Search results for: existential values
2234 Socio-Motor Experience between Affectivity and Movement from Harry Potter to Lord of the Rings
Authors: Manuela Gamba, Niki Mandolesi
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Teenagers today have little knowledge about how to move or play together. The adults who are part of sports culture must find an effective way to foster this essential ability. Our research in Italy uses a 'holistic model' based on fantasy literature to explore the relationships between the game identities and self-identities of young people and the achievement of psycho-motor, emotional and social well-being in the realms of sport and education. Physical activity projects were carried out in schools and extra-curricular associations in Rome, combining outdoor activities and distance learning. This holistic and malleable game model is inspired by fantasy accounts of the journeys taken in The Lord of Rings and Harry Potter books. We know that many have a lot of resistance to the idea of using fantasy and play as a pedagogical tool, but the results obtained in this experience are surprising. Our interventions and investigations focused on promoting self-esteem, awareness, a sense of belonging, social integration, cooperation, well-being, and informed decision making: a basis for healthy and effective citizenship. For teenagers, creative thinking is the right stimulus to involve and compare the story of characters to their own journey through social and self-reflective identity analysis. We observed how important it is to engage students emotionally as well as cognitively and that enabling them to play with identity through relationships with peers. There is a need today for a multidisciplinary synthesis of analog and digital values, especially in response to recent distance-living experiences. There is a need for a global reconceptualization of free time and nature in the human experience.Keywords: awareness, creativity, identity, play
Procedia PDF Downloads 1902233 Shelf Life of Frozen Processed Foods for Extended Durability
Authors: Manfreda Gerardo, Pasquali Frederique, Pepe Tiziana, Anastasio Aniello, Ianieri Adriana
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The aim of the research was to evaluate the shelf life of a REPFED’s product (lasagna alla bolognese), developed as a product to be marketed fresh after defrosting. Three different samples were prepared: A, B and C, which presented differences in relation to the recipe, pasteurization technique and packaging on which the trend of the shelf-life indicator parameters was evaluated during a period of prolonged shelf life. The analytical plan involved the measurement of microbiological, chemical-physical and organoleptic parameters over 7 moments of storage selected in a period of 33 days. CBT, LAB, enterobacteria, E. coli, yeasts, molds, S. coagulase positive, B. cereus, Salmonella spp and L. monocytogenes, pH, Aw, Kreiss test, peroxides, atmosphere inside the packages, and organoleptic characteristics were determined. The results demonstrated the effect of post-packaging pasteurization on the shelf life of fresh from frozen products. However, the products pasteurized at 95°C in the absence of steam showed microbiological parameters that were not appropriate for an extended shelf life of up to 60 days. On the contrary, the samples pasteurized at 98°C with steam saturation and counterpressure showed values compatible with an extended shelf life. The results of the chemical-physical analyses highlighted how recipe and packaging affect the chemical-physical and organoleptic parameters. In conclusion, this preliminary study confirmed the effectiveness of post-packaging pasteurization treatments aimed at extending the shelf life of the product, helping the food company to occupy market niches even very distant from the production sites.Keywords: shelf life, REPFED’s product, extended durability, pasteurization
Procedia PDF Downloads 282232 Design and Development of Constant Stress Composite Cantilever Beam
Authors: Vinod B. Suryawanshi, Ajit D. Kelkar
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Glass fiber reinforced composites materials, due their unique properties such as high mechanical strength to weight ratio, corrosion resistance, and impact resistance have huge potential as structural materials in automotive, construction and transportation applications. However, these properties often come at higher cost owing to complex design methods, difficult manufacturing processes and raw material cost. In this paper, a cost effective design and manufacturing approach for a composite cantilever beam structure is presented. A constant stress (variable cross section) beam concept has been used to design and optimize the shape of composite cantilever beam and thus obtain the reduction in material used. The variable cross section beam was fabricated from the glass epoxy prepregs using cost effective out of autoclave process. The drop ply technique has been successfully used to obtain the variation in the cross section along the span of the beam. In order to test the beam and validate the design, the beam was subjected to different end loads. Strain gauges were mounted along the length of the beam to obtain strains in the beam at different sections and loads. The strain values were used to calculate the flexural strength and bending stresses in the beam. The stresses obtained through strain measurements from the experiment were found to be uniform along the span of the beam, and thus validates the design. Finally, the finite element model for the constant stress beam was developed using commercial finite element simulation software. It was observed that the simulation results agreed very well with the experimental results.Keywords: beams, composites, constant cross-section, structures
Procedia PDF Downloads 3492231 Development of Method for Recovery of Nickel from Aqueous Solution Using 2-Hydroxy-5-Nonyl- Acetophenone Oxime Impregnated on Activated Charcoal
Authors: A. O. Adebayo, G. A. Idowu, F. Odegbemi
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Investigations on the recovery of nickel from aqueous solution using 2-hydroxy-5-nonyl- acetophenone oxime (LIX-84I) impregnated on activated charcoal was carried out. The LIX-84I was impregnated onto the pores of dried activated charcoal by dry method and optimum conditions for different equilibrium parameters (pH, adsorbent dosage, extractant concentration, agitation time and temperature) were determined using a simulated solution of nickel. The kinetics and adsorption isotherm studies were also evaluated. It was observed that the efficiency of recovery with LIX-84I impregnated on charcoal was dependent on the pH of the aqueous solution as there was little or no recovery at pH below 4. However, as the pH was raised, percentage recovery increases and peaked at pH 5.0. The recovery was found to increase with temperature up to 60ºC. Also it was observed that nickel adsorbed onto the loaded charcoal best at a lower concentration (0.1M) of the extractant when compared with higher concentrations. Similarly, a moderately low dosage (1 g) of the adsorbent showed better recovery than larger dosages. These optimum conditions were used to recover nickel from the leachate of Ni-MH batteries dissolved with sulphuric acid, and a 99.6% recovery was attained. Adsorption isotherm studies showed that the equilibrium data fitted best to Temkin model, with a negative value of constant, b (-1.017 J/mol) and a high correlation coefficient, R² of 0.9913. Kinetic studies showed that the adsorption process followed a pseudo-second order model. Thermodynamic parameter values (∆G⁰, ∆H⁰, and ∆S⁰) showed that the adsorption was endothermic and spontaneous. The impregnated charcoal appreciably recovered nickel using a relatively smaller volume of extractant than what is required in solvent extraction. Desorption studies showed that the loaded charcoal is reusable for three times, and so might be economical for nickel recovery from waste battery.Keywords: charcoal, impregnated, LIX-84I, nickel, recovery
Procedia PDF Downloads 1512230 Analysis of Exploitation Damages of the Frame Scaffolding
Authors: A. Robak, M. Pieńko, E. Błazik-Borowa, J. Bęc, I. Szer
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The analyzes and classifications presented in the article were based on the research carried out in year 2016 and 2017 on a group of nearly one hundred scaffoldings assembled and used on construction sites in different parts of Poland. During scaffolding selection process efforts were made to maintain diversification in terms of parameters such as scaffolding size, investment size, type of investment, location and nature of conducted works. This resulted in the research being carried out on scaffoldings used for church renovation in a small town or attached to the facades of classic apartment blocks, as well as on scaffoldings used during construction of skyscrapers or facilities of the largest power plants. This variety allows to formulate general conclusions about the technical condition of used frame scaffoldings. Exploitation damages of the frame scaffolding elements were divided into three groups. The first group includes damages to the main structural components, which reduce the strength of the scaffolding elements and hence the whole structure. The qualitative analysis of these damages was made on the basis of numerical models that take into account the geometry of the damage and on the basis of computational nonlinear static analyzes. The second group focuses on exploitation damages such as the lack of a pin on the guardrail bolt which may cause an imminent threat to people using scaffolding. These are local damages that do not affect the bearing capacity and stability of the whole structure but are very important for safe use. The last group consider damages that reduce only aesthetic values and do not have direct impact on bearing capacity and safety of use. Apart from qualitative analyzes the article will present quantitative analyzes showing how frequently given type of damage occurs.Keywords: scaffolding, damage, safety, numerical analysis
Procedia PDF Downloads 2592229 Distribution of Gamma-Radiation Levels in Core Sediment Samples in Gulf of İzmir, Eastern Aegean Sea, Turkey
Authors: D. Kurt, İ. F. Barut, Z. Ü. Yümün, E. Kam
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After development of the industrial revolution, industrial plants and settlements have spread widely on the sea coasts. This concentration also brings environmental pollution in the sea. This study focuses on the Gulf of İzmir where is located in West of Turkey and it is a fascinating natural gulf of the Eastern Aegean Sea. Investigating marine current sediment is extremely important to detect pollution. Natural radionuclides’ pollution of the marine environment which is also known as a significant environmental anxiety. Ground drilling cores (the depth of each sediment is variant) were collected from the Gulf of İzmir’s four different locations which were Karşıyaka, İnciraltı, Çeşmealtı and Bayraklı. These sediment cores were put in preserving bags with weight around 1 kg, and they were dried at room temperature in a week for moisture removal. Then, they were sieved with 1 mm sieve holes, and finally these powdered samples were relocation to polyethylene Marinelli beakers of 100 ml versions. Each prepared sediment was waited to reach radioactive equilibrium between uranium and thorium for 40 days. Gamma spectrometry measurements were settled using a HPG (High- Purity Germanium) semiconductor detector. Semiconductor detectors are very good at separating power of the energy, they are easily able to differentiate peaks that are pretty close to each other. That is why, gamma spectroscopy’s usage is common for the determination of the activities of U - 238, Th - 232, Ra - 226, Cr - 137 and K - 40 in Bq kg⁻¹. In this study, the results display that the average concentrations of activities’ values are in respectively; 2.2 ± 1.5 Bq/ kg⁻¹, 0.98 ± 0.02 Bq/ kg⁻¹, 8 ± 0.96 Bq/ kg⁻¹, 0.93 ± 0.14 Bq/ kg⁻¹, and 76.05 ± 0.93 Bq/ kg⁻¹. The outcomes of the study are able to be used as a criterion for forthcoming research and the obtained data would be pragmatic for radiological mapping of the precise areas.Keywords: gamma, Gulf of İzmir (Eastern Aegean Sea-Turkey), natural radionuclides, pollution
Procedia PDF Downloads 2582228 Biodiversity and Climate Change: Consequences for Norway Spruce Mountain Forests in Slovakia
Authors: Jozef Mindas, Jaroslav Skvarenina, Jana Skvareninova
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Study of the effects of climate change on Norway Spruce (Picea abies) forests has mainly focused on the diversity of tree species diversity of tree species as a result of the ability of species to tolerate temperature and moisture changes as well as some effects of disturbance regime changes. The tree species’ diversity changes in spruce forests due to climate change have been analyzed via gap model. Forest gap model is a dynamic model for calculation basic characteristics of individual forest trees. Input ecological data for model calculations have been taken from the permanent research plots located in primeval forests in mountainous regions in Slovakia. The results of regional scenarios of the climatic change for the territory of Slovakia have been used, from which the values are according to the CGCM3.1 (global) model, KNMI and MPI (regional) models. Model results for conditions of the climate change scenarios suggest a shift of the upper forest limit to the region of the present subalpine zone, in supramontane zone. N. spruce representation will decrease at the expense of beech and precious broadleaved species (Acer sp., Sorbus sp., Fraxinus sp.). The most significant tree species diversity changes have been identified for the upper tree line and current belt of dwarf pine (Pinus mugo) occurrence. The results have been also discussed in relation to most important disturbances (wind storms, snow and ice storms) and phenological changes which consequences are little known. Special discussion is focused on biomass production changes in relation to carbon storage diversity in different carbon pools.Keywords: biodiversity, climate change, Norway spruce forests, gap model
Procedia PDF Downloads 2882227 Research on the Aeration Systems’ Efficiency of a Lab-Scale Wastewater Treatment Plant
Authors: Oliver Marunțălu, Elena Elisabeta Manea, Lăcrămioara Diana Robescu, Mihai Necșoiu, Gheorghe Lăzăroiu, Dana Andreya Bondrea
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In order to obtain efficient pollutants removal in small-scale wastewater treatment plants, uniform water flow has to be achieved. The experimental setup, designed for treating high-load wastewater (leachate), consists of two aerobic biological reactors and a lamellar settler. Both biological tanks were aerated by using three different types of aeration systems - perforated pipes, membrane air diffusers and tube ceramic diffusers. The possibility of homogenizing the water mass with each of the air diffusion systems was evaluated comparatively. The oxygen concentration was determined by optical sensors with data logging. The experimental data was analyzed comparatively for all three different air dispersion systems aiming to identify the oxygen concentration variation during different operational conditions. The Oxygenation Capacity was calculated for each of the three systems and used as performance and selection parameter. The global mass transfer coefficients were also evaluated as important tools in designing the aeration system. Even though using the tubular porous diffusers leads to higher oxygen concentration compared to the perforated pipe system (which provides medium-sized bubbles in the aqueous solution), it doesn’t achieve the threshold limit of 80% oxygen saturation in less than 30 minutes. The study has shown that the optimal solution for the studied configuration was the radial air diffusers which ensure an oxygen saturation of 80% in 20 minutes. An increment of the values was identified when the air flow was increased.Keywords: flow, aeration, bioreactor, oxygen concentration
Procedia PDF Downloads 3892226 Design of Bacterial Pathogens Identification System Based on Scattering of Laser Beam Light and Classification of Binned Plots
Authors: Mubashir Hussain, Mu Lv, Xiaohan Dong, Zhiyang Li, Bin Liu, Nongyue He
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Detection and classification of microbes have a vast range of applications in biomedical engineering especially in detection, characterization, and quantification of bacterial contaminants. For identification of pathogens, different techniques are emerging in the field of biomedical engineering. Latest technology uses light scattering, capable of identifying different pathogens without any need for biochemical processing. Bacterial Pathogens Identification System (BPIS) which uses a laser beam, passes through the sample and light scatters off. An assembly of photodetectors surrounded by the sample at different angles to detect the scattering of light. The algorithm of the system consists of two parts: (a) Library files, and (b) Comparator. Library files contain data of known species of bacterial microbes in the form of binned plots, while comparator compares data of unknown sample with library files. Using collected data of unknown bacterial species, highest voltage values stored in the form of peaks and arranged in 3D histograms to find the frequency of occurrence. Resulting data compared with library files of known bacterial species. If sample data matching with any library file of known bacterial species, sample identified as a matched microbe. An experiment performed to identify three different bacteria particles: Enterococcus faecalis, Pseudomonas aeruginosa, and Escherichia coli. By applying algorithm using library files of given samples, results were compromising. This system is potentially applicable to several biomedical areas, especially those related to cell morphology.Keywords: microbial identification, laser scattering, peak identification, binned plots classification
Procedia PDF Downloads 1502225 The Effect of Neurocognitive Exercise Program on ADHD Symptoms, Attention, and Dynamic Balance in Medication Naive Children with ADHD: A Pilot Study
Authors: Nurullah Buker, Ezgi Karagoz, Yesim Salik Sengul, Sevay Alsen Guney, Gokhan Yoyler, Aylin Ozbek
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Attention Deficit Hyperactivity Disorder (ADHD) is one of the most common neurodevelopmental disorders with heterogeneous clinical features such as inattention, hyperactivity, and impulsivity. Many different types of exercise interventions were employed for children with ADHD. However, previous studies have usually examined the effects of non-specific exercise programs or short-term effects of exercise. The aim of this study is to investigate the effect of the Neurocognitive Exercise Program (NEP), which is a structured exercise program derived from Life Kinetik, and a relatively new for children with ADHD, on symptoms, attention, and dynamic balance in medication-naïve children with ADHD. Fourteen medication-naive children (7-12 years) with ADHD were included in the intervention group. NEP was performed once a week for ten weeks. The intervention group also performed a structured home exercise program for another six days, for ten weeks. The children in the intervention group were assessed at baseline, in the third month, in the sixth month, and in the twelfth month regarding ADHD-related symptoms, attention, and dynamic balance. Fifteen age-matched typically developing children were assessed once for establishing normative values. Hyperactivity-Impulsivity score and dynamic balance were found to improve after NEP in the ADHD group in the 3rd month (p<0.05). In addition, these results were similar for both groups after NEP and at the end of the 12th month (p>0.05). The NEP may provide beneficial effects on hyperactivity-impulsivity, oppositional defiant, and dynamic balance in children with ADHD, and the improvements may be maintained in the long term.Keywords: ADHD, attention problems, dynamic balance, neurocognitive exercise
Procedia PDF Downloads 812224 Clouds Influence on Atmospheric Ozone from GOME-2 Satellite Measurements
Authors: S. M. Samkeyat Shohan
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This study is mainly focused on the determination and analysis of the photolysis rate of atmospheric, specifically tropospheric, ozone as function of cloud properties through-out the year 2007. The observational basis for ozone concentrations and cloud properties are the measurement data set of the Global Ozone Monitoring Experiment-2 (GOME-2) sensor on board the polar orbiting Metop-A satellite. Two different spectral ranges are used; ozone total column are calculated from the wavelength window 325 – 335 nm, while cloud properties, such as cloud top height (CTH) and cloud optical thick-ness (COT) are derived from the absorption band of molecular oxygen centered at 761 nm. Cloud fraction (CF) is derived from measurements in the ultraviolet, visible and near-infrared range of GOME-2. First, ozone concentrations above clouds are derived from ozone total columns, subtracting the contribution of stratospheric ozone and filtering those satellite measurements which have thin and low clouds. Then, the values of ozone photolysis derived from observations are compared with theoretical modeled results, in the latitudinal belt 5˚N-5˚S and 20˚N - 20˚S, as function of CF and COT. In general, good agreement is found between the data and the model, proving both the quality of the space-borne ozone and cloud properties as well as the modeling theory of ozone photolysis rate. The found discrepancies can, however, amount to approximately 15%. Latitudinal seasonal changes of photolysis rate of ozone are found to be negatively correlated to changes in upper-tropospheric ozone concentrations only in the autumn and summer months within the northern and southern tropical belts, respectively. This fact points to the entangled roles of temperature and nitrogen oxides in the ozone production, which are superimposed on its sole photolysis induced by thick and high clouds in the tropics.Keywords: cloud properties, photolysis rate, stratospheric ozone, tropospheric ozone
Procedia PDF Downloads 2112223 Evaluating Cyanide Biodegradation by Bacteria Isolated from Gold Mine Effluents in Bulawayo, Zimbabwe
Authors: Ngonidzashe Mangoma, Caroline Marigold Sebata
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The release of cyanide-rich effluents from gold mines, and other industries, into the environment, is a global concern considering the well-known metabolic effects of cyanide in all forms of life. Such effluents need to be treated to remove cyanide, among other pollutants, before their disposal. This study aimed at investigating the possible use of bacteria in the biological removal of cyanide from cyanide-rich effluents. Firstly, cyanide-degrading bacteria were isolated from gold mine effluents and characterised. The isolates were then tested for their ability to grow in the presence of cyanide and their tolerance to increasing levels of the compound. To evaluate each isolate’s cyanide-degrading activities, isolates were grown in the simulated and actual effluent, and a titrimetric method was used to quantify residual cyanide over a number of days. Cyanide degradation efficiency (DE) was then calculated for each isolate. Identification of positive isolates involved 16S rRNA gene amplification and sequence analysis through BLAST. Six cyanide-utilising bacterial strains were isolated. Two of the isolates were identified as Klebsiella spp. while the other two were shown to be different strains of Clostridium bifermentans. All isolates showed normal growth in the presence of cyanide, with growth being inhibited at 700 mg/L cyanide and beyond. Cyanide degradation efficiency for all isolates in the simulated effluent ranged from 79% to 97%. All isolates were able to remove cyanide from actual gold mine effluent with very high DE values (90 – 94%) being recorded. Isolates obtained in this study were able to efficiently remove cyanide from both simulated and actual effluent. This observation clearly demonstrates the feasibility of the biological removal of cyanide from cyanide-rich gold mine effluents and should, therefore, motivate research towards the possible large-scale application of this technology.Keywords: cyanide effluent, bioremediation, Clostridium bifermentans, Klebsiella spp, environment
Procedia PDF Downloads 1782222 Effect of Depth on Texture Features of Ultrasound Images
Authors: M. A. Alqahtani, D. P. Coleman, N. D. Pugh, L. D. M. Nokes
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In diagnostic ultrasound, the echo graphic B-scan texture is an important area of investigation since it can be analyzed to characterize the histological state of internal tissues. An important factor requiring consideration when evaluating ultrasonic tissue texture is the depth. The effect of attenuation with depth of ultrasound, the size of the region of interest, gain, and dynamic range are important variables to consider as they can influence the analysis of texture features. These sources of variability have to be considered carefully when evaluating image texture as different settings might influence the resultant image. The aim of this study is to investigate the effect of depth on the texture features in-vivo using a 3D ultrasound probe. The left leg medial head of the gastrocnemius muscle of 10 healthy subjects were scanned. Two regions A and B were defined at different depth within the gastrocnemius muscle boundary. The size of both ROI’s was 280*20 pixels and the distance between region A and B was kept constant at 5 mm. Texture parameters include gray level, variance, skewness, kurtosis, co-occurrence matrix; run length matrix, gradient, autoregressive (AR) model and wavelet transform were extracted from the images. The paired t –test was used to test the depth effect for the normally distributed data and the Wilcoxon–Mann-Whitney test was used for the non-normally distributed data. The gray level, variance, and run length matrix were significantly lowered when the depth increased. The other texture parameters showed similar values at different depth. All the texture parameters showed no significant difference between depths A and B (p > 0.05) except for gray level, variance and run length matrix (p < 0.05). This indicates that gray level, variance, and run length matrix are depth dependent.Keywords: ultrasound image, texture parameters, computational biology, biomedical engineering
Procedia PDF Downloads 2962221 Trading off Accuracy for Speed in Powerdrill
Authors: Filip Buruiana, Alexander Hall, Reimar Hofmann, Thomas Hofmann, Silviu Ganceanu, Alexandru Tudorica
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In-memory column-stores make interactive analysis feasible for many big data scenarios. PowerDrill is a system used internally at Google for exploration in logs data. Even though it is a highly parallelized column-store and uses in memory caching, interactive response times cannot be achieved for all datasets (note that it is common to analyze data with 50 billion records in PowerDrill). In this paper, we investigate two orthogonal approaches to optimize performance at the expense of an acceptable loss of accuracy. Both approaches can be implemented as outer wrappers around existing database engines and so they should be easily applicable to other systems. For the first optimization we show that memory is the limiting factor in executing queries at speed and therefore explore possibilities to improve memory efficiency. We adapt some of the theory behind data sketches to reduce the size of particularly expensive fields in our largest tables by a factor of 4.5 when compared to a standard compression algorithm. This saves 37% of the overall memory in PowerDrill and introduces a 0.4% relative error in the 90th percentile for results of queries with the expensive fields. We additionally evaluate the effects of using sampling on accuracy and propose a simple heuristic for annotating individual result-values as accurate (or not). Based on measurements of user behavior in our real production system, we show that these estimates are essential for interpreting intermediate results before final results are available. For a large set of queries this effectively brings down the 95th latency percentile from 30 to 4 seconds.Keywords: big data, in-memory column-store, high-performance SQL queries, approximate SQL queries
Procedia PDF Downloads 2592220 Relationships of Driver Drowsiness and Sleep-Disordered Breathing Syndrome
Authors: Cheng-Yu Tsai, Wen-Te Liu, Yin-Tzu Lin, Chen-Chen Lo, Kang Lo
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Background: Driving drowsiness related to inadequate or disordered sleep accounts for a major percentage of traffic accidents. Sleep-disordered breathing (SDB) syndrome is a common respiratory disorder during sleep. However, the effects of SDB syndrome on driving fatigue remain unclear. Objective: This study aims to investigate the relationship between SDB pattern and driving drowsiness. Methodologies: The physical condition while driving was obtained from the questionnaires to classify the state of driving fatigue. SDB syndrome was quantified as the polysomnography, and the air flow pattern was collected by the thermistor and nasal pressure cannula. To evaluate the desaturation, the mean hourly number of greater than 3% dips in oxygen saturation was sentenced by reregistered technologist during examination in a hospital in New Taipei City (Taiwan). The independent T-test was used to investigate the correlations between sleep disorders related index and driving drowsiness. Results: There were 880 subjects recruited in this study, who had been done polysomnography for evaluating severity for obstructive sleep apnea syndrome (OSAS) as well as completed the driver condition questionnaire. Four-hundred-eighty-four subjects (55%) were classified as fatigue group, and 396 subjects (45%) were served as the control group. Significantly higher values of snoring index (242.14 ± 205.51 /hours) were observed in the fatigue group (p < 0.01). The value of respiratory disturbance index (RDI) (31.82 ± 19.34 /hours) in fatigue group were significantly higher than the control group (p < 0.01). Conclusion: We observe the considerable association between SDB syndrome and driving drowsiness. To promote traffic safety, SDB syndrome should be controlled and alleviated.Keywords: driving drowsiness, sleep-disordered breathing syndrome, snoring index, respiratory disturbance index.
Procedia PDF Downloads 1402219 Relation between Biochemical Parameters and Bone Density in Postmenopausal Women with Osteoporosis
Authors: Shokouh Momeni, Mohammad Reza Salamat, Ali Asghar Rastegari
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Background: Osteoporosis is the most prevalent metabolic bone disease in postmenopausal women associated with reduced bone mass and increased bone fracture. Measuring bone density in the lumbar spine and hip is a reliable measure of bone mass and can therefore specify the risk of fracture. Dual-energy X-ray absorptiometry(DXA) is an accurate non-invasive system measuring the bone density, with low margin of error and no complications. The present study aimed to investigate the relationship between biochemical parameters with bone density in postmenopausal women. Materials and methods: This cross-sectional study was conducted on 87 postmenopausal women referred to osteoporosis centers in Isfahan. Bone density was measured in the spine and hip area using DXA system. Serum levels of calcium, phosphorus, alkaline phosphatase and magnesium were measured by autoanalyzer and serum levels of vitamin D were measured by high-performance liquid chromatography(HPLC). Results: The mean parameters of calcium, phosphorus, alkaline phosphatase, vitamin D and magnesium did not show a significant difference between the two groups(P-value>0.05). In the control group, the relationship between alkaline phosphatase and BMC and BA in the spine was significant with a correlation coefficient of -0.402 and 0.258, respectively(P-value<0.05) and BMD and T-score in the femoral neck area showed a direct and significant relationship with phosphorus(Correlation=0.368; P-value=0.038). There was a significant relationship between the Z-score with calcium(Correlation=0.358; P-value=0.044). Conclusion: There was no significant relationship between the values of calcium, phosphorus, alkaline phosphatase, vitamin D and magnesium parameters and bone density (spine and hip) in postmenopausKeywords: osteoporosis, menopause, bone mineral density, vitamin d, calcium, magnesium, alkaline phosphatase, phosphorus
Procedia PDF Downloads 1762218 Impact of Mixed Prey Population on Predation Potential and Food Preference of a Predaceous Ladybird, Coccinella septempunctata
Authors: Ahmad Pervez
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We investigated predation potential and food preference of different life stages of a predaceous ladybird Coccinella septempunctata L. (Coleptera: Coccinellidae) using a nutritive food (mustard aphid, Lipaphis erysimi) and a toxic food (cabbage aphid, Brevicoryne brassicae). We gave monotypic prey, L. erysimi, then B. brassicae to all life stages and found that second, third and fourth instars and adult female C. septempunctata daily consumed greater number of former prey. However, the first instar and the adult male equally consumed both the prey. In choice condition, each larva, adult male and female consumed mixed aphid diet separately in three proportions (i.e. low: high, equal: equal and high: low densities of L. erysimi: B. brassicae). We hypothesized that life stages of C. septempunctata will prefer L. erysimi regardless of its proportions. Laboratory experiment supported this hypothesis only at the adult level showing high values of β and C preference indices. However, it rejects this hypothesis at the larval level, as larvae preferred B. brassicae in certain combinations and showed no preference in a few combinations. We infer that mixing of nutritive diet in a toxic diet may possibly overcome the probable nutritive deficiency and/or reduces the toxicity of toxic diet, especially to the larvae of C. septempunctata. Consumption of high proportion of B. brassicae mixed with fewer L. erysimi suggests that mixed diet could be better for the development of immature stages of C. septempunctata.Keywords: Coccinella septempunctata, predatory potential, prey preference, Lipaphis erysimi, Brevicoryne brassicae
Procedia PDF Downloads 1962217 Reinforced Concrete Foundation for Turbine Generators
Authors: Siddhartha Bhattacharya
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Steam Turbine-Generators (STG) and Combustion Turbine-Generator (CTG) are used in almost all modern petrochemical, LNG plants and power plant facilities. The reinforced concrete table top foundations are required to support these high speed rotating heavy machineries and is one of the most critical and challenging structures on any industrial project. The paper illustrates through a practical example, the step by step procedure adopted in designing a table top foundation supported on piles for a steam turbine generator with operating speed of 60 Hz. Finite element model of a table top foundation is generated in ANSYS. Piles are modeled as springs-damper elements (COMBIN14). Basic loads are adopted in analysis and design of the foundation based on the vendor requirements, industry standards, and relevant ASCE & ACI codal provisions. Static serviceability checks are performed with the help of Misalignment Tolerance Matrix (MTM) method in which the percentage of misalignment at a given bearing due to displacement at another bearing is calculated and kept within the stipulated criteria by the vendor so that the machine rotor can sustain the stresses developed due to this misalignment. Dynamic serviceability checks are performed through modal and forced vibration analysis where the foundation is checked for resonance and allowable amplitudes, as stipulated by the machine manufacturer. Reinforced concrete design of the foundation is performed by calculating the axial force, bending moment and shear at each of the critical sections. These values are calculated through area integral of the element stresses at these critical locations. Design is done as per ACI 318-05.Keywords: steam turbine generator foundation, finite element, static analysis, dynamic analysis
Procedia PDF Downloads 2952216 Implications of Dehusking and Aqueous Soaking on Anti-nutrients, Phytochemical Screening and Antioxidants Properties of Jack Beans (Canavalia Ensiformis L. DC)
Authors: Oseni Margaret Oladunni, Ogundele Joan Olayinka, Olusanya Olalekan Samuel, Akinniyi Modupe Olakintan
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The world's growing population is pushing humans to look for alternative food sources among underutilised or wild plants. One of these food sources has been identified as Canavalia enisiformis, or jack beans. The only issue with using jack beans is that they contain anti-nutrient chemicals, which must be removed or diminished in order for them to be fit for human consumption. The objective of this study is to determine the nutritional and industrial utility of Canavalia enisiformis by analysing the anti-nutrient, phytochemical, and antioxidant composition of raw whole seed and soaking dehusked seeds using established procedures. Phytate (23.48±0.24, 15.24±0.41 and 14.83±0.00), oxalate (4.32±0.09, 3.96±0.09 and 2.88±0.09), tannins (22.77±0.73, 18.68±0.03 and 17.50±0.46), and lectins (6.67±0.04, 6.20±0.01 and 6.42±0.07) exhibited the highest anti-nutrient values in raw whole seed and, at the very least, in dehusked, soaked seeds. The samples were subjected to phytochemical screening, which detected the presence of cardiac glycosides as well as anthraquinones, alkaloids, tannins, saponins, steroids, flavonoids, terpenoids, phlobatannins, and flavonoids. Due to the reduction in phytochemical contents quantified as a result of dehusking and soaking, phenolbatannins and anthraquinones were not found in the samples. The research findings also demonstrated elevated concentrations of several plausible phytochemical components with potential medical value, with the raw whole seed exhibiting the greatest capacity to scavenge free radicals. Accordingly, the study's findings validate the seed's therapeutic applications and imply that it might be an inexpensive source of antioxidants for humans and animals alike.Keywords: dehusking, soaking, anti-nutrients, antioxidants, jack bean
Procedia PDF Downloads 502215 Effectiveness of Myofascial Release Technique in Treatment of Sacroiliac Joint Hypo-Mobility in Postnatal Women
Authors: Ahmed A. Abd El Rahim, Mohamed M. M. Essa, Magdy M. A. Shabana, Said A. Mohamed, Mohamed Ibrahim Mabrouk
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Background: Sacroiliac joint (SIJ) dysfunction is considered the main cause of pregnancy-related back pain, which may continue to persist postnatally. Myofascial release technique (MFR) is an application of low-intensity, prolonged stretch to myofascial structures to improve function by increasing the sliding properties of restricted myofascial tissues. Purpose: This study was designed to investigate the effect of MFR on postnatal SIJ hypo-mobility. Materials and Methods: Fifty postnatal women complaining of SIJ hypo-mobility participated in this study. Their ages ranged from 26 to 35 yrs., and their body mass index (BMI) didn`t exceed 30 kg/m2. They were randomly assigned to two equal groups, group A (Gr. A) and group B (Gr. B). Both groups received three sessions per week for eight successive weeks. Gr. A received a traditional physical therapy program, while Gr. B received a traditional physical therapy program in addition to MFR. Doppler imaging of vibration was utilized to measure SIJ mobility pre- and post-intervention, and an electronic digital goniometer was used to measure back flexion and extension Range of motion. Results: Findings revealed a statistical improvement in post-intervention values of SIJ mobility in addition to trunk flexion and extension ROM in Gr. B compared to Gr. A (P<0.001). Conclusion: Adding MFR to traditional physical therapy programs is highly recommended in the treatment of SIJ hypo-mobility in postnatal women.Keywords: sacroiliac hypo-mobility, sacroiliac dysfunction, myofascial release technique, traditional physical therapy, postnatal
Procedia PDF Downloads 1022214 Aerodynamic Modeling Using Flight Data at High Angle of Attack
Authors: Rakesh Kumar, A. K. Ghosh
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The paper presents the modeling of linear and nonlinear longitudinal aerodynamics using real flight data of Hansa-3 aircraft gathered at low and high angles of attack. The Neural-Gauss-Newton (NGN) method has been applied to model the linear and nonlinear longitudinal dynamics and estimate parameters from flight data. Unsteady aerodynamics due to flow separation at high angles of attack near stall has been included in the aerodynamic model using Kirchhoff’s quasi-steady stall model. NGN method is an algorithm that utilizes Feed Forward Neural Network (FFNN) and Gauss-Newton optimization to estimate the parameters and it does not require any a priori postulation of mathematical model or solving of equations of motion. NGN method was validated on real flight data generated at moderate angles of attack before application to the data at high angles of attack. The estimates obtained from compatible flight data using NGN method were validated by comparing with wind tunnel values and the maximum likelihood estimates. Validation was also carried out by comparing the response of measured motion variables with the response generated by using estimates a different control input. Next, NGN method was applied to real flight data generated by executing a well-designed quasi-steady stall maneuver. The results obtained in terms of stall characteristics and aerodynamic parameters were encouraging and reasonably accurate to establish NGN as a method for modeling nonlinear aerodynamics from real flight data at high angles of attack.Keywords: parameter estimation, NGN method, linear and nonlinear, aerodynamic modeling
Procedia PDF Downloads 4462213 Increasing Sustainability Using the Potential of Urban Rivers in Developing Countries with a Biophilic Design Approach
Authors: Mohammad Reza Mohammadian, Dariush Sattarzadeh, Mir Mohammad Javad Poor Hadi Hosseini
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Population growth, urban development and urban buildup have disturbed the balance between the nature and the city, and so leading to the loss of quality of sustainability of proximity to rivers. While in the past, the sides of urban rivers were considered as urban green space. Urban rivers and their sides that have environmental, social and economic values are important to achieve sustainable development. So far, efforts have been made at various scales in various cities around the world to revitalize these areas. On the other hand, biophilic design is an innovative design approach in which attention to natural details and relation to nature is a fundamental concept. The purpose of this study is to provide an integrated framework of urban design using the potential of urban rivers (in order to increase sustainability) with a biophilic design approach to be used in cities in developing countries. The methodology of the research is based on the collection of data and information from research and projects including a study on biophilic design, investigations and projects related to the urban rivers, and a review of the literature on sustainable urban development. Then studying the boundary of urban rivers is completed by examining case samples. Eventually, integrated framework of urban design, to design the boundaries of urban rivers in the cities of developing countries is presented regarding the factors affecting the design of these areas. The result shows that according to this framework, the potential of the river banks is utilized to increase not only the environmental sustainability but also social, economic and physical stability with regard to water, light, and the usage of indigenous materials, etc.Keywords: urban rivers, biophilic design, urban sustainability, nature
Procedia PDF Downloads 2882212 In vivo Antidiarrheal and ex-vivo Spasmolytic Activities of the Aqueous Extract of the Roots of Echinops kebericho Mesfin in Rodents and Isolated Guinea-Pig Ileum
Authors: Fisseha Shiferie (Bpharm, Mpharm)
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Diarrhea is a common gastrointestinal disorder characterized by an increase in stool frequency and a change in stool consistency. Inspite of the availability of many drugs as antidiarrheal agents, the search for a drug with affordable cost and better efficacy is essential to overcome diarrheal problems. The root extract of Echinops kebericho, is used by traditional practitioners for the treatment of diarrhea. However, the scientific basis for this usage has not been yet established. The purpose of the present study was to evaluate the antidiarrheal and spasmolytic activities of the aqueous extract of the roots of E. kebericho in rodents and isolated guinea-pig ileum preparations. In the castor oil induced intestinal transit test, E. kebericho produced a significant (p < 0.01) dose dependent decrease in propulsion with peristaltic index values of 45.05±3.3, 42.71±2.25 and 33.17±3.3%, respectively at doses of 100, 200 and 400 mg/kg compared with 63.43±7.3% for control. In the castor oil-induced diarrhea test, the mean defecation was reduced from 1.81±0.18 to 0.99 ± 0.21 compared with 2.59 ±0.81 for control. The extract (at doses stated above) significantly decreased the volume of intestinal fluid secretion induced by castor oil (2.31±0.1 to 2.01±0.2) in relation to 3.28±0.3 for control. When tested on a guinea-pig ileum, root extract of Echinops kebericho exhibited a dose dependent spasmolytic effect, 23.07 % being its highest inhibitory effect. The results obtained in this study give some scientific support to the use of Echinops kebericho as an antidiarrheal agent due to its inhibitory effects on the different diarrheal parameters used in this study.Keywords: antidiarrheal activity, E. kebericho, traditional medicine, diarrhea, enteropooling, and intestinal transit
Procedia PDF Downloads 3192211 Response Surface Methodology Approach to Defining Ultrafiltration of Steepwater from Corn Starch Industry
Authors: Zita I. Šereš, Ljubica P. Dokić, Dragana M. Šoronja Simović, Cecilia Hodur, Zsuzsanna Laszlo, Ivana Nikolić, Nikola Maravić
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In this work the concentration of steep-water from corn starch industry is monitored using ultrafiltration membrane. The aim was to examine the conditions of ultrafiltration of steep-water by applying the membrane of 2.5nm. The parameters that vary during the course of ultrafiltration, were the transmembrane pressure, flow rate, while the permeate flux and the dry matter content of permeate and retentive were the dependent parameter constantly monitored during the process. Experiments of ultrafiltration are conducted on the samples of steep-water, which were obtained from the starch wet milling plant Jabuka, Pancevo. The procedure of ultrafiltration on a single-channel 250mm length, with inner diameter of 6.8mm and outer diameter of 10mm membrane were carried on. The membrane is made of a-Al2O3 with TiO2 layer obtained from GEA (Germany). The experiments are carried out at a flow rate ranging from 100 to 200lh-1 and transmembrane pressure of 1-3 bars. During the experiments of steep-water ultrafiltration, the change of permeate flux, dry matter content of permeate and retentive, as well as the absorbance changes of the permeate and retentive were monitored. The experimental results showed that the maximum flux reaches about 40lm-2h-1. For responses obtained after experiments, a polynomial model of the second degree is established to evaluate and quantify the influence of the variables. The quadratic equitation fits with the experimental values, where the coefficient of determination for flux is 0.96. The dry matter content of the retentive is increased for about 6%, while the dry matter content of permeate was reduced for about 35-40%, respectively. During steep-water ultrafiltration in permeate stays 40% less dry matter compared to the feed.Keywords: ultrafiltration, steep-water, starch industry, ceramic membrane
Procedia PDF Downloads 2842210 Don't Just Guess and Slip: Estimating Bayesian Knowledge Tracing Parameters When Observations Are Scant
Authors: Michael Smalenberger
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Intelligent tutoring systems (ITS) are computer-based platforms which can incorporate artificial intelligence to provide step-by-step guidance as students practice problem-solving skills. ITS can replicate and even exceed some benefits of one-on-one tutoring, foster transactivity in collaborative environments, and lead to substantial learning gains when used to supplement the instruction of a teacher or when used as the sole method of instruction. A common facet of many ITS is their use of Bayesian Knowledge Tracing (BKT) to estimate parameters necessary for the implementation of the artificial intelligence component, and for the probability of mastery of a knowledge component relevant to the ITS. While various techniques exist to estimate these parameters and probability of mastery, none directly and reliably ask the user to self-assess these. In this study, 111 undergraduate students used an ITS in a college-level introductory statistics course for which detailed transaction-level observations were recorded, and users were also routinely asked direct questions that would lead to such a self-assessment. Comparisons were made between these self-assessed values and those obtained using commonly used estimation techniques. Our findings show that such self-assessments are particularly relevant at the early stages of ITS usage while transaction level data are scant. Once a user’s transaction level data become available after sufficient ITS usage, these can replace the self-assessments in order to eliminate the identifiability problem in BKT. We discuss how these findings are relevant to the number of exercises necessary to lead to mastery of a knowledge component, the associated implications on learning curves, and its relevance to instruction time.Keywords: Bayesian Knowledge Tracing, Intelligent Tutoring System, in vivo study, parameter estimation
Procedia PDF Downloads 1722209 A Preliminary Analysis of Sustainable Development in the Belgrade Metropolitan Area
Authors: Slavka Zeković, Miodrag Vujošević, Tamara Maričić
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The paper provides a comprehensive analysis of the sustainable development in the Belgrade Metropolitan Region - BMA (level NUTS 2) preliminary evaluating the three chosen components: 1) economic growth and developmental changes; 2) competitiveness; and 3) territorial concentration and industrial specialization. First, we identified the main results of development changes and economic growth by applying Shift-share analysis on the metropolitan level. Second, the empirical evaluation of competitiveness in the BMA is based on the analysis of absolute and relative values of eight indicators by Spider method. Paper shows that the consideration of the national share, industrial mix and metropolitan/regional share in total Shift share of the BMA, as well as economic/functional specialization of the BMA indicate very strong process of deindustrialization. Allocative component of the BMA economic growth has positive value, reflecting the above-average sector productivity compared to the national average. Third, the important positive role of metropolitan/regional component in decomposition of the BMA economic growth is highlighted as one of the key results. Finally, comparative analysis of the industrial territorial concentration in the BMA in relation to Serbia is based on location quotient (LQ) or Balassa index as a valid measure. The results indicate absolute and relative differences in decrease of industry territorial concentration as well as inefficiency of utilizing territorial capital in the BMA. Results are important for the increase of regional competitiveness and territorial distribution in this area as well as for improvement of sustainable metropolitan and sector policies, planning and governance on this level.Keywords: Belgrade Metropolitan Area (BMA), comprehensive analysis / evaluation, economic growth, competitiveness, sustainable development
Procedia PDF Downloads 4452208 In-Vitro Dextran Synthesis and Characterization of an Intracellular Glucosyltransferase from Leuconostoc Mesenteroides AA1
Authors: Afsheen Aman, Shah Ali Ul Qader
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Dextransucrase [EC 2.4.1.5] is a glucosyltransferase that catalysis the biosynthesis of a natural biopolymer called dextran. It can catalyze the transfer of D-glucopyranosyl residues from sucrose to the main chain of dextran. This unique biopolymer has multiple applications in several industries and the key utilization of dextran lies on its molecular weight and the type of branching. Extracellular dextransucrase from Leuconostoc mesenteroides is most extensively studied and characterized. Limited data is available regarding cell-bound or intracellular dextransucrase and on the characterization of dextran produced by in-vitro reaction of intracellular dextransucrase. L. mesenteroides AA1 is reported to produce extracellular dextransucrase that catalyzes biosynthesis of a high molecular weight dextran with only α-(1→6) linkage. Current study deals with the characterization of an intracellular dextransucrase and in vitro biosynthesis of low molecular weight dextran from L. mesenteroides AA1. Intracellular dextransucrase was extracted from cytoplasm and purified to homogeneity for characterization. Kinetic constants, molecular weight and N-terminal sequence analysis of intracellular dextransucrase reveal unique variation with previously reported extracellular dextransucrase from the same strain. In vitro synthesized biopolymer was characterized using NMR spectroscopic techniques. Intracellular dextransucrase exhibited Vmax and Km values of 130.8 DSU ml-1 hr-1 and 221.3 mM, respectively. Optimum catalytic activity was detected at 35°C in 0.15 M citrate phosphate buffer (pH-5.5) in 05 minutes. Molecular mass of purified intracellular dextransucrase is approximately 220.0 kDa on SDS-PAGE. N-terminal sequence of the intracellular enzyme is: GLPGYFGVN that showed no homology with previously reported sequence for the extracellular dextransucrase. This intracellular dextransucrase is capable of in vitro synthesis of dextran under specific conditions. This intracellular dextransucrase is capable of in vitro synthesis of dextran under specific conditions and this biopolymer can be hydrolyzed into different molecular weight fractions for various applications.Keywords: characterization, dextran, dextransucrase, leuconostoc mesenteroides
Procedia PDF Downloads 3962207 Characteristic Composition and Sensory Contributions of Acidic Aroma in Mainstream Cigarette Smoke of Cherry-Red Tobacco
Authors: Tian Yangyang, Xu Zihe, Lu Junping, Yang Jizhou, Xu Yiqun, Wang Jiansong, Chen Chao, Yang Mengmeng, Guo Jianhua, Mu Wenjun, Wang Guiyao, Xue Chaoqun, Liang Taibo, Hu Liwei
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Cherry-red tobacco is receiving constant attention from cigarette enterprises because of its special flavor. This study aims to explore the material basis for the formation of the characteristic flavor of cherry-red tobacco and to clarify the distribution characteristics of the acidic aroma component groups in its mainstream smoke. In order to reach the aims of current study, this study employs GC/MS to examine the differences of distribution characteristics in particulate matter of mainstream cigarette smoke between cherry-red and common tobacco, meanwhile the aroma activity values (OVA) was used to compare the contribution of acidic aroma of cherry-red tobacco. The results showed that: 1) Isovaleric acid, acetic acid and butyric acid were the key acidic components in the mainstream smoke of the samples, followed by 3-methylvaleric acid, 4-methylvaleric acid and n-valeric acid. 2)Analysis of the release of these key sour fragrance components showed that the acidic aroma of "YUN 85" mainstream smoke was stronger than the leaf group, cherry-red tobacco was the weakest. In addition, aging had the effect of reducing the acidic components of cherry-red tobacco and the addition of cherry-red tobacco had little effect on the acidic components of the original leaf group. 3) For 14 acidic aroma(OAV>1) in smoke of cherry-red tobacco, 3-methylpentanoic acid, 4-methylpentanoic acid, pentanoic acid, and isovaleric acid were very prominent in contributing to acidic aroma, while pyruvic acid, 2-methylbutyric acid, hydrogenated acid, and propionic acid were less contribution.Keywords: cherry-red tobacco, acidic aroma, GC/MS, mainstream cigarette smoke, odor activity value
Procedia PDF Downloads 1372206 Dynamics of Parent to Adolescent Communication on Sexual and Reproductive Health in Sub-Saharan Africa: A Focus on Barriers and Policy Implications
Authors: Douglas Nyathi, Mxolisi Sibanda, Joram Ndlovuu, Thulani Dube, Innocent T. Mahiya
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Communication of sexual matters between the parents and adolescents has been seen as one of the strategies that could play a cardinal role in encouraging adolescents to be responsible and delay sexual debut or avoid unprotected sexual intercourse. The increasing rate of teenage pregnancies and new HIV/AIDS infections among adolescents in Sub-Saharan Africa makes the phenomenon worth analysis. The purpose of this paper is to interrogate the dynamics of parent-adolescent communication on sexual and reproductive health in Sub-Sahara. Specifically the paper focuses on barriers to communication between parents and adolescents on sexual and reproductive health and its policy implications. It emanates from the paper that communication on sexual and reproductive health at household level is triggered by death of a relative from a sexual related illness, suspicion on sexual activity, radio programmes and in some instances fliers. Literature engagement reveals that communication between parents and adolescents on sexual and reproductive health is made difficult by economic factors (poverty, lack of privacy and low self-esteem), household demographics (age, sex, class, death), socio-cultural factors (beliefs and religious values) as well as social media. We argue that there is need to use broadcast mediato come up with radio and television programmes that create family environments in which sexual and reproductive health issues are discussed. We also recommend that government departments and Non-Governmental Organisations concerned with sexuality issues need to undertake studies that can help dismantle taboos, prejudices and stereotypes that impede sexual and reproductive health communication between parents and adolescents.Keywords: parent, adolecsent, communication, sexual and reproductive health
Procedia PDF Downloads 4582205 Study of the Effect of the Contra-Rotating Component on the Performance of the Centrifugal Compressor
Authors: Van Thang Nguyen, Amelie Danlos, Richard Paridaens, Farid Bakir
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This article presents a study of the effect of a contra-rotating component on the efficiency of centrifugal compressors. A contra-rotating centrifugal compressor (CRCC) is constructed using two independent rotors, rotating in the opposite direction and replacing the single rotor of a conventional centrifugal compressor (REF). To respect the geometrical parameters of the REF one, two rotors of the CRCC are designed, based on a single rotor geometry, using the hub and shroud length ratio parameter of the meridional contour. Firstly, the first rotor is designed by choosing a value of length ratio. Then, the second rotor is calculated to be adapted to the fluid flow of the first rotor according aerodynamics principles. In this study, four values of length ratios 0.3, 0.4, 0.5, and 0.6 are used to create four configurations CF1, CF2, CF3, and CF4 respectively. For comparison purpose, the circumferential velocity at the outlet of the REF and the CRCC are preserved, which means that the single rotor of the REF and the second rotor of the CRCC rotate with the same speed of 16000rpm. The speed of the first rotor in this case is chosen to be equal to the speed of the second rotor. The CFD simulation is conducted to compare the performance of the CRCC and the REF with the same boundary conditions. The results show that the configuration with a higher length ratio gives higher pressure rise. However, its efficiency is lower. An investigation over the entire operating range shows that the CF1 is the best configuration in this case. In addition, the CRCC can improve the pressure rise as well as the efficiency by changing the speed of each rotor independently. The results of changing the first rotor speed show with a 130% speed increase, the pressure ratio rises of 8.7% while the efficiency remains stable at the flow rate of the design operating point.Keywords: centrifugal compressor, contra-rotating, interaction rotor, vacuum
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