950 resultados para Atmospheric C-14


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Nearly half of the earth's photosynthetically fixed carbon derives from the oceans. To determine global and region specific rates, we rely on models that estimate marine net primary productivity (NPP) thus it is essential that these models are evaluated to determine their accuracy. Here we assessed the skill of 21 ocean color models by comparing their estimates of depth-integrated NPP to 1156 in situ C-14 measurements encompassing ten marine regions including the Sargasso Sea, pelagic North Atlantic, coastal Northeast Atlantic, Black Sea, Mediterranean Sea, Arabian Sea, subtropical North Pacific, Ross Sea, West Antarctic Peninsula, and the Antarctic Polar Frontal Zone. Average model skill, as determined by root-mean square difference calculations, was lowest in the Black and Mediterranean Seas, highest in the pelagic North Atlantic and the Antarctic Polar Frontal Zone, and intermediate in the other six regions. The maximum fraction of model skill that may be attributable to uncertainties in both the input variables and in situ NPP measurements was nearly 72%. on average, the simplest depth/wavelength integrated models performed no worse than the more complex depth/wavelength resolved models. Ocean color models were not highly challenged in extreme conditions of surface chlorophyll-a and sea surface temperature, nor in high-nitrate low-chlorophyll waters. Water column depth was the primary influence on ocean color model performance such that average skill was significantly higher at depths greater than 250 m, suggesting that ocean color models are more challenged in Case-2 waters (coastal) than in Case-1 (pelagic) waters. Given that in situ chlorophyll-a data was used as input data, algorithm improvement is required to eliminate the poor performance of ocean color NPP models in Case-2 waters that are close to coastlines. Finally, ocean color chlorophyll-a algorithms are challenged by optically complex Case-2 waters, thus using satellite-derived chlorophyll-a to estimate NPP in coastal areas would likely further reduce the skill of ocean color models.

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Previous studies showed that livers from carnivorous birds have a higher gluconeogenic capacity and higher levels of gluconeogenic enzymes than livers from granivorous birds. In this work we compare the effects of fasting and adrenalectomy on gluconeogenesis. Fasting in the chicken elicited increased rates of incorporation of 14C from alanine into blood glucose, increased gluconeogenesis in liver slices, and increased activities of four gluconeogenic enzymes: glucose-6-phosphatase, phosphoenolpyruvate carboxykinase, alanine aminotransferase, and aspartate aminotransferase. These responses in the chicken resemble those observed in fasted rodents. In marked contrast, fasting in black vultures induced decreased rates of incorporation of alanine label into circulating glucose, decreased gluconeogenesis in liver slices, and no change in any of the four enzymes studied. This unusual response to fasting in the carnivorous bird is probably related to the high-protein-low-carbohydrate content of the diet. Fasted adrenalectomized birds (granivorous and carnivorous) had reduced rates of in vivo glucose synthesis, decreased liver gluconeogenesis, and lower activity of glucose-6-phosphatase and aspartate aminotransferase, without change in phosphoenolpyruvate carboxykinase and alanine aminotransferase activities.

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The sesquiterpenes cadina-4,10(15)-dien-3-one (1) and aromadendr-1(10)-en-9-one (squamulosone) (14) along with the triterpenoid methyl ursolate (21) were incubated with the fungus Mucor plumbeus ATCC 4740. Substrates 1, 14 and ursolic acid (20) were isolated from the plant Hyptis verticillata in large quantities. M. plumbeus hydroxylated 1 at C-12 and C-14. When the iron content of the medium was reduced, however, hydroxylation at these positions was also accompanied by epoxidation of the exocyclic double bond. In total nine new oxygenated cadinanes have been obtained. Sesquiterpene 14 was converted to the novel 2α,13-dihydroxy derivative along with four other metabolites. Methyl ursolate (21) was transformed to a new compound, methyl 3β,7β,21β-trihydroxyursa-9(11),12-dien-28-oate (22). Two other triterpenoids, 3β,28-dihydroxyurs-12-ene (uvaol) (23) and 3β,28-bis(dimethylcarbamoxy)urs-12-ene (24) were not transformed by the micro-organism, however. © 2002 Elsevier Science Ltd. All rights reserved.

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The aim of this study was to analyze temporal ..d vertical variation of the biomass and of phytoplankton primary productivity in an urban eutrophic reservoir, in relation to the physical and chemical characteristics of the water. The physical and chemical variables of the water were defined in the limnetic region of the reservoir, at depths of 0.0; 0.5; 1.0; 2.0; 3.0 and 4.0 meters. Three samples were taken to define both the physical and chemical variables, concomitantly with the biomass (chlorophyll-a and phaeophytin) and phytoplankton primary productivity (C-14 method). Based on data obtained on differences in depth of the mixture zone and the euphotic zone, it is hypothesised that, depending on the time of the year, phytoplankton is conditioned by differences in the light and nutrient regimes, which change according to the constant loads of nutrients thrown into the system. The highest concentration of chlorophyll-a in the photic zone of the limnetic region was observed in November 2000 (1,197.3 mg Chl L -1) and the lowest in November 1999 (94.0 mg ChI L -1), whereas the profiles of primary activity of phytoplankton presented the highest rates on the surface of the water column, with values varying from 84.7 (May 2000) to 1,376.7mg C m -3 h -1 (December 2000). Annual primary productivity was calculated at 1,567.0gC m -2y -1, considered euproductive. The primary productivity profiles reported in this study are typical of aquatic eutrophic systems, rich in plankton and with low light penetration. It can be stated that Garças Lake is a system that suffers from anthropogenic impact, through receiving large loads of organic pollution, reflecting on the physical and chemical characteristics of the water and on the high values of biomass and primary phytoplankton activity. © National Institute of Ecology, New Delhi.

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[Purpose] The purpose of this study was to verify the effect on body sway during quiet standing of the habitual weight carried by students in a backpack. [Subjects] Forty-six students between the ages of 8 and 14 years volunteered. [Method] The percentage of body weight (% BW) of each student's backpack was calculated and the students were separated into three groups based on the results: Group A (0-7% BW), Group B (7.01-14% BW) and Group C (14.01-21%BW). [Results] The use of the backpack increased the area of the CoP sway, displacement and mean speed of the CoP data in the antero-posterior and medial-lateral directions in Group C. [Conclusion] Therefore, observed responses in the body posture changes caused by the weight of the backpack were similar to those reported in other studies conducted with different methodos of investigation.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Natural, dissolved U-238-series radionuclides (U, Ra-226, Rn-222) and activity ratios (A.R.s: U-234/U-238; Ra-228/Ra-226) in Continental Intercalaire (Cl) groundwaters and limited samples from the overlying Complexe Terminal (CT) aquifers of Algeria and Tunisia are discussed alongside core measurements for U/Th (and K) in the contexts of radiological water quality, geochemical controls in the aquifer, and water residence times. A redox barrier is characterised downgradient in the Algerian Cl for which a trend of increasing U-234/U-238 A.R.s with decreasing U-contents due to recoil-dominated U-234 solution under reducing conditions allows residence time modelling similar to 500 ka for the highest enhanced A.R. = 3.17. Geochemical modelling therefore identifies waters towards the centre of the Grand Erg Oriental basin as palaeowaters in line with reported C-14 and Cl-36 ages. A similar U-234/U-238 trend is evidenced in a few of the Tunisian CI waters. The paleoage status of these waters is affirmed by both noble gas recharge temperatures and simple modelling of dissolved, radiogenic He-4-contents both for sampled Algerian and Tunisian CI and CT waters. For the regions studied these waters therefore should be regarded as "fossil" waters and treated effectively as a non-renewable resource. (C) 2014 The Authors. Published by Elsevier Ltd.

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The purpose of this study was to evaluate the effect of self-adhesive and self-etching resin cements on the bond strength of nonmetallic posts in different root regions. Sixty single-rooted human teeth were decoronated, endodontically treated, post-space prepared, and divided into six groups. Glass-fiber (GF) posts (Exacto, Angelus) and fiber-reinforced composite (FRC) posts (EverStick, StickTeck) were cemented with self-adhesive resin cement (Breeze) (SA) (Pentral Clinical) and self-etching resin cement (Panavia-F) (SE) (Kuraray). Six 1-mm-thick rods were obtained from the cervical (C), middle (M), and apical (A) regions of the roots. The specimens were then subjected to microtensile testing in a special machine (BISCO; Schaumburg, IL, USA) at a crosshead speed of 0.5 mm/min. Microtensile bond strength data were analyzed with two-way ANOVA and Tukey's tests. Means (and SD) of the MPa were: GF/SA/C: 14.32 (2.84), GF/SA/M: 10.69 (2.72), GF/SA/A: 6.77 (2.17), GF/SE/C: 11.56 (4.13), GF/SE/M: 6.49 (2.54), GF/SE/A: 3.60 (1.29), FRC/SA/C: 16.89 (2.66), FRC/SA/M: 13.18 (2.19), FRC/SA/A: 8.45 (1.77), FRC/SE/C: 13.69 (3.26), FRC/SE/M: 9.58 (2.23), FRC/SE/A: 5.62 (2.12). The difference among the regions was statistically significant for all groups (p < 0.05). The self-adhesive resin cement showed better results than the self-etching resin cement when compared to each post (p < 0.05). No statistically significant differences in bond strengths of the resin cements when comparable to each post (p > 0.05). The bond strength values were significantly affected by the resin cement and the highest values were found for self-adhesive resin cement.

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A grande diversidade das atividades industriais ocasiona durante o processo produtivo a geração de resíduos sólidos, líquidos e gasosos, que podem poluir e/ou contaminar o solo, a água e o ar. Embora existam regulamentos para o descarte desses resíduos, a inobservância às regras, a ineficiência dos tratamentos despoluentes e a inoperância de órgãos fiscalizadores permitem que, ainda hoje, sejam lançados ao ambiente grandes cargas de poluentes. Isso se aplica às indústrias de alimentos de origem animal. Felizmente, a visão dos empresários do setor vem mudando, na medida em que a imagem de uma empresa que conta com produtos e processos ambientalmente responsáveis representa parte das estratégias competitivas atuais. O objetivo deste trabalho foi demonstrar como um efluente industrial pode ser transformado em matéria prima para a obtenção de um produto com valor comercial, utilizando tecnologias reconhecidas pela indústria e a atividade microbiana. O efluente foi obtido em indústria de abate e processamento de tilápias, apresentado (valores médios) pH = 9,4, DQO = 1.127 mg/L, óleos e graxas = 1.166 mg/L, nitrogênio total = 813 mg/L, coliformes a 30–35o C = 1,0x105 NMP/mL, coliformes a 45o C = 0,41 NMP/mL, bolores e leveduras = 4,6x103 UFC/mL e, ocasionalmente, contendo Salmonella sp e Aeromonas sp. Os tratamentos físicos aplicados ao efluente incluíram gradeamento, filtração (50µm) e pasteurização (65o C/30 min). O cultivo de Rubrivivax gelatinosus foi realizado sob anaerobiose em reatores de vidro durante 7 dias, em temperatura ambiente (30±5o C) e 2.000±500 lux. A recuperação da biomassa foi feita por filtração tangencial (0,2 µm; 1,5 bar), centrifugação (3.400 g/30 min; 5o C) e liofilização (-40o C) e a pulverização foi realizada manualmente. A produção de massa celular atingiu 0,18 g/L, com produtividade de 0,0634 g/L.dia. O processo promoveu redução de 52% na DQO, 48% em óleos e graxas e 22% no nitrogênio total, gerando um resíduo com pH 7,9, livre de bactérias patogênicas e, portanto, apto ao descarte. O produto obtido apresentou cor vermelho escuro (L = 22,42; C = 14,22; h = 25,48), 4,55% de umidade, 57,39% de proteína, 11,08% de extrato etéreo, 4,05% de matéria mineral, 3,03 mg/g de oxicarotenóides, 20,27 NMP/g de coliformes a 30–35o C, <1,0 NMP/g de coliformes a 45o C, 1,2x103 UFC/g de bolores e leveduras e ausência de microrganismos patogênicos. Essas características apontam para um potencial pigmentante e nutricional positivo no produto, que pode encontrar aplicação na produção animal, com segurança microbiológica. Dessa forma, fecha-se um ciclo autosustentável que pode ser adotado na própria fonte geradora do resíduo industrial, permitindo a reversão de gastos com tratamento despoluente em receitas advindas da comercialização de um novo produto.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Lapa clas Boleiras rockshelter, a Paleoamerican archaeological site in Central Brazil, was intensely occupied by humans from 10,000 C-14 BP (11.8 cal kyr BP), until approximately 7500 C-14 BP (8.4 cal kyr BP). In this paper we present some interpretations about the formation processes operating on the site. One of our main conclusions is that the bulk of accumulated sediments at the site is of anthropogenic origin: they are constituted by volumetrically significant quantities of plant ash remains, what is somewhat unexpectedly in view of prevailing models about the lifestyle of Paleoamerican hunter-gatherers in South America. The evidence we discuss below is also consistent with paleoenvironmental data that suggest a dry period during the mid-Holocene in the region, probably leading to a decrease in human occupation [Araujo, A.G.M., Neves, W., Pilo, L.B., Atui, J.P., 2005. Holocene dryness and human Occupation in Brazil during the `Archaic Gap`. Quaternary Research 64, 298-307]. We surmise that both factors underpin a surprising reduction in sediment accumulation at the site during the mid-Holocene. (C) 2008 Published by Elsevier Ltd.

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The aim of the present study was to investigate the participation of the sympathetic nervous system (SNS) in the control of glycerol-3-P (G3P) generating pathways in white adipose tissue (WAT) of rats in three situations in which the plasma insulin levels are low. WAT from 48 h fasted animals, 3 day-streptozotocin diabetic animals and high-protein, carbohydrate-free (HP) diet-fed rats was surgical denervated and the G3P generation pathways were evaluated. Food deprivation, diabetes and the HP diet provoke a marked decrease in the rate of glucose uptake and glycerokinase (GyK) activity, but a significant increase in the glyceroneogenesis, estimated by the phosphoenolpyruvate carboxykinase (PEPCK) activity and the incorporation of 1-[C-14]-pyruvate into glycerol-TAG. The denervation provokes a reduction (similar to 70%) in the NE content of WAT in fasted, diabetic and HP diet-fed rats. The denervation induced an increase in WAT glucose uptake of fed, fasted, diabetic and HP diet-fed rats (40%, 60%, 3.2 fold and 35%, respectively). TAG-glycerol synthesis from pyruvate was reduced by denervation in adipocytes of fed (58%) and fasted (36%), saline-treated (58%) and diabetic (23%), and HP diet-fed rats (11%). In these same groups the denervation reduced the PEPCK mRNA expression (75%-95%) and the PEPCK activity (35%-60%). The denervation caused a similar to 35% decrease in GyK activity of control rats and a further similar to 35% reduction in the already low enzyme activity of fasted, diabetic and HP diet-fed rats. These data suggest that the SNS plays an important role in modulating G3P generating pathways in WAT, in situations where insulin levels are low. (C) 2012 Elsevier Inc. All rights reserved.