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Search Results: 1 - 10 of 11395 matches for " Rafael;Garbiate "
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Effect of temperature and pre-germination treatments on seed germination and seedling vigor of Jatropha curcas L
Leandro Henrique de Sousa Mota,Rafael Heinz,Marcos Vinicios Garbiate,Silvana de Paula Quint?o Scalon
Biotemas , 2012,
Abstract: To date, there are no official methods used to test the seed germination of physic nut (Jatropha curcas) and there have only been a few attempts to optimize the germination of this species. The objective of this study was to evaluate the effect of different temperatures and pre-germination treatments on the germination and seedling vigor of J. curcas. The treatments were arranged in a completely randomized factorial scheme with four temperatures (20, 25, 30 and 20-30°C) x two types of seeds (with and without the seed tegument) x six periods of water imbibition (0, 6, 12, 18, 24 and 30h). The seeds were sown using a roller system with four replications of 50 seeds for each treatment. The germination percentage was higher for seeds stored at 25°C, when the seed tegument was maintained. When the time of water imbibition was increased, the germination percentage decreased, as well as the index of germination velocity and the percentage of germination of the first count. Imbibition for up to 12h led to an increase in hypocotyl growth. For this species, the maximum germination potential and highest vigor were obtained at 25°C, for seeds with teguments that were maintained and were not submitted to water imbibition.
Decomposi??o e libera??o de nutrientes de resíduos culturais de crambe e nabo forrageiro
Heinz, Rafael;Garbiate, Marcos Vinicios;Viegas Neto, Antonio Luiz;Mota, Leandro Henrique de Sousa;Correia, Allan Michel Pereira;Vitorino, Antonio Carlos Tadeu;
Ciência Rural , 2011, DOI: 10.1590/S0103-84782011000900010
Abstract: this study aimed to evaluate the decomposition and nutrient release from crop residues of fodder radish and crambe in the implementation of no-tillage system. the experiment was conducted in a distroferric red latossol with 762g kg-1 of clay. the experimental design was randomized blocks with four replications. the treatments were applied in split plots, considering the species of cover crops (radish and crambe) as the main plots and harvest dates of decomposition bags (0, 15, 30, 45, 60, 75 days after management) as subplots. the cover crops were treated 60 days after management, in full bloom. radish presented a dry mass production of 5586kg ha-1 and crambe of 2688kg ha-1. the kinetics of residue decomposition had a behavior similar to the dynamics of nutrient release, with an initial rapid phase followed by a slower one. the k, p and mg are released more quickly for subsequent crops. the increased speed of nutrients release by crops occurred around 15 days after the biomass management.
Infiltra??o de água no solo em áreas cultivadas com cana-de-a?úcar sob diferentes sistemas de colheita e modelos de ajustes de equa??es de infiltra??o
Tomasini, Bruno A.;Vitorino, Antonio C. T.;Garbiate, Marcos V.;Souza, Cristiano M. A. de;A. Sobrinho, Teodorico;
Engenharia Agrícola , 2010, DOI: 10.1590/S0100-69162010000600007
Abstract: the sugarcane harvesting techniques do not always follow the precepts of soil conservation, which may influence soil physical properties with consequent change in the rate of soil water infiltration. the study aimed to evaluate the effect of different cropping systems (manual cutting and automated cutting) of sugarcanes (green and burned), on water infiltration in the soil and to determine the adequacy of mathematical models to estimate the rate of water infiltration in the soil profile. it was used a portable rainfall simulator calibrated to apply rainfall of 60 mm h-1. tests of water infiltration in the soil were carried out in three cropping systems: manual harvesting of burnt cane, mechanical harvest of green cane and mechanical harvesting of burnt cane. the quality of the adjustment of models was evaluated by non-linear regression between the estimated values and the mean observed for each treatment. in the treatment where mechanical harvesting was applied it was observed a decreasing in the final infiltration rate compared to the area under manual harvesting of burnt cane. the equation of horton was the most suitable to estimate the water infiltration rate in soil.
Eficiência agron?mica de superfosfato triplo e fosfato natural de Arad em cultivos sucessivos de soja e milho
Ono, Fábio Benedito;Montagna, Juliano;Novelino, José Oscar;Serafim, Milson Evaldo;Dallasta, Daniel Comiran;Garbiate, Marcos Vinicios;
Ciência e Agrotecnologia , 2009, DOI: 10.1590/S1413-70542009000300010
Abstract: the aim of this study was to evaluate the effects of phosphate fertilizer rates on soybean and corn crops, in crop rotation. the experiment was carried out in a greenhouse at the grande dourados university, in pots with samples of 5.5 dm3 clayey dystropherric red latosol, where the triple superphosphate (tsp) and the arad rock phosphate (arp) were used as p source. two kinds of arp were used. in one, the total p (arad t) was considered while in the other, only the p soluble fraction in citric acid at the concentration of 2% (arad sa) was considered, resulting in three factors of study, each with six levels of p (0, 56, 112, 224, 336, and 560 mg dm-3). the soybean was sowed in december 2006 and in the end of the cycle, the crop was harvested and evaluated for grain yield, p concentration in leaves and in the soil. after the soybean crop, it was turn for the corn sowing, which harvest occurred 76 days after sowing. the shoot dry matter and p concentrations in leaves were evaluated. the index of agronomic efficiency was calculated for both crops. we concluded that the tsp caused a better soybean grain yield, when compared to the arp. in the corn crop succeeding the soybean crop, the arp tended to be similar to the tsp values in the attributes evaluated.
Eros?o em entre sulcos em área cultivada com cana crua e queimada sob colheita manual e mecanizada
Garbiate, Marcos Vinícios;Vitorino, Antonio Carlos Tadeu;Tomasini, Bruno Andrade;Bergamin, Anderson Cristian;Panachuki, Elói;
Revista Brasileira de Ciência do Solo , 2011, DOI: 10.1590/S0100-06832011000600029
Abstract: although a number of studies related to environmental issues address air pollution, the increased use of biotechnology and mechanical harvesting of sugar cane, less attention has been paid to the negative environmental impacts caused by laminar erosion. this study aimed to determine the levels of organic matter (om) and nutrients (p, k, ca and mg) in sediment and runoff water from interrill erosion from different sugarcane harvest systems (green and burnt cane), on a loamy dystrophic red latosol (oxisol). the treatments consisted of burnt cane harvested by hand, mechanical harvesting of green cane and mechanical harvesting of burnt cane. a portable rainfall simulator was calibrated to apply rainfall of 60 mm h-1, for 50 min. the sediment concentration in runoff resulting from interrill erosion, as well as om, p, k, ca and mg were higher in the system with mechanical harvesting of burnt cane, while losses were lowest from the system with mechanized harvesting of green cane. the soil physical quality is negatively influenced by the management system with mechanical harvesting of burnt cane, due to the pressure exerted by the harvest machine traffic. however, crop residues distributed across the soil surface at mechanical harvesting of green cane reduce losses of soil, nutrients and om in the sediment, and increase the soil resistance against physical degradation caused by machinery traffic for mechanical harvesting of sugarcane.
Sustainable and Economic Alternative for the Electric Supply of Isolated Communities in the Brazilian Off-Grid Systems  [PDF]
Rebeca Doctors, Rafael Kelman
Journal of Power and Energy Engineering (JPEE) , 2017, DOI: 10.4236/jpee.2017.59012
Abstract: Roughly 99% of the demand for electricity in Brazil is supplied by a national interconnected grid. The remaining 1% is spread in several “isolated systems” of the Amazon region—mini-grids that rely on expensive diesel gensets due to high commodity and transportation costs. The isolated systems also have remote communities disconnected altogether from the mini-grids with inadequate health, education and leisure services. These communities are precariously supplied by small inefficient diesel gensets that run for a few hours per day. In this article, we propose a sustainable and economic alternative for the electric supply of the remote communities of isolated systems through a combination of photovoltaic solar generation and storage. The objective is to improve access to electricity with savings for the communities. The present paper outlines a public policy to meet this objective.
The Difference in Calcium Levels in Aspergillus nidulans Grown on Glucose or Pectin  [PDF]
Janice Aparecida Rafael, Suraia Said
Advances in Microbiology (AiM) , 2012, DOI: 10.4236/aim.2012.22016
Abstract: Understanding the growth regulatory mechanisms in filamentous fungi is very important for the production of medicines for antifungal therapies. It is well established that Ca2+ gradient is essential for hyphal growth and that one mechanism responsible for the Ca2+ cellular concentration starts with the hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2) by receptor-regulated forms of phosphoinositide-specific phospholipase C (PI-PLC). In the present study the levels of calcium in Aspergillus nidulans wild type (A26) and plcA-deficient mutant (AP27) growing in a carbon source readily assimilated, as glucose or pectin a non-readily assimilated carbon source was investigated. Intracellular calcium levels in A26 were higher in the presence of glucose than in pectin, but lower in AP27 independently of the carbon source and in AP27 the vesicular calcium distribution occurred mainly at the apex of the hyphae. Delay in nuclear division was also observed if A26 and AP27 were grown in pectin presence when compared with growth in glucose. For the first time, it is demonstrated that the levels of intracellular Ca2+ were higher when A. nidulans was growing in glucose than in a non readily assimilated carbon source as pectin. Further, it also showed that the plcA gene, although not essential, may be responsible for high-molecular weight carbon source recongnation, for the intracellular Ca2+ levels maintenance and consequently by the nuclear division in A. nidulans.
Evaluation of Inherent Uncertainties of the Homogeneous Effective Thermal Conductivity Approach in Modeling of Printed Circuit Boards for Space Applications  [PDF]
Rafael Lopes Costa, Valeri Vlassov
Journal of Electronics Cooling and Thermal Control (JECTC) , 2013, DOI: 10.4236/jectc.2013.31005
Abstract:

Electronic components are normally assembled to printed circuit boards (PCBs). Such components generate heat in operation which must be conducted away efficiently from the small mounting areas to frames where the PCB is fixed. The temperature of the component depends on heat dissipation rate, technology and parameters of mounting, component placement and finally effective thermal conductivity (keff) of the board. The temperature of some components may reach significant magnitudes over 100°C while the PCB frame is kept at near-ambient temperature. The reliability of electronic components is directly related to operating temperature; so the thermal project should be able to provide a correct temperature prediction of all PCB components under the hottest operational condition. In space applications, the main way to spread and reject heat of electronic equipment is by thermal conduction once there is no air available to apply convection-based cooling techniques. The PCB keff is an important parameter for the electronics thermal analysis when the PCB is modeled as a simplified homogeneous board with a unique thermal conductivity. In this paper, an intrinsic uncertainty of such approach is firstly reveled and its magnitude is evaluated for a real space use PCB. The simulation uses SINDA/FLUINT Thermal Desktop and aims to determine the keff of the PCB by comparison between a detailed multi-layered anisotropic model and an

Experimental Evidence of Capillary Interruption of a Liquid Jet  [PDF]
Taha Massalha, Rafael M. Digilov
Open Journal of Applied Sciences (OJAppS) , 2014, DOI: 10.4236/ojapps.2014.47037
Abstract: We observe the gravity discharge of liquid through the short cylindrical tube of diameter of 2 mm and aspect ratio 2.5 and 10 attached to the underside of Mariotte bottle. When the hydrostatic head is reduced and approaches to a certain value, a laminar jet escaped from the nozzle is interrupted and the discharge is drop wise. The plot of the discharge rate as a function of hydrostatic head does not pass through the origin as predicted by Torricelli law for an ideal liquid. We attribute this feature to the energy losses related with creating a new free surface area of the jet. The measurements for water and aqueous ethanol solution are compared with theoretical predictions based on the modified Bernoulli equation with the interfacial energy density correction and good agreement is observed.
Restricted partitions
Rafael Jakimczuk
International Journal of Mathematics and Mathematical Sciences , 2004, DOI: 10.1155/s0161171204306502
Abstract: We prove a known partitions theorem by Bell in an elementary and constructive way. Our proof yields a simple recursive method to compute the corresponding Sylvester polynomials for the partition. The previous known methods to obtain these polynomials are in general not elementary.
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