Search

Assessing forest stands is crucial for managing and planning the use of these resources. Forest inventory is the instrument that provides information about the stand situation, which can be costly and time consuming. In order to facilitate and reduce the time spent obtaining these data, the main objective of this work was to evaluate the accuracy of volume and biomass estimates per unit area with data from remote sensing. Forty sample units were allocated and georeferenced, in which all trees with diameter at breast height (DBH) ≥ 5 cm were inventoried. Sequentially, the cubage was performed in order to obtain individual biomass, volume, and adjustment of the individual models. With data from georeferenced images of the study area, the vegetation indices MSAVI (Modified Soil-Adjusted Vegetation Index) and NDVI (Normalized Difference Vegetation Index) were obtained. The volume and biomass estimation using remote sensing variables were carried out through the adjustment of sigmoidal models by regression analysis, which used a combination of the average values of the vegetation indices and the basal area of the plot/hectares as an independent variable. The fit statistics and the accuracy of the tested models presented consistent results to estimate forest production. The results showwd that indices derived from remote sensing techniques associated with forest variables information could accurately estimate the volume and biomass of Eucalyptus spp. plantations.

Time has been an elusive concept to grasp. Although we do not yet understand it properly, there have been advances made in regard to how we can explain it. One such advance is the Page–Wootters mechanism. In this mechanism, time is seen as an inaccessible coordinate and the apparent passage of time arises as a consequence of correlations between the subsystems of a global state. Here we propose a measure that captures the relational character of the mechanism, showing that the internal coherence is the necessary ingredient for the emergence of time in the Page–Wootters model. Also, we connect it to results in quantum thermodynamics, showing that it is directly related to the extractable work from quantum coherence.

The prediction of biological processes, which involve growth and plant development, is possible via the adjustment of mathematical models. In forest areas, these models assist in management practices, silviculture, harvesting, and soil fertility. Diameter, basal area, and height are predictors of volume and biomass estimates in forest stands. This study utilized different non-linear models for estimating biomass and nutrient values in the aerial biomass and roots of an unmanaged eucalypt stand in Cerrado dystrophic soil. It was hypothesized that the models would estimate the nutrients of the aboveground biomass and roots after meeting the selection and validation criteria. By statistical analysis of the parameters and subsequent validation, the Schumacher&ndash, Hall model was presented to be the best fit for biomass and nutrients. This result confirmed the ability of different variables, including diameter, basal area, and height, to be predicted. Estimating the nutrient values in the aboveground biomass and roots allowed a better understanding of the quality of the vegetal residues that remained in the soil. For dystrophic soils, which occur in the Cerrado, these estimates become even more relevant.

Hábitos alimentares de universitários apresentam-se na maioria das vezes inadequados, caracterizado pelo baixo consumo de frutas e verduras e alta ingestão de alimentos ricos em gorduras e açúcares. Dessa forma, este grupo apresenta um maior risco de contrair doenças crônicas não transmissíveis (DCNT). Diante disso, o propósito deste estudo foi avaliar os hábitos alimentares de estudantes universitários da UFS. Foram entrevistados, , 718 universitários dos cursos das áreas de exatas (300), humanas (180) e saúde (238), O instrumento utilizado para coleta de dados foi uma adaptação do questionário do Ministério da Saúde, além do da auto-referição do peso e da estatura. Os resultados mostraram que a maioria (69,6%) dos universitários encontrava-se eutróficos e 17,9% com excesso de peso (principalmente entre os homens, p

Canopy cover has significant effects on the understory environment, including upon light availability for seedling growth. The aim of the present study was to verify spatial heterogeneity and seasonal changes in the canopy cover of a dense Cerrado area, and their relationship to understory photosynthetic active radiation availability. Leaf area index (LAI) values in the rainy season varied from 0.9 to 4.83, with 40% of the values ranging from 4.0 to 5.0, while in the dry season LAI varied from 0.74 to 3.3, with 53% of the values oscillating from 2.0 to 3.0. Understory light (Q(i)) and the Lambert-Beer ratio (Q(i)/Q(o)) were taken around noon on sunny days (between 11:00 AM and 1:00 PM). They were also statistically different (p0.01) between the dry and wet seasons, with 72% of sampled points in the rainy season presenting photosynthetic photon flux density (PPFD) values lower than 250 micromol x m(-2)/s around noon, whereas in the dry season, most PPFD values varied from 1500 to 1817 micromol x m(-2)/s, thus providing high light availability for understory plants. In most of the studied sites, understory plants did not even receive enough light for 50% of their photosynthetic capacity in the wet season. In contrast during the dry season, Q(i)/Q(o) values of 0.8 to 1.0 were observed in more than 50% of the points, thereby allowing for photosynthetic light saturation. Thus, light variability around noon was higher during the dry season than in the wet season, its heterogeneity being related to spatial complexity in the canopy cover.

We study the 1/N expansion of field theories in the stochastic quantization method of Parisi and Wu using the supersymmetric functional approach. This formulation provides a systematic procedure to implement the 1/N expansion which resembles the ones used in the equilibrium. The 1/N perturbation theory for the nonlinear sigma-model in two dimensions is worked out as an example.

Vacuum polarization effects are nonperturbatively incorporated into the photon propagator to eliminate the severe infrared problems characteristic of (2+1)-dimensional QED (${\mathrm{QED}}_{3}$). The theory is thus rephrased in terms of a massive vector boson whose mass is ${\mathit{e}}^{2}$/8\ensuremath{\pi}. Subsequently, it is shown that electron-electron bound states are possible on ${\mathrm{QED}}_{3}$.

Frequently, the life of the tools used in sheet metal forming operations is determined by a phenomenon known as galling, which originates from the adhesion of the sheet to the forming tool surface. The application of coating architectures composed by single or multiple layers of Physical Vapor Deposition (PVD) films, such as TiN, TiCN, CrN, TiCNAl, may significantly reduce the chemical interaction in the contact, up to the point that no significant adhesion may be observed for an extended number of forming operations. Usually, the evaluation of the behavior of different thin film architectures is conducted using tribometers that may or may not reproduce the conditions found in industrial practice. This work presents a tribological analysis of coated and uncoated surfaces of tools used in industrial sheet metal forming operations and discusses the capability of laboratory tests in reproducing the situations found in practice.

The classical limit for generalized partition functions is obtained using coherent states. In this framework it is presented a general procedure to obtain all the corrections to the classical limit. In particular, the first and second order quantum corrections are worked out explicitly, and the classical limit for the Tsallis thermostatistics is determined. The results of this work generalize the ones obtained by E. Wigner (Phys. Rev. 40 (1932) 749) for usual statistical mechanics., latex, 12 pages, to appears in Phys. A