723 research outputs found

    Fermentation profile and microbial population in soybean silages with inoculant and powdered molasses

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    Fermentation profile and microbial population were assessed in soybean silages without any additive (control), with inoculant (I), with I + powdered molasses (I+M), and with powdered molasses only (M). Soybean plants were harvested at the R6 stage and ensiled in 2kg-capacity laboratory silos. The additives were added to the natural matter base of silages. The assessed fermentation periods were 1, 3, 7, 14, 28, and 56 days. A 4×6 factorial arrangement (4 additives × 6 fermentation periods) in a completely randomized design with 3 replicates was used. Lactic, acetic, and butyric acids concentrations were influenced by additives and periods (P< 0.05). It was observed higher lactic acid values to control silages, on the 56 th day. Lower average values of acetic and butyric acids were observed to I+M and M silages. It was observed quadratic effect to pH values with a reduction estimated of 0.5504, 0.5358, 0.6312 and 0.6680 units to pH values to control, I, I+M, and M silages in the first 10 days. A maximum lactic acid bacteria population was observed at the 28 th day of fermentation in silages with inoculant. The inoculant and powdered molasses improve the fermentation profile of soybean silages

    In silico mechano-chemical model of bone healing for the regeneration of critical defects: The effect of BMP-2

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    The healing of bone defects is a challenge for both tissue engineering and modern ortho- paedics. This problem has been addressed through the study of scaffold constructs com- bined with mechanoregulatory theories, disregarding the influence of chemical factors and their respective delivery devices. Of the chemical factors involved in the bone healing pro- cess, bone morphogenetic protein-2 (BMP-2) has been identified as one of the most power- ful osteoinductive proteins. The aim of this work is to develop and validate a mechano- chemical regulatory model to study the effect of BMP-2 on the healing of large bone defects in silico. We first collected a range of quantitative experimental data from the literature con- cerning the effects of BMP-2 on cellular activity, specifically proliferation, migration, differen- tiation, maturation and extracellular matrix production. These data were then used to define a model governed by mechano-chemical stimuli to simulate the healing of large bone de- fects under the following conditions: natural healing, an empty hydrogel implanted in the de- fect and a hydrogel soaked with BMP-2 implanted in the defect. For the latter condition, successful defect healing was predicted, in agreement with previous in vivo experiments. Further in vivo comparisons showed the potential of the model, which accurately predicted bone tissue formation during healing, bone tissue distribution across the defect and the quantity of bone inside the defect. The proposed mechano-chemical model also estimated the effect of BMP-2 on cells and the evolution of healing in large bone defects. This novel in silico tool provides valuable insight for bone tissue regeneration strategies

    Computational model of mesenchymal migration in 3D under chemotaxis

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    Cell chemotaxis is an important characteristic of cellular migration, which takes part in crucial aspects of life and development. In this work, we propose a novel in silico model of mesenchymal 3D migration with competing protrusions under a chemotactic gradient. Based on recent experimental observations, we identify three main stages that can regulate mesenchymal chemotaxis: chemosensing, dendritic protrusion dynamics and cell–matrix interactions. Therefore, each of these features is considered as a different module of the main regulatory computational algorithm. The numerical model was particularized for the case of fibroblast chemotaxis under a PDGF-bb gradient. Fibroblasts migration was simulated embedded in two different 3D matrices – collagen and fibrin – and under several PDGF-bb concentrations. Validation of the model results was provided through qualitative and quantitative comparison with in vitro studies. Our numerical predictions of cell trajectories and speeds were within the measured in vitro ranges in both collagen and fibrin matrices. Although in fibrin, the migration speed of fibroblasts is very low, because fibrin is a stiffer and more entangling matrix. Testing PDGF-bb concentrations, we noticed that an increment of this factor produces a speed increment. At 1 ng mL-1 a speed peak is reached after which the migration speed diminishes again. Moreover, we observed that fibrin exerts a dampening behavior on migration, significantly affecting the migration efficiency

    Massive lower gastrointestinal bleeding from idiopathic ileocolonic varix: report of a case

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    Dis Colon Rectum. 2006 Apr;49(4):524-6. Massive lower gastrointestinal bleeding from idiopathic ileocolonic varix: report of a case. Lopes LM, Ramada JM, Certo MG, Pereira PR, Soares JM, Ribeiro M, Areias J, Pinho C. SourceGastroenterology Department, Hospital Geral Santo António, Porto, Portugal. [email protected] Abstract Idiopathic varices of the entire colon are very rare. We report on a 64-year-old patient with massive lower gastrointestinal hemorrhage from an extensive ileocolonic varix. Diagnosis was established by colonoscopy. The patient underwent an emergency ileocolectomy with satisfactory results. This rare case shows the importance of colonoscopy in the evaluation of patients with lower gastrointestinal hemorrhage and reminds us that sometimes the diagnosis is not what we expect. Recognition of this abnormality is important because varices may be the cause of massive lower gastrointestinal hemorrhage. PMID: 16395635 [PubMed - indexed for MEDLINE

    Widespread hybridization between Invasive bleak (Alburnus alburnus) and Iberian chub (Squalius spp.): A neglected conservation threat

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    Hybridization between native and nonnative fish species is a major conservation issue, especially in ecosystems with high levels of endemism, such as Iberian streams. To date, hybridization with the invasive bleak Alburnus alburnus has been reported for the Iberian chub Squalius alburnoides and S. pyrenaicus and in scattered locations only. However, the bleak is spreading in the region, potentially increasing the risks of hybridization with other Squalius species. To gather a more comprehensive picture on the current geography of hybridization, we compiled records on hybrids between bleak and chub in Portugal and conducted genetical assessments of hybrids between bleak and S. carolitertii. We found that hybridization with bleak is widespread throughout Portuguese river basins and involves at least S. alburnoides, S. pyrenaicus and S. carolitertii. Hybridization with bleak may not only cause waste of reproductive effort and damage the genetic integrity of these endemic species but also promote shifts in the reproductive dynamics of the S. alburnoides hybrid complex, which includes individuals with various ploidy levels and combinations of parental genomes, reproducing sexually and asexually. We recommend that future studies characterize the fitness of bleak hybrids and their ecological and genetic interactions with native fish, in order to design effective conservation measures

    Peixes

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    Os peixes sao organismos aquaticos que associamosde imediato aos rios, mas sobre os quais existe aindamuito desconhecimento. Neste capitulo damos a conhecer asespecies que existem em Portugal, como estao distribuidasno nosso territorio, que fatores ambientais determinam a suaocorrencia, que comportamentos exibem, que ameacas pairamsobre as suas populacoes, ou como podem ser utilizadoscomo sentinelas para monitorizar o estado ecologico dos rios.Sao ainda descritas as principais caracteristicas dos habitatsdulciaquicolas portugueses e das associacoes piscicolas que neles ocorrem, e discutidos quais os principais fatores ambientaisque terao contribuido para a distribuicao das especiesno nosso territorio. Face as pressoes de natureza antropica aque estao sujeitos, e dado destaque aos principais fatores deameaca a conservacao dos peixes dulciaquicolas e migradores,e as medidas de mitigacao mais adequadas a sua proteção

    Inflationary perturbation theory is geometrical optics in phase space

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    A pressing problem in comparing inflationary models with observation is the accurate calculation of correlation functions. One approach is to evolve them using ordinary differential equations ("transport equations"), analogous to the Schwinger-Dyson hierarchy of in-out quantum field theory. We extend this approach to the complete set of momentum space correlation functions. A formal solution can be obtained using raytracing techniques adapted from geometrical optics. We reformulate inflationary perturbation theory in this language, and show that raytracing reproduces the familiar "delta N" Taylor expansion. Our method produces ordinary differential equations which allow the Taylor coefficients to be computed efficiently. We use raytracing methods to express the gauge transformation between field fluctuations and the curvature perturbation, zeta, in geometrical terms. Using these results we give a compact expression for the nonlinear gauge-transform part of fNL in terms of the principal curvatures of uniform energy-density hypersurfaces in field space.Comment: 22 pages, plus bibliography and appendix. v2: minor changes, matches version published in JCA

    Effect of titanium tetrafluoride and amine fluoride treatment combined with carbon dioxide laser irradiation on enamel and dentin erosion

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    OBJECTIVE: This in vitro study aimed to analyze the influence of carbon dioxide (CO(2)) laser irradiation on the efficacy of titanium tetrafluoride (TiF(4)) and amine fluoride (AmF) in protecting enamel and dentin against erosion. METHODS: Bovine enamel and dentin samples were pretreated with carbon dioxide (CO(2)) laser irradiation only (group I), TiF(4) only (1% F, group II), CO(2) laser irradiation before (group III) or through (group IV) TiF(4) application, AmF only (1% F, group V), or CO(2) laser irradiation before (group VI) or through (group VII) AmF application. Controls remained untreated. Ten samples of each group were then subjected to an erosive demineralization and remineralization cycling for 5 days. Enamel and dentin loss were measured profilometrically after pretreatment, 4 cycles (1 day), and 20 cycles (5 days) and statistically analyzed using analysis of variance and Scheffe's post hoc tests. Scanning electron microscopy (SEM) analysis was performed in pretreated but not cycled samples (two samples each group). RESULTS: After 20 cycles, there was significantly less enamel loss in groups V and IV and significantly less dentin loss in group V only. All other groups were not significantly different from the controls. Lased surfaces (group I) appeared unchanged in the SEM images, although SEM images of enamel but not of dentin showed that CO(2) laser irradiation affected the formation of fluoride precipitates. CONCLUSION: AmF decreased enamel and dentin erosion, but CO(2) laser irradiation did not improve its efficacy. TiF(4) showed only a limited capacity to prevent erosion, but CO(2) laser irradiation significantly enhanced its ability to reduce enamel erosion

    Review of the underpass alocation on the highway SP-225, Brotas-SP, Brazil, and the relationship with wild animals roadkills and landscape structure

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    The Road Ecology theme is new in Brazil and in Latin America in \ud general. Few studies and scientific publications were made in this area \ud with specific and replicable methodology. Underpasses were allocated on \ud the highway SP- 225, in the year of 2008, according to previous studies of \ud hotspots of roadkills made by IBAMA (Environmental Brazilian Institute), \ud but none of them considered the influence of the landscape structure on \ud the surrounding habitat. So, we aimed to analyze and understand which \ud component of the landscape structure can influence the roadkills in a \ud Brazilian highway and analyze if these underpasses was located in areas \ud of hotspots roadkills. Medium and large mammals carcasses were \ud collected by Centrovias (a private enterprise that managed the road) from \ud May 2005 to June 2006 in 56 km stretch on the highway SP- 225 in the \ud 110 \ud city of Brotas, São Paulo, Brazil. Were created occurrences reports for \ud each roadkilled animal containing: date, time, local on the highway (km + \ud m), geographic coordinate and the specie affected. Forest-patch metrics \ud (number of fragments, proportion of forest and size of the largest pacth) \ud were extracted from a 2008 CBERS 2B-CCD image using Fragstats \ud (version 3.3) to examine the best predictor to medium and large \ud mammals roadkills. Following a visual classification three land cover \ud classes were mapped (forest, non-forest and water) and 13 buffers zones \ud with 5 km were selected around the highway SP-225. An exploratory data \ud analysis was conducted through the Pearson‟s correlation and 6 models (1 \ud null model) were built to conduct a model selection procedure based on \ud the AICc value. There were 48 medium and large mammals roadkills on \ud the 56 stretch sampled between May 2005 and June 2006. The best model \ud selected to predict medium and large mammals roadkills on the SP- 225, \ud was the proportion of forest (wAICc = 0.97) on the 5 km surrounding \ud habitat. From 13 buffer zones analyzed, 4 presented the highest number \ud of roadkills (mean = 21.75, sd = 2.21) and the highest proportion of \ud forest (mean = 24.17, sd = 2.34), so the higher the proportion of forest, \ud higher will be the number of roadkills. In two of these buffer zones were \ud allocated an appropriate number of underpasses. In all the buffer zones \ud we had roadkills occurrence, but in three of them none underpass was \ud allocated. Despite the fact that there is a low number of roadkills in these \ud buffers (range: 2-4) the presence of at least one underpass will be \ud necessary to avoid these roadkills. The others buffers also had a low \ud number of roadkills (range: 4-6) but there are almost the same number of \ud underpasses allocated in the buffers zones with the higher number of \ud roadkills. The number of roadkills is strictly related to the proportion of \ud forest in the surrounding habitat, so we highlight the importance of the \ud landscape structure to predict the occurrence of medium size and large \ud bodied mammals roadkills and the use of this tool to allocate underpasses \ud in future road ecology studies
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