and a few hours for an entire eukaryotic proteome not considering the generation of the alignments. For over 1000 entirely sequenced organisms, the predictions are directly available as downloads. The web server is available at http://www.rostlab.org/services/loctree3. PMID:24848019

Goldberg, Tatyana; Hecht, Maximilian; Hamp, Tobias; Karl, Timothy; Yachdav, Guy; Ahmed, Nadeem; Altermann, Uwe; Angerer, Philipp; Ansorge, Sonja; Balasz, Kinga; Bernhofer, Michael; Betz, Alexander; Cizmadija, Laura; Do, Kieu Trinh; Gerke, Julia; Greil, Robert; Joerdens, Vadim; Hastreiter, Maximilian; Hembach, Katharina; Herzog, Max; Kalemanov, Maria; Kluge, Michael; Meier, Alice; Nasir, Hassan; Neumaier, Ulrich; Prade, Verena; Reeb, Jonas; Sorokoumov, Aleksandr; Troshani, Ilira; Vorberg, Susann; Waldraff, Sonja; Zierer, Jonas; Nielsen, Henrik; Rost, Burkhard

2014-07-01

363

Parallel search of strongly ordered game trees  

SciTech Connect

The alpha-beta algorithm forms the basis of many programs that search game trees. A number of methods have been designed to improve the utility of the sequential version of this algorithm, especially for use in game-playing programs. These enhancements are based on the observation that alpha beta is most effective when the best move in each position is considered early in the search. Trees that have this so-called strong ordering property are not only of practical importance but possess characteristics that can be exploited in both sequential and parallel environments. This paper draws upon experiences gained during the development of programs which search chess game trees. Over the past decade major enhancements of the alpha beta algorithm have been developed by people building game-playing programs, and many of these methods will be surveyed and compared here. The balance of the paper contains a study of contemporary methods for searching chess game trees in parallel, using an arbitrary number of independent processors. To make efficient use of these processors, one must have a clear understanding of the basic properties of the trees actually traversed when alpha-beta cutoffs occur. This paper provides such insights and concludes with a brief description of a refinement to a standard parallel search algorithm for this problem. 33 references.

Marsland, T.A.; Campbell, M.

1982-12-01

364

UniTree Name Server internals  

SciTech Connect

The UniTree Name Server (UNS) is one of several servers which make up the UniTree storage system. The Name Server is responsible for mapping names to capabilities Names are generally human readable ASCII strings of any length. Capabilities are unique 256-bit identifiers that point to files, directories, or symbolic links. The Name Server implements a UNIX style hierarchical directory structure to facilitate name-to-capability mapping. The principal task of the Name Server is to manage the directories which make up the UniTree directory structure. The principle clients of the Name Server are the FTP Daemon, NFS and a few UniTree utility routines. However, the Name Server is a generalized server and will accept messages from any client. The purpose of this paper is to describe the internal workings of the UniTree Name Server. In cases where it seems appropriate, the motivation for a particular choice of algorithm as description of the algorithm itself will be given.

Mecozzi, D.; Minton, J.

1996-01-01

365

Numerical simulations of dwarf galaxy merger trees  

NASA Astrophysics Data System (ADS)

We investigate the evolution of dwarf galaxies using N-body/smoothed particle hydrodynamics simulations that incorporate their formation histories through merger trees constructed using the extended Press-Schechter formalism. The simulations are computationally cheap and have high spatial resolution. We compare the properties of galaxies with equal final mass but with different merger histories with each other and with those of observed dwarf spheroidals and irregulars. We show that the merger history influences many observable dwarf galaxy properties. We identify two extreme cases that make this influence stand out most clearly: (i) merger trees with one massive progenitor that grows through relatively few mergers and (ii) merger trees with many small progenitors that merge only quite late. At a fixed halo mass, a type (i) tree tends to produce galaxies with larger stellar masses, larger half-light radii, lower central surface brightness and, since fewer potentially angular momentum cancelling mergers are required to build up the final galaxy, a higher specific angular momentum, compared with a type (ii) tree. We do not perform full-fledged cosmological simulations and therefore cannot hope to reproduce all observed properties of dwarf galaxies. However, we show that the simulated dwarfs are similar to real ones.

Cloet-Osselaer, A.; De Rijcke, S.; Vandenbroucke, B.; Schroyen, J.; Koleva, M.; Verbeke, R.

2014-08-01

366

High-performance OCR preclassification trees  

NASA Astrophysics Data System (ADS)

We present an automatic method for constructing high-performance preclassification decision trees for OCR. Good preclassifiers prune the set of alternative classes to many fewer without erroneously pruning the correct class. We build the decision tree using greedy entropy minimization, using pseudo-randomly generated training samples derived from a model of imaging defects, and then `populate' the tree with many more samples to drive down the error rate. In [BM94] we presented a statistically rigorous stopping rule for population that enforces a user-specified upper bound on error: this works in practice, but is too conservative, driving the error far below the bound. Here, we describe a refinement that achieves the user- specified accuracy more closely and thus improves the pruning rate of the resulting tree. The method exploits the structure of the tree: the essential technical device is a leaf-selection rule based on Good's Theorem [Good53]. We illustrate its effectiveness through experiments on a pan-European polyfont classifier.

Baird, Henry S.; Mallows, C. L.

1995-03-01

367

Phylogenetic tree shapes resolve disease transmission patterns  

PubMed Central

Background and Objectives: Whole-genome sequencing is becoming popular as a tool for understanding outbreaks of communicable diseases, with phylogenetic trees being used to identify individual transmission events or to characterize outbreak-level overall transmission dynamics. Existing methods to infer transmission dynamics from sequence data rely on well-characterized infectious periods, epidemiological and clinical metadata which may not always be available, and typically require computationally intensive analysis focusing on the branch lengths in phylogenetic trees. We sought to determine whether the topological structures of phylogenetic trees contain signatures of the transmission patterns underlying an outbreak. Methodology: We use simulated outbreaks to train and then test computational classifiers. We test the method on data from two real-world outbreaks. Results: We show that different transmission patterns result in quantitatively different phylogenetic tree shapes. We describe topological features that summarize a phylogeny’s structure and find that computational classifiers based on these are capable of predicting an outbreak’s transmission dynamics. The method is robust to variations in the transmission parameters and network types, and recapitulates known epidemiology of previously characterized real-world outbreaks. Conclusions and implications: There are simple structural properties of phylogenetic trees which, when combined, can distinguish communicable disease outbreaks with a super-spreader, homogeneous transmission and chains of transmission. This is possible using genome data alone, and can be done during an outbreak. We discuss the implications for management of outbreaks.

Colijn, Caroline; Gardy, Jennifer

2014-01-01

368

The tree tenure factor in agroforestry with particular reference to Africa  

Microsoft Academic Search

Rights over trees are often distinct from rights over land. Tree tenure consists of a bundle of rights over trees and their produce which may be held by different people at different times. These rights include the right to own or inherit trees, the right to plant trees, the right to use trees and tree products, the right to dispose

Louise Fortmann

1985-01-01

369

Efficient exploration of the space of reconciled gene trees.  

PubMed

Gene trees record the combination of gene-level events, such as duplication, transfer and loss (DTL), and species-level events, such as speciation and extinction. Gene tree-species tree reconciliation methods model these processes by drawing gene trees into the species tree using a series of gene and species-level events. The reconstruction of gene trees based on sequence alone almost always involves choosing between statistically equivalent or weakly distinguishable relationships that could be much better resolved based on a putative species tree. To exploit this potential for accurate reconstruction of gene trees, the space of reconciled gene trees must be explored according to a joint model of sequence evolution and gene tree-species tree reconciliation. Here we present amalgamated likelihood estimation (ALE), a probabilistic approach to exhaustively explore all reconciled gene trees that can be amalgamated as a combination of clades observed in a sample of gene trees. We implement the ALE approach in the context of a reconciliation model (Szöll?si et al. 2013), which allows for the DTL of genes. We use ALE to efficiently approximate the sum of the joint likelihood over amalgamations and to find the reconciled gene tree that maximizes the joint likelihood among all such trees. We demonstrate using simulations that gene trees reconstructed using the joint likelihood are substantially more accurate than those reconstructed using sequence alone. Using realistic gene tree topologies, branch lengths, and alignment sizes, we demonstrate that ALE produces more accurate gene trees even if the model of sequence evolution is greatly simplified. Finally, examining 1099 gene families from 36 cyanobacterial genomes we find that joint likelihood-based inference results in a striking reduction in apparent phylogenetic discord, with respectively. 24%, 59%, and 46% reductions in the mean numbers of duplications, transfers, and losses per gene family. The open source implementation of ALE is available from https://github.com/ssolo/ALE.git. PMID:23925510

Szöllõsi, Gergely J; Rosikiewicz, Wojciech; Boussau, Bastien; Tannier, Eric; Daubin, Vincent

2013-11-01

370

Scattering measurements on natural and model trees  

NASA Technical Reports Server (NTRS)

The acoustical back scattering from a simple scale model of a tree has been experimentally measured. The model consisted of a trunk and six limbs, each with 4 branches; no foliage or twigs were included. The data from the anechoic chamber measurements were then mathematically combined to construct the effective back scattering from groups of trees. Also, initial measurements have been conducted out-of-doors on a single tree in an open field in order to characterize its acoustic scattering as a function of azimuth angle. These measurements were performed in the spring, prior to leaf development. The data support a statistical model of forest scattering; the scattered signal spectrum is highly irregular but with a remarkable general resemblance to the incident signal spectrum. Also, the scattered signal's spectra showed little dependence upon scattering angle.

Rogers, James C.; Lee, Sung M.

1990-01-01

371

Competitive neural trees for pattern classification.  

PubMed

This paper presents competitive neural trees (CNeT's) for pattern classification. The CNeT contains m-ary nodes and grows during learning by using inheritance to initialize new nodes. At the node level, the CNeT employs unsupervised competitive learning. The CNeT performs hierarchical clustering of the feature vectors presented to it as examples, while its growth is controlled by forward pruning. Because of the tree structure, the prototype in the CNeT close to any example can be determined by searching only a fraction of the tree. This paper introduces different search methods for the CNeT, which are utilized for training as well as for recall. The CNeT is evaluated and compared with existing classifiers on a variety of pattern classification problems. PMID:18255815

Behnke, S; Karayiannis, N B

1998-01-01

372

Minimum spanning trees for community detection  

NASA Astrophysics Data System (ADS)

A simple deterministic algorithm for community detection is provided by using two rounds of minimum spanning trees. By comparing the first round minimum spanning tree (1st-MST) with the second round spanning tree (2nd-MST) of the network, communities are detected and their overlapping nodes are also identified. To generate the two MSTs, a distance matrix is defined and computed from the adjacent matrix of the network. Compared with the resistance matrix or the communicability matrix used in community detection in the literature, the proposed distance matrix is very simple in computation. The proposed algorithm is tested on real world social networks, graphs which are failed by the modularity maximization, and the LFR benchmark graphs for community detection.

Wu, Jianshe; Li, Xiaoxiao; Jiao, Licheng; Wang, Xiaohua; Sun, Bo

2013-05-01

373

Parameter identification in multinomial processing tree models.  

PubMed

Multinomial processing tree models form a popular class of statistical models for categorical data that have applications in various areas of psychological research. As in all statistical models, establishing which parameters are identified is necessary for model inference and selection on the basis of the likelihood function, and for the interpretation of the results. The required calculations to establish global identification can become intractable in complex models. We show how to establish local identification in multinomial processing tree models, based on formal methods independently proposed by Catchpole and Morgan (1997) and by Bekker, Merckens, and Wansbeek (1994). This approach is illustrated with multinomial processing tree models for the source-monitoring paradigm in memory research. PMID:20805606

Schmittmann, Verena D; Dolan, Conor V; Raijmakers, Maartje E J; Batchelder, William H

2010-08-01

374

Tree attenuation at 20 GHz: Foliage effects  

NASA Technical Reports Server (NTRS)

Static tree attenuation measurements at 20 GHz (K-Band) on a 30 deg slant path through a mature Pecan tree with and without leaves showed median fades exceeding approximately 23 dB and 7 dB, respectively. The corresponding 1% probability fades were 43 dB and 25 dB. Previous 1.6 GHz (L-Band) measurements for the bare tree case showed fades larger than those at K-Band by 3.4 dB for the median and smaller by approximately 7 dB at the 1% probability. While the presence of foliage had only a small effect on fading at L-Band (approximately 1 dB additional for the median to 1% probability range), the attenuation increase was significant at K-Band, where it increased by about 17 dB over the same probability range.

Vogel, Wolfhard J.; Goldhirsh, Julius

1993-01-01

375

The inverse problem for certain tree parameters  

PubMed Central

Let p be a graph parameter that assigns a positive integer value to every graph. The inverse problem for p asks for a graph within a prescribed class (here, we will only be concerned with trees), given the value of p. In this context, it is of interest to know whether such a graph can be found for all or at least almost all integer values of p. We will provide a very general setting for this type of problem over the set of all trees, describe some simple examples and finally consider the interesting parameter “number of subtrees”, where the problem can be reduced to some number-theoretic considerations. Specifically, we will prove that every positive integer, with only 34 exceptions, is the number of subtrees of some tree.

Czabarka, Eva; Szekely, Laszlo; Wagner, Stephan

2009-01-01

376

How do trees know it is autumn?  

NASA Astrophysics Data System (ADS)

To predict how forests will respond to climate change, it is necessary to understand how trees actually interpret environmental signals that the winter is approaching and use them to induce growth arrest, cold hardiness development, autumn leaf senescence and abscission. Autumn phenology traits and also under strong genetic control, and there exist within most tree species large variation in most phenology traits. Our model system is aspen (Populus tremula); one of the most widespread and abundant deciduous trees on earth. Growth arrest/bud set and cold hardiness in aspen is triggered by the gradual shortening of the photoperiod is the late season, and the molecular details behind have to some extent been deciphered. The molecular machinery triggering autumn leaf senescence - a trait developed to minimise nutrient loss - is in contrast, very poorly understood but bud set/growth arrest is a prerequisite for aspens to develop a competence to respond to the environmental signals triggering senescence. Once competence is developed, initiation of senescence seems to be triggered not by the daylength but some other daylight cue, and once senescence has been initiated the progression is influenced by temperature. The nitrogen, as well as carbohydrate, status interact can modify the senescence program of the tree. We are also identifying the precise genetic polymorphisms that are responsible for natural variation in autumn phenology traits in aspen, and study how different populations have different genetic makeups that provide local adaptation. Taken together, other environmental factors are more important than temperature is setting the timetable for aspens in the autumn. Although much less is know how autumn phenology traits are regulated in other tree species, the effect that increasing temperatures may have on future tree populations will also be discussed.

Jansson, Stefan

2014-05-01

377

Rooting gene trees without outgroups: EP rooting.  

PubMed

Gene sequences are routinely used to determine the topologies of unrooted phylogenetic trees, but many of the most important questions in evolution require knowing both the topologies and the roots of trees. However, general algorithms for calculating rooted trees from gene and genomic sequences in the absence of gene paralogs are few. Using the principles of evolutionary parsimony (EP) (Lake JA. 1987a. A rate-independent technique for analysis of nucleic acid sequences: evolutionary parsimony. Mol Biol Evol. 4:167-181) and its extensions (Cavender, J. 1989. Mechanized derivation of linear invariants. Mol Biol Evol. 6:301-316; Nguyen T, Speed TP. 1992. A derivation of all linear invariants for a nonbalanced transversion model. J Mol Evol. 35:60-76), we explicitly enumerate all linear invariants that solely contain rooting information and derive algorithms for rooting gene trees directly from gene and genomic sequences. These new EP linear rooting invariants allow one to determine rooted trees, even in the complete absence of outgroups and gene paralogs. EP rooting invariants are explicitly derived for three taxon trees, and rules for their extension to four or more taxa are provided. The method is demonstrated using 18S ribosomal DNA to illustrate how the new animal phylogeny (Aguinaldo AMA et al. 1997. Evidence for a clade of nematodes, arthropods, and other moulting animals. Nature 387:489-493; Lake JA. 1990. Origin of the metazoa. Proc Natl Acad Sci USA 87:763-766) may be rooted directly from sequences, even when they are short and paralogs are unavailable. These results are consistent with the current root (Philippe H et al. 2011. Acoelomorph flatworms are deuterostomes related to Xenoturbella. Nature 470:255-260). PMID:22593551

Sinsheimer, Janet S; Little, Roderick J A; Lake, James A

2012-01-01

378

Rooting Gene Trees without Outgroups: EP Rooting  

PubMed Central

Gene sequences are routinely used to determine the topologies of unrooted phylogenetic trees, but many of the most important questions in evolution require knowing both the topologies and the roots of trees. However, general algorithms for calculating rooted trees from gene and genomic sequences in the absence of gene paralogs are few. Using the principles of evolutionary parsimony (EP) (Lake JA. 1987a. A rate-independent technique for analysis of nucleic acid sequences: evolutionary parsimony. Mol Biol Evol. 4:167–181) and its extensions (Cavender, J. 1989. Mechanized derivation of linear invariants. Mol Biol Evol. 6:301–316; Nguyen T, Speed TP. 1992. A derivation of all linear invariants for a nonbalanced transversion model. J Mol Evol. 35:60–76), we explicitly enumerate all linear invariants that solely contain rooting information and derive algorithms for rooting gene trees directly from gene and genomic sequences. These new EP linear rooting invariants allow one to determine rooted trees, even in the complete absence of outgroups and gene paralogs. EP rooting invariants are explicitly derived for three taxon trees, and rules for their extension to four or more taxa are provided. The method is demonstrated using 18S ribosomal DNA to illustrate how the new animal phylogeny (Aguinaldo AMA et al. 1997. Evidence for a clade of nematodes, arthropods, and other moulting animals. Nature 387:489–493; Lake JA. 1990. Origin of the metazoa. Proc Natl Acad Sci USA 87:763–766) may be rooted directly from sequences, even when they are short and paralogs are unavailable. These results are consistent with the current root (Philippe H et al. 2011. Acoelomorph flatworms are deuterostomes related to Xenoturbella. Nature 470:255–260).

Sinsheimer, Janet S.; Little, Roderick J. A.; Lake, James A.

2012-01-01

379

Bronchial tree modeling and 3D reconstruction  

NASA Astrophysics Data System (ADS)

Providing an in-vivo and non-invasive tool for 3D reconstruction of anatomical tree structures (vascular networks and bronchial tree) from 2D or pseudo-3D data acquisition remains today a key and challenging issue for computer vision in medical imaging. In this paper, we address this issue within the specific framework of airways. Our contribution consists of a realistic 3D modeling of the bronchial tree structure. Mathematical and physical principles here involved refer to 3D mathematical morphology (3DMM), Diffusion Limited Aggregation (DLA), energy-based modeling and fractal representations. Here, a model-based 3D reconstruction of the bronchial tree is achieved in a fully-automated way. The tree segmentation is performed by applying a DLA-based propagation. The initialization results from the 3DMM procedure. Energy modeling and fractals are used to overcome the well- known cases of subdivision ambiguities and artifact generation related to such a complex topological structure. Therefore, the proposed method is robust with respect to anatomical variabilities. The 3D bronchial tree reconstruction is finally visualized by using a semi-transparent volume rendering technique which provides brochogram- like representations. The developed method was applied to a data set acquired within a clinical framework by using both double- and multiple- detector CT scanners (5 patients corresponding to 1500 axial slices, including both normal and strong pathological cases). Results thus obtained, compared with a previously-developed 2D/3D technique, show significant improvements and accuracy increase of the 3D reconstructions.

Fetita, Catalin I.; Preteux, Francoise J.

2000-10-01

380

PhyBin: binning trees by topology.  

PubMed

A major goal of many evolutionary analyses is to determine the true evolutionary history of an organism. Molecular methods that rely on the phylogenetic signal generated by a few to a handful of loci can be used to approximate the evolution of the entire organism but fall short of providing a global, genome-wide, perspective on evolutionary processes. Indeed, individual genes in a genome may have different evolutionary histories. Therefore, it is informative to analyze the number and kind of phylogenetic topologies found within an orthologous set of genes across a genome. Here we present PhyBin: a flexible program for clustering gene trees based on topological structure. PhyBin can generate bins of topologies corresponding to exactly identical trees or can utilize Robinson-Fould's distance matrices to generate clusters of similar trees, using a user-defined threshold. Additionally, PhyBin allows the user to adjust for potential noise in the dataset (as may be produced when comparing very closely related organisms) by pre-processing trees to collapse very short branches or those nodes not meeting a defined bootstrap threshold. As a test case, we generated individual trees based on an orthologous gene set from 10 Wolbachia species across four different supergroups (A-D) and utilized PhyBin to categorize the complete set of topologies produced from this dataset. Using this approach, we were able to show that although a single topology generally dominated the analysis, confirming the separation of the supergroups, many genes supported alternative evolutionary histories. Because PhyBin's output provides the user with lists of gene trees in each topological cluster, it can be used to explore potential reasons for discrepancies between phylogenies including homoplasies, long-branch attraction, or horizontal gene transfer events. PMID:24167782

Newton, Ryan R; Newton, Irene L G

2013-01-01

381

Decision tree approach for soil liquefaction assessment.  

PubMed

In the current study, the performances of some decision tree (DT) techniques are evaluated for postearthquake soil liquefaction assessment. A database containing 620 records of seismic parameters and soil properties is used in this study. Three decision tree techniques are used here in two different ways, considering statistical and engineering points of view, to develop decision rules. The DT results are compared to the logistic regression (LR) model. The results of this study indicate that the DTs not only successfully predict liquefaction but they can also outperform the LR model. The best DT models are interpreted and evaluated based on an engineering point of view. PMID:24489498

Gandomi, Amir H; Fridline, Mark M; Roke, David A

2013-01-01

382

A survey of decision tree classifier methodology  

NASA Technical Reports Server (NTRS)

Decision Tree Classifiers (DTC's) are used successfully in many diverse areas such as radar signal classification, character recognition, remote sensing, medical diagnosis, expert systems, and speech recognition. Perhaps, the most important feature of DTC's is their capability to break down a complex decision-making process into a collection of simpler decisions, thus providing a solution which is often easier to interpret. A survey of current methods is presented for DTC designs and the various existing issue. After considering potential advantages of DTC's over single stage classifiers, subjects of tree structure design, feature selection at each internal node, and decision and search strategies are discussed.

Safavian, S. Rasoul; Landgrebe, David

1990-01-01

383

A survey of decision tree classifier methodology  

NASA Technical Reports Server (NTRS)

Decision tree classifiers (DTCs) are used successfully in many diverse areas such as radar signal classification, character recognition, remote sensing, medical diagnosis, expert systems, and speech recognition. Perhaps the most important feature of DTCs is their capability to break down a complex decision-making process into a collection of simpler decisions, thus providing a solution which is often easier to interpret. A survey of current methods is presented for DTC designs and the various existing issues. After considering potential advantages of DTCs over single-state classifiers, subjects of tree structure design, feature selection at each internal node, and decision and search strategies are discussed.

Safavian, S. R.; Landgrebe, David

1991-01-01

384

A grey tree frog (Hyla versicolor).  

NSDL National Science Digital Library

A grey tree frog (Hyla versicolor). Amphibian species are declining globally, and pesticides may play a role, but their concentrations are often low in nature. Carbaryl is a common pesticide that can become more lethal for frogs under certain environmental conditions. A recent study has found that predatory stress, a common pressure for most amphibians, can make carbaryl exposure much more deadly to gray tree frogs. This suggests that apparently safe concentrations of pesticides can become more deadly to some amphibian species when combined with predator cues. This photograph originally appeared on the cover of Ecological Applications (13:4) in December of 2003.

Relyea, Rick

2010-02-12

385

Glued trees algorithm under phase damping  

NASA Astrophysics Data System (ADS)

We study the behaviour of the glued trees algorithm described by Childs et al. in [1] under decoherence. We consider a discrete time reformulation of the continuous time quantum walk protocol and apply a phase damping channel to the coin state, investigating the effect of such a mechanism on the probability of the walker appearing on the target vertex of the graph. We pay particular attention to any potential advantage coming from the use of weak decoherence for the spreading of the walk across the glued trees graph.

Lockhart, J.; Di Franco, C.; Paternostro, M.

2014-01-01

386

Optimal parallel evaluation of AND trees  

NASA Technical Reports Server (NTRS)

A quantitative analysis based on both preemptive and nonpreemptive critical-path scheduling algorithms is presently conducted for the optimal degree of parallelism required in evaluating a given AND tree. The optimal degree of parallelism is found to depend on problem complexity, precedence-graph shape, and task-time distribution along each path. In addition to demonstrating the optimality of the preemptive critical-path scheduling algorithm for evaluating an arbitrary AND tree on a fixed number of processors, the possibility of efficiently ascertaining tight bounds on the number of processors for optimal processor-time efficiency is illustrated.

Wah, Benjamin W.; Li, Guo-Jie

1990-01-01

387

Genome-Scale Phylogenetics: Inferring the Plant Tree of Life from 18,896 Gene Trees  

PubMed Central

Phylogenetic analyses using genome-scale data sets must confront incongruence among gene trees, which in plants is exacerbated by frequent gene duplications and losses. Gene tree parsimony (GTP) is a phylogenetic optimization criterion in which a species tree that minimizes the number of gene duplications induced among a set of gene trees is selected. The run time performance of previous implementations has limited its use on large-scale data sets. We used new software that incorporates recent algorithmic advances to examine the performance of GTP on a plant data set consisting of 18,896 gene trees containing 510,922 protein sequences from 136 plant taxa (giving a combined alignment length of >2.9 million characters). The relationships inferred from the GTP analysis were largely consistent with previous large-scale studies of backbone plant phylogeny and resolved some controversial nodes. The placement of taxa that were present in few gene trees generally varied the most among GTP bootstrap replicates. Excluding these taxa either before or after the GTP analysis revealed high levels of phylogenetic support across plants. The analyses supported magnoliids sister to a eudicot + monocot clade and did not support the eurosid I and II clades. This study presents a nuclear genomic perspective on the broad-scale phylogenic relationships among plants, and it demonstrates that nuclear genes with a history of duplication and loss can be phylogenetically informative for resolving the plant tree of life.

Burleigh, J. Gordon; Bansal, Mukul S.; Eulenstein, Oliver; Hartmann, Stefanie; Wehe, Andre; Vision, Todd J.

2011-01-01

388

Confirmatory Tree Sampling for Tritium in Trees at the Salmon Site, Mississippi  

SciTech Connect

The sampling was conducted on April 20, 21, and 22, 2010. DOE acquired 36 samples for analysis, approximately 10 percent of the total number of samples the Mississippi Forestry Commission acquired. The plan was to sample trees that the Mississippi Forestry Commission also sampled, so that a tree-by-tree comparison of analysis results could be made. The Mississippi Forestry Commission provided DOE with latitude and longitude coordinates, determined by a global positioning system (GPS), for each sampled tree. The Mississippi Forestry Commission also placed a blaze-orange number on each sampled tree. DOE used a GPS unit to assist in locating trees for sampling. DOE acquired one sample from an off-site location to have a reference for comparison to on-site results if necessary. The other 35 samples were acquired on site, for a total of 36 samples. Figure 1 shows the sampling locations, the sample identifiers DOE assigned, and the corresponding tree numbers the Mississippi Forestry Commission assigned

None

2010-06-01

389

Estimation of tree water relationships using a Soil-Tree-Atmosphere Continuum model  

NASA Astrophysics Data System (ADS)

To better understand root-soil water interactions, a mature white fir (Abies concolor) and the surrounding root zone were continuously monitored (sap flow, canopy stem water potential, soil moisture, and temperature), to characterize tree hydrodynamics. We present a hydrodynamic flow model, simulating unsaturated flow in the soil and tree with stress functions controlling spatially distributed root water uptake and canopy transpiration. Using the van Genuchten functions, we parameterize the effective retention and unsaturated hydraulic conductivity functions of the tree sapwood and soil, soil and canopy stress functions, and radial root zone distribution. To parameterize the in-situ tree water relationships, we combine a numerical model with observational data in an optimization framework, minimizing residuals between simulated and measured observational data of soil and tree canopy. Using the MCMC method, the HYDRUS model is run in an iterative process that adjusts parameters until residuals are minimized. Using these optimized parameters, the HYDRUS model simulates diurnal tree water potential and sap flow as a function of tree height, in addition to spatially distributed changes in soil water storage and soil water potential.

Hopmans, Jan; Hartsough, Peter; Rings, Joerg; Kandalous, Maziar; Kamai, Tamir; Vrugt, Jasper; Simunek, Jirka

2014-05-01

390

Exploring within-tree architectural development of two apple tree cultivars over 6 years.  

PubMed

The present study addresses the prediction of apple tree development, taking into account both the number and within-tree position of tree components. The architectural development of two trees per scion cultivar, 'Fuji' and 'Braeburn', was studied by describing all shoots over 6 years. Flowering and fruiting were observed over 3 years. The description included different scales [entire trees, axes, growth units (GUs) and metamers], and the analysis compared all axes of the trees as a function of their branching order and age. Three main aspects of vegetative development were investigated: the quantity of primary growth; the number and nature of developing axillary shoots; and meristem death. Results confirm the existence of within-tree morphological gradients, and show that the decrease in growth was comparable in magnitude for all axes and GUs, irrespective of their position. This decrease results from a reduction in the number of metamers per GU, which was modelled by an exponential function. The decrease in growth involved changes in the number and nature of the axillary shoots, which could be described by simple functions. The probability of spur death was constant over the years but differed according to cultivar and type of bearing shoot. The within-tree probability of flowering and fruiting was predictable for 'Braeburn' because axes, regardless of their position and type, had a high probability of flowering and a low probability of fruit set which led to a regular bearing habit. In contrast, 'Fuji' had an alternating bearing behaviour that was more complex to predict. This appeared to result from a synchronized increase in the probability that all GUs at tree scale are floral, combined with a high probability of fruit set. The consequences of these results for both yield prediction and architectural simulations are discussed. PMID:12495924

Costes, E; Sinoquet, H; Kelner, J J; Godin, C

2003-01-01

391

iGLASS: An Improvement to the GLASS Method for Estimating Species Trees from Gene Trees  

PubMed Central

Abstract Several methods have been designed to infer species trees from gene trees while taking into account gene tree/species tree discordance. Although some of these methods provide consistent species tree topology estimates under a standard model, most either do not estimate branch lengths or are computationally slow. An exception, the GLASS method of Mossel and Roch, is consistent for the species tree topology, estimates branch lengths, and is computationally fast. However, GLASS systematically overestimates divergence times, leading to biased estimates of species tree branch lengths. By assuming a multispecies coalescent model in which multiple lineages are sampled from each of two taxa at L independent loci, we derive the distribution of the waiting time until the first interspecific coalescence occurs between the two taxa, considering all loci and measuring from the divergence time. We then use the mean of this distribution to derive a correction to the GLASS estimator of pairwise divergence times. We show that our improved estimator, which we call iGLASS, consistently estimates the divergence time between a pair of taxa as the number of loci approaches infinity, and that it is an unbiased estimator of divergence times when one lineage is sampled per taxon. We also show that many commonly used clustering methods can be combined with the iGLASS estimator of pairwise divergence times to produce a consistent estimator of the species tree topology. Through simulations, we show that iGLASS can greatly reduce the bias and mean squared error in obtaining estimates of divergence times in a species tree.

Rosenberg, Noah A.

2012-01-01

392

Surveying Dead Trees and CO2-Induced Stressed Trees Using AVIRIS in the Long Valley Caldera  

NASA Technical Reports Server (NTRS)

Since 1980 the Long Valley Caldera in the eastern Sierra Nevada (California) has shown signs of renewed volcanic activity. Frequent earthquakes, a re-inflation of the caldera, hydrothermal activity and gas emissions are the outer symptoms of this renewed activity. In 1990 and 1991 several areas of dying trees were found around Mammoth Mountain. The cause of the die off of the trees was first sought in the persistent drought in the preceding years. However, the trees died regardless of age and species. Farrar et al. (1995) started a soil-gas survey in 1994 in the dead-tree areas and found carbon dioxide concentrations ranging from 30 to 96% at soil depths between 30 and 60 cm. CO2 concentrations in the atmosphere are usually around 0.03% and in the soil profile CO2 levels do commonly not exceed 4 to 5%. Although not much is known about the effect of high levels of carbon dioxide in the soil profile on roots, it is most likely that the trees are dying due to oxygen deprivation: the CO2 drives the oxygen out of the soil. So far, four sites of dead trees have been mapped around Mammoth Mountain. The two largest dying trees sites are located near Horseshoe Lake and near Mammoth Mountain Main Lodge covering approximately an area of 10 and 8 ha respectively. Analysis of the gas composition regarding the He-3/He-4 ratio and the percentage biogenic carbon reveals the source of the gas: the magma body beneath the Long Valley Caldera. Until recently it was not known that volcanoes release abundant carbon dioxide from their flanks as diffuse soil emanations. As a result of the magma gas emission around Mammoth Mountain there is an excellent sequence of dead trees, stressed trees, healthy trees and bare soil surfaces. This research site provides excellent opportunities to: (1) Study the capabilities of imaging spectrometry to map stressed (and dead) pine and fir species; (2) Study methods to separate the vivid vegetation, stressed vegetation and dead vegetation from the soil background of glacial deposits and crystalline rocks. The dead tree areas are located on the flanks of Mammoth Mountain (N:37 deg 37' 45" and W:119 deg 02' 05") at an elevation between 2600 and 3000 meters. The area is covered by an open type of Montane Forest. The dominant tree species are Lodgepole Pine (Pinus contorta), the Red Fir (Abies magnifica) and the Jeffrey Pine (Pinus jeffreyi). The soil surface near Horseshoe Lake is generally fairly bright. The surface is covered by glacial deposits (till) consisting mainly of weathered granitic rocks.

deJong, Steven M.

1996-01-01

393

TreeQ-VISTA: An Interactive Tree Visualization Tool withFunctional Annotation Query Capabilities  

SciTech Connect

Summary: We describe a general multiplatform exploratorytool called TreeQ-Vista, designed for presenting functional annotationsin a phylogenetic context. Traits, such as phenotypic and genomicproperties, are interactively queried from a relational database with auser-friendly interface which provides a set of tools for users with orwithout SQL knowledge. The query results are projected onto aphylogenetic tree and can be displayed in multiple color groups. A richset of browsing, grouping and query tools are provided to facilitatetrait exploration, comparison and analysis.Availability: The program,detailed tutorial and examples are available online athttp://genome-test.lbl.gov/vista/TreeQVista.

Gu, Shengyin; Anderson, Iain; Kunin, Victor; Cipriano, Michael; Minovitsky, Simon; Weber, Gunther; Amenta, Nina; Hamann, Bernd; Dubchak,Inna

2007-05-07

394

Water, gravity and trees: Relationship of tree-ring widths and total water storage dynamics  

NASA Astrophysics Data System (ADS)

Water stored in the subsurface as groundwater or soil moisture is the main fresh water source not only for drinking water and food production but also for the natural vegetation. In a changing environment water availability becomes a critical issue in many different regions. Long-term observations of the past are needed to improve the understanding of the hydrological system and the prediction of future developments. Tree ring data have repeatedly proved to be valuable sources for reconstructing long-term climate dynamics, e.g. temperature, precipitation and different hydrological variables. In water-limited environments, tree growth is primarily influenced by total water stored in the subsurface and hence, tree-ring records usually contain information about subsurface water storage. The challenge is to retrieve the information on total water storage from tree rings, because a training dataset of water stored in the sub-surface is required for calibration against the tree-ring series. However, measuring water stored in the subsurface is notoriously difficult. We here present high-precision temporal gravimeter measurements which allow for the depth-integrated quantification of total water storage dynamics at the field scale. In this study, we evaluate the relationship of total water storage change and tree ring growth also in the context of the complex interactions of other meteorological forcing factors. A tree-ring chronology was derived from a Norway spruce stand in the Bavarian Forest, Germany. Total water storage dynamics were measured directly by the superconducting gravimeter of the Geodetic Observatory Wettzell for a 9-years period. Time series were extended to 63-years period by a hydrological model using gravity data as the only calibration constrain. Finally, water storage changes were reconstructed based on the relationship between the hydrological model and the tree-ring chronology. Measurement results indicate that tree-ring growth is primarily controlled by total water storage in the subsurface. But high uncertainties intervals of the correlation coefficient urges for the extension of the measurement period. This multi-disciplinary study, combining hydrology, dendrochronology and geodesy shows that temporal gravimeter measurements may give us the unique opportunity to retrieve the information of total water storage contained in tree-ring records to reconstruct total water storage dynamics. Knowing the relationship of water storage and tree-ring growth can also support the reconstruction of other climate records based on tree-ring series, help with hydrological model testing and can improve our knowledge of long-term variations of water storage in the past.

Creutzfeldt, B.; Heinrich, I.; Merz, B.; Blume, T.; Güntner, A.

2012-04-01

395

Screening for antimicrobial activity of ten medicinal plants used in Colombian folkloric medicine: A possible alternative in the treatment of non-nosocomial infections  

PubMed Central

Background The antimicrobial activity and Minimal Inhibitory Concentration (MIC) of the extracts of Bidens pilosa L., Bixa orellana L., Cecropia peltata L., Cinchona officinalis L., Gliricidia sepium H.B. & K, Jacaranda mimosifolia D.Don, Justicia secunda Vahl., Piper pulchrum C.DC, P. paniculata L. and Spilanthes americana Hieron were evaluated against five bacteria (Staphylococcus aureus, Streptococcus ? hemolític, Bacillus cereus, Pseudomonas aeruginosa, and Escherichia coli), and one yeast (Candida albicans). These plants are used in Colombian folk medicine to treat infections of microbial origin. Methods Plants were collected by farmers and traditional healers. The ethanol, hexane and water extracts were obtained by standard methods. The antimicrobial activity was found by using a modified agar well diffusion method. All microorganisms were obtained from the American Type Culture Collection (ATCC). MIC was determined in the plant extracts that showed some efficacy against the tested microorganisms. Gentamycin sulfate (1.0 ?g/ml), clindamycin (0.3 ?g/ml) and nystatin (1.0 ?g/ml) were used as positive controls. Results The water extracts of Bidens pilosa L., Jacaranda mimosifolia D.Don, and Piper pulchrum C.DC showed a higher activity against Bacillus cereus and Escherichia coli than gentamycin sulfate. Similarly, the ethanol extracts of all species were active against Staphylococcus aureus except for Justicia secunda. Furthermore, Bixa orellana L, Justicia secunda Vahl. and Piper pulchrum C.DC presented the lowest MICs against Escherichia coli (0.8, 0.6 and 0.6 ?g/ml, respectively) compared to gentamycin sulfate (0.9 8g/ml). Likewise, Justicia secunda and Piper pulchrum C.DC showed an analogous MIC against Candida albicans (0.5 and 0.6 ?g/ml, respectively) compared to nystatin (0.6 ?g/ml). Bixa orellana L, exhibited a better MIC against Bacillus cereus (0.2 ?g/ml) than gentamycin sulfate (0.5 ?g/ml). Conclusion This in vitro study corroborated the antimicrobial activity of the selected plants used in folkloric medicine. All these plants were effective against three or more of the pathogenic microorganisms. However, they were ineffective against Streptococcus ? hemolytic and Pseudomonas aeruginosa. Their medicinal use in infections associated with these two species is not recommended. This study also showed that Bixa orellana L, Justicia secunda Vahl. and Piper pulchrum C.DC could be potential sources of new antimicrobial agents.

Rojas, Jhon J; Ochoa, Veronica J; Ocampo, Saul A; Munoz, John F

2006-01-01

396

Tree Planters' Notes. Volume 41, Number 1, Spring 1990.  

National Technical Information Service (NTIS)

Contents: Tree survival and growth on graded and ungraded minesoil; Acorn sowing date affects field performance of blue and valley oaks; Stratification not required for tree-of-heaven seed germination; Dry site survival of bareroot and container seedlings...

1990-01-01

397

Vertex topological indices and tree expressions, generalizations of continued fractions  

PubMed Central

We expand on the work of Hosoya to describe a generalization of continued fractions called “tree expressions.” Each rooted tree will be shown to correspond to a unique tree expression which can be evaluated as a rational number (not necessarily in lowest terms) whose numerator is equal to the Hosoya index of the entire tree and whose denominator is equal to the tree with the root deleted. In the development, we use Z(G) to define a natural candidate ?(G, v) for a “vertex topological index” which is a value applied to each vertex of a graph, rather than a value assigned to the graph overall. Finally, we generalize the notion of tree expression to “labeled tree expressions” that correspond to labeled trees and show that such expressions can be evaluated as quotients of determinants of matrices that resemble adjacency matrices.

2010-01-01

398

Time-dependent event tree technique for modelling recovery operations.  

National Technical Information Service (NTIS)

The development of a simplified time dependent event tree methodology is presented. The technique is especially applicable to describe recovery operations in nuclear reactor accident scenarios initiated by support system failures. The event tree logic is ...

P. Kohut R. Fitzpatrick

1991-01-01

399

The Evolution of Fruit Tree Productivity: A Review.  

PubMed

The Evolution of Fruit Tree Productivity: A Review. Domestication of fruit trees has received far less attention than that of annual crop plants. In particular, very little is known about the evolution of fruit tree productivity. In the wild, most tree species reach reproductive maturity after a long period of juvenility and even then, sexual reproduction appears sporadically, often in a mode of masting. Environmental constraints limit trees' reproductive activity in their natural, wild habitats, resulting in poor, irregular productivity. Early fructification and regular, high rates of productivity have been selected by people, unconsciously and consciously. The reviewed evidence indicates an evolutionary continuum of productivity patterns among trees of wild habitats, intermediary domesticates, and the most advanced domesticates. Alternate bearing appears to represent an intermediate step in the fruit tree evolutionary pathway. The existence of a molecular, genetic mechanism that controls trees' sexual reproduction and fruiting pattern is suggested. PMID:23538880

Goldschmidt, Eliezer E

2013-03-01

400

Influence diagrams and decision trees for severe accident management.  

National Technical Information Service (NTIS)

A review of relevant methodologies based on Influence Diagrams (IDs), Decision Trees (DTs), and Containment Event Trees (CETs) was conducted to assess the practicality of these methods for the selection of effective strategies for Severe Accident Manageme...

W. W. J. Goetz

1996-01-01

401

Coastal Plain Community Tree Guide Benefits, Costs, and Strategic Planting.  

National Technical Information Service (NTIS)

This report quantifies benefits and costs for representative large, medium, and small broadleaf trees and coniferous trees in the Coastal Plain region: the species chosen as representative are the Southern live oak (Quercus virginiana), Southern magnolia ...

E. G. McPherson J. R. Simpson K. E. Vargas P. J. Peper S. L. Gardner

2006-01-01

402

Fault Tree and Damage Assessment List Utility (User Guide).  

National Technical Information Service (NTIS)

The Fault Tree and Damage Assessment List (FTD) utility is designed to assist in the development of criticality analyses. It provides an interactive graphical user interface for the construction, editing, and viewing of deactivation diagrams (fault trees)...

T. S. Christy

2005-01-01

403

Visual exploration of parameter influence on phylogenetic trees.  

PubMed

Evolutionary relationships between organisms are frequently derived as phylogenetic trees inferred from multiple sequence alignments (MSAs). The MSA parameter space is exponentially large, so tens of thousands of potential trees can emerge for each dataset. A proposed visual-analytics approach can reveal the parameters' impact on the trees. Given input trees created with different parameter settings, it hierarchically clusters the trees according to their structural similarity. The most important clusters of similar trees are shown together with their parameters. This view offers interactive parameter exploration and automatic identification of relevant parameters. Biologists applied this approach to real data of 16S ribosomal RNA and protein sequences of ion channels. It revealed which parameters affected the tree structures. This led to a more reliable selection of the best trees. PMID:24808199

Hess, Martin; Bremm, Sebastian; Weissgraeber, Stephanie; Hamacher, Kay; Goesele, Michael; Wiemeyer, Josef; von Landesberger, Tatiana

2014-01-01

404

Tree Crown Condition in Missouri, 2000-2003.  

National Technical Information Service (NTIS)

The Forest Service, U.S. Department of Agriculture, Forest Inventory and Analysis (FIA) Program uses visual assessments of tree crown condition to monitor changes and trends in forest health. This report describes three FIA tree crown condition indicators...

K. C. Randolph W. K. Moser

2009-01-01

405

Clustering with an Improved Self-Organizing Tree  

NASA Astrophysics Data System (ADS)

A self-organizing tree (S-TREE) has a self-organizing capability and better performance than previously reported tree-structured clustering. In the S-TREE algorithm, since a tree grows in greedy fashion, a pruning mechanism is necessary to reduce the effect of bad leaf nodes. Extra nodes are pruned when the tree reaches a predetermined maximum size (U). U is problem-dependent and is therefore difficult to specify beforehand. Furthermore, since U gives the limit of tree growth and also prevents self-organizing of the tree, it may produce unnatural clustering. We are presenting a new pruning algorithm without U. In this paper, we present results showing the performance of the new pruning algorithm using samples generated from normal distributions. The results of computational experiments showed that the new pruning algorithm works well for clustering of those samples.

Suzuki, Yukinori; Sasaki, Yasue

406

USE OF SEWAGE SLUDGE FOR FOREST-TREE SEEDLING PRODUCTION  

EPA Science Inventory

Research was undertaken to determine the beneficial and harmful effects of using dewatered, digested sewage sludge in: (1) containerized production of forest tree seedlings, (2) tree seedling production in a conventional outdoor nursery, (3) establishment and growth of transplant...

407

An Overlay Tree Building Control Protocol  

Microsoft Academic Search

TBCP is a generic ree Building Control Protocol designedto build overlay spanning trees among participants of a multicast session,without any specific help from the network routers. TBCP therefore fallsinto the general category of protocols and mechanisms often referred toas Application-Level Multicasting. TBCP is an efficient, distributed protocolthat operates with partial knowledge of the group membershipand restricted network topology information. One

Laurent Mathy; Roberto Canonico; David Hutchison

2001-01-01

408

Why trees and shrubs but rarely trubs?  

PubMed

An analysis of the maximum height of woody plant species across the globe reveals that an intermediate size is remarkably rare. We speculate that this may be due to intrinsic suboptimality or to ecosystem bistability with open landscapes favouring shrubs, and closed canopies propelling trees to excessive tallness. PMID:24951396

Scheffer, Marten; Vergnon, Remi; Cornelissen, J Hans C; Hantson, Stijn; Holmgren, Milena; van Nes, Egbert H; Xu, Chi

2014-08-01

409

Zoomology: ComparingTwo Large Hierarchical Trees  

Microsoft Academic Search

Zoomology compares two classification datasets. In our solution the two trees are merged into a single overview, which unfolds top to bottom and left to right. Color represents rank, and the width of a classification node corresponds to the number of its descendants. Matched twin detail windows allow similarities and differences to be compared as the user navigates their hierarchies

Jin Young Hong; Jonathan D'Andries; Mark Richman; Maryann Westfall

2003-01-01

410

Group Mutual Exclusion In Tree Networks  

Microsoft Academic Search

The group mutual exclusion (GME) problem deals with sharing a set of (m) mutu- ally exclusive resources among all (n) processes of a network. Processes are allowed to be in a critical section simultaneously provided they request the same resource. We pre- sent three group mutual exclusion solutions for tree networks. All three solutions do not use process identifiers and

Joffroy Beauquier; Sébastien Cantarell; Ajoy Kumar Datta; Franck Petit

2002-01-01

411

Towards developmental modelling of tree root systems  

Microsoft Academic Search

Knowledge of belowground structures and processes is essential for understanding and predicting ecosystem functioning, and consequently in the development of adaptive strategies to safeguard production from trees and woody plants into the future. In the past, research has mainly been concentrated on growth models for the prediction of agronomic or forest production. Newly emerging scientific challenges, e.g. climate change and

B. Tobin; J. ?ermák; D. Chiatante; F. Danjon; A. Di Iorio; L. Dupuy; A. Eshel; C. Jourdan; T. Kalliokoski; R. Laiho; N. Nadezhdina; B. Nicoll; L. Pagès; J. Silva; I. Spanos

2007-01-01

412

Composites: Trees for Data Parallel Programming  

Microsoft Academic Search

Data parallel programming languages offer ease of pro- gramming and debugging and scalability of parallel pro- grams to increasing numbers of processors. Unfortunately, the usefulness of these languages for non-scientific pro- grammers and loosely coupled parallel machines is cur- rently limited. In this paper, we present the composite tree model which seeks to provide greater flexibility via parallel data types,

Mark Chu-carroll; Lori L. Pollock

1994-01-01

413

Decision trees aid production facility design  

Microsoft Academic Search

Decision trees can help in designing cost effective offshore topside facilities for both large and small projects. This methodology rapidly evaluates crude\\/gas production topsides for reducing overall facility installed cost. Preinvesting in offshore topsides for handling upside uncertainties in reservoir withdrawal may significantly improve the internal rate of return (IRR) for the overall field development. An offshore field development plan

J. J. MacDonald; R. S. Smith

1997-01-01

414

Another Approach of Mesh-Connected trees  

Microsoft Academic Search

Mesh network is commonly seen in parallel computation network, as it is straightforward and easy to expand. Two- dimensional mesh network also attract considerable attention in the VLSI layout due to its simplicity. In applying binary tree to the layout of VLSI array in the form of H, better flexibility and regularity might be achieved. Based on the advantages of

Gene Eu Jan

2004-01-01

415

Modeling huanglongbing transmission within a citrus tree  

PubMed Central

The citrus disease huanglongbing (HLB), associated with an uncultured bacterial pathogen, is threatening the citrus industry worldwide. A mathematical model of the transmission of HLB between its psyllid vector and citrus host has been developed to characterize the dynamics of the vector and disease development, focusing on the spread of the pathogen from flush to flush (a newly developing cluster of very young leaves on the expanding terminal end of a shoot) within a tree. This approach differs from that of prior models for vector-transmitted plant diseases where the entire plant is the unit of analysis. Dynamics of vector and host populations are simulated realistically as the flush population approaches complete infection. Model analysis indicates that vector activity is essential for initial infection but is not necessary for continued infection because infection can occur from flush to flush through internal movement in the tree. Flush production, within-tree spread, and latent period are the most important parameters influencing HLB development. The model shows that the effect of spraying of psyllids depends on time of initial spraying, frequency, and efficacy of the insecticides. Similarly, effects of removal of symptomatic flush depend on the frequency of removal and the time of initiation of this practice since the start of the epidemic. Within-tree resistance to spread, possibly affected by inherent or induced resistance, is a major factor affecting epidemic development, supporting the notion that alternate routes of transmission besides that by the vector can be important for epidemic development.

Chiyaka, Christinah; Singer, Burton H.; Halbert, Susan E.; Morris, J. Glenn; van Bruggen, Ariena H. C.

2012-01-01

416

An Asymptotically Optimal Multiversion B-Tree  

Microsoft Academic Search

In a variety of applications, we need to keep track of the development of a data set over time. For maintain- ing and querying these multiversion data efficiently, external storage structures are an absolute necessity. We propose a multiversion B-tree that supports insertions and deletions of data items at the current version and range queries and exact match queries for

Bruno Becker; Stephan Gschwind; Thomas Ohler; Bernhard Seeger; Peter Widmayer

1996-01-01

417

LVIS Tree Height Cross Section (false color)  

NSDL National Science Digital Library

This animation starts with a false-color map of tree heights north of San Jose, Costa Rica, and changes to a close-up 3D cut-away of a section of the forest, also in false color. Data from LVIS observations taken in March, 1998.

Jones, Randall; Blair, Bryan

1999-09-17

418

Runge-Kutta methods, trees, and Mathematica  

Microsoft Academic Search

A simple and elementary proof of Butcher's theorem on the order conditions of Runge-Kutta methods is presented. It is based on a recursive definition of rooted trees and avoids combinatorial tools such as labelings and Faa di Bruno's formula. This strictly recursive approach can easily and elegantly be implemented using modern computer algrebra systems like Mathematica. The full but short

Folkmar Bornemann

2002-01-01

419

Tree Adjoining Grammars for RNA Structure Prediction  

Microsoft Academic Search

In this paper, we are concerned with identifying a subclass of tree adjoining grammars (TAGs) that is suitable for the application to modeling and predicting RNA secondary structures. The goal of this paper is twofold: For the purpose of applying to the RNA secondary structure prediction problem, we first introduce a special subclass of TAGs and develop a fast parsing

Yasuo Uemura; Aki Hasegawa; Satoshi Kobayashi; Takashi Yokomori

1999-01-01

420

The Case of the Similar Trees.  

ERIC Educational Resources Information Center

A possible logical flaw based on similar triangles is discussed with the Sherlock Holmes mystery, "The Muskgrave Ritual." The possible flaw has to do with the need for two trees to have equal growth rates over a 250-year period in order for the solution presented to work. (MP)

Meyer, Rochelle Wilson

1982-01-01

421

Modeling huanglongbing transmission within a citrus tree.  

PubMed

The citrus disease huanglongbing (HLB), associated with an uncultured bacterial pathogen, is threatening the citrus industry worldwide. A mathematical model of the transmission of HLB between its psyllid vector and citrus host has been developed to characterize the dynamics of the vector and disease development, focusing on the spread of the pathogen from flush to flush (a newly developing cluster of very young leaves on the expanding terminal end of a shoot) within a tree. This approach differs from that of prior models for vector-transmitted plant diseases where the entire plant is the unit of analysis. Dynamics of vector and host populations are simulated realistically as the flush population approaches complete infection. Model analysis indicates that vector activity is essential for initial infection but is not necessary for continued infection because infection can occur from flush to flush through internal movement in the tree. Flush production, within-tree spread, and latent period are the most important parameters influencing HLB development. The model shows that the effect of spraying of psyllids depends on time of initial spraying, frequency, and efficacy of the insecticides. Similarly, effects of removal of symptomatic flush depend on the frequency of removal and the time of initiation of this practice since the start of the epidemic. Within-tree resistance to spread, possibly affected by inherent or induced resistance, is a major factor affecting epidemic development, supporting the notion that alternate routes of transmission besides that by the vector can be important for epidemic development. PMID:22783015

Chiyaka, Christinah; Singer, Burton H; Halbert, Susan E; Morris, J Glenn; van Bruggen, Ariena H C

2012-07-24

422

Practical Parallel Algorithms for Minimum Spanning Trees  

Microsoft Academic Search

We study parallel algorithms for computing the minimum spanning tree of a weighted undirected graph G with n vertices and m edges. We consider an input graph G with m n p, where p is the number of processors. For this case, we show that simple algorithms with data- independent communication patterns are efficient, both in theory and in practice.

Frank K. H. A. Dehne; Silvia Götz

1998-01-01

423

Tree swallow reproductive investment, stress, and parasites  

Microsoft Academic Search

We reduced or increased tree swallow, Tachycineta bicolor (Vieillot, 1808), clutch sizes by three eggs (50% of modal clutch size) to test experimentally for relationships between stress and parasite loads. In the first year of the study (1996), we enumerated two measures of stress (granulocyte to non-granulocyte ratios and heterophil to lympho- cyte ratios), blood parasites, and ectoparasites living on

Dave Shutler; Adele Mullie; Robert G. Clark

2004-01-01

424

Evaluation Theory Tree Re-Examined  

ERIC Educational Resources Information Center

When examining various evaluation prescriptive theories comparatively, we find it helpful to have a framework showing how they are related that highlights features that distinguish theoretical perspectives, thus a "theory" about theories. The evaluation theory tree that we presented in Alkin's recent book, "Evaluation Roots" [Eisner, E. (2004).…

Christie, Christina A.; Alkin, Marvin C.

2008-01-01

425

3D Point Cloud Tree Modeling.  

National Technical Information Service (NTIS)

Three-dimensional (3D) point cloud models of trees were developed using the software packages Maya and MATLAB. These models are to be assembled into a forest scene that can be used for producing simulated Laser Detection and Ranging (LADAR) imagery of obj...

A. Davies M. Graham

2010-01-01

426

Repeatability of TREES Rotor Bore Inspection System.  

National Technical Information Service (NTIS)

The repeatability of near-bore flaw detection and sizing of the Turbine Rotor Examination and Evaluation System (TREES) developed in EPRI RP502 was examined by making many repeat scans of sample blocks containing fatigue cracks and embedded spherical- and...

F. V. Ammirato

1982-01-01

427

Hardwood Tree Grades for Factory Lumber.  

National Technical Information Service (NTIS)

The Forest Service hardwood tree grades for factory lumber are described, and lumber grade yields for 11 species are presented in the report. The yields, expressed in board feet, are based on equations in which dbh sq and merchantable height were used as ...

L. F. Hanks

1976-01-01

428

Isoprene emission from tropical tree species.  

PubMed

Foliar emission of isoprene was measured in nine commonly growing tree species of Delhi, India. Dynamic flow enclosure technique was used and gas samples were collected onto Tenax-GC/Carboseive cartridges, which were then attached to the sample injection system in the gas chromatograph (GC). Eluting compounds were analysed using a flame ionisation detector (FID). Out of the nine tree species, isoprene emission was found in six species (Eucalyptus sp., Ficus benghalensis, Ficus religiosa, Mangifera indica, Melia azedarach, and Syzygium jambolanum), whereas, in the remaining three tree species (Alstonia scholaris, Azadirachta indica, and Cassia fistula) no isoprene emission was detected or the levels of emission were negligible or below the detection limit (BDL). Among six tree species, the highest hourly emission (10.2 +/- 6.8 microg g(-1) leaf dry weight, average of five seasons) was observed in Ficus religiosa, while minimum emission was from Melia azedarach (2.2 +/- 4.9 microg g(-1) leaf dry weight, average of five seasons). Isoprene emission (average of six species), over five seasons, was found to vary between 3.9 and 8.5 microg g(-1) leaf dry weight during the rainy season. In addition, significant diurnal variation in isoprene emission was observed in each species. The preliminary estimate made in this study on the annual biogenic VOC emission from India may probably be the first of its kind from this part of the world. PMID:15701397

Padhy, P K; Varshney, C K

2005-05-01

429

Multistate Block Diagrams and Fault Trees  

Microsoft Academic Search

This paper shows how to model a multistate system with multistate components using binary variables. This modeling technique allows current binary algorithms for block diagrams and fault trees to be applied to multistate systems. Several multistate examples are presented, and some cases in which computational efficiency can be enhanced are discussed.

Alan P. Wood

1985-01-01

430

The Tree, the Cross and Global Capitalism  

Microsoft Academic Search

Has Christianity, a religion with incarnation at its heart, devalued the flesh through an over-emphasis on the cross? In this article Lisa Isherwood's response is an overwhelming 'yes'. Isherwood argues that the devaluation of the flesh has hindered Christianity's efforts to address the genocidal realities of global capitalism. She suggests that a return to the tree found in Eden and

Lisa Isherwood

2001-01-01

431

?-Glucosidase inhibitors from Devil tree ( Alstonia scholaris)  

Microsoft Academic Search

?-Glucosidase inhibitors are used in the treatment of non-insulin-dependent diabetes mellitus. We attempt to isolate ?-glucosidase inhibitors from 24 traditional Thai medicinal plant samples. Potent ?-glucosidase inhibitory activity was found in aqueous methanol extract of dried Devil tree (Alstonia scholaris) leaves. Active principles against ?-glucosidase, prepared from rat small intestine acetone powder, were isolated and identified. The structures of these

Nilubon Jong-Anurakkun; Megh Raj Bhandari; Jun Kawabata

2007-01-01

432

Randomized path coloring on binary trees  

Microsoft Academic Search

Motivated by the problem of WDM routing in all-optical networks, we study the following NP-hard problem. We are given a directed binary tree T and a set R of directed paths on T. We wish to assign colors to paths of R, in such way that no two paths that share a directed arc of T are assigned the same

Vincenzo Auletta; Ioannis Caragiannis; Christos Kaklamanis; Pino Persiano

2002-01-01

433

Optimal Distribution Tree for Internet Streaming Media  

Microsoft Academic Search

Internet radio and television stations require significant bandwidth to support delivery of high quality audio and video streams to a large number of receivers. IP multicast is an appropriate delivery model for these applications. However, widespread deployment of IP multicast on the Internet is unlikely in the near future. An alternative is to build a multicast tree in the application

Min Sik Kim; Simon S. Lam; Dong-young Lee

2003-01-01

434

Silver Trees: Chemistry on a TEM Grid  

EPA Science Inventory

The copper/carbon substrate of a TEM grid reacted with aqueous silver nitrate solution within minutes to yield spectacular tree-like silver dendrites, without using any added capping or reducing reagents. These results demonstrate a facile, aqueous, room temperature synthesis of...

435

Information Ranking and Power Laws on Trees  

Microsoft Academic Search

We study the situations when the solution to a weighted stochastic recursion has a power law tail. To this end, we develop two complementary approaches, the first one extends Goldie's (1991) implicit renewal theorem to cover recursions on trees; and the second one is based on a direct sample path large deviations analysis of weighted recursive random sums. We believe

Predrag R. Jelenkovic; Mariana Olvera-Cravioto

2009-01-01

436

The Average Height of Planted Plane Trees.  

National Technical Information Service (NTIS)

An asymptotic expression for the average height of a planted plane tree is derived, based on an asymptotic series for sums such as the Summation (k > or = 1) of (2n, N + K) d(k) and the Summation (k > or = 1) of (e to the (-k squared/n) power) d(k), where...

D. E. Knuth N. G. de Bruijn S. O. Rice

1971-01-01

437

TREAT (TREe-based Association Test)  

Cancer.gov

TREAT is an R package for detecting complex joint effects in case-control studies. The test statistic is derived from a tree-structure model by recursive partitioning the data. Ultra-fast algorithm is designed to evaluate the significance of association between candidate gene and disease outcome

438

User Experiments with Tree Visualization Systems  

Microsoft Academic Search

This paper describes a comparative experiment with five well- known tree visualization systems, and Windows Explorer as a baseline system. Subjects performed tasks relating to the structure of a directory hierarchy, and to attributes of files and directories. Task completion times, correctness and user satisfaction were measured, and video recordings of subjects' interaction with the systems were made. Significant system

Alfred Kobsa

2004-01-01

439

Industrial design process composition based design tree  

Microsoft Academic Search

Designers need aided resources to finish product design. During design process, designers need different resources at every design state, so it's necessary to decompose design process into separate design states. Industrial design process decomposition is researched in this paper, and design tree is brought forward to help composing design process, at last industrial design process composition model is built based

Mingjiu Yu; Changde Lu; Suihuai Yu

2009-01-01

440

Maxdiff kd-trees for data condensation  

Microsoft Academic Search

Prototype selection on the basis of conventional clustering algorithms results in good representation but is extremely time-taking on large data sets. kd-trees, on the other hand, are exceptionally efficient in terms of time and space requirements for large data sets, but fail to produce a reasonable representation in certain situations. We propose a new algorithm with speed comparable to the

B. Lakshmi Narayan; C. A. Murthy; Sankar K. Pal

2006-01-01

441

Tree Doctor: A Software Package for Graphical Manipulation and Animation of Tree Structures.  

National Technical Information Service (NTIS)

A system is presented for graphically editing, manipulating, and animating formal tree structures. The central design consideration was the choice of direct manipulation as the basic user interface method. Functions and components of the package are expla...

P. Desain

1985-01-01

442

Trace Gold Reveals Tree?s Past (PR 05-099)  

NSF Publications Database

... a new method to detect trace elements in tree rings, researchers at Cornell University and Penn ... rings and correlated several of the bands to a number of volcanic eruptions over the past 500 years ...

443

Spectra of weighted generalized Bethe trees joined at the root  

Microsoft Academic Search

A generalized Bethe tree is a rooted tree in which vertices at the same distance from the root have the same degree. Let {Bi:1?i?m} be a set of trees such that, for i=1,2,…,m,(1)Bi is a generalized Bethe tree of ki levels,(2)the vertices of Bi at the level j have degree di,ki-j+1 for j=1,2,…,ki, and(3)the edges of Bi joining the vertices

Oscar Rojo

2008-01-01

444

An Algorithm for Inferring Mitogenome Rearrangements in a Phylogenetic Tree  

Microsoft Academic Search

Given the mitochondrial gene orders and the phylogenetic relationship of a set of unichromosomal taxa, we study the problem\\u000a of finding a plausible and parsimonious assignment of genomic rearrangement events to the edges of the given phylogenetic\\u000a tree. An algorithm called algorithm TreeREx (tree rearrangement explorer) is proposed for solving this problem heuristically. TreeREx is based on an extended version

Matthias Bernt; Daniel Merkle; Martin Middendorf

2008-01-01

445

Suffix trees: How to do Google search in bioinformatics?  

NSDL National Science Digital Library

This module will introduce the suffix tree data structure and its many applications in string matching and bioinformatics, describe how suffix trees are built on a serial computer, discuss the challenges associated with building the tree in parallel, explain one application in bioinformatics (pattern matching) that uses suffix tree, develop a method to implement pattern matching on a distributed memory parallel computer, and describe how to analyze parallel performance and identify improvements.

Kalyanaraman, Ananth

446

Nitrogen fixation by trees in relation to soil nitrogen economy  

Microsoft Academic Search

The N2-fixing potential (NFP) (i.e. the amount of fixed N2 in a constraint-free environment) of N2-fixing trees (NFTs) varies with the genotype. The NFP can be higher than 30-50 g N2 fixed tree-1 year-1 in the most active species, be they leguminous trees such asAlbizia lebbeck, Gliricidia sepium andLeucaena leucocephala, or actinorhizal trees such asCasuarina equisetifolia. The actual amount of

Y. R. Dommergues

1995-01-01

447

Response of Forest Trees to Increased Atmospheric CO2  

Microsoft Academic Search

The CO2 fertilization hypothesis stipulates that rising atmospheric CO2 has a positive effect on tree growth due to increasing availability of carbon. The objective of this paper is to compare the recent literature related to both field CO2-enriched experiments with trees and empirical dendrochronological studies detecting CO2 fertilization effects in tree-rings. This will allow evaluation of tree growth responses to

Jian-Guo Huang; Yves Bergeron; Bernhard Denneler; Frank Berninger; Jacques Tardif

2007-01-01

448

The water relations of trees on karst  

NASA Astrophysics Data System (ADS)

The ecohydrology of karst has not received much attention, despite the disproportionally large effect that karst ecosystems might have on the availability of global freshwater quantity and quality. Theoretical considerations suggest that the ecohydrology of woody plants in karst, specifically where soil cover is thin and trees take root in the epikarst, could be very different from that of woody plants in systems with deep soils. I explore the mechanistic basis and possible ecohydrologic consequences of these differences, as well as present the results of a field study into the water relations of trees in karst. The study examined the water sources and water relations of Quercus fusiformis (Small) and Juniperus ashei (Buchholz) in the karst region of the eastern Edwards Plateau, Texas (USA). Stable isotope analysis of stem water suggested that both trees used evaporatively enriched water stored in the epikarst. Q. fusiformis had consistently higher predawn water potentials than J. ashei during drought. However, epikarst structure had strong effects on the predawn water potentials experienced during drought. Although the water potentials of both species recovered after drought- breaking rain events, associated shifts in stem water isotope ratios did not indicate significant uptake of rainwater from the shallow soil. A hypothesis is developed to explain this phenomenon invoking a piston-flow mechanism that pushes water stored in macropores into the pseudomatrix and into the presumed active root zones of the trees. The study suggests that tree species of the Edwards Plateau do not commonly reduce aquifer recharge by tapping directly into macropores or perched water tables, but more likely by reducing water storage in the pseudomatrix of the epikarst.

Schwinning, S.

2008-05-01

449

Tracing retinal vessel trees by transductive inference  

PubMed Central

Background Structural study of retinal blood vessels provides an early indication of diseases such as diabetic retinopathy, glaucoma, and hypertensive retinopathy. These studies require accurate tracing of retinal vessel tree structure from fundus images in an automated manner. However, the existing work encounters great difficulties when dealing with the crossover issue commonly-seen in vessel networks. Results In this paper, we consider a novel graph-based approach to address this tracing with crossover problem: After initial steps of segmentation and skeleton extraction, its graph representation can be established, where each segment in the skeleton map becomes a node, and a direct contact between two adjacent segments is translated to an undirected edge of the two corresponding nodes. The segments in the skeleton map touching the optical disk area are considered as root nodes. This determines the number of trees to-be-found in the vessel network, which is always equal to the number of root nodes. Based on this undirected graph representation, the tracing problem is further connected to the well-studied transductive inference in machine learning, where the goal becomes that of properly propagating the tree labels from those known root nodes to the rest of the graph, such that the graph is partitioned into disjoint sub-graphs, or equivalently, each of the trees is traced and separated from the rest of the vessel network. This connection enables us to address the tracing problem by exploiting established development in transductive inference. Empirical experiments on public available fundus image datasets demonstrate the applicability of our approach. Conclusions We provide a novel and systematic approach to trace retinal vessel trees with the present of crossovers by solving a transductive learning problem on induced undirected graphs.

2014-01-01

450

TEC-Tree: A Low-Cost, Parallelizable Tree for Efficient Defense Against Memory Replay Attacks  

Microsoft Academic Search

Replay attacks are often the most costly attacks to thwart when dealing with off-chip memory integrity. With a trusted System-on-Chip, the existing countermeasures against replay require a large amount of on-chip memory to provide tamper-proof storage for metadata such as hash values or nonces. Tree-based strategies can be deployed to reduce this unacceptable overhead; for example, the well-known Merkle tree

Reouven Elbaz; David Champagne; Ruby B. Lee; Lionel Torres; Gilles Sassatelli; Pierre Guillemin

2007-01-01

451

Construction of event-tree\\/fault-tree models from a Markov approach to dynamic system reliability  

Microsoft Academic Search

While the event-tree (ET)\\/fault-tree (FT) methodology is the most popular approach to probability risk assessment (PRA), concerns have been raised in the literature regarding its potential limitations in the reliability modeling of dynamic systems. Markov reliability models have the ability to capture the statistical dependencies between failure events that can arise in complex dynamic systems. A methodology is presented that

Paolo Bucci; Jason Kirschenbaum; L. Anthony Mangan; Tunc Aldemir; Curtis Smith; Ted Wood

2008-01-01

452

Combining Static\\/Dynamic Fault Trees and Event Trees Using Bayesian Networks  

Microsoft Academic Search

In this study, an alternative approach for combining Fault Trees (FT) and Event Trees (ET) using capabilities of Bayesian\\u000a networks (BN) for dependency analysis is proposed. We focused on treating implicit and explicit weak s-dependencies that may\\u000a exist among different static\\/dynamic FTs related to an ET. In case of combining implicit s-dependent static FTs and ET that\\u000a combinatorial approaches fail

S. M. Hadi Hosseini; Makoto Takahashi

2007-01-01

453

Vacuum Pumping Increases Sap Yields from Sugar Maple Trees.  

National Technical Information Service (NTIS)

Vacuum pumping was installed in plastic tubing systems for collecting sugar maple sap. An individual-tree study demonstrated that vacuum pumping increases sap yield and that the increased sap volume is drawn from the tree. A large-scale study (171 trees) ...

B. M. Blum M. R. Koelling

1968-01-01

454

Tree growth monitoring by means of digital partial discharge measurements  

Microsoft Academic Search

In this work results relevant to electrical treeing tests performed on several ethylvinylacetate EVA (with different vinylacetate percentage) and on cross linked polyethylene (XLPE) (of two different lots) polymer materials are presented. During the tree growth the partial discharges (PDs) were monitored by means of a digital PD acquisition system and the tree morphologies were optically evidenced by means of

F. Guastavino; B. Cerutti

2003-01-01

455

Reconstructing 3D Tree Models from Instrumented Photographs  

Microsoft Academic Search

The realistic modeling of vegetation is an important problem in computer graphics. Vegetation adds a significant diension of realism to a scene. Trees, in particular, form an integral part of architectural landscapes. Many techniques and modeling packages have been developed for constructing a tree of a particular type. However, variations between two trees of a single type can be very

Ilya Shlyakhter; Max Rozenoer; Julie Dorsey; Seth J. Teller

2001-01-01

456

Machine Learning Through Signature Trees. Applications to Human Speech.  

ERIC Educational Resources Information Center

A signature tree is a binary decision tree used to classify unknown patterns. An attempt was made to develop a computer program for manipulating signature trees as a general research tool for exploring machine learning and pattern recognition. The program was applied to the problem of speech recognition to test its effectiveness for a specific…

White, George M.

457

Evaluating the Use of Dominance Trees for C and COBOL  

Microsoft Academic Search

This paper evaluates the suitability of dominance trees as a means of re-modularising legacy systems. It uses two factors to assess the suitability of the dominance tree approach as a restructuring mechanism. Firstly, it considers if dominance tree analysis identifies suitable reuse candidates and secondly, if the candidates generated represent an improvement to the structure of the code. Applications from

Elizabeth Burd; Malcolm Munro

1999-01-01

458

Tree Rings, Climate Change and the Rainy Season  

NSDL National Science Digital Library

This video shows the potential of dendrochronology (tree ring study) to shed light on climatic conditions of the past. Scientists at Columbia University's Lamont-Doherty Earth Observatory read the growth rings of ancient trees to understand the history and workings of the monsoon. In addition, historical accounts are correlated with data from tree rings to better understand these events.

University, Earth I.

459

Extract Deep Web-Detail Pages with Simple Tree Match  

Microsoft Academic Search

In this paper, we provide a method to extract data from Deep Web-Detail Pages. The method use the Simple Tree Match to compute the max match value between two trees, and use the Hungarian algorithm to trace the result of the STM compute, after this we use tree merge method to generate Wrapper. At last, we use Term Frequency to

Wei Zhang; Ye Deng; Ranran Du; Qiuhong Wang

2011-01-01

460

Unpalatable plants facilitate tree sapling survival in wooded pastures  

Microsoft Academic Search

Summary 1. In endangered wooded pasture ecosystems established tree saplings are frequently found in spatial association with protective structures, suggesting nurse effects. This associational resistance is thought to be a driving force behind tree regeneration in wooded pastures. Experimental evidence for associational resistance is, however, scarce. We studied the effects of unpalatable plants on tree sapling performance in a wooded

CHRISTIAN SMIT; JAN DEN OUDEN; HEINZ MÜLLER-SCHÄRER

2006-01-01

461

Macroscopic Models of Clique Tree Growth for Bayesian Networks  

Microsoft Academic Search

In clique tree clustering, inference consists of propagation in a clique tree compiled from a Bayesian network. In this paper, we develop an analytical approach to characterizing clique tree growth as a function of increasing Bayesian net- work connectedness, specifically: (i) the expected number of moral edges in their moral graphs or (ii) the ratio of the num- ber of

Ole J. Mengshoel

2007-01-01

462

Out on a Limb: Investigating the Anatomy of Tree Limbs  

ERIC Educational Resources Information Center

The author presents several upper elementary science activities involving tree limbs that were collected after severe weather conditions. The activities involved 3rd-grade students arranging tree limb pieces in the correct order from the trunk to the tip of the limb, measuring the pieces, determining the age of a tree limb by its rings,…

Shaw, Edward L.

2008-01-01

463

Tree Pollen and Hospitalization for Asthma in Urban Canada  

Microsoft Academic Search

Background: Allergy to tree pollen is common and aeroallergens have been associated with severe asthma exacerbations in the community setting. To determine the impact of different trees on asthma, we tested the association between daily hospitalizations for asthma and daily concentrations of different tree pollens in 10 large Canadian cities. Methods: Daily time-series analyses were employed to remove unwanted temporal

Robert E. Dales; Sabit Cakmak; Stan Judek; Frances Coates

2008-01-01

464

Computer animation of swaying trees based on physical simulation  

Microsoft Academic Search

This paper presents a series of techniques for generating animations of trees swaying in the wind, in consideration of the influences that the tree shapes and leaf sizes give to the air current. To do the simulation of the wind around a tree having a complicated shape, it is necessary to consider the influence that some objects obstructing the wind

Y. Akagi; K. Kitajima

2006-01-01

465

Biomass equations for sixty-five North American tree species  

Microsoft Academic Search

The paper presents a comprehensive review of the biomass equations for 65 North American tree species. All equations are of the form M = aDb, where M is the oven-dry weight of the biomass component of a tree (kg), D is diameter at breast height (DBH) (cm), and a and b are parameters. Equations for the following tree components were

Michael T. Ter-Mikaelian; Michael D. Korzukhin

1997-01-01

466

Rooting the Eukaryote Tree by Using a Derived Gene Fusion  

Microsoft Academic Search

Single-gene trees have failed to locate the root of the eukaryote tree because of systematic biases in sequence evolution. Structural genetic data should yield more reliable insights into deep phylogenetic relationships. We searched major protist groups for the presence or absence of a gene fusion in order to locate the root of the eukaryote tree. In striking contrast to previous

Alexandra Stechmann; Thomas Cavalier-Smith

2002-01-01

467

SUPERIOR SHADE TREE SELECTIONS FOR THE SOUTHEASTERN UNITED STATES  

Microsoft Academic Search

A 13-year study at the Auburn University Pied- mont Substation has evaluated over 200 different trees. Data collected have included attrition, growth rate and ornamental characteristics. These data have provided information which nurserymen, landscapers and urban foresters use to select tree species and cultivars for residential and urban settings. Among trees showing superior performance in criteria used in the evaluation

J. David Williams; Donna C. Fare; Charles H. Gilliam; Gary J. Keever; Harry G. Ponder; John T. Owen; Greg Creech

468

Form and structure of maple trees in urban environments  

Microsoft Academic Search

The form and structure of maple trees in an urban environment were measured and compared with the original design intent prepared 25 years previously. Bio-physical characteristics of the sites were also measured in an attempt to relate tree characteristics to environmental stress.Sugar maple (Acer saccharum) trees planted in turfed areas survived and were determined to possess a form and structure

Tracey-Lee Schwets; Robert D Brown

2000-01-01

469

Ultralow Voltage Nanoelectronics Powered Directly, and Solely, From a Tree  

Microsoft Academic Search

Complex patterns of electrical potential differences exist across the structure of a tree. We have characterized these voltages, and measured values ranging from a few millivolts to a few hundred millivolts for Bigleaf maple trees. These potential differences provide a unique opportunity to power nanoelectronic circuits directly from a tree. We have designed, constructed, and successfully tested two ICs, powered

Carlton Himes; Eric Carlson; Ryan J. Ricchiuti; Brian P. Otis; Babak A. Parviz

2010-01-01

470

Pattern trees for regression and fuzzy systems modeling  

Microsoft Academic Search

Fuzzy pattern tree induction has recently been introduced as a novel classification method in the context of machine learning. Roughly speaking, a pattern tree is a hierarchical, tree-like structure, whose inner nodes are marked with generalized (fuzzy) logical operators and whose leaf nodes are associated with fuzzy predicates on input attributes. In this paper, we adapt the method of pattern

Robin Senge; E. Hullermeier

2010-01-01

471

Tree-climbing mangrove crabs: a case of convergent evolution  

Microsoft Academic Search

Several crab species of the families Sesarmidae and Grapsidae (Crustacea: Brachyura: Grapsoidea) are known to climb mangrove trees. They show different degrees of dependence on arboreal life, with only a few of them thriving in the tree canopies and feeding on fresh leaves. Some of the sesarmid tree-dwelling crabs share a number of morphological characters and therefore have been considered

Sara Fratini; Marco Vannini; Stefano Cannicci; Christoph D. Schubart

2005-01-01

472

CHEMICAL ANALYSIS OF TREES INFESTED BY THE ASIAN LONGHORNED BEETLE  

Microsoft Academic Search

In the past few years, the Asian Longhorned Beetle (Anoplophora glabripennis) has infested various species of trees throughout the United States, and it threatens to do billions of dollars worth of damage. This study sought to identify various factors that may affect the selectivity of the Asian Longhorned Beetle (ALB) for specific host tree species. Trees studied included the Sugar

Robert Bruce; Deepa Cherla; Pedro Duran; Josephine Li; Tanvi Rastogi; Aaron Sin

473

Cluster-Based Construction of Tree Crown from Scanned Data  

Microsoft Academic Search

It is a challenge task to reconstruct a real tree from scattered scanned points in virtual reality. Although many progresses have been made on main branch structures and overall tree shape, reconstructions are still not faithful in terms of silhouette and details. We push the idea that 3D reconstruction of the tree crown shapes may help to constrain reconstruction of

Chao Zhu; Xiaopeng Zhang; Marc JAEGER; Yinghui Wang

2009-01-01

474

Mycorrhizal relations in trees for agroforestry and land rehabilitation  

Microsoft Academic Search

The mycorrhizal stimulation of trees by increasing the efficiency of nutrient uptake from soil is discussed with special reference to tree species used in agroforestry\\/sylvopastoral systems. The occurrence of the two major classes of mycorrhizas is indicated as are the soil, plant and fungus factors affecting the size of the response. The low intensity of rooting of many tree species

Kurt Haselwandter; Glynn D. Bowen

1996-01-01

475

Simulation of electrical tree growth in solid insulating materials  

Microsoft Academic Search

Contents In this paper the electrical tree growth in solid insulating materials is modeled using von Neumann's Cellular Automata (CA). The model is based upon the assumption that the electric stress at the end of a conducting tip quite often approaches the dielectric strength of the material and that progressive breakdown can occur by electrical tree formation. Because of tree

I. Karafylliflis; M. G. Danikas; A. Thanailakis; A. M. Bruning

1998-01-01

476

Analysis methods for fault trees that contain secondary failures  

Microsoft Academic Search

The fault tree methodology is appropriate when the component level failures (basic events) occur independently. One situation where the conditions of independence are not met occurs when secondary failure events appear in the fault tree structure. Guidelines for fault tree construction that have been utilized for many years encourage the inclusion of secondary failures along with primary failures and command

S Dunnett; J D Andrews

2004-01-01

477

A new approach to solve dynamic fault trees  

Microsoft Academic Search

The traditional static fault trees with AND, OR and voting gates cannot capture the dynamic behavior of system failure mechanisms such as sequence-dependent events, spares and dynamic redundancy management and priorities of failure events. Therefore, researchers introduced dynamic gates into fault trees to capture these sequence-dependent failure mechanisms. Dynamic fault trees are generally solved using automatic conversion to Markov models;

S. Amari; G. Dill; E. Howald

2003-01-01

478

A new algorithm for computer-aided fault tree synthesis  

Microsoft Academic Search

Fault tree analysis (FTA) has been used in the chemical process industry (CPI) for systematic safety and reliability analysis during the past decades. Conventional manual construction of fault trees can be extremely time consuming and vulnerable to human error. A computer-aided fault tree synthesis methodology can be an initial step, or as an independent check to assist or supplement manual

Y. Wang; T. Teague; S. Mannan

2002-01-01

479

Simple Learning Algorithms for Decision Trees and Multivariate Polynomials  

Microsoft Academic Search

There were two techniques in the literature for learning multivariate polynomialsand decision trees. These are learning decision trees under the uniform distributionvia the Fourier Spectrum [Kushilevitz, Mansour 93 and Jackson 94] and learningdecision trees and multivariate polynomials under any distribution via Lattice Theory[Bshouty 94, Schapire and Sellie 93]. These two approaches are used for provingthe learnability of many other interesting

Nader H. Bshouty; Yishay Mansour

1995-01-01

480

Using Decision Trees to Construct a Practical Parser  

Microsoft Academic Search

This paper describes novel and practical Japanese parsers that uses decision trees. First, we construct a single decision tree to estimate modification probabilities; how one phrase tends to modify another. Next, we introduce a boosting algorithm in which several decision trees are constructed and then combined for probability estimation. The two constructed parsers are evaluated by using the EDR Japanese

Masahiko Haruno; Satoshi Shirai; Yoshifumi Ooyama

1998-01-01

481

Using Decision Trees to Construct a Practical Parser  

Microsoft Academic Search

This paper describes a novel and practical Japanese parser that uses decision trees. First, we construct a single decision tree to estimate modification probabilities; how one phrase tends to modify another. Next, we introduce a boosting algorithm in which several decision trees are constructed and then combined for probability estimation. The constructed parsers are evaluated using the EDR Japanese annotated

Masahiko Haruno; Satoshi Shirai; Yoshifumi Ooyama

1999-01-01

482

Hyperspectral image lossless compression based on prediction tree algorithm  

Microsoft Academic Search

A new hyperspectral image compression algorithm-NMST (Near Min Spanning Tree) is proposed. The near minimum spanning tree is constructed according to the image structure and is taken as a prediction tree in image compression. The result shows the NMST algorithm can improve the compression speed with little decrease of compression ratio.

HengShu Liu; LianQing Huang

2003-01-01

483

Tree of Life: An Introduction to Microbial Phylogeny  

NSDL National Science Digital Library

How do phylogenetic trees help us look more closely at microbial evolution? Explore sequence data and extend your tree thinking to examine possible relationships between the microbes and other life forms. The Biology Workbench provides access to data and tools for investigating these relationships. * read a phylogenetic tree

Beverly Brown (Nazareth College;Biology); Sam Fan (Bradley University;Biology); LeLeng To Isaacs (Goucher College;Biology); Min-Ken Liao (Furman University;Biology)

2006-05-20

484

Perceptron Trees: A Case Study In Hybrid Concept Representations  

Microsoft Academic Search

The paper presents a case study in examining the bias of two particular formalisms: decision trees and linear threshold units. The immediate result is a new hybrid representation, called a percep- tron tree, and an associated learning algorithm called the perceptron tree error correction proce- dure. The longer term result is a model for ex- ploring issues related to understanding

Paul E. Utgoff

1988-01-01

485

Experiences with Streaming Construction of SAH KD-Trees  

Microsoft Academic Search

A major reason for the recent advancements in ray tracing perfor- mance is the use of optimized acceleration structures, namely kd- trees based on the surface area heuristic (SAH). Though algorithms exist to build these search trees in O(nlogn), the construction times for larger scenes are still high and do not allow for rebuilding the kd-tree every frame to support

Stefan Popov; MPI Informatik; Hans-Peter Seidel; Philipp Slusallek

2004-01-01

486

ForestTreeDB: a database dedicated to the mining of tree transcriptomes.  

PubMed

ForestTreeDB is intended as a resource that centralizes large-scale expressed sequence tag (EST) sequencing results from several tree species (http://foresttree.org/ftdb). It currently encompasses 344,878 quality sequences from 68 libraries, from diverse organs of conifer and hybrid poplar trees. It utilizes the Nimbus data model to provide a hosting system for multiple projects, and uses object-relational mapping APIs in Java and Perl for data accesses within an Oracle database designed to be scalable, maintainable and extendable. Transcriptome builds or unigene sets occupy the focal point of the system. Several of the five current species-specific unigenes were used to design microarrays and SNP resources. The ForestTreeDB web application provides the means for multiple combination database queries. It presents the user with a list of discrete queries to retrieve and download large EST datasets or sequences from precompiled unigene assemblies. Functional annotation assignment is not trivial in conifers which are distantly related to angiosperm model plants. Optimal annotations are achieved through database queries that integrate results from several procedures based open-source tools. ForestTreeDB aims to facilitate sequence mining of coherent annotations in multiple species to support comparative genomic approaches. We plan to continuously enrich ForestTreeDB with other resources through collaborations with other genomic projects. PMID:17130142

Pavy, Nathalie; Johnson, James J; Crow, John A; Paule, Charles; Kunau, Timothy; MacKay, John; Retzel, Ernest F

2007-01-01

487

PypeTree: A Tool for Reconstructing Tree Perennial Tissues from Point Clouds  

PubMed Central

The reconstruction of trees from point clouds that were acquired with terrestrial LiDAR scanning (TLS) may become a significant breakthrough in the study and modelling of tree development. Here, we develop an efficient method and a tool based on extensive modifications to the skeletal extraction method that was first introduced by Verroust and Lazarus in 2000. PypeTree, a user-friendly and open-source visual modelling environment, incorporates a number of improvements into the original skeletal extraction technique, making it better adapted to tackle the challenge of tree perennial tissue reconstruction. Within PypeTree, we also introduce the idea of using semi-supervised adjustment tools to address methodological challenges that are associated with imperfect point cloud datasets and which further improve reconstruction accuracy. The performance of these automatic and semi-supervised approaches was tested with the help of synthetic models and subsequently validated on real trees. Accuracy of automatic reconstruction greatly varied in terms of axis detection because small (length < 3.5 cm) branches were difficult to detect. However, as small branches account for little in terms of total skeleton length, mean reconstruction error for cumulated skeleton length only reached 5.1% and 1.8% with automatic or semi-supervised reconstruction, respectively. In some cases, using the supervised tools, a perfect reconstruction of the perennial tissue could be achieved.

Delagrange, Sylvain; Jauvin, Christian; Rochon, Pascal

2014-01-01

488

TreeQA: quantitative genome wide association mapping using local perfect phylogeny trees.  

PubMed

The goal of genome wide association (GWA) mapping in modern genetics is to identify genes or narrow regions in the genome that contribute to genetically complex phenotypes such as morphology or disease. Among the existing methods, tree-based association mapping methods show obvious advantages over single marker-based and haplotype-based methods because they incorporate information about the evolutionary history of the genome into the analysis. However, existing tree-based methods are designed primarily for binary phenotypes derived from case/control studies or fail to scale genome-wide. In this paper, we introduce TreeQA, a quantitative GWA mapping algorithm. TreeQA utilizes local perfect phylogenies constructed in genomic regions exhibiting no evidence of historical recombination. By efficient algorithm design and implementation, TreeQA can efficiently conduct quantitative genom-wide association analysis and is more effective than the previous methods. We conducted extensive experiments on both simulated datasets and mouse inbred lines to demonstrate the efficiency and effectiveness of TreeQA. PMID:19209719

Pan, Feng; McMillan, Leonard; Pardo-Manuel De Villena, Fernando; Threadgill, David; Wang, Wei

2009-01-01

489

The Future of Large Old Trees in Urban Landscapes  

PubMed Central

Large old trees are disproportionate providers of structural elements (e.g. hollows, coarse woody debris), which are crucial habitat resources for many species. The decline of large old trees in modified landscapes is of global conservation concern. Once large old trees are removed, they are difficult to replace in the short term due to typically prolonged time periods needed for trees to mature (i.e. centuries). Few studies have investigated the decline of large old trees in urban landscapes. Using a simulation model, we predicted the future availability of native hollow-bearing trees (a surrogate for large old trees) in an expanding city in southeastern Australia. In urban greenspace, we predicted that the number of hollow-bearing trees is likely to decline by 87% over 300 years under existing management practices. Under a worst case scenario, hollow-bearing trees may be completely lost within 115 years. Conversely, we predicted that the number of hollow-bearing trees will likely remain stable in semi-natural nature reserves. Sensitivity analysis revealed that the number of hollow-bearing trees perpetuated in urban greenspace over the long term is most sensitive to the: (1) maximum standing life of trees; (2) number of regenerating seedlings ha?1; and (3) rate of hollow formation. We tested the efficacy of alternative urban management strategies and found that the only way to arrest the decline of large old trees requires a collective management strategy that ensures: (1) trees remain standing for at least 40% longer than currently tolerated lifespans; (2) the number of seedlings established is increased by at least 60%; and (3) the formation of habitat structures provided by large old trees is accelerated by at least 30% (e.g. artificial structures) to compensate for short term deficits in habitat resources. Immediate implementation of these recommendations is needed to avert long term risk to urban biodiversity.

Le Roux, Darren S.; Ikin, Karen; Lindenmayer, David B.; Manning, Adrian D.; Gibbons, Philip

2014-01-01

490

Analyzing and Synthesizing Phylogenies Using Tree Alignment Graphs  

PubMed Central

Phylogenetic trees are used to analyze and visualize evolution. However, trees can be imperfect datatypes when summarizing multiple trees. This is especially problematic when accommodating for biological phenomena such as horizontal gene transfer, incomplete lineage sorting, and hybridization, as well as topological conflict between datasets. Additionally, researchers may want to combine information from sets of trees that have partially overlapping taxon sets. To address the problem of analyzing sets of trees with conflicting relationships and partially overlapping taxon sets, we introduce methods for aligning, synthesizing and analyzing rooted phylogenetic trees within a graph, called a tree alignment graph (TAG). The TAG can be queried and analyzed to explore uncertainty and conflict. It can also be synthesized to construct trees, presenting an alternative to supertrees approaches. We demonstrate these methods with two empirical datasets. In order to explore uncertainty, we constructed a TAG of the bootstrap trees from the Angiosperm Tree of Life project. Analysis of the resulting graph demonstrates that areas of the dataset that are unresolved in majority-rule consensus tree analyses can be understood in more detail within the context of a graph structure, using measures incorporating node degree and adjacency support. As an exercise in synthesis (i.e., summarization of a TAG constructed from the alignment trees), we also construct a TAG consisting of the taxonomy and source trees from a recent comprehensive bird study. We synthesized this graph into a tree that can be reconstructed in a repeatable fashion and where the underlying source information can be updated. The methods presented here are tractable for large scale analyses and serve as a basis for an alternative to consensus tree and supertree methods. Furthermore, the exploration of these graphs can expose structures and patterns within the dataset that are otherwise difficult to observe.

Smith, Stephen A.; Brown, Joseph W.; Hinchliff, Cody E.

2013-01-01

491

Analyzing and synthesizing phylogenies using tree alignment graphs.  

PubMed

Phylogenetic trees are used to analyze and visualize evolution. However, trees can be imperfect datatypes when summarizing multiple trees. This is especially problematic when accommodating for biological phenomena such as horizontal gene transfer, incomplete lineage sorting, and hybridization, as well as topological conflict between datasets. Additionally, researchers may want to combine information from sets of trees that have partially overlapping taxon sets. To address the problem of analyzing sets of trees with conflicting relationships and partially overlapping taxon sets, we introduce methods for aligning, synthesizing and analyzing rooted phylogenetic trees within a graph, called a tree alignment graph (TAG). The TAG can be queried and analyzed to explore uncertainty and conflict. It can also be synthesized to construct trees, presenting an alternative to supertrees approaches. We demonstrate these methods with two empirical datasets. In order to explore uncertainty, we constructed a TAG of the bootstrap trees from the Angiosperm Tree of Life project. Analysis of the resulting graph demonstrates that areas of the dataset that are unresolved in majority-rule consensus tree analyses can be understood in more detail within the context of a graph structure, using measures incorporating node degree and adjacency support. As an exercise in synthesis (i.e., summarization of a TAG constructed from the alignment trees), we also construct a TAG consisting of the taxonomy and source trees from a recent comprehensive bird study. We synthesized this graph into a tree that can be reconstructed in a repeatable fashion and where the underlying source information can be updated. The methods presented here are tractable for large scale analyses and serve as a basis for an alternative to consensus tree and supertree methods. Furthermore, the exploration of these graphs can expose structures and patterns within the dataset that are otherwise difficult to observe. PMID:24086118

Smith, Stephen A; Brown, Joseph W; Hinchliff, Cody E

2013-01-01

492

Fatality Assessment and Control Evaluation (FACE) Report for New Jersey: Groundman Killed by Falling Tree Section at Tree Removal Operation.  

National Technical Information Service (NTIS)

On October 2, 2005, an 18-year-old groundman for a small tree trimming company was killed when he was struck by a falling section of tree. The incident occurred at a private residence where the company had been hired to remove four trees and to prune a fi...

2007-01-01

493

A Method to Quantify Plant Availability and Initiating Event Frequency Using a Large Event Tree, Small Fault Tree Model  

Microsoft Academic Search

South Texas Project uses a large fault tree to produce scenarios (minimal cut sets) used in quantification of plant availability and event frequency predictions. On the other hand, the South Texas Project probabilistic risk assessment model uses a large event tree, small fault tree for quantifying core damage and radioactive release frequency predictions. The South Texas Project is converting its

Ernest J. Kee; Alice Sun; Shawn Rodgers; ElmiraV Popova; Paul Nelson; Vera Moiseytseva; Eric Wang

2006-01-01

494

Fatality Assessment and Control Evaluation (FACE) Report for New Jersey: Tree Climber Crushed by Falling Tree Section.  

National Technical Information Service (NTIS)

On June 4, 2001, a 24-year-old tree trimmer was killed when the tree to which he was secured fractured beneath him and fell to the ground. Since he was tied to the tree with his lanyard, he fell with the broken section, and was crushed under it.

2002-01-01

495

An Adjuvant-Free Mouse Model of Tree Nut Allergy Using Hazelnut as a Model Tree Nut  

Microsoft Academic Search

Background: Tree nut allergy, a major group of food allergy, is often linked to fatal or near-fatal systemic anaphylaxis. Currently, an adjuvant-free mouse model to study tree nut hypersensitivity is unavailable. Here we tested the hypothesis that transdermal exposure to hazelnut, a model tree nut, without the use of an adjuvant is sufficient to sensitize mice for immediate hypersensitivity reaction

Neil Patrick Birmingham; Sitaram Parvataneni; Hanem M. Ahmed Hassan; Jack Harkema; Sridhar Samineni; Lalitha Navuluri; Caleb James Kelly; Venu Gangur

2007-01-01

496

Investigating the Underlying Causes of Tree Mortality with Carbon and Oxygen Isotopes in Tree-rings  

NASA Astrophysics Data System (ADS)

Increasing rates of tree mortality in the western United States have potentially profound effects on native biodiversity and ecosystem structure and function. Regional drought and insect or pathogen outbreaks have been implicated; however, the underlying cause(s) of recent tree mortality remain unclear. Hypotheses include 1) hydraulic failure; 2) carbon starvation; or 3) increased susceptibility to pests due to (1) and/or (2). We examined evidence for and against these hypotheses by measuring patterns in the ?13C and ?18O of tree-rings from the last 50 years in eight species of isohydric and anisohydric trees, both living and dead, from across the western United States. We compared isotopic compositions of ?13C and ?18O between living and dead trees with models of expected isotope responses to hydraulic failure, carbon starvation and pest infestation to eliminate or support specific mechanisms of tree mortality. Our data thus far show that Pinaceae (including Abies, Picea, Pinus, and Psuedotsuga) respond isohydrically to drought, while Cupressaceae (including Calocedrus, Juniperus, and Sequoiadendron) respond anisohydrically to drought. We expect that in water-limited forests, Pinaceae will exhibit more rapid and pronounced increases in ?13C and ?18O, attributable to water stress, than in Cupressaceae. However, we observe variable results within Pinaceae and between live and dead trees within a given species. For example, in Piñon from various sites in New Mexico, dead trees had either higher or lower ?13C in the years preceding their death than living trees at the same site. The isotopic patterns associated with mortality varied between energy-limited (Oregon, Washington, high-elevation Colorado and California) and water-limited (low-elevation Colorado and New Mexico) forests in a predictable manner. We expect dying trees in energy-limited systems to show changes in ?13C but not in ?18O. Our preliminary conclusions are that either: 1) multiple mechanisms of mortality occur across the western United States; or 2) similar mechanisms may result in differing isotopic patterns between sites and species.

English, N. B.; McDowell, N.; Allen, C. D.; Das, A. J.; Mora, C. I.; Stephenson, N. L.

2010-12-01

497

Microwave Soil Moisture Retrieval Under Trees  

NASA Technical Reports Server (NTRS)

Soil moisture is recognized as an important component of the water, energy, and carbon cycles at the interface between the Earth's surface and atmosphere. Current baseline soil moisture retrieval algorithms for microwave space missions have been developed and validated only over grasslands, agricultural crops, and generally light to moderate vegetation. Tree areas have commonly been excluded from operational soil moisture retrieval plans due to the large expected impact of trees on masking the microwave response to the underlying soil moisture. Our understanding of the microwave properties of trees of various sizes and their effect on soil moisture retrieval algorithms at L band is presently limited, although research efforts are ongoing in Europe, the United States, and elsewhere to remedy this situation. As part of this research, a coordinated sequence of field measurements involving the ComRAD (for Combined Radar/Radiometer) active/passive microwave truck instrument system has been undertaken. Jointly developed and operated by NASA Goddard Space Flight Center and George Washington University, ComRAD consists of dual-polarized 1.4 GHz total-power radiometers (LH, LV) and a quad-polarized 1.25 GHz L band radar sharing a single parabolic dish antenna with a novel broadband stacked patch dual-polarized feed, a quad-polarized 4.75 GHz C band radar, and a single channel 10 GHz XHH radar. The instruments are deployed on a mobile truck with an 19-m hydraulic boom and share common control software; real-time calibrated signals, and the capability for automated data collection for unattended operation. Most microwave soil moisture retrieval algorithms developed for use at L band frequencies are based on the tau-omega model, a simplified zero-order radiative transfer approach where scattering is largely ignored and vegetation canopies are generally treated as a bulk attenuating layer. In this approach, vegetation effects are parameterized by tau and omega, the microwave vegetation opacity and single scattering albedo. One goal of our current research is to determine whether the tau-omega model can work for tree canopies given the increased scatter from trees compared to grasses and crops, and. if so, what are effective values for tau and omega for trees.

O'Neill, P.; Lang, R.; Kurum, M.; Joseph, A.; Jackson, T.; Cosh, M.

2008-01-01

498

Positive, Negative and Net Effects of Shrub-Tree Seedling Interactions in Red Pine Ecosystems  

Microsoft Academic Search

In forested ecosystems, young tree seedlings interact with already established vegetation such as adult trees, shrubs, herbs, understory trees, and other juvenile trees. The extent and nature of these interactions can affect growth rates of tree seedlings and their probability of survival. Thick shrub understories are thought to deter regeneration through increased mortality and slow growth of tree seedlings and

R. Montromery; P. B. Reich; S. B. Boyden; B. J. Palik

2009-01-01

499

Paleo Slide Set: Tree Rings: Ancient Chronicles of Environmental Change  

NSDL National Science Digital Library

This slide show explains how trees record information about past environments and climate in their annual growth rings. Dendrochronology is the science that studies tree rings. This set includes a narrative background and color photos depicting dendrochronological techniques, including tree coring in the field, sample preparation, cross-dating, standardization, and chronology building. In addition, there are photos and graphics of tree physiology and climatic interpretations derived from tree ring data at sites around the world. This slide set can be used as an educational tool for studying current environmental issues such as drought, global warming, and dendroclimatology. Each photograph can be enlarged for better viewing.

500