Anatomia foliar de Vernonia condensata Baker, (Boldo Africano).

Asteraceae é a maior família do grupo das Angiospermas, dentre as inúmeras plantas da família está a Vernonia condensata Baker, popularmente conhecida como boldo africano. O trabalho tem como objetivo gerar dados anatômicos que sejam uteis na caracterização e comparação com indivíduos da mesma família. Para tal, foram coletadas folhas de indivíduos adultos, das quais se processou cortes paradermicos e transversais a mão livre, estes clarificados e posteriormente submetidos à coloração diferencial. As células epidérmicas da face adaxial e abaxial, em vista frontal, apresentam formato irregular e paredes anticlinais sinuosas, com estriação cuticular. Em corte transversal, as faces são unisseriadas, sendo que as células da face adaxial apresentam-se com formato que varia entre retangular e algumas vezes quadrangular, enquanto que células da face abaxial são levemente papilosas. As folhas são anfiestomáticas com estômatos anomocíticos. Em ambas as faces ocorrem dois tipos de tricomas glandulares, sendo um de haste longa e um curto. O mesofilo é dorsiventral, o parênquima paliçádico é biestratificado e o parênquima lacunoso é formado por células irregulares. Observa-se na nervura central um conjunto de células colenquimáticas, o tecido vascular é unicolateral constituído por células de floema e xilema. A ocorrência de diversas estruturas em comum com outras de sua família, ressalta a necessidade de ampliar os estudos neste grupamento vegetal.PIBIC-2011

EXERGETIC OPTIMIZATION OF AN ABSORPTION REFRIGERATION

Nowadays, several scientific studies aim to improve the refrigeration systems commonly used to reduce the consumption of electric energy as well as the environmental impact caused by this equipment. However, it is desired that this be done together with increased efficiency and reduced production cost of the system. Absorption refrigeration systems offer this opportunity to save energy, as they can use thermal energy to produce, residual heat and geothermal energy as primary energy. In addition, they use very ecological working fluids, drawing the attention of the scientific academic world in recent decades. Currently, thermodynamic analyzes based on exergy are increasingly being implemented to calculate the performance of thermodynamic systems, where just considering COP as an efficiency parameter is no longer sufficient. The exergetic analysis takes into account the irreversibility of the system and can indicate which components need to be improved to have a better system performance. Taking this into account, this paper presents the modeling and exergetic optimization of an absorption refrigeration system that uses ammonia and water as working fluids. The thermodynamic model of the refrigerator was developed based on the principles of mass and energy conservation under the steady-state, and was implemented using the Engineering Equation Solver (EES) software. Regarding the performance of the modeled refrigerator, a value of COP = 0.4571. A parametric analysis of the system was carried out with the results obtained numerically from the proposed model, where the relevance of some operating parameters for the performance coefficient and the exergetic efficiency of the system was evaluated. An exergetic analysis of the system was also carried out, where it was shown that the generator and the absorber are responsible for 56.4% and 29.2%, respectively of the total destroyed exergy. Moreover, based on the proposed thermodynamic model, an exergetic optimization of the cooling system was performed based on parameters such as generator temperature and absorber pressure. Thus, it can be concluded that the model developed can be used as a useful tool in the study of absorption chillers possible to predict the impact on the system performance, taking into account various operating conditions

Dynamics of Multi-Player Games

We analyze the dynamics of competitions with a large number of players. In our model, n players compete against each other and the winner is decided based on the standings: in each competition, the mth ranked player wins. We solve for the long time limit of the distribution of the number of wins for all n and m and find three different scenarios. When the best player wins, the standings are most competitive as there is one-tier with a clear differentiation between strong and weak players. When an intermediate player wins, the standings are two-tier with equally-strong players in the top tier and clearly-separated players in the lower tier. When the worst player wins, the standings are least competitive as there is one tier in which all of the players are equal. This behavior is understood via scaling analysis of the nonlinear evolution equations.Comment: 8 pages, 8 figure

Efeitos de doses de nitrogênio e potássio por fertirrigação na cultura da banana.

A banana (Musa spp.) pertencente ao gênero Musa e família Musaceae, é originária das regiões tropicais do mundo. Objetivou-se avaliar o efeito de cinco doses de nitrogênio e cinco doses de potássio aplicadas através da água de irrigação por microaspersão nos parâmetros de produção da bananeira cultivar prata anã

Time-dependent quantum scattering in 2+1 dimensional gravity

The propagation of a localized wave packet in the conical space-time created by a pointlike massive source in 2+1 dimensional gravity is analyzed. The scattering amplitude is determined and shown to be finite along the classical scattering directions due to interference between the scattered and the transmitted wave functions. The analogy with diffraction theory is emphasized.Comment: 15 pages in LaTeX with 3 PostScript figure

Melon prdutivity under different soil coverings and irrigation system in Petrolina - PE

The objective of this work was to evaluate the influence of irrigation system and soil cover on yield of yellow melon in Petrolina / PE. The experiment was carried out in the period from April 09, 2016 to June 8, 2016 and was conducted at the Petrolina campus in the IF Sertão - PE rural area, with a randomized complete block design, 2 x 2 x 3 plot scheme, (One and two lines of drippers per row of plants), and the subsubparcels, three soil cover (black mulching cover), two plots of hybrids (Gladial and 10/00), subplots, two irrigation systems, Cover with mulching grey and without soil cover) and six replicates. Mulching efficiency (MPP) was studied in the soil cover and irrigation system located with drippers for the production of yellow hybrid melon 10/00 and Gladial under field conditions. It was verified the statistical influence of the soil cover on melon productivity

Energy of general 4-dimensional stationary axisymmetric spacetime in the teleparallel geometry

The field equation with the cosmological constant term is derived and the energy of the general 4-dimensional stationary axisymmetric spacetime is studied in the context of the hamiltonian formulation of the teleparallel equivalent of general relativity (TEGR). We find that, by means of the integral form of the constraints equations of the formalism naturally without any restriction on the metric parameters, the energy for the asymptotically flat/de Sitter/Anti-de Sitter stationary spacetimes in the Boyer-Lindquist coordinate can be expressed as $E=\frac{1}{8\pi}\int_S d\theta d\phi(sin\theta \sqrt{g_{\theta\theta}}+\sqrt{g_{\phi\phi}}-(1/\sqrt{g_{rr}})(\partial{\sqrt{g_ {\theta\theta} g_{\phi\phi}}}/\partial r))$. It is surprised to learn that the energy expression is relevant to the metric components $g_{rr}$, $g_{\theta\theta}$ and $g_{\phi\phi}$ only. As examples, by using this formula we calculate the energies of the Kerr-Newman (KN), Kerr-Newman Anti-de Sitter (KN-AdS), Kaluza-Klein, and Cveti\v{c}-Youm spacetimes.Comment: 12 page