19 research outputs found
Numerical 3D simulation of blood flow in a symmetrical stenotic artery influenced by a strong non-uniform magnetic field
No full textIn this bachelor thesis, blood flow in simplified stenosed and unstenosed arteries under influence of a steady localized non-uniform magnetic field is investigated by performing 3D numerical simulations. The mathematical model is a combination of the principles of ferrohydrodynamics (FHD), magnetohydrodynamics (MHD) and a simplified set of Amperes law and Maxwell's equations. The numerical solving is performed with a non-commercial FORTRAN77 code, based on the finite volume method with a second order central differencing scheme (CDS). The blood is modelled as an incompressible homogeneous Newtonian fluid. As a result, it is found that the magnetic field can create and influence the size of recirculations in the mainstream and also creates significantly large secondary motions. Furthermore, the wall shear stress (WSS) on the artery walls is investigated. The WSS profile shows a significantly different profile when a magnetic field is applied.Applied Science
Binaural CASA algorithm for speech source localization: Advancements in noisy and reverberant situations
No full textIn this thesis a binaural CASA localization algorithm is developed for the implementation in a binaural hearing aid with downstream speech enhancement. Two binaural CASA localization algorithms, based on the Albani model, are proposed to enhance the localization performance in noisy and reverberant acoustic environments. The Albani model is extended with a zero-lag interaural coherence (IC) time window pre-selection, detection of multiple sources per time-window, coincidence detection between interaural level and time differences (ILD and ITD) and a lagged time window comparison, in the proposed extended Albani algorithm. A further addition to the proposed extended Albani algorithm with a binaural cue selector based on an inhibition process, is proposed in the extended Albani algorithm with cue selection by inhibition. Performed simulations show that the extended Albani algorithm performs the best in noisy situations up to a SNR level of -12 dB and the extended Albani algorithm with cue selection by inhibition performs the best in reverberant situations up to a reverberation time of 2.0 s. These proposed localization algorithms show a better performance than the present known CASA methods in both noise and reverberation.Laboratory for Acoustical Imaging and Sound ControlImaging Science & TechnologyApplied Science
Author response: The nature of postural tremor in Parkinson disease
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Insights to emitter saturation current densities of boron implanted samples based on defects simulations
No full textEmitter saturation current densities, Joe have been investigated with different boron implantation dose and annealing conditions. The higher thermal budgets used here are shown experimentally to improve Joe, implying more complete defect dissolution. Simulations show that significant degradation in Joe can be attributed to the presence of dislocation loops. In addition, in cases where dislocation loops have been annealed, high dose boron implantation still results in stable boron interstitial clusters, which contributes to Joe degradation.MicroelectronicsElectrical Engineering, Mathematics and Computer Scienc
Resilience of Amazonian landscapes to agricultural intensification
No full textISBN: 978-94-6257-443-4 Author: Catarina C. Jakovac Title: Resilience of Amazonian landscapes to agricultural intensification Swidden cultivation is the traditional agricultural system in riverine Amazonia, which supports local livelihoods and transforms landscapes. In the last decades, riverine Amazonia has been undergoing important transformations related to population migration and market integration. In this study I investigated whether these socio-economic transformations could be inducing agricultural intensification and what are the consequences of such intensification for the resilience of the swidden cultivation systems in the region of the middle-Amazonas river, Brazil. This region is one of the largest producers of cassava flour (farinha in Portuguese) in the Brazilian Amazon, which is the local staple food. By combining information from field surveys, farmers interviews and remote sensing time-series, I investigated how agricultural intensification is taking place at the landscape level, and what are the consequences for secondary forests (fallows) regrowth and swiddens productivity. The results of this study show that swidden cultivation has been intensified in the last three decades, evidenced by an increase in the frequency of swidden-fallow cycles and a decrease in the length of the fallow period, from 9 to 5 years on average. I also found that agricultural intensification was associated to land accessibility and market orientation. Across the region, swiddens are dominated by a single cassava variety that is preferred by the market, reducing the possibilities for adaptation to pests outbreaks and environmental variations. At the field level, repeated swidden-fallow cycles under a short-fallow-period regime (of 5 yrs) leads to a decrease in the recovery capacity of secondary forests (reduced regrowth rate, lower species alpha- and beta-diversity, and changed species composition). Intensification also leads to a reduction in the labour productivity of swiddens (reduced cassava yield and higher weeding labour demand), and consequently in household income. I found that management-environment feedbacks play a key role in the decrease of swiddens and fallows productivity. The sprouting and persistent species favoured by cutting, burning and weeding practices are slow growing and form secondary forests with limited potential to fertilize the next cropping field and to suppress weeds. This results in a higher demand for weeding, which in itself will further favour strong-sprouting species. Such feedbacks reinforce the adverse effects of intensification on the environment and for livelihoods. Although farmers recognize thresholds for managing resilience, such as the formation of tired lands (terras cansadas in Portuguese), the combination of a low-nutrient-requiring crop, increasing farinha prices and shortage of accessible land, is encouraging farmers to keep on cultivating in already exhausted lands, and is pushing the system over such threshold. To enhance the resilience of swidden cultivation systems in the context of riverine Amazonia, management-environment feedbacks should be broken and market opportunities should be broadened beyond cassava, to include forest products that can be harvested within the swidden-fallow landscape, such as nuts, fruits and timber from fast-growing species. Thus, the proper management of secondary succession is key for assuring resilience to swidden-fallow landscapes and for promoting the integration of production and nature conservation in human modified landscapes.</p
The role of Cryptosporidium parvum-derived phospholipase in intestinal epithelial cell invasion
No full textIn the Cryptosporidium parvum-infected intestinal epithelial cell, the parasite occupies an unusual extracytoplasmic location at the luminal surface, but how the invading zoites interact with the host cell to achieve this niche is poorly understood. This study examined the role of secretory phospholipase A2 (sPLA2), a known virulence factor for several pathogenic microorganisms, in establishing C. parvum intracellularly. Initially, it was established that there was sPLA2 activity in homogenates of C. parvum oocysts. C. parvum reproduction in two human enterocyte cell lines was significantly reduced by a specific PLA inhibitor, p-bromophenacylbromide, and by sheep anti-sPLA2 antibodies developed against PLA2 of bee (Apis mellifera) venom. Treatment of either C. parvum sporozoites or enterocytes with sPLA2 derived from cobra (Naja naja) venom before initiation of infection increased the numbers of intracellular parasites. Thus, C. parvum PLA2 may play an important part in establishing the parasite within the enterocyte
Antioxidant and antimicrobial activities of a purified polysaccharide from yerba mate (Ilex paraguariensis)
No full textThis study investigated the antioxidant, antimicrobial and cytotoxic properties of a purified yerba mate polysaccharide.
The yerba mate polysaccharide showed a prominent antioxidant activity as evaluated by 2,2-diphenyl-1-
picrylhydrazyl (DPPH•)-radical scavenging activity (IC50 = 1.25 ± 0.10 mg/mL), 3-ethyl benzothiazoline-6-
sulphonic acid (ABTS•+)-radical scavenging activity (IC50 = 0.41 ± 0.05 mg/mL), and hydroxyl scavenging activity
(IC50= 3.36 ± 0.31 mg/mL). The antioxidant activity evaluated as the ferric ion reduction power (FRAP)
and oxygen radical absorbance radical assay (ORAC), expressed as trolox equivalents,were 20.84±1.61 μMTE/-
mg and 556.30± 12.83 μM TE/mg, respectively. The purified yerbamate polysaccharide presented high antimicrobial
activity against several bacterial and fungal strains; however, no cytotoxicity against all four tumor human
cell lines assessed.The authors thank the Conselho Nacional de Desenvolvimento Científico
e Tecnológico (CNPq, Proc. 3079/2015-8) for funding this study.
Author V.G. Correa thanks Coordenação de Aperfeiçoamento do Pessoal
do Ensino Superior (CAPES) for the financial support provided for their
post-graduate studies in Universidade Estadual de Maringá. R.C.G.
Corrêa thanks CAPES Foundation,Ministry of Education, Brazil (process
number 88881.120010/2016–01) for funding her postdoctoral internship
in Polytechnic Institute of Bragança. A. Bracht, R.A. Peralta and
R.M. Peralta are research grant recipients of CNPq.info:eu-repo/semantics/publishedVersio
Machine availability and productivity during timber harvester machine operator training
No full textMachine availability and timber harvest productivity in commercial forestry are influenced in part by operator performance. This work aimed to evaluate the behavior of these two variables; machine availability and productivity during the training period for the harvester operators. The study was conducted within a forestry company in Brazil. A sample of 30 individuals were trained and assessed over 11 months for their productivity and machine availability data. Monthly average data were compared using the Tukey test, in both evaluated variables. The results showed a significant difference in productivity and also in machine availability data during the training period, simultaneously presenting a productivity increase until the sixth month of operation and a decrease in machine availability. Productivity started with an average of 9 m.PMH0-1 reaching 24 m.PMH0-1 at its peak and stabilizing around 20 m.PMH0-1. Machine availability started at 84%, decreased to an average of 78%, and increased to around 88% until present. Both demonstrated a tendency towards stabilization until the ninth month of operation. The harvester operator training period influenced machine availability and productivity, with this study’s results serving as important information in support of the operational planning, staff sizing, and resources during forest harvesting machine operator training period.The presentation of the authors' names and (or) special characters in the title of the pdf file of the accepted manuscript may differ slightly from what is displayed on the item page. The information in the pdf file of the accepted manuscript reflects the original submission by the author
Transcatheter treatment of hepatocellular carcinoma with doxorubicin-loaded dc bead (DEBDOX): Technical recommendations
No full textTranarterial chemoembolization (TACE) has been established by a meta-analysis of randomized controlled trials as the standard of care for nonsurgical patients with large or multinodular noninvasive hepatocellular carcinoma (HCC) isolated to the liver and with preserved liver function. Although conventional TACE with administration of an anticancer-in-oil emulsion followed by embolic agents has been the most popular technique, the introduction of embolic drug-eluting beads has provided an alternative to lipiodol-based regimens. Experimental studies have shown that TACE with drug-eluting beads has a safe pharmacokinetic profile and results in effective tumor killing in animal models. Early clinical experiences have confirmed that drug-eluting beads provide a combined ischemic and cytotoxic effect locally with low systemic toxic exposure. Recently, the clinical value of a TACE protocol performed by using the embolic microsphere DC Bead loaded with doxorubicin (DEBDOX; drug-eluting bead doxorubicin) has been shown by randomized controlled trials. An important limitation of conventional TACE has been the inconsistency in the technique and the treatment schedules. This limitation has hampered the acceptance of TACE as a standard oncology treatment. Doxorubicin-loaded DC Bead provides levels of consistency and repeatability not available with conventional TACE and offers the opportunity to implement a standardized approach to HCC treatment. With this in mind, a panel of physicians took part in a consensus meeting held during the European Conference on Interventional Oncology in Florence, Italy, to develop a set of technical recommendations for the use of DEBDOX in HCC treatment. The conclusions of the expert panel are summarized. © 2011 The Author(s)
Teacher appraisal : the impact of observation on teachers’ classroom behaviour
No full textThis thesis is based on three English language teacher case studies located in the Middle
East where classroom discourse has been analysed in order to establish the impact that
an appraisal observer has on teachers‘ behaviour. The literature suggests that the
presence of an observer alters events in the classroom, but to date there has not been any
research into the nature of these changes which draws on transcripts of observed lessons.
Each teacher recorded a model (observed) and a pedagogic (non–observed) lesson with
similar parameters so that they could be compared, and commonalities and differences
identified. The teachers were then interviewed in order to establish their understanding
of the salient features of appraisal observations, as were three supervisors responsible for
observing teachers in similar contexts. Transcripts of the lessons were analysed using
SETT (Walsh, 2006), and the interview data was also transcribed and evaluated.
The results indicate that there are significant differences between model and pedagogic
lessons in terms of the external factors (planning, sequencing, interaction, amount of
administration, student use of L1). However, the internal factors (the features of
ongoing verbal interaction between teacher and students in the classroom) remain
fundamentally the same whether or not an observer is present, although the teacher
demonstrates greater control in a model lesson.
By analysing transcripts of classroom interaction, this research indicates what happens
in the classroom when teachers are being observed, providing data to confirm existing
claims about observer effects, and suggesting that the learner role is greater than
originally thought. The importance of observer training is identified, as well as the need
for a fundamental review of observation, encompassing all parties involved, if it is to be
a true reflection of the classroom behaviour of the teacher being observed
