RESUMO
This paper evaluates emissions to the atmosphere of biologically available nitrogen compounds in a region characterized by intensive sugar cane biofuel ethanol production. Large emissions of NH3 and NOx, as well as particulate nitrate and ammonium, occur at the harvest when the crop is burned, with the amount of nitrogen released equivalent to approximately 35% of annual fertilizer-N application. Nitrogen oxides concentrations show a positive association with fire frequency, indicating that biomass burning is a major emission source, with mean concentrations of NOx doubling in the dry season relative to the wetseason. During the dry season biomass burning is a source of NH3, with other sources (wastes, soil, biogenic) predominant during the wet season. Estimated NO2-N, NH3-N, NO3- -N and NH4+ -N emission fluxes from sugar cane burning in a planted area of ca. 2.2 x 10(6) ha are 11.0, 1.1, 0.2, and 1.2 Gg N yr(-1), respectively.
Assuntos
Poluentes Atmosféricos/análise , Fontes Geradoras de Energia , Compostos de Nitrogênio/análise , Saccharum , Agricultura , Etanol , Gerenciamento de Resíduos/métodosRESUMO
Proteus mirabilis is an important uropathogen that can cause complicated urinary tract infections (UTI). It produces several types of fimbriae, including mannose-resistant Proteus-like (MR/P) fimbriae and P. mirabilis fimbriae (PMF). Previously, we determined that these fimbriae affect the ability of P. mirabilis to colonize the urinary tract. The objective of this study was to analyse the effect of the simultaneous lack of P. mirabilis MR/P and PMF fimbriae in UTI pathogenesis. A double mutant lacking both fimbriae was generated by allelic replacement mutagenesis. This mutant was characterized genetically and phenotypically, and tested using an in vitro uroepithelial cell adhesion assay and the ascending UTI murine model. In vitro adhesion to uroepithelial cells by the P. mirabilis pmfA/mrpA-D mutant was reduced when compared with the wild-type, although no significant differences were observed when it was compared with the single mrpA-D and pmfA mutants. However, in vivo assays showed that colonization of kidneys and bladders by the P. mirabilis pmfA/mrpA-D mutant was significantly reduced when compared with the wild-type and both single mutants. These results indicate that, although redundancy can occur, MR/P and PMF fimbriae have specific and additive roles in P. mirabilis UTI.
Assuntos
Fímbrias Bacterianas/fisiologia , Manose/farmacologia , Proteus mirabilis/patogenicidade , Proteus/patogenicidade , Infecções Urinárias/etiologia , Animais , Aderência Bacteriana , Proteínas de Bactérias/fisiologia , Feminino , Camundongos , Fenótipo , VirulênciaRESUMO
The size distributed composition of ambient aerosols is used to explore seasonal differences in particle chemistry and to show that dry deposition fluxes of soluble species, including important plant nutrients, increase during periods of biomass (sugar cane trash) burning in São Paulo State, Brazil. Measurements were made at a single site centrally located in the State's sugar cane growing region but away from the immediate vicinity of burns, so that the airsampled was representative of the regional background. Calculation of ion equivalent balances showed that during burning periods smaller particles (Aitken and accumulation modes) were more acidic, containing higher concentrations of SO4(2-), oxalate, NO3-, HCOO-, CH3COO-, and CI-, but insufficient NH4+ and K+ to achieve neutrality. Larger particles showed an anion deficit due to the presence of unmeasured ions and comprised resuspended dusts modified by accumulation of nitrate, chloride, and organic anions. Increases of resuspended particles during the burning season were attributed to release of earlier deposits from the surfaces of burning vegetation as well as increased vehicle movement on unsurfaced roads. During winter months the relative contribution of combined emissions from road transport and industry diminished due to increased emissions from biomass combustion and other activities specifically associated with the harvest period. Positive increments in annual particulate dry deposition fluxes due to higher fluxes during the sugar cane harvest were 44.3% (NH4+), 42.1% (K+), 31.8% (Mg2+), 30.4% (HCOO-), 12.8% (CI-), 6.6% (CH3COO-), 5.2% (Ca2+), 3.8% (SO4(2-)), and 2.3% (NO3-). Na+ and oxalate fluxes were seasonally invariant. Annual aerosol dry deposition fluxes (kg ha(-1)) were 0.5 (Na+), 0.25 (NH4+), 0.39 (K+), 0.51 (Mg2+), 3.19 (Ca2+), 1.34 (Cl-), 4.47 (NO3-), 3.59 (SO4(2-)), 0.58 (oxalate), 0.71 (HCOO-), and 1.38 (CH3COO-). Contributions of this mechanism to combined aerosol dry deposition and precipitation scavenging (inorganic species, excluding gaseous dry deposition) were 31% (Na+), 8% (NH4+), 26% (K+), 63% (Mg2+), 66% (Ca2+), 32% (Cl-), 33% (NO3-), and 36% (SO4(2-)).
Assuntos
Aerossóis , Poluentes Atmosféricos/análise , Incineração , Agricultura , Biomassa , Brasil , Poeira , Monitoramento Ambiental , Tamanho da Partícula , Estações do AnoRESUMO
We report here on the application of a compact ultraviolet spectrometer to measurement of NO2 emissions from sugar cane field burns in São Paulo, Brazil. The time-resolved NO2 emission from a 10 ha plot peaked at about 240 g (NO2) s(-1), and amounted to a total yield of approximately 50 kg of N, or about 0.5 g (N) m(-2). Emission of N as NOx (i.e., NO + NO2) was estimated at 2.5 g (N) m(-2), equivalent to 30% of applied fertilizer nitrogen. The corresponding annual emission of NOx nitrogen from São Paulo State sugar cane burning was >45 Gg N. In contrast to mechanized harvesting, which does not require prior burning of the crop, manual harvesting with burning acts to recycle nitrogen into surface soils and ecosystems.
Assuntos
Agricultura , Poluentes Atmosféricos/análise , Dióxido de Nitrogênio/análise , Agricultura/métodos , Agricultura/estatística & dados numéricos , Brasil , Monitoramento Ambiental/métodos , Monitoramento Ambiental/estatística & dados numéricos , Incineração/métodos , Saccharum , Fumaça/análise , Espectrofotometria UltravioletaRESUMO
Proteus mirabilis expresses different types of fimbriae simultaneously. Several fimbrial types have been described and their role in the colonization of the urinary tract is under study. Previously, P. mirabilis fimbriae (PMF) have been shown to be associated with bacterial colonization of the lower urinary tract but not of the kidneys. In this study, a pmfA mutant was generated and used in several in vivo and in vitro studies. Two different urinary tract infection models in the mouse and two in vitro assays of bacterial adhesion to uroepithelial cells were performed. Expression of PmfA in a collection of P. mirabilis strains of different sources was also assessed. The results shown here indicate that PMF are involved in both bladder and kidney colonization by P. mirabilis and that these fimbriae are widely distributed among P. mirabilis isolates from different origins since all strains tested expressed PmfA.
Assuntos
Fímbrias Bacterianas/fisiologia , Rim/microbiologia , Infecções por Proteus/fisiopatologia , Proteus mirabilis/genética , Bexiga Urinária/microbiologia , Animais , Primers do DNA , Modelos Animais de Doenças , Camundongos , Mutagênese Sítio-Dirigida , Reação em Cadeia da Polimerase , Proteus mirabilis/patogenicidade , Proteus mirabilis/ultraestrutura , Virulência/genéticaRESUMO
The problem of the relationship between mind and brain is discussed as a particular case of the problem of the relationship between mind and body, itself a product which results from adoption of the Cartesian paradigm. Following the procedures of Ryle(1) we will use, as a working hypothesis, the supposition that this problem might be dissolved through careful examination of its presuppositions. A possible way of approaching the relationship between mind and body using the theory of self-organization will be outlined. Our discussion will proceed as follows: 1) History of the problem of the mind/body relationship in the Cartesian paradigm; 2) proposed solutions to the mind/brain problem and some of their limitations; 3) Ryle's proposal for a dissolution of the mind/body problem; 4) an outiline of the mind/body relationship from the perspective of self-organization theory.