Dam failure and mammals

Brazil experienced the largest socioenvironmental catastrophe of its history, caused by a tailings dam failure, known as “Mariana disaster”. The wave of iron-mining waste buried villages, contaminated the Doce River, and left an immense ocean plume. The Doce River watershed is the largest in southeast Brazil, and located in the Atlantic Forest domain, presenting an outstanding economic, social, and biological relevance. Although the effects of such tragic events are usually assessed through fish assemblage changes, mammals have important effects on environment structure and regeneration. Inventories are of prime importance for adequate conservation efforts as well as for evaluating impacts of any disaster. Therefore, the aim of this paper was to present an updated assessment of mammalian list collected in the affected portion of Doce River before the dam failure therefore contributing to future conservation efforts. Data collection comprised specimens deposited in Museu Nacional/UFRJ, the oldest mammal collection of Brazil, and literature review. The two surveys together retrieved 157 species from 31 families and 11 orders, representing around 60% of the known mammalian diversity in the Atlantic Forest, including some in critical conservation condition, such as the Franciscana dolphin, the northern muriqui and the giant otter. Mining is a byproduct of present society, with dam breaches as a recurring problem. Facing the importance of Doce River to both Brazilian biodiversity and society, the chain of events must be taken into account in environmental rehabilitation strategies, and taxa less commonly assessed, like mammals, should be included.

Conservation conditions of chainsaws and electric chainsaws and safety of the farmers who operate these machines

The increasing use of chainsaws in rural areas has demanded the health of rural producers who operate these machines. Thus, the objective of this work was to evaluate the conservation conditions of chainsaws with a 2-stroke Otto Cycle engine and check if they meet NR12 Annex V, as well as confirm whether users meet NR31 in terms of training for use. With the aid of a questionnaire and visits to farms, 103 chainsaws were verified in six municipalities in the central region of the State of Rio Grande do Sul. After organizing the data in an electronic spreadsheet, descriptive statistics and canonical correlation were performed. The questions were divided into four groups, namely: operational, mandatory machine safety equipment, cutting set, and engine. The conservation condition of the machines was seen as worrisome. This is because it was found that 66.01% of machines did not have a saber guard and 49.51% of these were worn out. In addition, 97.08% of the producers did not take a chainsaw operation course, and 85.44% reported not using Personal Protective Equipment (PPE), therefore, in disagreement with the NR6, NR12 Annex V, and NR31 standards. It was clear the need for the operators to carry out training on the safe use and handling of chainsaws.

Dependency of conservation conditions of Takase stone Buddha, Oita, Japan, on anisotropy of liquid water diffusivity

Takase Stone Buddhas is one of the important old stone buddha sculptures curved into the inner wall of a cave in Oita, Japan. It is located in the cave curved into the cliff of a hill of volcanic tuff. In general, because the cave is currently protected from rain and direct solar radiation by the roof shelter and waterproof treatment, the Buddhas is well conserved and no currently ongoing weathering can be clearly observed. However, because of a high ground water level, there is a concern in the influence of water evaporation at and near the surface of the stone buddhas and the wall of the cave on their deterioration. In the past, we conducted a long-term field survey of conservation environment to obtain yearly data set of the conservation environment that can be used as input of numerical simulations of heat and water transport in the material. In this paper, we report measurement data of the ground water level as well as the liquid water diffusivity of the tuff stone that significantly affects the conservation condition. We also performed numerical analyses on heat and moisture transport in the tuff stone layer and stone buddhas. The simulation results show that the conservation condition of Takase stone Buddha strongly depends on the anisotropy of liquid water diffusivity of the tuff stone.

Stability of Discontinuous Galerkin Spectral Element Schemes for Wave Propagation when the Coefficient Matrices have Jumps

We use the behavior of the $$L_{2}$$ L 2 norm of the solutions of linear hyperbolic equations with discontinuous coefficient matrices as a surrogate to infer stability of discontinuous Galerkin spectral element methods (DGSEM). Although the $$L_{2}$$ L 2 norm is not bounded in terms of the initial data for homogeneous and dissipative boundary conditions for such systems, the $$L_{2}$$ L 2 norm is easier to work with than a norm that discounts growth due to the discontinuities. We show that the DGSEM with an upwind numerical flux that satisfies the Rankine–Hugoniot (or conservation) condition has the same energy bound as the partial differential equation does in the $$L_{2}$$ L 2 norm, plus an added dissipation that depends on how much the approximate solution fails to satisfy the Rankine–Hugoniot jump.

An Efficient Algorithm for Solving Hyperbolic Partial Differential Equations with a Nonlocal Conservation Condition

In this paper, a numerical scheme based on the Galerkin method is extended for solving one-dimensional hyperbolic partial differential equations with a nonlocal conservation condition. To achieve this goal, we apply the interpolating scaling functions. The most important advantages of these bases are orthonormality, interpolation, and having flexible vanishing moments. In other words, to increase the accuracy of the approximation, we can individually or simultaneously increase both the degree of polynomials (multiplicity r ) and the level of refinement (refinement level J ). The convergence analysis is investigated, and numerical examples guarantee it. To show the ability of the proposed method, we compare it with existing methods, and it can be confirmed that our results are better than them.

Marangoni convection in layers of water-based nanofluids under the effect of rotation

A linear stability analysis is performed for the onset of Marangoni convection in a horizontal layer of a nanofluid heated from below and affected by rotation. The top boundary of the layer is assumed to be impenetrable to nanoparticles with their distribution being determined from a conservation condition while the bottom boundary is assumed to be a rigid surface with fixed temperature. The motion of the nanoparticles is characterized by the effects of thermophoresis and Brownian diffusion. A modification model is used in which the effects of Brownian diffusion and thermophoresis are taken into consideration by new expressions in the nanoparticle mass flux. Also, material properties of the nanofluid are modelled by non-constant constitutive expressions depending on nanoparticle volume fraction. The steady-state solution is shown to be well approximated by an exponential distribution of the nanoparticle volume fraction. The Chebyshev-Tau method is used to obtain the critical thermal and nanoparticle Marangoni numbers. Different stability boundaries are obtained using the modified model and the rotation.

A revised model for the effect of nanoparticle mass flux on the thermal instability of a nanofluid layer

A revised model of the nanoparticle mass flux is introduced and used to study the thermal instability of the Rayleigh-Benard problem for a horizontal layer of nanofluid heated from below. The motion of nanoparticles is characterized by the effects of thermophoresis and Brownian diffusion. The nanofluid layer is confined between two rigid boundaries. Both boundaries are assumed to be impenetrable to nanoparticles with their distribution being determined from a conservation condition. The material properties of the nanofluid are allowed to depend on the local volume fraction of nanoparticles and are modelled by non-constant constitutive expressions developed by Kanafer and Vafai based on experimental data. The results show that the profile of the nanoparticle volume fraction is of exponential type in the steady-state solution. The resulting equations of the problem constitute an eigenvalue problem which is solved using the Chebyshev tau method. The critical values of the thermal Rayleigh number are calculated for several values of the parameters of the problem. Moreover, the critical eigenvalues obtained were real-valued, which indicates that the mode of instability is via a stationary mode.

Assessing the histological changes in fish gills as environmental bioindicators in Paraty and Sepetiba bays in Rio de Janeiro, Brazil

The use of fish species uses as bioindicators is an important environmental monitoring tool. Histological biomarkers are adopted to assess the health conditions of different organisms and to indicate an environmental hazard. Histology can be applied as an effective method to analyze the effects of pollutants and other stressors. Accordingly, histological changes in the gill epithelium were analyzed to assess the adoption of fish species Menticirrhus americanus (Linnaeus, 1758) and Micropogonias furnieri (Desmarest, 1823) as a bioindicator to measure environmental quality in Paraty and Sepetiba bays, in Rio de Janeiro. A random sample of 58 fish was collected from the assessed bays. We found Paraty Bay to be in good conservation condition, whereas Sepetiba Bay is contaminated. The fish species collected from Sepetiba Bay showed lesions such as epithelial lifting, aneurysm, and necrosis in the gills; thus, it was possible to suggest that histological biomarkers be used bioindicators to measure the environmental impact in these bays.