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Trees
Kinds of Trees Terms modified by Trees Selected AbstractsAllometric Models for Tree Volume and Total Aboveground Biomass in a Tropical Humid Forest in Costa Rica1BIOTROPICA, Issue 1 2005Milena Segura ABSTRACT Allometric equations for the estimation of tree volume and aboveground biomass in a tropical humid forest were developed based on direct measurements of 19 individuals of seven tree species in Northern Costa Rica. The volume and the biomass of the stems represented about two-thirds of the total volume and total aboveground biomass, respectively. The average stem volume varied between 4 and 11 Mg/tree and the average total aboveground biomass ranged from 4 to 10 mg/tree. The mean specific gravity of the sampled trees was 0.62 ± 0.06 (g/cm3). The average biomass expansion factor was 1.6 ± 0.2. The best-fit equations for stem and total volume were of logarithmic form, with diameter at breast height (R2= 0.66 , 0.81) as an independent variable. The best-fit equations for total aboveground biomass that were based on combinations of diameter at breast height, and total and commercial height as independent variables had R2 values between 0.77 and 0.87. Models recommended for estimating total aboveground biomass are based on diameter at breast height, because the simplicity of these models is advantageous. This variable is easy to measure accurately in the field and is the most common variable recorded in forest inventories. Two widely used models in literature tend to underestimate aboveground biomass in large trees. In contrast, the models developed in this study accurately estimate the total aboveground biomass in these trees. RESUMEN Ecuaciones alométricas para la estimación de volumen y biomasa aérea de árboles en un bosque húmedo tropical fueron desarrollados basados en mediciones directas de 19 individuos de siete especies de árboles al norte de Costa Rica. El volumen y la biomasa del tronco representaron cerca de dos terceras partes del volumen total del árbol y de la biomasa aérea total. El volumen promedio del tronco varió entre 4 y 11 Mg/árbol y el promedio de la biomasa aérea total varió entre 4 y 10 mg/árbol. La gravedad específica promedio de los árboles muestreados fué de 0.62 ± 0.06 (g/cm3). El factor de expansión de biomasa promedio fué de 1.6 ± 0.2. Las ecuaciones de mejor ajuste para el volumen de tallo y total fueron de tipo logarítmico, con el diámetro a la altura de pecho (R2= 0.66 a 0.81) como variable independiente. Las ecuaciones de mejor ajuste para biomasa aérea total, las cuales fueron basadas en combinaciones de diámetro a la altura de pecho y altura total y comercial como variables independientes, presentaron valores de R2 entre 0.77 y 0.87. Los modelos recomendados para estimar biomasa aérea total están basados en diámetro a la altura de pecho, porque la simplicidad de estos modelos es ventajosa. Esta variable es de fácil medición en el campo y tiene mayor precision, además, es la más comúnmente registrada en inventarios forestales. Dos modelos ampliamente usados en la literature tienden a subestimar la biomasa aérea total en árboles grandes. En contraste, los modelos desarrollados en este estudio, estiman con mayor precisión la biomasa aérea total de estos árboles. [source] THE APPLE DOESN'T FALL FAR FROM THE TREE (OR DOES IT?): INTERGENERATIONAL PATTERNS OF ANTISOCIAL BEHAVIOR,THE AMERICAN SOCIETY OF CRIMINOLOGY 2008 SUTHERLAND ADDRESS,CRIMINOLOGY, Issue 2 2009TERENCE P. THORNBERRY There is a growing literature on intergenerational studies of antisocial behavior and a growing understanding of the unique contributions they are likely to make. At the same time, the field has yet to agree on core design features for intergenerational study. In this article, I propose a set of defining design elements that all intergenerational studies should meet and I discuss the advantages of these studies for enhancing our understanding of the onset and course of delinquent careers. I then use data from the ongoing Rochester Intergenerational Study to illustrate these points and the potential yield of intergenerational studies. In particular, I examine intergenerational continuities in antisocial behavior and school disengagement, test the cycle of violence hypothesis to see whether a history of maltreatment increases the likelihood of perpetration of maltreatment, and estimate a structural equation model to help identify mediating pathways that link parents and children with respect to antisocial behavior. [source] LARGE-SCALE SIMULATION OF THE HUMAN ARTERIAL TREECLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 2 2009L Grinberg SUMMARY 1Full-scale simulations of the virtual physiological human (VPH) will require significant advances in modelling, multiscale mathematics, scientific computing and further advances in medical imaging. Herein, we review some of the main issues that need to be resolved in order to make three-dimensional (3D) simulations of blood flow in the human arterial tree feasible in the near future. 2A straightforward approach is computationally prohibitive even on the emerging petaflop supercomputers, so a three-level hierarchical approach based on vessel size is required, consisting of: (i) a macrovascular network (MaN); (ii) a mesovascular network (MeN); and (iii) a microvascular network (MiN). We present recent simulations of MaN obtained by solving the 3D Navier,Stokes equations on arterial networks with tens of arteries and bifurcations and accounting for the neglected dynamics through proper boundary conditions. 3A multiscale simulation coupling MaN,MeN,MiN and running on hundreds of thousands of processors on petaflop computers will require no more than a few CPU hours per cardiac cycle within the next 5 years. The rapidly growing capacity of supercomputing centres opens up the possibility of simulation studies of cardiovascular diseases, drug delivery, perfusion in the brain and other pathologies. [source] A LIKELIHOOD FRAMEWORK FOR INFERRING THE EVOLUTION OF GEOGRAPHIC RANGE ON PHYLOGENETIC TREESEVOLUTION, Issue 11 2005Richard H. Ree Abstract At a time when historical biogeography appears to be again expanding its scope after a period of focusing primarily on discerning area relationships using cladograms, new inference methods are needed to bring more kinds of data to bear on questions about the geographic history of lineages. Here we describe a likelihood framework for inferring the evolution of geographic range on phylogenies that models lineage dispersal and local extinction in a set of discrete areas as stochastic events in continuous time. Unlike existing methods for estimating ancestral areas, such as dispersal-vicariance analysis, this approach incorporates information on the timing of both lineage divergences and the availability of connections between areas (dispersal routes). Monte Carlo methods are used to estimate branch-specific transition probabilities for geographic ranges, enabling the likelihood of the data (observed species distributions) to be evaluated for a given phylogeny and parameterized paleogeographic model. We demonstrate how the method can be used to address two biogeographic questions: What were the ancestral geographic ranges on a phylogenetic tree? How were those ancestral ranges affected by speciation and inherited by the daughter lineages at cladogenesis events? For illustration we use hypothetical examples and an analysis of a Northern Hemisphere plant clade (Cercis), comparing and contrasting inferences to those obtained from dispersal-vicariance analysis. Although the particular model we implement is somewhat simplistic, the framework itself is flexible and could readily be modified to incorporate additional sources of information and also be extended to address other aspects of historical biogeography. [source] Evaluation of 6 Prognostic Models Used to Calculate Mortality Rates in Elderly Heart Failure Patients With a Fatal Heart Failure AdmissionCONGESTIVE HEART FAILURE, Issue 5 2010Andria L. Nutter The objective was to evaluate 6 commonly used heart failure (HF) prognostic models in an elderly, fatal HF population. Predictive models have been established to quantify risk among HF patients. The validation of these models has not been adequately studied, especially in an elderly cohort. Applying a single-center, retrospective study of serially admitted HF patients who died while in the hospital or within 30 days of discharge, the authors evaluated 6 prognostic models: the Seattle Heart Failure Model (SHFM), Heywood's model, Classification and Regression Tree (CART) Analysis, the Heart Failure Survival Score (HFSS), Heart Failure Risk Scoring System, and Pocock's score. Eighty patients were included (mean age, 82.7 ± 8.2 years). Twenty-three patients (28.75%) died in the hospital. The remainder died within 30 days of discharge. The models' predictions varied considerably from one another and underestimated the patients' actual mortality. This study demonstrates that these models underestimate the mortality risk in an elderly cohort at or approaching the end of life. Moreover, the predictions made by each model vary greatly from one another. Many of the models used were not intended for calculation during hospitalization. Development of improved models for the range of patients with HF syndromes is needed. Congest Heart Fail. 2010;16:196,201. © 2010 Wiley Periodicals, Inc. [source] Conserving the Tree of LifeCONSERVATION BIOLOGY, Issue 2 2007W. John Kress No abstract is available for this article. [source] Got a Right to the Tree of Life Religious Jurisdiction, Religious Infrastructures, and Urban Religious TerritoryCROSSCURRENTS, Issue 3 2008David D. Daniels III [source] Steps towards a centralized nervous system in basal bilaterians: Insights from neurogenesis of the acoel Symsagittifera roscoffensisDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 8 2010Henrike Semmler Due to its proposed basal position in the bilaterian Tree of Life, Acoela may hold the key to our understanding of the evolution of a number of bodyplan features including the central nervous system. In order to contribute novel data to this discussion we investigated the distribution of ,-tubulin and the neurotransmitters serotonin and RFamide in juveniles and adults of the sagittiferid Symsagittifera roscoffensis. In addition, we present the expression pattern of the neuropatterning gene SoxB1. Adults and juveniles exhibit six serotonergic longitudinal neurite bundles and an anterior concentration of serotonergic sensory cells. While juveniles show an "orthogon-like" arrangement of longitudinal neurite bundles along the anterior-posterior axis, it appears more diffuse in the posterior region of adults. Commissures between the six neurite bundles are present only in the anterior body region of adults, while irregularly distributed individual neurites, often interconnected by serotonergic nerve cells, are found in the posterior region. Anti-RFamide staining shows numerous individual neurites around the statocyst. The orthogon-like nervous system of S. roscoffensis is confirmed by ,-tubulin immunoreactivity. In the region of highest neurotransmitter density (i.e., anterior), the HMG-box gene SrSoxB1, a transcription factor known to be involved in neurogenesis in other bilaterians, is expressed in juvenile specimens. Accordingly, SoxB1 expression in S. roscoffensis follows the typical pattern of higher bilaterians that have a brain. Thus, our data support the notion that Urbilateria already had the genetic toolkit required to form brain-like neural structures, but that its morphological degree of neural concentration was still low. [source] An investigation of the hydrological requirements of River Red Gum (Eucalyptus camaldulensis) Forest, using Classification and Regression Tree modellingECOHYDROLOGY, Issue 2 2009Li Wen Abstract River Red Gum (Eucalyptus camaldulensis) is widely distributed throughout many water courses and floodplains within inland Australia. In recent years, accelerated decline of River Red Gum condition has been observed in many locations, and field observations of the degradation are consistent with the reduction of flooding. However, there are few publications that quantitatively investigate the relationships between River Red Gum condition and flooding history. We applied Classification and Regression Tree (CART) to model the minimum flooding requirement of River Red Gum forest/woodland in Yanga National Park, located on the Lower Murrumbidgee Floodplain, southeast Australia, using crown conditions derived from historical aerial photographs spanning more than 40 years. The model produced has a moderate reliability with an overall accuracy of 64·1% and a Kappa index of 0·543. The model brings in important insights about the relationship between River Red Gum community type, flood frequency and flood duration. Our results demonstrated that (1) CART analysis is a simple yet powerful technique with significant potential for application in river and environmental flow management; (2) River Red Gum communities on the Lower Murrumbidgee Floodplain require periodic inundation (3,5 years) for a duration of up to 64 days to be in moderate to good conditions; (3) Although the crown conditions of different community types displayed similar degradation trends, they have distinct flooding requirements; and (4) The River Red Gum community in Yanga National Park may be managed as hydrological units given limited environmental water allocations. Copyright © 2009 John Wiley & Sons, Ltd. [source] Genetic differences in growth of an invasive tree speciesECOLOGY LETTERS, Issue 6 2001Evan Siemann Invasive plants are often more vigorous in their introduced ranges than in their native ranges. This may reflect an innate superiority of plants from some habitats or an escape from their enemies. Another hypothesis proposes that invasive plants evolve increased competitive ability in their introduced range. We present the results of a 14-year common garden experiment with the Chinese Tallow Tree (Sapium sebiferum) from its native range (Asia), place of introduction to North America (Georgia) and areas colonized a century later (Louisiana and Texas). Invasive genotypes, especially those from recently colonized areas, were larger than native genotypes and more likely to produce seeds but had lower quality, poorly defended leaves. Our results demonstrate significant post-invasion genetic differences in an invasive plant species. Post-introduction adaptation by introduced plants may contribute to their invasive success and make it difficult to predict problem species. [source] Reliability modelling of uninterruptible power supply systems using fault tree analysis methodEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 6 2009Mohd Khairil Rahmat Abstract The aim of this paper is to investigate the reliability parameters estimation method for the uninterruptible power supply (UPS) systems using the Fault Tree Analysis (FTA) technique. FTA is a top,down approach to identify all potential causes leading to system failure. The computation of the system's failure probability is the main goal of this analysis, as this value can be used to calculate other important system reliability parameters such as failure rates, mean time between failures and reliability. In this paper, the FTA method was applied to five different UPS topologies and the results obtained were compared and discussed in detail. By comparing the critical fault path of the system, it was found that the inverter failures contributed most significantly to the system failure. It was also found that the probability of failure of a UPS system can be reduced by the inclusion of bypass supply, given that the failure rate of the events that causing the failure of the bypass supply should be lower compared to the ones for the main utility supply. Finally, to validate the results obtained from this method, comparisons were made to the results from other methods such as the Reliability Block Diagram, Boolean Truth Table, Probability Tree, Monte-Carlo Simulation and Field Data reliability estimation methods. Copyright © 2008 John Wiley & Sons, Ltd. [source] Tree-based characterization of low index circuit configurations without passivity restrictionsINTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS, Issue 2 2008Alfonso J. Encinas Abstract The present paper addresses index characterizations in differential-algebraic models of electrical circuits without the need for passivity assumptions. Positive definiteness conditions on the conductance, capacitance and inductance matrices are replaced by certain algebraic assumptions on the so-called proper trees for augmented node analysis and normal trees for modified node analysis. The current discussion is restricted to index-0 and index-1 systems; for the latter, the analysis is based upon certain matrix factorizations which split the topological information from the electrical features of the devices. Several examples illustrate the scope of our framework. Copyright © 2007 John Wiley & Sons, Ltd. [source] Optimizing Patching-based multicast for video-on-demand in wireless mesh networksINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 9-10 2010Fei Xie Abstract In this work, we study the application of video-on-demand (VoD) in wireless mesh networks (WMN), a next generation edge technology to provide broadband data access in residential, business and even city-wise networks. We adopt a Patching-based multicast technique to better utilize the bandwidth resources in the mesh network. We optimize the Patching-based multicast by addressing two critical problems, namely, the Minimum Cost Multicast Tree (MCMT) problem and the Maximum Benefit Multicast Group (MBMG) problem. The MCMT problem is to find a MCMT in the network. We show that finding such a tree in the WMN can be formulated as a graph theory problem, which is to find the tree with minimum number of non-leaf nodes, and which spans all the nodes in the multicast group. We further prove the problem is NP-hard and propose a fast greedy algorithm to accommodate the real-time feature of the VoD application. We solve the MBMG problem by minimizing the communication of a Patching group in the entire network. A Markov model is proposed to capture the growth of the multicast group in the WMN. Simulation study results validate the proposed solutions of the two problems. Copyright © 2009 John Wiley & Sons, Ltd. [source] A new vision for the field: Introduction to the second special issue on the unified theoryJOURNAL OF CLINICAL PSYCHOLOGY, Issue 1 2005Gregg R. Henriques This is the second of two issues of the Journal of Clinical Psychology focused on the validity and usefulness of a new theoretical vision for the field (Henriques, 2003). The first two contributions from Rand and Ilardi and Geary both enrich the argument that psychology needs to be effectively connected with biology and physics and that the unified theory (via Behavioral Investment Theory) is highly successful in this way. The authors of the subsequent three articles,Shaffer, Quackenbush, and Shealy,show that the Tree of Knowledge System (through the Justification Hypothesis) is deeply commensurate with the dominant paradigms in the social sciences. Thus, the group of authors of these five articles demonstrates the viability of the unified theory both from bottom-up and top-down viewpoints. In the sixth article, the author addresses some important problems that potentially arise with the development of a clearly defined discipline. In the concluding article I address the concerns about the proposal raised by the contributors to the two special issues and articulate how the unified theory lays the foundation for the development of a useful mass movement in psychology. © 2004 Wiley Periodicals, Inc. J Clin Psychol. [source] Toward a consilient science of psychologyJOURNAL OF CLINICAL PSYCHOLOGY, Issue 1 2005Kevin L. Rand From its inception, psychology has been characterized by conceptual fragmentation and slow scientific progress (Henriques, 2004; Meehl, 1978). In contrast, the natural sciences have achieved in recent decades a remarkable degree of consilience,the linking of fact, theory, and method across disciplines (and subdisciplines) and across nested levels of informational complexity (Wilson, 1998). Although such consilience serves as a potent catalyst of scientific discovery, there exists several barriers to the emergence of a consilient science of psychology (e.g., the persistent influence of dualism, longstanding internecine discord, resistance to perceived reductionism, etc.). We discuss the manner in which the development of metatheoretical frameworks (including Henriques' Tree of Knowledge model) may play an important role in addressing such barriers. Likewise, we describe the hybrid interdisciplinary domain of cognitive neuroscience, which provides an empirically testable metatheory and a promising consilient bridge between psychology and the natural sciences. © 2004 Wiley Periodicals, Inc. J Clin Psychol. [source] Defining psychology: What can it do for us?JOURNAL OF CLINICAL PSYCHOLOGY, Issue 12 2004David A.F. Haaga "Psychology," like many abstract terms, is difficult to define precisely. Henriques' (this issue) argument that psychology, though unified and coherent, actually spans two realms,psychological formalism ("the science of mind," this issue) and human psychology ("the science of human behavior at the individual level," this issue),seems likely to improve the clarity of the concept. The strongest contribution of his analysis may be its placing "psychology" in the larger conceptual framework of the Tree of Knowledge taxonomy. © 2004 Wiley Periodicals, Inc. J Clin Psychol. [source] The evidence-based paradox and the question of the Tree of KnowledgeJOURNAL OF EVALUATION IN CLINICAL PRACTICE, Issue 5 2008Amit Saad BMedSc MA(Phil) [source] Vegetative Storage Protein with Trypsin Inhibitor Activity Occurs in Sapindus mukorassi, a Sapindaceae Deciduous TreeJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 4 2009Shi-Biao Liu Abstract A vegetative storage protein (VSP) with trypsin inhibitor activity in a deciduous tree, Sapindus mukorassi, was characterized by means of sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Western-blot, immuno-histochemical localization, light- and electro-microscopy, together with analysis of proteinase inhibitor activity of the purified VSP in vitro. There were two proteins with molecular masses of about 23 and 27 kDa in a relatively high content in the bark tissues of terminal branches of S. mukorassi in leafless periods. The proteins decreased markedly during young shoot development, indicating their role in seasonal nitrogen storage. Immuno-histochemical localization with the polyclonal antibodies raised against the 23 kDa protein demonstrated that the 23 kDa protein was the major component of protein inclusions in protein-storing cells. The protein inclusions were identified by protein-specific staining and should correspond to the electron-dense materials in different forms in the vacuoles of phloem parenchyma cells and phloem ray parenchyma cells under an electron microscope. So, the 23 kDa protein was a typical VSP in S. mukorassi. The 23 and 27 kDa proteins shared no immuno-relatedness, whereas the 23 kDa protein was immuno-related with the 22 kDa VSP in lychee and possessed trypsin inhibitor activity. The 23 kDa protein may confer dual functions: nitrogen storage and defense. [source] Fluctuation of Vegetative Storage Proteins in the Seedlings of Swietenia macrophylla, Analogous to the Seasonal Changes of Those in the Shoot of the Adult TreeJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 3 2007Ya-Qin Han Abstract In order to identify appropriate plant materials for studying the gene expression and biological function of vegetative storage proteins (VSPs) in woody plants, the VSPs in the seedlings of Swietenia macrophylla King were investigated by using light microscopy, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western-blotting. The seed of S. macrophylla was rich in storage proteins that accumulated in the vacuoles of cotyledon parenchyma cells in appearance of compact spherical grains. The growth and development of S. macrophylla seedlings were characterized by an obvious growth rhythm. The storage proteins in seeds disappeared during seedling growth while VSPs appeared in the stem 2 weeks after seedling leaves matured. Thereafter, the VSPs in the seedling stem almost exhausted during new shoot growth, and when the leaves of new shoot just matured, both the stem beneath the new shoot of seedlings and the stem of new shoot started to accumulate VSPs. Nitrogen application dramatically increased the level of VSPs, but had little influence on the dynamics of VSP consumption and accumulation in seedling stem. Together with these data, the fluctuation of VSPs in seedlings was very similar to that in the branches of the adult trees. In addition, seedlings are easy to be treated due to their small size. Our results suggested that S. macrophylla seedlings were suitable for investigating the biological roles of VSPs and the mechanism of nitrogen storage in trees. [source] Natterer's bats prefer foraging in broad-leaved woodlands and river corridorsJOURNAL OF ZOOLOGY, Issue 3 2008P. G. Smith Abstract We studied habitat selection by radio tracking Natterer's bats Myotis nattereri foraging in a grassland,woodland landscape. We tested the hypothesis that selection of foraging habitat is random at two levels: firstly, the selection of individual foraging ranges and secondly, the choice of foraging habitats made by individuals within these foraging ranges. Habitat selection was random at neither level. When selecting foraging ranges, bats maximized the area of semi-natural broad-leaved woodland and improved grassland and minimized that of dense coniferous plantations. During foraging, semi-natural broad-leaved woodland and river corridors were preferred, while dense coniferous plantations were avoided. Within individual foraging ranges, the intensity of foraging activity over river corridor habitat and semi-natural broad-leaved woodland was 8.2 and 3.8 times higher, respectively, than that over improved grassland. For successful management of Natterer's bat populations, semi-natural broad-leaved woodland should be retained. Clear felling of large blocks of native broad-leaved woodland should be avoided and conifers should not be used for reforestation. Tree cover along river banks should be encouraged and protected. [source] CNS Permeability of Drugs Predicted by a Decision TreeMOLECULAR INFORMATICS, Issue 4 2006Claudia Andres Abstract To predict the ability of drug-like molecules to penetrate the Central Nervous System (CNS), a decision tree was generated. This algorithm was designed to make a straight forward yes/no decision about the permeability of the blood-brain barrier for a given substance, based on the numerical criteria of a large variety of molecular descriptors. The decision tree achieved a prediction accuracy of 96% for the 186 compounds of the training set and 84% for the test set comprising 38 molecules. We found that CNS+drugs are predicted with a higher accuracy (>94%) than CNS- substances (>89%). [source] The Push Tree problemNETWORKS: AN INTERNATIONAL JOURNAL, Issue 4 2004Frédéric Havet Abstract In this article, we introduce the Push Tree problem, which exposes the tradeoffs between the use of push and pull mechanisms in information distribution systems. One of the interesting features of the Push Tree problem is that it provides a smooth transition between the minimum Steiner Tree and the Shortest Path problems. We present initial complexity results and analyze heuristics. Moreover, we discuss what lessons can be learned from the static and deterministic Push Tree problem for more realistic scenarios characterized by high uncertainty and changing information request and update patterns. © 2004 Wiley Periodicals, Inc. NETWORKS, Vol. 44(4), 281,291 2004 [source] The Living Tree of Nursing TheoriesNURSING FORUM, Issue 3 2003Charlotte Tourville RN TOPIC Three behavioral theories have been used to develop major nursing theories: interactive, systems, and developmental. PURPOSE To provide a symbolic image as a framework for nurses to visualize the multitude of nursing theories starting with the first nurse theorist, Florence Nightingale. SOURCES Published research articles, authors' experience, educational classes and workshops. CONCLUSIONS The Living Tree helps organize various nursing theories so a nurse can apply the theories to practice. [source] Pattern of Flower and Fruit Production in Stryphnodendron adstringens, an Andromonoecious Legume Tree of Central BrazilPLANT BIOLOGY, Issue 6 2003P. L. Ortiz Abstract: Patterns of flower and fruit production in racemes of Stryphnodendron adstringens, an andromonoecious Brazilian savanna tree species, were studied in two natural areas near Uberlândia-MG. Racemes were divided in three parts: apex, centre, and base. Number of flowers, gender, and nectar and pollen production were analyzed for each section. Frequency of visitors to each part of the inflorescence was also quantified. Hand self- and cross-pollinations were performed in complete racemes and fruit set used to determine breeding system. The racemes produced a mean of 329 flowers, more densely packed in the central portion. Hermaphrodite and male flowers occur along the inflorescence but hermaphrodite flowers are more common in the centre. Fruit set was markedly low but does not seem to be limited by pollination service, since free open-pollinated racemes and hand cross-pollinated ones do not differ in fruit production rates. Fruits resulted mostly from cross-pollinated flowers and fruit production was biased to the central portion of the raceme. Nectar yield was higher in the central portion of the raceme and visitors arrived more commonly on this portion of the inflorescence. However, most flowers did not produce nectar. The pattern of fruit production seems to be a consequence of the hermaphrodite flower distribution in the raceme and it is not constrained by pollen flow or flower opening sequence. [source] The functional correlates of jaw-muscle fiber architecture in tree-gouging and nongouging callitrichid monkeysAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 3 2009Andrea B. Taylor Abstract Common (Callithrix jacchus) and pygmy (Cebuella pygmaea) marmosets and cotton-top tamarins (Saguinus oedipus) share broadly similar diets of fruits, insects, and tree exudates. Marmosets, however, differ from tamarins in actively gouging trees with their anterior dentition to elicit tree exudates flow. Tree gouging in common marmosets involves the generation of relatively wide jaw gapes, but not necessarily relatively large bite forces. We compared fiber architecture of the masseter and temporalis muscles in C. jacchus (N = 18), C. pygmaea (N = 5), and S. oedipus (N = 13). We tested the hypothesis that tree-gouging marmosets would exhibit relatively longer fibers and other architectural variables that facilitate muscle stretch. As an architectural trade-off between maximizing muscle excursion/contraction velocity and muscle force, we also tested the hypothesis that marmosets would exhibit relatively less pinnate fibers, smaller physiologic cross-sectional areas (PCSA), and lower priority indices (I) for force. As predicted, marmosets display relatively longer-fibered muscles, a higher ratio of fiber length to muscle mass, and a relatively greater potential excursion of the distal tendon attachments, all of which favor muscle stretch. Marmosets further display relatively smaller PCSAs and other features that reflect a reduced capacity for force generation. The longer fibers and attendant higher contraction velocities likely facilitate the production of relatively wide jaw gapes and the capacity to generate more power from their jaw muscles during gouging. The observed functional trade-off between muscle excursion/contraction velocity and muscle force suggests that primate jaw-muscle architecture reflects evolutionary changes related to jaw movements as one of a number of functional demands imposed on the masticatory apparatus. Am J Phys Anthropol, 2009. © 2009 Wiley-Liss, Inc. [source] Though the Fig Tree Does not Blossom: Toward a Responsible Theology of Christian Hope , By Ellen Ott MarshallRELIGIOUS STUDIES REVIEW, Issue 2 2007Charlene Burns No abstract is available for this article. [source] Discrete-time survival treesTHE CANADIAN JOURNAL OF STATISTICS, Issue 1 2009Imad Bou-hamad MSC 2000: Primary 62N99; secondary 62G08 Abstract Tree-based methods are frequently used in studies with censored survival time. Their structure and ease of interpretability make them useful to identify prognostic factors and to predict conditional survival probabilities given an individual's covariates. The existing methods are tailor-made to deal with a survival time variable that is measured continuously. However, survival variables measured on a discrete scale are often encountered in practice. The authors propose a new tree construction method specifically adapted to such discrete-time survival variables. The splitting procedure can be seen as an extension, to the case of right-censored data, of the entropy criterion for a categorical outcome. The selection of the final tree is made through a pruning algorithm combined with a bootstrap correction. The authors also present a simple way of potentially improving the predictive performance of a single tree through bagging. A simulation study shows that single trees and bagged-trees perform well compared to a parametric model. A real data example investigating the usefulness of personality dimensions in predicting early onset of cigarette smoking is presented. The Canadian Journal of Statistics 37: 17-32; 2009 © 2009 Statistical Society of Canada Arbres de survie à temps discret Les méthodes d'arbres sont fréquemment utilisées lors d'études impliquant des données censurées. La structure d'un arbre ainsi que la facilité avec laquelle il peut être interprété font de lui un outil utile afin d'identifier des facteurs de pronostique et de prédire les probabilités de survie conditionnelles d'un individu étant donné ses covariables. Les méthodes existantes ont été développées pour traiter une variable temporelle continue. En pratique, il arrive fréquemment que la variable mesurant le temps de survie soit mesurée selon une échelle discrète. Les auteurs proposent une nouvelle méthode pour construire un arbre qui est spécialement adaptée aux variables de survie à temps discret. Le critère de division peut être vu comme étant une extension, au cas de censure à droite, du critère d'entropie pour une variable catégorielle. La sélection de l'arbre final est basée sur une méthode d'élagage combinée avec une correction bootstrap. Les auteurs présentent également une méthode simple pour améliorer, potentiellement, la performance d'un seul arbre avec le bagging. Une étude par simulation montre que des arbres seuls et des arbres "baggés" performent bien comparativement à un modèle paramétrique. Les auteurs présentent aussi une illustration de la nouvelle méthode avec des vraies données qui investiguent l'utilité d'utiliser des dimensions de la personnalité afin de prévoir le début de l'utilisation de la cigarette. La revue canadienne de statistique 37: 17-32; 2009 © 2009 Société statistique du Canada [source] Tree and forest characteristics influence sleeping site choice by golden lion tamarinsAMERICAN JOURNAL OF PRIMATOLOGY, Issue 9 2007Sarah J. Hankerson Abstract Lion tamarin monkeys are among a small number of primates that repeatedly use a few tree holes for the majority of their sleeping sites. To better understand why lion tamarins rely on tree holes as sleeping sites, we compared the physical characteristics of frequently used sleeping sites, infrequently used sleeping sites, and randomly selected forest locations at multiple spatial scales. From 1990 to 2004, we recorded 5,235 occurrences of sleeping site use by 10 groups of golden lion tamarins (Leontopithecus rosalia) in Poço das Antas Reserve, Rio de Janeiro State, Brazil. Of those, 63.6% were tree holes. Bamboo accounted for an additional 17.5% of observations. Frequently used tree holes were more likely to be found in living trees and their entrances were at lower canopy heights than infrequently used tree holes. We also found that frequently used sleeping sites, in comparison to random sites, were more likely to be found on hillsides, be close to other large trees, have a lower percent of canopy cover, and have larger diameter at breast height. Topography and small-scale variables were more accurate than were habitat-level classifications in predicting frequently used sleeping sites. There are ample tree holes available to these lion tamarins but few preferred sites to which they return repeatedly. The lion tamarins find these preferred sites wherever they occur including in mature forest and in relics of older forest embedded in a matrix of secondary forest. Am. J. Primatol. 69:976,988, 2007. © 2007 Wiley-Liss, Inc. [source] Tree of Souls: The Mythology of Judaism.THE JOURNAL OF POPULAR CULTURE, Issue 4 2006Howard Schwartz No abstract is available for this article. [source] Evaluating the Ability of Tree-Based Methods and Logistic Regression for the Detection of SNP-SNP InteractionANNALS OF HUMAN GENETICS, Issue 3 2009M. García-Magariños Summary Most common human diseases are likely to have complex etiologies. Methods of analysis that allow for the phenomenon of epistasis are of growing interest in the genetic dissection of complex diseases. By allowing for epistatic interactions between potential disease loci, we may succeed in identifying genetic variants that might otherwise have remained undetected. Here we aimed to analyze the ability of logistic regression (LR) and two tree-based supervised learning methods, classification and regression trees (CART) and random forest (RF), to detect epistasis. Multifactor-dimensionality reduction (MDR) was also used for comparison. Our approach involves first the simulation of datasets of autosomal biallelic unphased and unlinked single nucleotide polymorphisms (SNPs), each containing a two-loci interaction (causal SNPs) and 98 ,noise' SNPs. We modelled interactions under different scenarios of sample size, missing data, minor allele frequencies (MAF) and several penetrance models: three involving both (indistinguishable) marginal effects and interaction, and two simulating pure interaction effects. In total, we have simulated 99 different scenarios. Although CART, RF, and LR yield similar results in terms of detection of true association, CART and RF perform better than LR with respect to classification error. MAF, penetrance model, and sample size are greater determining factors than percentage of missing data in the ability of the different techniques to detect true association. In pure interaction models, only RF detects association. In conclusion, tree-based methods and LR are important statistical tools for the detection of unknown interactions among true risk-associated SNPs with marginal effects and in the presence of a significant number of noise SNPs. In pure interaction models, RF performs reasonably well in the presence of large sample sizes and low percentages of missing data. However, when the study design is suboptimal (unfavourable to detect interaction in terms of e.g. sample size and MAF) there is a high chance of detecting false, spurious associations. [source] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||