717 research outputs found
Towards multifunctional landscapes coupling low carbon feed and bioenergy production with restorative agriculture: Economic deployment potential of grass-based biorefineries
Grass-based biomass from grasslands can be used as feedstock in green biorefineries (GBs) that produce a range of biobased products. In addition, adjustments made as part of crop rotation to increase areas under temporary grasslands can yield benefits such as carbon sequestration, increased soil productivity, reduced eutrophication and reduced need for pesticides. In this paper, a flexible modeling framework is developed to analyze the deployment options for GBs that use grassâclover to produce protein feed and feedstock for bioenergy. The focus is placed on optimal deployment, considering system configuration and operation, as well as land use changes designed to increase grassâclover cultivation on cropland. A case study involving 17 counties in Sweden showed that the deployment of GB systems could support biomethane and protein feed production corresponding to 5â60 and 13â154%, respectively, of biomethane and soybean feed imports to Sweden in 2020
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Molecular characterization of the stomach microbiota in patients with gastric cancer and controls
Persistent infection of the gastric mucosa by Helicobacter pylori, can initiate an inflammatory cascade that progresses into atrophic gastritis, a condition associated with reduced capacity for secretion of gastric acid and an increased risk in developing gastric cancer. The role of H. pylori as an initiator of inflammation is evident but the mechanism for development into gastric cancer has not yet been proven. A reduced capacity for gastric acid secretion allows survival and proliferation of other microbes that normally are killed by the acidic environment. It has been postulated that some of these species may be involved in the development of gastric cancer, however their identities are poorly defined. In this study, the gastric microbiota from ten patients with gastric cancer was characterized and compared with five dyspeptic controls using the molecular profiling approach, terminal-restriction fragment length polymorphism (T-RFLP), in combination with 16S rRNA gene cloning and sequencing. T-RFLP analysis revealed a complex bacterial community in the cancer patients that was not significantly different from the controls. Sequencing of 140 clones revealed 102 phylotypes, with representatives from five bacterial phyla (Firmicutes, Bacteroidetes, Proteobacteria, Actinobacteria and Fusobacteria). The data revealed a relatively low abundance of H. pylori and showed that the gastric cancer microbiota was instead dominated by different species of the genera Streptococcus, Lactobacillus, Veillonella and Prevotella. The respective role of these species in development of gastric cancer remains to be determined
Gene conversion in human rearranged immunoglobulin genes
Over the past 20 years, many DNA sequences have been published suggesting that all or part of the V<sub>H</sub> segment of a rearranged immunoglobulin gene may be replaced in vivo. Two different mechanisms appear to be operating. One of these is very similar to primary V(D)J recombination, involving the RAG proteins acting upon recombination signal sequences, and this has recently been proven to occur. Other sequences, many of which show partial V<sub>H</sub> replacements with no addition of untemplated nucleotides at the V<sub>H</sub>âV<sub>H</sub> joint, have been proposed to occur by an unusual RAG-mediated recombination with the formation of hybrid (coding-to-signal) joints. These appear to occur in cells already undergoing somatic hypermutation in which, some authors are convinced, RAG genes are silenced. We recently proposed that the latter type of V<sub>H</sub> replacement might occur by homologous recombination initiated by the activity of AID (activation-induced cytidine deaminase), which is essential for somatic hypermutation and gene conversion. The latter has been observed in other species, but not in human Ig genes, so far. In this paper, we present a new analysis of sequences published as examples of the second type of rearrangement. This not only shows that AID recognition motifs occur in recombination regions but also that some sequences show replacement of central sections by a sequence from another gene, similar to gene conversion in the immunoglobulin genes of other species. These observations support the proposal that this type of rearrangement is likely to be AID-mediated rather than RAG-mediated and is consistent with gene conversion
The variable functional effects of the pacing site in normal and scarred ventricles
The pacing site has been shown to influence functional improvement with cardiac resynchronization therapy. We evaluated the effects of the pacing site on left ventricular (LV) function in an animal model.
Equilibrium radionuclide angiography was acquired in sinus rhythm (NSR) and with ventricular pacing, from three pacing sites in seven normal and eight infarcted dogs. QRS duration, electrical activation pattern, wall motion, LV ejection fraction (EF), synchrony of ventricular contraction, and mean arterial pressure (MAP), were related to the pacing site and infarct size, during each of 120 episodes. Little changed during pacing in normals. In infarcted dogs, LV wall motion, and synchrony worsened, LVEF and MAP often fell. These changes related to altered activation patterns which were influenced by the pacing site but were not related to infarct size.
Hemodynamic and functional LV changes after infarction were found to vary with the pacing site and associated conduction and synchrony
Common variation at 12q24.13 (OAS3) influences chronic lymphocytic leukemia risk
Common variation at 12q24.13 (OAS3) influences chronic lymphocytic leukemia ris
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