As pastagens e seu manejo no Centro-Sul do Brasil

Although the cattle industry of south-central Brazil is of great importance to the economy of the country and the nutrition of the people, present pasture practices have only short term viability. The continuing decrease in productivity of pasture lands has led to consideration of legumes and fertilization to satisfy the primary need for nitrogen. Both alternatives are examined and in conclusion the establishment of legumes is economically viable depending on site conditions and distance from market. Adequate provisions for seasonal shortages, and the establishment of rotational grazing systems are also essential.A indústria pecuária do centro-sul brasileiro constitui importante contribuição para a economia nacional e para a alimentação das populações. Contudo, percebe-se que os atuais métodos de pastoreio não podem continuar por muito tempo. A produtividade das pastagens vem diminuindo constantemente; e isso levou a pensar no uso das leguminosas e na fertilização das terras, para suprir a necessidade primária de nitrogênio. Ambas as alternativas foram examinadas, concluindo-se que o estabelecimento de leguminosas é economicamente viável, dependendo das condições da localização e distância do mercado; mas é necessário também fazer provisões para os períodos de escassez, bem como implantar o sistema da rotatividade dos pastos

Survival of Escherichia coli on onion during field curing and packout.

The Food and Drug administration has expressed concern that Onions (Allium cepa) irrigated with water contaminated with high rates of Escherichia coli could harbor E. coli on their surface or interior. On the other hand, since onions contain antimicrobial compounds and field conditions may not be conducive to E. coli survival, the E. coli population on the surface of onions might become negligible through the course of field curing. Further, the relationship between the E. coli in the irrigation water to the E. coli on onion bulbs after field curing, harvest, and packout has not been studied. To determine if E. coli should be of concern in onion production, we sought to measure the die-off of E. coli on onions between the last irrigation and harvest and the presence of E. coli on onions after packout. Well water was tested and had no E. coli; ditch water intentionally run across a pasture prior to use had 218 to > 2400 MPN of E. coli/100ml. Onions were sampled from those furrow irrigated (ditch water) and those drip irrigated (well water) starting at lifting 3 September 2013 for four consecutive weeks. At 0 and 28 days after lifting, both interior and exterior of the onions were tested for E. coli. At 7, 14, and 21 days after lifting, only the exterior of the onions was tested. None of the onions contained E. coli internally at 0 or 28 days after lifting. At lifting E. coli was present on the exterior of both the drip and furrow irrigated onions and seemed to be largely unrelated to the irrigation water. The exterior E. coli contamination decreased rapidly after lifting. After harvest and packout on 14 October 2013, no E. coli was detected on the onion bulb exteriors from either irrigation treatment. E. coli introduced into the onion field through furrow irrigation was not present on or in the packed out onion bulbs

Movement of Escherichia coli in soil as applied in irrigation water.

The US Food and Drug Administration (FDA) has proposed that If irrigation water exceeds 235 colony-forming units (CFU) of E. coli /100 ml in any one sample or 126 CFU/100 ml in the average of any five consecutive samples, growers would have to cease using that water in any way that directly contacts the surface of fresh produce (FDA 2013). The FDA has proposed that these E. coli levels are an indication of high risk of bacterial contamination of fresh onion (Allium cepa L.) bulbs regardless of the irrigation system. If onion irrigation exceeds 235 CFU, it is not known whether the contaminated water applied by furrow or drip irrigation actually reaches the onion bulb. Soil could filter E. coli and other bacteria before irrigation water reaches onion bulbs. ?Vaquero? onions were grown on Owyhee silt loam. In our preliminary studies reported here, well water free of E. coli was applied to onions through drip irrigation or through furrow irrigation. A second water source was intentionally enriched with E. coli by being run across a pasture and recaptured prior to use. Furrow and drip irrigation were used to apply this water containing 218 to >2400 MPN/100ml for 11+ hours per irrigation. E. coli was monitored in the soil water at the end of irrigation cycles through direct sampling of the soil. Soil water was also sampled using sterile soil solution capsules (SSSC) to sample E. coli in the soil water that moved into place, to differentiate the movement of soil water from the soil water already in place. Soil water measurements were made adjacent to the water source, half way to the bulbs, and immediately adjacent to the onion bulbs. For furrow irrigation with ditch water the E. coli counts in the soil next to the onion bulbs was only 0% and 21% of the counts in the irrigation water following the first and second irrigations, respectively. During subsequent furrow irrigations, the E. coli counts in the soil water next to the onion bulbs exceeded the counts in the irrigation water. For drip irrigation with ditch water, the E. coli counts in the soil solution next to the onion bulbs remained very low. The soil water sampled by the SSSC adjacent to the onion bulbs drip-irrigated with ditch water also had very low E. coli counts

Gene expression differs in susceptible and resistant amphibians exposed to Batrachochytrium dendrobatidis.

Chytridiomycosis, the disease caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), has devastated global amphibian biodiversity. Nevertheless, some hosts avoid disease after Bd exposure even as others experience near-complete extirpation. It remains unclear whether the amphibian adaptive immune system plays a role in Bd defence. Here, we describe gene expression in two host species-one susceptible to chytridiomycosis and one resistant-following exposure to two Bd isolates that differ in virulence. Susceptible wood frogs (Rana sylvatica) had high infection loads and mortality when exposed to the more virulent Bd isolate but lower infection loads and no fatal disease when exposed to the less virulent isolate. Resistant American bullfrogs (R. catesbeiana) had high survival across treatments and rapidly cleared Bd infection or avoided infection entirely. We found widespread upregulation of adaptive immune genes and downregulation of important metabolic and cellular maintenance components in wood frogs after Bd exposure, whereas American bullfrogs showed little gene expression change and no evidence of an adaptive immune response. Wood frog responses suggest that adaptive immune defences may be ineffective against virulent Bd isolates that can cause rapid physiological dysfunction. By contrast, American bullfrogs exhibited robust resistance to Bd that is likely attributable, at least in part, to their continued upkeep of metabolic and skin integrity pathways as well as greater antimicrobial peptide expression compared to wood frogs, regardless of exposure. Greater understanding of these defences will ultimately help conservationists manage chytridiomycosis

Canonical Coordinates and Meson Spectra for Scalar Deformed N=4 SYM from the AdS/CFT Correspondence

Five supersymmetric scalar deformations of the AdS_5xS^5 geometry are investigated. By switching on condensates for the scalars in the N=4 multiplet with a form which preserves a subgroup of the original R-symmetry, disk and sphere configurations of D3-branes are formed in the dual supergravity background. The analytic, canonical metric for each geometry is formulated and the singularity structure is studied. Quarks are introduced into two of the corresponding field theories using D7-brane probes and the pseudoscalar meson spectrum is calculated. For one of the condensate configurations, a mass gap is found and shown analytically to be present in the massless limit. It is also found that there is a stepped spectrum with eigenstate degeneracy in the limit of small quark masses. In the case of a second, similar deformation, it is necessary to understand the full D3-D7 brane interaction to study the limit of small quark masses. It is seen that simple solutions to the equations of motion for the other three geometries are unlikely to exist.Comment: 16 pages, 7 figures, references added, typos correcte

Simulated filtration pond to remove Escherichia coli from irrigation water.

The United States Food and Drug Administration?s (FDA) proposed water rules to implement the Food Safety Modernization Act (FSMA) could leave some growers, especially those who rely on an irrigation system based on recycled water, unable to irrigate fresh produce with their irrigation water, especially those who rely on an irrigation system based on recycled water. Irrigation water could be treated with chlorine, ozone, or other product to reduce the bacterial load in the water; however, at present not one of these options has been approved by the Environmental Protection Agency for treating irrigation water. In an attempt to reduce the number of bacteria present in irrigation water entering a farm, a simulated filter pond was constructed using gravel, sand, and silt-loam soil. The filter pond sought to utilize in part what occurs naturally with the filtration of water through the soil profile. This natural process provides clean water in wells and aquifers. The simulated pond reduced the Escherichia coli load in water by 95% with a flow rate of 3.9 gal/h/yd2. In order to increase the water productivity of the simulated filter pond, most of the dirt was removed; subsequently the E. coli filtration rate went to 55% and 46%, with flow rates of 12.9 gal/h/yd2 and 17.6 gal/h/yd2, respectively

Three Flavour QCD from the Holographic Principle

Building on recent research into five-dimensional holographic models of QCD, we extend this work by including the strange quark with an SU(3)_L\times SU(3)_R gauge symmetry in the five-dimensional theory. In addition we deform the naive $AdS$ metric with a single parameter, thereby breaking the conformal symmetry at low energies. The vector and axial vector sectors are studied in detail and both the masses and decay constants are calculated with the additional parameters. It is shown that with a single extra degree of freedom, exceptional agreement with experimental results can be obtained in the light quark sector while the kaon sector is found to give around 10% agreement with lattice results. We propose some simple extensions to this work to be taken up in future research.Comment: 9 pages, 1 figure, references adde

A metastable equilibrium model for the relative abundances of microbial phyla in a hot spring

Many studies link the compositions of microbial communities to their environments, but the energetics of organism-specific biomass synthesis as a function of geochemical variables has rarely been assessed. We describe a thermodynamic model that integrates geochemical and metagenomic data for biofilms sampled at five sites along a thermal and chemical gradient in the outflow channel of the hot spring known as ‘‘Bison Pool’’ in Yellowstone National Park. The relative abundances of major phyla in individual communities sampled along the outflow channel are modeled by computing metastable equilibrium among model proteins with amino acid compositions derived from metagenomic sequences. Geochemical conditions are represented by temperature and activities of basis species, including pH and oxidation-reduction potential quantified as the activity of dissolved hydrogen. By adjusting the activity of hydrogen, the model can be tuned to closely approximate the relative abundances of the phyla observed in the community profiles generated from BLAST assignments. The findings reveal an inverse relationship between the energy demand to form the proteins at equal thermodynamic activities and the abundance of phyla in the community.Although the metabolisms used by many members of these communities are driven by chemical disequilibria, the results support the possibility that higher-level patterns of chemotrophic microbial ecosystems are shaped by metastable equilibrium states that depend on both the composition of biomass and the environmental conditions

Insights into the Conformation of Aminofluorene-Deoxyguanine Adduct in a DNA Polymerase Active Site

The active site conformation of the mutagenic fluoroaminofluorene-deoxyguanine adduct (dG-FAF, N-(2′-deoxyguanosin-8-yl)-7-fluoro-2-aminofluorene) has been investigated in the presence of Klenow fragment of Escherichia coli DNA polymerase I (Kfexo−) and DNA polymerase β (pol β) using 19F NMR, insertion assay, and surface plasmon resonance. In a single nucleotide gap, the dG-FAF adduct adopts both a major-groove- oriented and base-displaced stacked conformation, and this heterogeneity is retained upon binding pol β. The addition of a non-hydrolysable 2′-deoxycytosine-5′-[(α,β)-methyleno]triphosphate (dCMPcPP) nucleotide analog to the binary complex results in an increase of the major groove conformation of the adduct at the expense of the stacked conformation. Similar results were obtained with the addition of an incorrect dAMPcPP analog but with formation of the minor groove binding conformer. In contrast, dG-FAF adduct at the replication fork for the Kfexo− complex adopts a mix of the major and minor groove conformers with minimal effect upon the addition of non-hydrolysable nucleotides. For pol β, the insertion of dCTP was preferred opposite the dG-FAF adduct in a single nucleotide gap assay consistent with 19F NMR data. Surface plasmon resonance binding kinetics revealed that pol β binds tightly with DNA in the presence of correct dCTP, but the adduct weakens binding with no nucleotide specificity. These results provide molecular insights into the DNA binding characteristics of FAF in the active site of DNA polymerases and the role of DNA structure and sequence on its coding potential

A note on conductivity and charge diffusion in holographic flavour systems

We analyze the charge diffusion and conductivity in a Dp/Dq holographic setup that is dual to a supersymmetric Yang-Mills theory in p+1 dimensions with N_f<< N_c flavour degrees of freedom at finite temperature and nonvanishing U(1) baryon number chemical potential. We provide a new derivation of the results that generalize the membrane paradigm to the present context. We perform a numerical analysis in the particular case of the D3/D7 flavor system. The results obtained support the validity of the Einstein relation at finite chemical potential.Comment: 15 pages, 3 figures, v2 with minor correction