37 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
No full textItem does not contain fulltext1 p
Chemical composition, nutritional value, and biological evaluation of tunisian okra pods (abelmoschus esculentus L. moench)
No full textThe aim of this work was to perform an unprecedented in-depth study on the bioactive phytochemicals of Abelmoschus esculentus L. Moench Tunisian landrace (Marsaouia). For this purpose, its nutritional, aroma volatile, and phenolic profiles were characterized, and sundry biological activities were assessed in vitro. The approximate composition revealed that total dietary fiber as the most abundant macronutrient, mainly insoluble dietary fiber, followed by total carbohydrates and proteins. In addition, okra pods were rich in K, Ca, Mg, organic acids, tocopherols, and chlorophylls. Gas Chromatography-Electron Impact Mass Spectrometry (GC-EIMS) analysis showed that oxygenated monoterpenes, sesquiterpene hydrocarbons, and phenylpropanoids were the predominant essential volatile components in A. esculentus pods. A total of eight flavonols were detected by High-Performance Liquid Chromatography coupled to a DAD detector and mass spectrometry by electrospray ionization (HPLC-DAD-MS/ESI); with quercetin-3-O-glucoside being the majority phenolic component, followed by quercetin-O-pentosyl-hexoside and quercetin-dihexoside. This pioneering study, evidences that Tunisian okra display promising antioxidant and cytotoxic actions, in addition to relevant inhibitory effects against α-amylase and α-glucosidase enzymes, and interesting analgesic activity.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) for financial
support through national funds FCT/MCTES to CIMO (UIDB/00690/2020); National funding by FCT, P.I., through
the institutional scientific employment program-contract for L. Barros and M.I. Dias contract; to FEDER-Interreg
España-Portugal programme for financial support through the project 0377_Iberphenol_6_E. and to ALIMNOVA
UCM Research group (Reference 951505) and OTRI UCM-F Sabor y Salud (252-2017) project. R.C.G. Corrêa is a
research grant recipient of Cesumar Institute of Science Technology and Innovation (ICETI).info:eu-repo/semantics/publishedVersio
Cerebral pathological and compensatory mechanisms in the premotor phase of leucine-rich repeat kinase 2 parkinsonism
No full textContains fulltext :
102362.pdf (Publisher’s version ) (Open Access)Compensatory cerebral mechanisms can delay motor symptom onset in Parkinson's disease. We aim to characterize these compensatory mechanisms and early disease-related changes by quantifying movement-related cerebral function in subjects at significantly increased risk of developing Parkinson's disease, namely carriers of a leucine-rich repeat kinase 2-G2019S mutation associated with dominantly inherited parkinsonism. Functional magnetic resonance imaging was used to examine cerebral activity evoked during internal selection of motor representations, a core motor deficit in clinically overt Parkinson's disease. Thirty-nine healthy first-degree relatives of Ashkenazi Jewish patients with Parkinson's disease, who carry the leucine-rich repeat kinase 2-G2019S mutation, participated in this study. Twenty-one carriers of the leucine-rich repeat kinase 2-G2019S mutation and 18 non-carriers of this mutation were engaged in a motor imagery task (laterality judgements of left or right hands) known to be sensitive to motor control parameters. Behavioural performance of both groups was matched. Mutation carriers and non-carriers were equally sensitive to the extent and biomechanical constraints of the imagined movements in relation to the current posture of the participants' hands. Cerebral activity differed between groups, such that leucine-rich repeat kinase 2-G2019S carriers had reduced imagery-related activity in the right caudate nucleus and increased activity in the right dorsal premotor cortex. More severe striatal impairment was associated with stronger effective connectivity between the right dorsal premotor cortex and the right extrastriate body area. These findings suggest that altered movement-related activity in the caudate nuclei of leucine-rich repeat kinase 2-G2019S carriers might remain behaviourally latent by virtue of cortical compensatory mechanisms involving long-range connectivity between the dorsal premotor cortex and posterior sensory regions. These functional cerebral changes open the possibility to use a prospective study to test their relevance as early markers of Parkinson's disease.12 p
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
Farmers’ preferences for methods of receiving information on new farming practices: a study based on paddy cultivation
No full textThe paddy farmers are one of largest population in Sri Lankan agricultural sector.
Ampara is the predominant district for paddy cultivation where majority of farmers are struggling to
obtain accurate and reliable information on time. Therefore, the study is designed to describe
information seeking behavior and information access methods of the paddy farmers. A conceptual
model was developed based on the literature for the study. The empirical data were collected from
randomly selected 110 farmers representing from 11 divisional secretariats divisions in the
Ampara district. They were critically analyzed. The demographic characters such as age,
educational level, farming experience and farm land ownership influence the paddy farmers’
information needs and the information access methods. Not a single farmer is identified as none
information seeker for paddy cultivation practices and a farmer needs information on at least a
single cultivation practices. Information rich farmers in all cultivation practices obtain higher yield. It
is true, by considering cultivation practices as individually. On field demonstration and video
demonstration are the higher preference for information access methods. Field trip, group
discussion and guest speaker or consultants are the second preferential methods. Publication and
workshop are identified as third prefer methods. Web or electronic information, home study and
practical short courses are the least preference methods for information access for the paddy
farmers
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
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
