Projection of diametric distribution and carbon stock of a managed forest in Manaus/AM.

Projeção da distribuição diamétrica e do estoque de carbono de floresta manejada na Amazônia. A prognose do crescimento de florestas é importante para o manejo florestal, para o planejamento dos ciclos de corte subsequentes e para mostrar as tendências que a floresta apresentará no futuro. Este trabalho avaliou a utilização de um modelo estocástico - a Cadeia de Markov - na projeção da distribuição diamétrica e do estoque de carbono de uma floresta submetida à exploração seletiva experimental em Manaus/AM

Previous exercise training increases levels of PPAR-α in long-term post-myocardial infarction in rats, which is correlated with better inflammatory response

OBJECTIVE: Exercise is a protective factor for cardiovascular morbidity and mortality, with unclear mechanisms. Changing the myocardial metabolism causes harmful consequences for heart function and exercise contributes to metabolic adjustment modulation. Peroxisome proliferator-activated receptors (PPARs) are also myocardium metabolism regulators capable of decreasing the inflammatory response. We hypothesized that PPAR-α is involved in the beneficial effects of previous exercise on myocardial infarction (MI) and cardiac function, changing the expression of metabolic and inflammatory response regulators and reducing myocardial apoptosis, which partially explains the better outcome. METHODS AND RESULTS: Exercised rats engaged in swimming sessions for 60 min/day, 5 days/week, for 8 weeks. Both the exercised rats and sedentary rats were randomized to MI surgery and followed for 1 week (EI1 or SI1) or 4 weeks (EI4 or SI4) of healing or to sham groups. Echocardiography was employed to detect left ventricular function and the infarct size. Additionally, the TUNEL technique was used to assess apoptosis and immunohistochemistry was used to quantitatively analyze the PPAR-α, TNF-α and NF-κB antigens in the infarcted and non-infarcted myocardium. MI-related mortality was higher in SI4 than in EI4 (25% vs 12%), without a difference in MI size. SI4 exhibited a lower shortening fraction than EI4 did (24% vs 35%) and a higher apoptosis/area rate (3.97±0.61 vs 1.90±1.82) in infarcted areas (both p=0.001). Immunohistochemistry also revealed higher TNF-α levels in SI1 than in EI1 (9.59 vs 4.09,

On Non-Linear Actions for Massive Gravity

In this work we present a systematic construction of the potentially ghost-free non-linear massive gravity actions. The most general action can be regarded as a 2-parameter deformation of a minimal massive action. Further extensions vanish in 4 dimensions. The general mass term is constructed in terms of a "deformed" determinant from which this property can clearly be seen. In addition, our formulation identifies non-dynamical terms that appear in previous constructions and which do not contribute to the equations of motion. We elaborate on the formal structure of these theories as well as some of their implications.Comment: v3: 22 pages, minor comments added, version to appear in JHE

Global phase time and path integral for the Kantowski--Sachs anisotropic univers

The action functional of the anisotropic Kantowski--Sachs cosmological model is turned into that of an ordinary gauge system. Then a global phase time is identified for the model by imposing canonical gauge conditions, and the quantum transition amplitude is obtained by means of the usual path integral procedure of Fadeev and Popov.Comment: 11 page

Dinâmica e estoque de carbono em floresta primária na região de Manaus/AM.

Este trabalho analisou dados de três inventários florestais realizados na área da Floresta Experimental, pertencente à Embrapa Amazônia Ocidental e localizada no km 54 da BR-174, em Manaus/AM. O objetivo foi estudar a dinâmica da floresta - taxas de incremento, recrutamento e mortalidade - além do estoque de carbono, em uma área de floresta primária, sem qualquer tipo de intervenção

Quantum Aspects of Massive Gravity II: Non-Pauli-Fierz Theory

We investigate the non-Pauli-Fierz(nPF) theory, a linearized massive gravity with a generic graviton mass term, which has been ignored due to a ghost in its spectrum and the resultant loss of unitarity. We first show that it is possible to use the Lee-Wick mechanism, a unitarization through the decay of a ghost, in order to handle the sixth mode ghost of nPF, and then check for the quantum consistency. Once proven to be consistent, nPF could become a viable candidate for a large distance modification of gravity, because it naturally solves the intrinsic problems that most dark energy/modified gravity models suffer from: It smoothly converges to general relativity at short distances, and the small graviton mass necessary to modify gravity at large scales can be stable under the radiative corrections from the minimal gravity-to-matter coupling.Comment: 1+16pp, accepted for JHE

Height-diameter allometry of tropical forest trees

Tropical tree height-diameter (H:D) relationships may vary by forest type and region making large-scale estimates of above-ground biomass subject to bias if they ignore these differences in stem allometry. We have therefore developed a new global tropical forest database consisting of 39 955 concurrent H and D measurements encompassing 283 sites in 22 tropical countries. Utilising this database, our objectives were: 1. to determine if H:D relationships differ by geographic region and forest type (wet to dry forests, including zones of tension where forest and savanna overlap). 2. to ascertain if the H:D relationship is modulated by climate and/or forest structural characteristics (e.g. stand-level basal area, A). 3. to develop H:D allometric equations and evaluate biases to reduce error in future local-to-global estimates of tropical forest biomass. Annual precipitation coefficient of variation (PV), dry season length (SD), and mean annual air temperature (TA) emerged as key drivers of variation in H:D relationships at the pantropical and region scales. Vegetation structure also played a role with trees in forests of a high A being, on average, taller at any given D. After the effects of environment and forest structure are taken into account, two main regional groups can be identified. Forests in Asia, Africa and the Guyana Shield all have, on average, similar H:D relationships, but with trees in the forests of much of the Amazon Basin and tropical Australia typically being shorter at any given D than their counterparts elsewhere. The region-environment-structure model with the lowest Akaike\u27s information criterion and lowest deviation estimated stand-level H across all plots to within amedian −2.7 to 0.9% of the true value. Some of the plot-to-plot variability in H:D relationships not accounted for by this model could be attributed to variations in soil physical conditions. Other things being equal, trees tend to be more slender in the absence of soil physical constraints, especially at smaller D. Pantropical and continental-level models provided less robust estimates of H, especially when the roles of climate and stand structure in modulating H:D allometry were not simultaneously taken into account

Composição florística e estrutura da regeneração natural de árvores após a exploração florestal na Floresta Estadual do Antimary - Acre, Brasil.

As florestas dominadas por bambu no sudoeste da Amazônia cobrem uma área de aproximadamente 161.500 km², distribuídas nos Estados do Acre, do Amazonas e uma parte adjacente da Amazônia peruana. As Florestas com bambu são um bom exemplo de ecossistemas que requerem maior foco e considerações especiais de manejo florestal. O presente estudo teve como objetivo verificar a regeneração natural de espécies arbóreas em uma área de Floresta Aberta com Bambu no sudoeste da Amazônia brasileira após a exploração florestal

Aplicação do modelo de vegetação dinâmica IBIS às condições de floresta de terra firme na região central da Amazônia.

É fundamental para os Modelos de Vegetação Dinâmica Global (DVGM na sigla em inglês) representar corretamente o ciclo diário, as variações sazonais e interanuais das trocas de massa e energia entre o ecossistema e a atmosfera, a hidrologia do solo, a fenologia das plantas e a evolução do estoque de carbono do ecossistema. Este estudo dedica-se a validação e calibração do DVGM IBIS (Integrated Biosphere Simulator) para um ecossistema de floresta tropical úmida de terra firme, localizada na Reserva Biológica do Cuieiras do INPA. Foram utilizados nove anos de dados meteorológicos da torre de fluxo K34, como também dados de diâmetro de árvores, medidas de sonda de nêutrons, de liteira fina e foi realizado um ajuste nos parâmetros físicos do solo do modelo. Os resultados indicam que o modelo representa bem o balanço hídrico, assim como o saldo de radiação e o fluxo de calor latente, porém não representa tão bem os fluxos de calor sensível e de CO2, o índice de área foliar (LAI) e os estoques de liteira fina e biomassa. Os resultados mostram a necessidade de definir um tipo funcional de planta específico para representar a floresta tropical úmida de terra firme da Amazônia e a inclusão de uma subrotina de eventos severos

Local Unit Invariance, Back-Reacting Tractors and the Cosmological Constant Problem

When physics is expressed in a way that is independent of local choices of unit systems, Riemannian geometry is replaced by conformal geometry. Moreover masses become geometric, appearing as Weyl weights of tractors (conformal multiplets of fields necessary to keep local unit invariance manifest). The relationship between these weights and masses is through the scalar curvature. As a consequence mass terms are spacetime dependent for off-shell gravitational backgrounds, but happily constant for physical, Einstein manifolds. Unfortunately this introduces a naturalness problem because the scalar curvature is proportional to the cosmological constant. By writing down tractor stress tensors (multiplets built from the standard stress tensor and its first and second derivatives), we show how back-reaction solves this naturalness problem. We also show that classical back-reaction generates an interesting potential for scalar fields. We speculate that a proper description of how physical systems couple to scale, could improve our understanding of naturalness problems caused by the disparity between the particle physics and observed, cosmological constants. We further give some ideas how an ambient description of tractor calculus could lead to a Ricci-flat/CFT correspondence which generalizes the AdS side of Maldacena's duality to a Ricci-flat space of one higher dimension.Comment: 20 pages, 2 figure