Matrix dimensions bias demographic inferences: implications for comparative plant demography

While the wealth of projection matrices in plant demography permits comparative studies, variation in matrix dimensions complicates interspecific comparisons. Collapsing matrices to a common dimension may facilitate such comparisons but may also bias the inferred demographic parameters. Here we examine how matrix dimension affects inferred demographic elasticities and how different collapsing criteria perform. We analyzed 13×13 matrices representing nine plant species, collapsing these matrices (i) into even 7×7, 5×5, 4×4, and 3×3 matrices and (ii) into 5×5 matrices using different criteria. Stasis and fecundity elasticities increased when matrix dimension was reduced, whereas those of progression and retrogression decreased. We suggest a collapsing criterion that minimizes dissimilarities between the original- and collapsed-matrix elasticities and apply it to 66 plant species to study how life span and growth form influence the relationship between matrix dimension and elasticities. Our analysis demonstrates that (i) projection matrix dimension has significant effects on inferred demographic parameters, (ii) there are better-performing methods than previously suggested for standardizing matrix dimension, and (iii) herbaceous perennial projection matrices are particularly sensitive to changes in matrix dimensionality. For comparative demographic studies, we recommend normalizing matrices to a common dimension by collapsing higher classes and leaving the first few classes unaltered

Electric Switching of the Charge-Density-Wave and Normal Metallic Phases in Tantalum Disulfide Thin-Film Devices

We report on switching among three charge-density-wave phases - commensurate, nearly commensurate, incommensurate - and the high-temperature normal metallic phase in thin-film 1T-TaS2 devices induced by application of an in-plane electric field. The electric switching among all phases has been achieved over a wide temperature range, from 77 K to 400 K. The low-frequency electronic noise spectroscopy has been used as an effective tool for monitoring the transitions, particularly the switching from the incommensurate charge-density-wave phase to the normal metal phase. The noise spectral density exhibits sharp increases at the phase transition points, which correspond to the step-like changes in resistivity. Assignment of the phases is consistent with low-field resistivity measurements over the temperature range from 77 K to 600 K. Analysis of the experimental data and calculations of heat dissipation suggest that Joule heating plays a dominant role in the electric-field induced transitions in the tested 1T-TaS2 devices on Si/SiO2 substrates. The possibility of electrical switching among four different phases of 1T-TaS2 is a promising step toward nanoscale device applications. The results also demonstrate the potential of noise spectroscopy for investigating and identifying phase transitions in materials.Comment: 32 pages, 7 figure

Proximal business intelligence on the semantic web

This is the post-print version of this article. The official version can be accessed from the link below - Copyright @ 2010 Springer.Ubiquitous information systems (UBIS) extend current Information System thinking to explicitly differentiate technology between devices and software components with relation to people and process. Adapting business data and management information to support specific user actions in context is an ongoing topic of research. Approaches typically focus on providing mechanisms to improve specific information access and transcoding but not on how the information can be accessed in a mobile, dynamic and ad-hoc manner. Although web ontology has been used to facilitate the loading of data warehouses, less research has been carried out on ontology based mobile reporting. This paper explores how business data can be modeled and accessed using the web ontology language and then re-used to provide the invisibility of pervasive access; uncovering more effective architectural models for adaptive information system strategies of this type. This exploratory work is guided in part by a vision of business intelligence that is highly distributed, mobile and fluid, adapting to sensory understanding of the underlying environment in which it operates. A proof-of concept mobile and ambient data access architecture is developed in order to further test the viability of such an approach. The paper concludes with an ontology engineering framework for systems of this type – named UBIS-ONTO

Empirical Evidence of the Metacognitive Model of Rumination and Depression in Clinical and Nonclinical Samples: A Systematic Review and Meta-Analysis

Rumination is considered a cognitive vulnerability factor in the development and maintenance of depression. The metacognitive model of rumination and depression suggests that the development of rumination and its association with depression partly depends on metacognitive beliefs. Two metacognitive beliefs about rumination have been identified: positive beliefs about its utility and negative beliefs about the uncontrollability and its negative social consequences. We conducted a systematic review and meta-analysis aimed: (1) to analyze the associations between metacognitive beliefs and rumination and depression; (2) to test the metacognitive model, using a Two-Stage Structural Equation Modeling approach (TSSEM). Literature search retrieved 41 studies. These 41 studies (N = 10,607) were included in the narrative synthesis and meta-analysis, and 16 studies (N = 4477) were comprised for the TSSEM. Results indicated metacognitive beliefs are associated with rumination and depression. Measures on metacognitive beliefs about rumination indicated that positive beliefs showed moderate associations with rumination (r = 0.50), and low with depression (r = 0.27); whereas negative beliefs showed moderate associations with both rumination (r = 0.46) and depression (r = 0.49). These results were consistent across studies using different instruments to measure metacognitive beliefs, and in both clinical and nonclinical samples. Moreover, results of the TSSEM analyses showed that the metacognitive model had a good fit. In sum, our results are in line with the metacognitive model of rumination and depression, highlighting that metacognitive beliefs are relevant factors to understand why people ruminate and get depressed. Future directions and clinical implications are discussed

Ajuste de algoritmo de identificación visual para uso en aplicaciones de navegación autónoma de robots

This article describes the adjustment of an algorithm developed by the research group for the visual identification of geometric shapes in real time on embedded systems. This algorithm was proposed inside the group, and in spite of its correct theoretical support, it presented problems when working in real applications. The purpose of the adjustment was to increase the robustness against different levels of lighting and implement it on a real robot for performance tests in the laboratory. The tasks programmed in the robot include the identification of landmarks in the environment for the activation of navigation policies. From the results achieved, a better behavior of the algorithm is observed, making its use very promising.Este artículo describe el ajuste de un algoritmo desarrollado por el grupo de investigación para la identificación visual de formas geométricas en tiempo real sobre sistemas embebidos. Dicho algoritmo fue propuesto al interior del grupo, y pese a su correcto soporte teórico, presentó problemas al funcionar en aplicaciones reales. En el ajuste realizado se buscó incrementar la robustez frente a diferentes niveles de iluminación, e implementarlo sobre un robot real para pruebas de desempeño en laboratorio. Las tareas programadas en el robot incluyen la identificación de \textit{landmarks} en el ambiente para la activación de políticas de navegación. A partir de los resultados alcanzados se observa un mejor comportamiento del algoritmo haciendo muy promisoria su utilización

White-tailed deer (Odocoileus virginianus) positively affect the growth of mature northern red oak (Quercus rubra) trees

Understanding and predicting the effects of deer (Cervidae) on forest ecosystems present significant challenges in ecosystem ecology. Deer herbivory can cause large changes in the biomass and species composition of forest understory plant communities, including early life-cycle trees (i.e., seedlings and saplings). Such changes can impact juvenile to adult transitions and the future age structure and species composition of mature forests. Changes to understory vegetation also impact flow of energy and nutrients in forest ecosystems. Studies examining the influence of deer on mature trees, however, are rare and rely on extrapolating effects from early life cycle stages of trees. We tested the hypothesis that the absence of deer would result in an increase in the growth rate of mature trees by examining the impact of white-tailed deer (Odocoileus virginianus) on mature canopy trees. We examined incremental growth in individuals of Quercus rubra, an important component of temperate deciduous forests in North America, inside and outside 16-year deer exclosures in eastern U.S. deciduous forests. We found that adult trees inside exclosures grew less than those directly exposed to deer. Our findings highlight the indirect effects of white-tailed deer on the growth of adult individuals of Q. rubra in a way opposite of what would be expected from previous studies based on immature or understory tree populations. We suggest the increased growth of adult trees in the presence of deer may be explained by increased nutrient inputs through deer fecal and urine deposits and the alteration of the competitive environment belowground through the reduction of understory vegetation by browsing. Underscoring the ecological and demographic importance of adult trees in forest ecosystems, results from this study suggest the direct and indirect effects of deer on mature trees should not be overlooked

Tree growth and treeline responses to temperature: Different questions and concepts

[No abstract available

Dioxin Toxicity In Vivo Results from an Increase in the Dioxin-Independent Transcriptional Activity of the Aryl Hydrocarbon Receptor

The Aryl hydrocarbon receptor (Ahr) is the nuclear receptor mediating the toxicity of dioxins -widespread and persistent pollutants whose toxic effects include tumor promotion, teratogenesis, wasting syndrome and chloracne. Elimination of Ahr in mice eliminates dioxin toxicity but also produces adverse effects, some seemingly unrelated to dioxin. Thus the relationship between the toxic and dioxin-independent functions of Ahr is not clear, which hampers understanding and treatment of dioxin toxicity. Here we develop a Drosophila model to show that dioxin actually increases the in vivo dioxin-independent activity of Ahr. This hyperactivation resembles the effects caused by an increase in the amount of its dimerisation partner Ahr nuclear translocator (Arnt) and entails an increased transcriptional potency of Ahr, in addition to the previously described effect on nuclear translocation. Thus the two apparently different functions of Ahr, dioxin-mediated and dioxin-independent, are in fact two different levels (hyperactivated and basal, respectively) of a single function

Influencia de ciclos alternativos alimentación-ayuno sobre los principales enzimas del metabolismo renal de carbohidratos

In order to explain the changes previously described by us in the renal carbohydrate metabolism during different starved-feed cycles (1), the effects of this nutritional situation on the most important enzymes in volved in the glycolytic and gluconeogenic processes have been studied. In general, during the feed-state all the glycolytic enzymes increased its activities whereas a decrease was found in the gluconeogenic ones. Opposite effects were obtanined during starvation. Several mechanism of enzymatic regulation are shown throughout the development of these nutritional conditions.Con objeto de explicar molecularmente los cambios descritos en el metabolismo renal de carbohidratos (1) se han estudiado los efectos que diferentes ciclos de alimentación y ayuno presentan sobre los principales enzimas implicados en los procesos glucolítico y gluconeogénico. En general durante el período de alimentación se activan los enzimas glucolíticos y se inhiben los gluconeogénicos .. Efectos opuestos se observan durante los períodos de ayuno. Estos resultados permiten concluir que la corteza renal es capaz de adaptar continuamente los mecanismos enzimáticos necesarios para ajustar el destino de macronutrientes tanto de procedencia exógena como endógena