915 research outputs found
Damage dissipation and localization during fatigue in unidirectional glass/carbon fibre hybrid composites
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Effects of plant polyphenols and mannan-oligosaccharides on growth performance, antioxidant defense system and inflammatory responses of ileal mucosa in Escherichia coli Challenged piglets
No full textThe objective of the current study was to evaluate the possible protective effects of nutritional supplements (plant polyphenols (PP) mixture containing anthocyanin, catechins, chlorgenic and oleuropein as active ingredients, mannan oligosaccharide (MOS) and PP+MOS) on growth performance, systemic antioxidant capacity and gut health in piglets under Escherichia coli challenged condition. Ninety six weanling piglets (Stambo HBI Dalland 40) (22-d-old) were homogenously allocated to 24 pens and fed a basal diet for one week. After the adaptation period, piglets were divided into 4 treatments (6 replicates with 4 piglets per treatment) and fed a basal diet or the basal diet supplemented with 0.1% of PP, MOS or PP+MOS for 6 weeks. At 21 and 25 d, half of the piglets in each treatment were orally inoculated with 4 ml of E.coli (1×109cfu/ml) or same amount of saline water. Plasma samples collected at 7, 21, 25, 27 and 34 d and ileac mucosa samples prepared at 25 and 27 d were determined for antioxidative property and intestinal inflammatory responsive parameters. Dietary PP+MOS worsened the feed efficiency throughout the experiment. Compared to PP+MOS treatment, control group had better feed conversion ratio (FCR) during first two weeks, dietary MOS improved feed efficiency during 7 - 14 d, 0 - 34 d and 0 - 42 d, and dietary PP decreased FCR throughout the trial. Supplementation of PP markedly enhanced the systemic antioxidant property with higher total antioxidant capacity and lower malondialchehyche content compared to control or PP+MOS treatment at 21 d. At 4 d post infection (DPI), challenge didn’t affect antioxidant capacity, dietary PP or MOS increased plasma GSH-Px activity. Increased plasma Malondialdehyde content, decreased plasma total antioxidant capacity (TAOC) and catalase (CAT) activity were observed at 6 DPI. Reduced TAOC were seen in challenged piglets, dietary PP or MOS increased TAOC compared to PP+MOS diet, dietary PP or PP+MOS increased CAT activity than basal or MOS diet at 13 DPI. Challenged increased plasma ceruloplasmin at 4 and 6 DPI, dietary PP or PP+MOS decreased ceruloplasmin compared to basal diet at 6 DPI. Increased ileac activities of inducible nitric oxide synthase (iNOS) and myeloperoxidase (MPO) as well as nitric oxide (NO) production were observed in challenged piglets at 4 and 6 DPI. At 6 DPI, Dietary PP significantly inhibited the elevation of MPO activity and iNOS activity as well as NO production due to challenge. The overall results demonstrated that nutritional supplementation PP improved growth performance and dietary PP or MOS improved feed efficiency in presence of E.coli challenge. Dietary PP or MOS had the potential to improve the antioxidant property, and dietary PP favorably modulated gut mucosa inflammatory response induced by E.coli infection. Dietary combination of PP and MOS did not show effects and even was adverse to growth performance probably due to some unclear interactions between PP and MOS that warranted further research
Effect of a post-weaning diet supplemented with functional feed additives on ileal transcriptome activity and serum cytokines in piglets challenged with polysaccharide
No full texttThis study evaluated the potential of a weanling diet supplemented with trace minerals, vitamins, pre-biotics, essential oils, antioxidants and bovine colostrum (BC) to modulate the inflammatory responseof low-weight (LW) and high-weight (HW) piglets challenged with lipopolysaccharide (LPS). At wean-ing (20 ± 1 d), litters from 32 sows were assigned to four groups: control diet (CTL), CTL plus dietarysupplements (DS) or the antibiotic chlortetracycline (ATB), or DS plus BC in place of plasma proteinsin the weanling diet (DS + BC). At 37 d (T0), two LW and two HW piglets were bled to evaluate ex vivocytokine production by LPS activated peripheral blood mononuclear cells (PBMCs). In parallel, LW andHW piglets received intraperitoneal LPS and were bled at slaughter at 4 h (T4) or 18 h (T18) post-injection.Ileal tissues from these piglets and two unchallenged medium weight (MW) piglets per treatment wereexcised and analyzed by microarray. At T0, cytokine production of LPS-activated PBMCs was not affectedby dietary treatments. At T4 after LPS challenge, serum concentrations of TNF-, IL-6, IL-8, and IL-10were increased in all piglets (P < 0.01). Interestingly, the LW piglets had a higher TNF- level than theHW piglets did (P = 0.05). Dietary treatments had no effect on the piglet serum concentration of thesecytokines neither at T4 nor at T18. Microarray data and QPCR analysis reveal that several genes weredifferentially expressed in the LPS-challenged piglets in comparison with the two control MW piglets(P < 0.001). However, the dietary treatments had a slight effect on the ileal gene expression of the T4 andT18 LPS-challenged piglets when all piglets were included in the analysis. But when body weight (LW andHW) was considered as a fixed effect, the microarray analysis showed that the expression of 54 genes wasdifferentially modulated by the dietary treatments in the T4 and T18 LPS-challenged LW piglets (P < 0.05)while in HW piglets no difference was observed. QPCR analyses confirm that the level expression of sev-eral genes was reduced in LW piglets fed DS or DS + BC diet compared with ATB piglets. In conclusion, LPSchallenge induced a transitional inflammation in weanling piglets that was characterized by increasedblood-circulating cytokines and gut transcriptome activity. Results also suggest that the weanling dietsupplemented with feed additives attenuated the ileal gene response to the LPS challenge, an effect thatwas more pronounced in the LW piglets
Combined imaging and velocity estimation by Joint Migration Inversion
No full textSeismic imaging projects aim to reveal the structure of the earths crust from seismic data. These projects typically include three separate processing steps, being: \u95 attenuation of multiple reflections in the seismic data. \u95 estimating seismic wave propagation velocities from the seismic data. \u95 mapping the measured reflection data to the proper subsurface location by migration. In this thesis, we present a novel approach termed Joint Migration Inversion (JMI) that combines the estimation of seismic wave propagation velocities with the migration of seismic data. Additionally, JMI is capable of using multiple reflections to improve its velocity estimates and migration results, effectively removing the need to suppress multiple reflections in the seismic data. Joint Migration Inversion is posed as an inverse problem that solves for the subsurface parameters of reflectivity and velocity. This means that we use a forward model, termed Full Wavefield Modelling, that synthesizes seismic data based on a reflectivity model and a velocity model. We then we update the reflectivity model and velocity model until the synthesized data accurately matches the measured seismic data. Because Full Wavefield Modeling accounts for the nonlinear relationship between wavefields and reflectivity, leading to transmission effects and multiple scattering, the inversion scheme will automatically use these nonlinearities to optimise its reflectivity estimates as well as its velocity estimates. To update the reflectivity and velocity models JMI uses a gradient descent scheme, which is an iterative local optimisation algorithm. This thesis demonstrates the feasibility of Joint Migration Inversion by applying it to several numerically generated datasets, showcasing its ability to estimate kinematically accurate velocity models and to image the subsurface accurately in the presence of strong internal multiples and complex subsurface structures. We discuss the robustness of JMI, showing why we feel that the method will not suffer from cycle-skipping and that it will give accurate results given a wide variety of starting models. Finally, we present a case study where JMI is applied to a 2D section of a field dataset, showing the pre-processing steps required for a successful inversion and showing that JMI performs well on field data.Imaging PhysicsApplied Science
Transparency in actions on requirements
No full textThe combination between agile software engineering and distributed engineering is gaining a growing interest. Combining these however creates an interesting paradox. Where agile clearly states that documentation is not the most important thing, from the field of globally distributed engineering a higher focus on documentation is observed. In this thesis the field of requirements engineering is also taken into the mix. Combining these three a user-story model is defined to take advantage of the, on first sight, downside of working distributed. The fact that face-to-face communication is not possible means that all the communication has to be done using technological support and thus that this communication can be saved. This premise gives an interesting opportunity to keep track of the actions that are taken on user-stories as a result of a conversation. By saving the conversation and coupling the action to parts of that conversation.Software EngineeringComputer ScienceElectrical Engineering, Mathematics and Computer Scienc
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