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Search Results: 1 - 10 of 13095 matches for " Gustavo Gonzaga;Camargo "
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Tratamento de efluentes de carcinicultura por macrófitas aquáticas flutuantes
Henry-Silva, Gustavo Gonzaga;Camargo, Antonio Fernando Monteiro;
Revista Brasileira de Zootecnia , 2008, DOI: 10.1590/S1516-35982008000200002
Abstract: the efficiency of systems composed of two species of floating aquatic macrophyte (eichhornia crassipes and pistia stratiotes) to treat effluents from shrimp culture was evaluated in this research. the effluent originated from a pond populated with macrobrachium amazonicum. treatment systems consisted of 12 experimental tanks with aquatic macrophyte and three tanks without plants (control). water samples were collected from the fresh water supply and before and after passing through the treatment systems. there are no differences in the removal of nutrients between the two species. the higher nutrient removal was observed for total phosphorus (41.9% by control; 71.6% by e. crassipes; 69.9 by p. stratiotes; 72.5% by e. crassipes + p. stratiotes and 72.1 by p. stratiotes + e. crassipes) and turbidity (30.6% by control; 80.2% by e. crassipes; 75.2 by p. stratiotes; 79.8% by e. crassipes + p. stratiotes and 81.5 by p. stratiotes + e. crassipes). the systems containing aquatic macrophytes were efficient in nitrogen and phosphorus removal from m. amazonicum culture.
Efficiency of aquatic macrophytes to treat Nile tilapia pond effluents
Henry-Silva, Gustavo Gonzaga;Camargo, Antonio Fernando Monteiro;
Scientia Agricola , 2006, DOI: 10.1590/S0103-90162006000500003
Abstract: the effluents from fish farming can increase the quantity of suspended solids and promote the enrichment of nitrogen and phosphorus in aquatic ecosystems. in this context, the aim of this work was to evaluate the efficiency of three species of floating aquatic macrophytes (eichhornia crassipes, pistia stratiotes and salvinia molesta) to treat effluents from nile tilapia culture ponds. the effluent originated from a 1,000-m2 pond stocked with 2,000 male nile tilapia oreochromis niloticus. the treatment systems consisted of 12 experimental tanks, three tanks for each macrophyte species, and three control tanks (without plants). water samples were collected from the: (i) fish pond source water, (ii) effluent from fish pond and (iii) effluents from the treatment tanks. the following water variables were evaluated: turbidity, total and dissolved nitrogen, ammoniacal-n, nitrate-n, nitrite-n, total phosphorus and dissolved phosphorus. e. crassipes and p. stratiotes were more efficient in total phosphorus removal (82.0% and 83.3%, respectively) and total nitrogen removal (46.1% and 43.9%, respectively) than the s. molesta (72.1% total phosphorus and 42.7% total nitrogen) and the control (50.3% total phosphorus and 22.8% total nitrogen), indicating that the treated effluents may be reused in the aquaculture activity.
Efficiency of aquatic macrophytes to treat Nile tilapia pond effluents
Henry-Silva Gustavo Gonzaga,Camargo Antonio Fernando Monteiro
Scientia Agricola , 2006,
Abstract: The effluents from fish farming can increase the quantity of suspended solids and promote the enrichment of nitrogen and phosphorus in aquatic ecosystems. In this context, the aim of this work was to evaluate the efficiency of three species of floating aquatic macrophytes (Eichhornia crassipes, Pistia stratiotes and Salvinia molesta) to treat effluents from Nile tilapia culture ponds. The effluent originated from a 1,000-m2 pond stocked with 2,000 male Nile tilapia Oreochromis niloticus. The treatment systems consisted of 12 experimental tanks, three tanks for each macrophyte species, and three control tanks (without plants). Water samples were collected from the: (i) fish pond source water, (ii) effluent from fish pond and (iii) effluents from the treatment tanks. The following water variables were evaluated: turbidity, total and dissolved nitrogen, ammoniacal-N, nitrate-N, nitrite-N, total phosphorus and dissolved phosphorus. E. crassipes and P. stratiotes were more efficient in total phosphorus removal (82.0% and 83.3%, respectively) and total nitrogen removal (46.1% and 43.9%, respectively) than the S. molesta (72.1% total phosphorus and 42.7% total nitrogen) and the control (50.3% total phosphorus and 22.8% total nitrogen), indicating that the treated effluents may be reused in the aquaculture activity.
Crescimento de Pistia stratiotes em diferentes condi??es de temperatura e fotoperíodo
Cancian, Leonardo Farage;Camargo, Antonio Fernando Monteiro;Silva, Gustavo Henrique Gonzaga;
Acta Botanica Brasilica , 2009, DOI: 10.1590/S0102-33062009000200027
Abstract: temperature and photoperiod are abiotic variables that directly influence aquatic macrophyte production. they also determine the geographic distribution of the species and affect community structure. the aim of this study was to evaluate the growth of pistia stratiotes in different temperature and photoperiod regimes. p. stratiotes plants were conditioned in growth chambers with controlled temperature and photoperiod. six treatments were used: 1 (15 oc/8 h photoperiod); 2 (15 oc/12 h); 3 (25 oc/8 h); 4 (25 oc/12 h); 5 (30 oc/8 h) and 6 (30 oc/12 h). the highest biomass gain occurred with treatment number 4 which showed significant differences (p<0.05) compared to treatments number 1, 5 and 6. in treatments 1, 5 and 6 the final biomass was lower than the initial biomass of p. stratiotes. the greatest biomass reduction occurred in treatment number 6 which was significantly lower than in treatments 2, 3 and 4. the highest sprout production was observed in treatments at 25 oc, while in treatments at 15 oc and 30 oc sprouting was greatly reduced. we conclude that temperature and photoperiod influence p. stratiotes growth and higher growth rates occurred at 25 oc and 12-hour photoperiod.
Os efeitos da redu??o da jornada de trabalho de 48 para 44 horas semanais em 1988
Gonzaga, Gustavo M.;Menezes Filho, Naércio Aquino;Camargo, José Márcio;
Revista Brasileira de Economia , 2003, DOI: 10.1590/S0034-71402003000200003
Abstract: the reduction of standard weekly working time from the current level of 44 hours to 40 hours has recently been proposed by the main central unions as a way to create jobs and reduce unemployment in brazil. the idea, known as work-sharing, is that the reduction in average hours per worker would allow the same tasks to be performed by more employees, a notion which has been challenged in the theoretical and empirical literature. the objective of this paper is to study the effects of the workweek reduction from 48 to 44 hours prescribed by the 1988 constitution on the brazilian labor market. we find that the constitutional changes reducing actual working hours did not change the probability of the affected worker became unemployed in 1989 (relative to other years), reduced the probability of the affected worker of not having a job in 1989 (which includes those that left the labor force) and implied a relative increase in real hourly wages (although lower than observed for workers that reduced the workweek time in other years). these results suggest that the working time reduction did not have a negative impact on employment in the short run (12 months after the constitutional change).
Características limnológicas da coluna d'água e dos efluentes de viveiros de cria??o de camar?es-da-amaz?nia
Henry-Silva, Gustavo Gonzaga;Camargo, Antonio Fernando Monteiro;Pontes, Cibele Soares;Miyase, Leonardo Kazuya;
Revista Brasileira de Zootecnia , 2010, DOI: 10.1590/S1516-35982010001000001
Abstract: the objective of this research was to characterize the effluents of fish ponds of macrobrachium amazonicum cultured in different densities of farming and to analyze the daily variation (24 hours) of the vertical temperature and oxygen saturation profile of the water column of the ponds. the study was conducted during a period of three months using 12 rectangular 100 m2 earthen ponds supplied with m. amazonicum individuals in four densities of farming (40, 60, 80 and 100 individuals/m2), each one evaluated with three replicates. follow-up of the daily variation of the temperature and of the saturation of the dissolved oxygen was monthly carried out in the fish ponds (from the surface to the bottom). it was determined, in the effluent caused by the prawn farming, the values of total-n, ammoniacal-n, nitrite-n, nitrate-n, total-p, orthophosphate-p and turbidity. daily stratifications and desestratifications of temperature and of the saturation oxygen were recorded, irrespective of farming density, characterizing the ponds as a polimitic system of circulation. the higher the density of cultivation of m. amazonicum, the higher the values of total-p, total-n, orthophosphate-p, n-ammoniacal and turbidity.
Digestibilidade aparente de macrófitas aquáticas pela tilápia-do-nilo (Oreochromis niloticus) e qualidade da água em rela??o às concentra??es de nutrientes
Henry-Silva, Gustavo Gonzaga;Camargo, Antonio Fernando Monteiro;Pezzato, Luiz Edivaldo;
Revista Brasileira de Zootecnia , 2006, DOI: 10.1590/S1516-35982006000300003
Abstract: the objectives of this trial were to determine the apparent digestibility coefficients (adc) of crude protein and amino acids for two species of free floating aquatic macrophytes (eichhornia crassipes and pistia stratiotes) by nile tilapia (oreochromis niloticus) and to determine the water quality of digestibility aquariums in relation nitrogen and phosphorus concentrations. tree feeds were developments, containing 0.10% of chromic oxide - iii, one being the reference diet (purified) and the others containing 30% of aquatic macrophytes. the nile tilapias (58.8 + 18.5 g) were fed to apparent satiation and the faeces were collected by modified guelph system. the average adc of crude protein and amino acids were, respectively, 93.17 and 93.32% for diet reference; 59.23 and 60.35% for e. crassipes; and 52.24 and 57.40% for p. stratiotes. no significant differences were observed among the adc of protein and of amino acids of the plants ingredients. the results showed lower efficiency by tilapia of nile in assimilate the most amino acids of the e. crassipes and p. stratiotes. it is possible to conclude that excretory products in the nile tilapia increase the concentrations of nitrogen and phosphorus, independent of feed.
Os efeitos da redu o da jornada de trabalho de 48 para 44 horas semanais em 1988
Gonzaga Gustavo M.,Menezes Filho Naércio Aquino,Camargo José Márcio
Revista Brasileira de Economia , 2003,
Abstract: A redu o da jornada de trabalho de 44 para 40 horas semanais tem sido freqüentemente proposta pelas centrais sindicais como solu o para a escassa gera o de empregos no país. A idéia, conhecida como partilha do trabalho (work-sharing), é que a redu o de jornada permitiria que o mesmo trabalho fosse repartido por mais trabalhadores. No entanto, a maior parte dos artigos contesta a base teórica e a observa o empírica de ocorrência de partilha do trabalho. O objetivo deste artigo é estudar os efeitos da redu o de jornada prescrita pela Constitui o de 1988, de 48 para 44 horas por semana, sobre o mercado de trabalho no Brasil. Os resultados do exercício empírico mostram que as altera es da Constitui o, referentes à jornada de trabalho, provocaram uma queda da jornada efetiva de trabalho, n o aumentaram a probabilidade de o trabalhador afetado pela mudan a ficar desempregado em 1989 (quando comparada a outros anos), diminuíram a probabilidade de o trabalhador afetado de ficar sem emprego em 1989 (o que inclui os que saíram da for a de trabalho) e implicaram um aumento do salário real horário (apesar de menor do que o observado para trabalhadores que reduziram a jornada em outros anos). Esses resultados indicam que, no curto prazo (nos 12 meses seguintes à mudan a constitucional), a redu o de jornada n o teve efeitos negativos sobre o emprego.
Influence of aquaculture effluents on the growth of Salvinia molesta
Pistori, Raquel Eduarda Trevisan;Henry-Silva, Gustavo Gonzaga;Biudes, José Francisco Vicente;Camargo, Antonio Fernando Monteiro;
Acta Limnologica Brasiliensia , 2010, DOI: 10.4322/actalb.02202007
Abstract: objective: aquaculture generates social and economic benefits, but also causes impacts on the environment. one of the major impacts is the release of untreated effluents into rivers, reservoirs, and lakes, which can affect aquatic populations and communities. in this study, we tested the hypothesis that effluent from aquaculture favors the growth of the floating aquatic macrophyte salvinia molesta; methods: the study was carried out in a non-impacted reservoir (nir) and in another reservoir (ir) that is impacted by discharges of aquaculture effluents, and lasted for nine months. in each of the reservoirs, we installed four experimental units containing 10 ramets of s. molesta. monthly, we measured limnological variables of the water and the biomass of s. molesta in both reservoirs; results: the temperature, turbidity, electrical conductivity, alkalinity, chlorophyll-a, total kjeldahl nitrogen, and total phosphorus were higher in the ir in all the collection months. at the end of the experiment, the concentrations of total nitrogen and phosphorus in the biomass of s. molesta from the ir were higher than those in plants from the nir. the estimated support capacity (k) for s. molesta in the nir was 3.0 ± 0.7 g dm.m-2 and in the ir was 37.4 ± 2.4 g dm.m-2; conclusions: it was concluded that the discharge of aquaculture effluent modifies the limnological characteristics of the water of the receiving reservoir, and that the growth of salvinia molesta is favored by the aquaculture effluent, because of the increases in the concentrations of nitrogen and phosphorus in the water.
A partilha do trabalho e a demanda dinamica por trabalhadores e horas
Pereira, Rodrigo;Gonzaga, Gustavo;
Revista Brasileira de Economia , 2001, DOI: 10.1590/S0034-71402001000100001
Abstract: this paper investigates whether a reduction in standard hours has a positive impact on the employment level, an effect known in the literature as work-sharing. the innovation here is to include employment adjustment costs in the theoretical model. this feature introduces interesting dynamic aspects, which make it possible to study optimal paths of employment and average hours both in the short and the long run. the main result is that work-sharing does not occur even in the presence of employment adjustment costs.
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