Genetic Divergence of Toxoplasma gondii Strains Associated with Ocular Toxoplasmosis, Brazil

Brazilian strains of T. gondii differ from lineages in North America and Europe; these differences may underlie severe ocular disease

How and when perceptions of top management bottom-line mentality inhibit supervisors’ servant leadership behavior

Extending existing bottom-line mentality (BLM) perspectives, we provide a new theoretical account of how supervisors’ perceptions of top management BLM influence supervisors’ servant leadership (SL) behavior. Using role theory, we propose that these perceptions inhibit supervisors’ SL behavior by reducing their SL role conceptualization or the extent to which supervisors consider SL part of their work responsibility. Further, given that the process underlying the relationship between perceived top management BLM and supervisor SL behavior may be explained by social learning theory and human adaptive capacity perspectives, we examine the incremental validity of supervisor SL role conceptualization versus supervisor BLM and empathy as mediating mechanisms. We also propose low perspective-taking among supervisors as a boundary condition that exacerbates the negative effect of perceived top management BLM on SL role conceptualization, which then results in less servant leader behavior. Data from two multi-wave field studies in China and the United Kingdom provided some support for our hypotheses. Across unique cultural contexts, our findings highlight the value of a role theory perspective in understanding perceptions of top management BLM. We discuss critical theoretical and practical implications of these findings and avenues for subsequent research

Gauge fixing and the Hamiltonian for cylindrical spacetimes

We introduce a complete gauge fixing for cylindrical spacetimes in vacuo that, in principle, do not contain the axis of symmetry. By cylindrically symmetric we understand spacetimes that possess two commuting spacelike Killing vectors, one of them rotational and the other one translational. The result of our gauge fixing is a constraint-free model whose phase space has four field-like degrees of freedom and that depends on three constant parameters. Two of these constants determine the global angular momentum and the linear momentum in the axis direction, while the third parameter is related with the behavior of the metric around the axis. We derive the explicit expression of the metric in terms of the physical degrees of freedom, calculate the reduced equations of motion and obtain the Hamiltonian that generates the reduced dynamics. We also find upper and lower bounds for this reduced Hamiltonian that provides the energy per unit length contained in the system. In addition, we show that the reduced formalism constructed is well defined and consistent at least when the linear momentum in the axis direction vanishes. Furthermore, in that case we prove that there exists an infinite number of solutions in which all physical fields are constant both in the surroundings of the axis and at sufficiently large distances from it. If the global angular momentum is different from zero, the isometry group of these solutions is generally not orthogonally transitive. Such solutions generalize the metric of a spinning cosmic string in the region where no closed timelike curves are present.Comment: 12 pages, accepted for publication in Physical Review

Aboveground biomass of a "campina" ecosystem in Roraima, Northern of Brazilian Amazonia

The aboveground biomass of a "campina" ecosystem was estimated in Roraima, in the northern portion of Brazilian Amazonia. The biomass was determined from a phytosociological inventory (1 ha) and distributed between two categories: (1) grassy-woody, composed of "herbs+lichens" (Poaceae, Cyperaceae, Eriocaulaceae, Cladonia spp), Bromeliaceae, seedlings, fine and coarse litter and, (2) woody, composed of trees and bushes. The grassy-woody category was estimated by the direct method (cutting and weighing) in 10 1-m² plots, taking advantage of transects of the inventory. The category woody was estimated by the indirect method cutting 98 individuals of different species and diameters. A model was generated to express the relationship among total dry above-ground biomass (kg), base circumference (cm) and total height (m) for the individuals in this category. The equation was applied to the 3,966 ind.ha-1 observed in the inventory. The total biomass was estimated at 15.91 t.ha-1, of which 2.20 ± 0.23 t.ha-1 (13.8%) was in the grassy-woody category and 13.70 ± 7.13 t.ha-1 (86.2%) in woody category. The tree species with the highest biomass was Humiria balsamifera (Aubl.) St. Hill. (8.43 t.ha-1), followed by Pagamea guianensis Aubl. (1.14 t.ha-1). These results are important for refining the calculations of greenhouse-gas emissions from burning and decomposition of above-ground biomass in "campina" ecosystems in the Amazon region.Foi estimada a biomassa (viva + morta) acima do solo de um ecossistema de "campina" localizado em Roraima, norte da Amazônia brasileira. A biomassa foi determinada a partir de um inventário fitossociológico (1 ha amostral) e distribuída em dois estratos(1) gramíneo-lenhoso, composto de "ervas + liquens" (Poaceae, Cyperaceae, Eriocaulaceae, Cladonia spp), Bromeliaceae, plântulas, "litter" fino e grosso e, (2) arbóreo-arbustivo, composto por árvores e arbustos. O estrato gramíneo-lenhoso foi estimado pelo método direto (corte e pesagem) através de 10 quadras de 1m², aproveitando os transectos do inventário. O estrato arbóreo-arbustivo foi estimado pelo método indireto com o corte de 98 indivíduos de diferentes espécies e diâmetros. Foi gerado um modelo para expressar a relação entre a biomassa seca total (kg), a circunferência de base (cm) e a altura total (m) para os indivíduos deste estrato. A equação foi aplicada nos 3.966 indivíduos.ha-1 observados no inventário. A biomassa total foi estimada em 15,91 t.ha-1, sendo 2,20 ± 0,23 t.ha-1 (13,8%) do estrato gramíneo-lenhoso e 13,70 ± 7,13 t.ha-1 (86,2%) do arbóreo-arbustivo. A espécie arbórea de maior biomassa foi Humiria balsamifera (Aubl.) St. Hill. (8,43 t.ha-1), seguida de Pagamea guianensis Aubl. (1,14 t.ha-1). Estes resultados são importantes para refinar os cálculos de emissão de gases do efeito estufa pela queima e decomposição da biomassa acima do solo em ecossistemas de campinas na Amazônia

Closing in on the properties of antihydrogen

Conference review, with some speculation in the closing section

TRY plant trait database – enhanced coverage and open access

Plant traits—the morphological, anatomical, physiological, biochemical and phenological characteristics of plants—determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait‐based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits—almost complete coverage for ‘plant growth form’. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait–environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives