Search results for: optimal control involving ODEs

Authors: Omid Ataei Nia, Karim Salahshoor

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In this paper, a new precise and reliable sensor network methodology is introduced for unit processes and operations using the Constriction Coefficient Particle Swarm Optimization (CPSO) method. CPSO is introduced as a new search engine for optimal sensor network design purposes. Furthermore, a Square Root Unscented Kalman Filter (SRUKF) algorithm is employed as a new data reconciliation technique to enhance the stability and accuracy of the filter. The proposed design procedure incorporates precision, cost, observability, reliability together with importance-of-variables (IVs) as a novel measure in Instrumentation Criteria (IC). To the best of our knowledge, no comprehensive approach has yet been proposed in the literature to take into account the importance of variables in the sensor network design procedure. In this paper, specific weight is assigned to each sensor, measuring a process variable in the sensor network to indicate the importance of that variable over the others to cater to the ultimate sensor network application requirements. A set of distinct scenarios has been conducted to evaluate the performance of the proposed methodology in a simulated Continuous Stirred Tank Reactor (CSTR) as a highly nonlinear process plant benchmark. The obtained results reveal the efficacy of the proposed method, leading to significant improvement in accuracy with respect to other alternative sensor network design approaches and securing the definite allocation of sensors to the most important process variables in sensor network design as a novel achievement.

Keywords: constriction coefficient PSO, importance of variable, MRMSE, reliability, sensor network design, square root unscented Kalman filter

Procedia PDF Downloads 164

Authors: N. Nalini, Bhanu Prakash Gopularam

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The term data security refers to the degree of resistance or protection given to information from unintended or unauthorized access. The core principles of information security are the confidentiality, integrity and availability, also referred as CIA triad. Cloud computing services are classified as SaaS, IaaS and PaaS services. With cloud adoption the confidential enterprise data are moved from organization premises to untrusted public network and due to this the attack surface has increased manifold. Several cloud computing platforms like OpenStack, Eucalyptus, Amazon EC2 offer users to build and configure public, hybrid and private clouds. While the traditional encryption based on PKI infrastructure still works in cloud scenario, the management of public-private keys and trust certificates is difficult. The Identity based Public Key Cryptography (also referred as ID-PKC) overcomes this problem by using publicly identifiable information for generating the keys and works well with decentralized systems. The users can exchange information securely without having to manage any trust information. Another advantage is that access control (role based access control policy) information can be embedded into data unlike in PKI where it is handled by separate component or system. In OpenStack cloud platform the keystone service acts as identity service for authentication and authorization and has support for public key infrastructure for auto services. In this paper, we explain OpenStack security architecture and evaluate the PKI infrastructure piece for data confidentiality. We provide method to integrate ID-PKC schemes for securing data while in transit and stored and explain the key measures for safe guarding data against security attacks. The proposed approach uses JPBC crypto library for key-pair generation based on IEEE P1636.3 standard and secure communication to other cloud services.

Keywords: data confidentiality, identity based cryptography, secure communication, open stack key stone, token scoping

Procedia PDF Downloads 389

Authors: Adel Salem Bahakeem, Ahmad Jamal, Mir Md. Maruf Morshed, Elwaleed Awad Khidir

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Direct Current (DC) servo motors, or simply DC motors, play an important role in many industrial applications such as manufacturing of plastics, precise positioning of the equipment, and operating computer-controlled systems where speed of feed control, maintaining the position, and ensuring to have a constantly desired output is very critical. These parameters can be controlled with the help of control systems such as the Proportional Integral Derivative (PID) controller. The aim of the current work is to investigate the effects of Proportional (P) and Integral (I) controllers on the steady state and transient response of the DC motor. The controller gains are varied to observe their effects on the error, damping, and stability of the steady and transient motor response. The current investigation is conducted experimentally on a servo trainer CE 110 using analog PI controller CE 120 and theoretically using Simulink in MATLAB. Both experimental and theoretical work involves varying integral controller gain to obtain the response to a steady-state input, varying, individually, the proportional and integral controller gains to obtain the response to a step input function at a certain frequency, and theoretically obtaining the proportional and integral controller gains for desired values of damping ratio and response frequency. Results reveal that a proportional controller helps reduce the steady-state and transient error between the input signal and output response and makes the system more stable. In addition, it also speeds up the response of the system. On the other hand, the integral controller eliminates the error but tends to make the system unstable with induced oscillations and slow response to eliminate the error. From the current work, it is desired to achieve a stable response of the servo motor in terms of its angular velocity subjected to steady-state and transient input signals by utilizing the strengths of both P and I controllers.

Keywords: DC servo motor, proportional controller, integral controller, controller gain optimization, Simulink

Procedia PDF Downloads 113

Authors: Inigo Beckett

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In forensic investigations, it is often the case that the most potentially useful recorded evidence derives from coincidental imagery, recorded immediately before or during an incident, and that during the incident (e.g. a ‘failure’ or fire event), the evidence is changed or destroyed. To an image analysis expert involved in photogrammetric analysis for Civil or Criminal Proceedings, traditional computer vision methods involving calibrated cameras is often not appropriate because image metadata cannot be relied upon. This paper presents an approach for resolving this problem, considering in particular and by way of a case study, the angle of a simple ladder shown in a photograph. The UK Health and Safety Executive (HSE) guidance document published in 2014 (INDG455) advises that a leaning ladder should be erected at 75 degrees to the horizontal axis. Personal injury cases can arise in the construction industry because a ladder is too steep or too shallow. Ad-hoc photographs of such ladders in their incident position provide a basis for analysis of their angle. This paper presents a direct approach for ascertaining the position of the camera and the angle of the ladder simultaneously from the photograph(s) by way of a workflow that encompasses a novel application of projective geometry and matrix analysis. Mathematical analysis shows that for a given pixel ratio of directly measured collinear points (i.e. features that lie on the same line segment) from the 2D digital photograph with respect to a given viewing point, we can constrain the 3D camera position to a surface of a sphere in the scene. Depending on what we know about the ladder, we can enforce another independent constraint on the possible camera positions which enables us to constrain the possible positions even further. Experiments were conducted using synthetic and real-world data. The synthetic data modeled a vertical plane with a ladder on a horizontally flat plane resting against a vertical wall. The real-world data was captured using an Apple iPhone 13 Pro and 3D laser scan survey data whereby a ladder was placed in a known location and angle to the vertical axis. For each case, we calculated camera positions and the ladder angles using this method and cross-compared them against their respective ‘true’ values.

Keywords: image analysis, projective geometry, homography, photogrammetry, ladders, Forensics, Mathematical modeling, planar geometry, matrix analysis, collinear, cameras, photographs

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Authors: Sujit Kumar Pradhan, Anil Kumar, Vijay Kumar

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The testing process of the software during the software development time is a crucial step as it makes the software more efficient and dependable. To estimate software’s reliability through the mean value function, many software reliability growth models (SRGMs) were developed under the assumption that operating and testing environments are the same. Practically, it is not true because when the software works in a natural field environment, the reliability of the software differs. This article discussed an SRGM comprising change-point and imperfect debugging in a simulated testing environment. Later on, we extended it in a multi-release direction. Initially, the software was released to the market with few features. According to the market’s demand, the software company upgraded the current version by adding new features as time passed. Therefore, we have proposed a generalized multi-release SRGM where change-point and imperfect debugging concepts have been addressed in a simulated testing environment. The failure-increasing rate concept has been adopted to determine the change point for each software release. Based on nine goodness-of-fit criteria, the proposed model is validated on two real datasets. The results demonstrate that the proposed model fits the datasets better. We have also discussed the optimal release time of the software through a cost model by assuming that the testing and debugging costs are time-dependent.

Keywords: software reliability growth models, non-homogeneous Poisson process, multi-release software, mean value function, change-point, environmental factors

Procedia PDF Downloads 78

Authors: Julia Langen

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This article describes the challenges of a wireless charging system for a cab waiting lane in a public space and presents a concept for solving them. In this concept, multiple cabs can be charged simultaneously and during stopping and rolling. Particular technical challenges are a coil topology that meets the EMF requirements and an intelligent control concept that allows the individual coil segments to be switched on and off. The charging concept explained here is currently being implemented as a pilot project, so that initial results on the operation can be presented.

Keywords: charge lane, inductive charging solution, smart city, wireless power transfer

Procedia PDF Downloads 181

Authors: Ebele V. Okoli, Emmanuel Nwobi, Dozie Ezechukwu, Ijeoma Itanyi

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One in seven people worldwide suffer from a disability. 80% of people with disabilities live in developing countries. Negative attitudes and misconceptions among health-care providers constitute barri¬ers to optimal health care for people with disabilities. This underscores the relevance of a study of the attitude of Nigerian medical students towards disability and their willingness to work in the disability sector. This was a descriptive cross-sectional study conducted among 254 penultimate and final year medical students of a university in southeastern Nigeria. The mean age of the students was 24.8 ± 3.12 years. Majority of the students were male (75.2%), single (96.9%), of the Igbo tribe (86.6%), Christian (97.6%) and grew up in urban areas (68.1%). Results indicated that the medical students had a predominantly positive attitude towards people with disability as 73.8% had a positive attitude and mean attitude score was 67.03 ± 0.14 (positive attitude = 61 – 120, negative attitude = 0 - 60). Chi-square analysis did not show any significant effect of demographic and social factors on the students’ attitude towards People with Disabilities. The students were mostly willing to work in areas that address the challenges of people with disability (70.4%) but a greater proportion had never heard about Disability Studies (67.5%). About a third of the students (33.2%) would like to travel abroad to practice in the disability sector. Conclusions: The students generally had a positive attitude towards people with disability and a greater percentage were willing to work in the disability sector in their future career. About two-thirds had however, never heard about disability studies. There was some potential for brain drain among the students as a third of the population intended to practice abroad on graduation.

Keywords: attitudes, career interest, disability, medical students

Procedia PDF Downloads 363

Authors: M. G. Shilina

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The prospects for political and economic development of the Eurasian space are currently discussed at both governmental and expert levels. New concepts actively proposed by the Eurasian governments require the analysis and search for effective implementation options. In the paper, an attempt to identify effective solutions to the problems surrounding the current economic integration of the Eurasian states is given on the basis of an interdisciplinary, comprehensive, structured analysis. The phenomenon is considered through the prism of the international law, world economy and politics, combined with the study of existing intergovernmental practice. The modeling method was taken as the basis for the research and is supplemented by legal and empirical methods. The detailed multi-level model of practical construction the 'Great Eurasia' (the GE) concept is proposed, the option for building a phased interaction in Eurasia is given through the prism of construction by the Eurasian Economic Union (the EAEU) as the main tool. The Shanghai Cooperation Organization (the SCO) is seen as the most promising element of the model. The SCO is capable of streamlining the formation of the GE and determine the transformation of Eurasia into a common economic space. Effective development of the economic integration between Eurasian states on the framework of the SCO is optimal. The SCO+ could be used as a platform for integration-integration processes formation. The creation of stable financial ties could become the basis for the possible formation of an expanded transregional integration platform. The paper concludes that the implementation of the proposed model could entail a gradual economic rapprochement of Eurasia and beyond.

Keywords: economic integration, The Eurasian Economic Union, The European Union, The Shanghai Cooperation Organization, the silk road economic belt

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Authors: Sadegh Sadeghi, Negar Shabani

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From a thermal point of view, zeotropic mixtures are likely to be more efficient than azeotropic fluids in low-temperature thermodynamic cycles due to their suitable boiling characteristics. In this study, performance of a low-temperature Kalina cycle with R717/water working fluid used in different existing power plants is mathematically investigated. To analyze the behavior of the cycle, mass conservation, energy conservation, and exergy balance equations are presented. With regard to the similarity in molar mass of R717 (17.03 gr/mol) and water (18.01 gr/mol), there is no need to alter the size of Kalina system components such as turbine and pump. To optimize the cycle energy and exergy efficiencies simultaneously, a constrained multi-objective optimization is carried out applying an Artificial Bee Colony algorithm. The main motivation behind using this algorithm lies on its robustness, reliability, remarkable precision and high–speed convergence rate in dealing with complicated constrained multi-objective problems. Convergence rates of the algorithm for calculating the optimal energy and exergy efficiencies are presented. Subsequently, due to the importance of exergy concept in Kalina cycles, exergy destructions occurring in the components are computed. Finally, the impacts of pressure, temperature, mass fraction and mass flow rate on the energy and exergy efficiencies are elaborately studied.

Keywords: artificial bee colony algorithm, binary zeotropic mixture, constrained multi-objective optimization, energy efficiency, exergy efficiency, Kalina cycle

Procedia PDF Downloads 157

Authors: Xiaowei Zhang, Min Xu, Saeid Habibi, Fengjun Yan, Ryan Ahmed

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Recently, Electric Vehicles (EVs) have received extensive consideration since they offer a more sustainable and greener transportation alternative compared to fossil-fuel propelled vehicles. Lithium-Ion (Li-ion) batteries are increasingly being deployed in EVs because of their high energy density, high cell-level voltage, and low rate of self-discharge. Since Li-ion batteries represent the most expensive component in the EV powertrain, accurate monitoring and control strategies must be executed to ensure their prolonged lifespan. The Battery Management System (BMS) has to accurately estimate parameters such as the battery State-of-Charge (SOC), State-of-Health (SOH), and Remaining Useful Life (RUL). In order for the BMS to estimate these parameters, an accurate and control-oriented battery model has to work collaboratively with a robust state and parameter estimation strategy. Since battery physical parameters, such as the internal resistance and diffusion coefficient change depending on the battery state-of-life (SOL), the BMS has to be adaptive to accommodate for this change. In this paper, an extensive battery aging study has been conducted over 12-months period on 5.4 Ah, 3.7 V Lithium polymer cells. Instead of using fixed charging/discharging aging cycles at fixed C-rate, a set of real-world driving scenarios have been used to age the cells. The test has been interrupted every 5% capacity degradation by a set of reference performance tests to assess the battery degradation and track model parameters. As battery ages, the combined model parameters are optimized and tracked in an offline mode over the entire batteries lifespan. Based on the optimized model, a state and parameter estimation strategy based on the Extended Kalman Filter (EKF) and the relatively new Smooth Variable Structure Filter (SVSF) have been applied to estimate the SOC at various states of life.

Keywords: lithium-ion batteries, genetic algorithm optimization, battery aging test, parameter identification

Procedia PDF Downloads 271

Authors: Mengjia Zhi, Xingmei Wei, Xiang Gao, Shiyang Liu, Zhiran Huang, Li Yang, Jing Sun

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Background: To understand the consumption trend of opioid analgesics and the consumption adequacy of opioid analgesic treatment for moderate to severe pain in China, as well as the pain control level of China with international perspective. Importance: To author’s best knowledge, this is the first study in China to measure the adequacy of opioid analgesic treatment for moderate to severe pain considering disease pattern and with the standardized pain treatment guideline. Methods: A retrospective analysis was carried out to show the consumption frequency (daily defined doses, DDDs) of opioid analgesics and its trend in China from 2006 to 2016. Adequacy of consumption measure (ACM) was used to measure the number of needed morphine equivalents and the overall adequacy of opioid analgesic treatment of moderate to severe pain in China, and compared with international data. Results: The consumption frequency of opioid analgesics (DDDs) in China increased from 13,200,000 DDDs in 2006 to 44,200,000 DDDs in 2016, and showed an increasing trend. The growth rate was faster at first, especially in 2013, then slowed down, decreased slightly in 2015. The ACM of China increased from 0.0032 in 2006 to 0.0074 in 2016, with an overall trend of growth. The ACM level of China has been always a very poor level during 2006-2016. Conclusion: The consumption of opioid analgesics for the treatment of moderate to severe pain in China has always been inadequate. There is a huge gap between China and the international level. There are many reasons behind this problem, which lie in different aspects, including medical staff, patients and the public, health systems and social & cultural aspects. It is necessary to strengthen the training and education of medical staff and the patients, to use mass media to disseminate scientific knowledge of pain management, to encourage communications between doctors and patients, to improve regulatory system for the controlled medicines and the overall health systems, and to balance the regulatory goal for avoidance of abuse, and the social goal of meeting the increasing needs of the people for better life.

Keywords: opioid analgesics, adequate consumption measure, pain control, China

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Authors: R. Fardid, R. Coppes

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Introduction: In mediastinal radiotherapy and to a lesser extend also in total-body irradiation (TBI) radiation exposure may lead to development of cardiac diseases. Radiation-induced heart disease is dose-dependent and it is characterized by a loss of cardiac function, associated with progressive heart cells degeneration. We aimed to determine the in-vivo radiation effects on fibronectin, ColaA1, ColaA2, galectin and TGFb1 gene expression levels in left ventricle heart tissues of rats after irradiation. Material and method: Four non-treatment adult Wistar rats as control group (group A) were selected. In group B, 4 adult Wistar rats irradiated to 20 Gy single dose of 150 Mev proton beam locally in heart only. In heart plus lung irradiate group (group C) 4 adult rats was irradiated by 50% of lung laterally plus heart radiation that mentioned in before group. At 8 weeks after radiation animals sacrificed and left ventricle heart dropped in liquid nitrogen for RNA extraction by Absolutely RNA® Miniprep Kit (Stratagen, Cat no. 400800). cDNA was synthesized using M-MLV reverse transcriptase (Life Technologies, Cat no. 28025-013). We used Bio-Rad machine (Bio Rad iQ5 Real Time PCR) for QPCR testing by relative standard curve method. Results: We found that gene expression of fibronectin in group C significantly increased compared to control group, but it was not showed significant change in group B compared to group A. The levels of gene expressions of Cola1 and Cola2 in mRNA did not show any significant changes between normal and radiation groups. Changes of expression of galectin target significantly increased only in group C compared to group A. TGFb1 expressions in group C more than group B showed significant enhancement compared to group A. Conclusion: In summary we can say that 20 Gy of proton exposure of heart tissue may lead to detectable damages in heart cells and may distribute function of them as a component of heart tissue structure in molecular level.

Keywords: gene expression, heart damage, proton irradiation, radiotherapy

Procedia PDF Downloads 490

Authors: Prasad Urvashi, Wynn Yezarni, Williams Shehan, Ravindran Arun

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Introduction: Primary health services are often the first point of contact that patients with mental illness have with the healthcare system. A number of tools have been developed to increase detection of depression in the context of primary care. However, one challenge amongst many includes utilizing these tools within the limited primary care consultation timeframe. Therefore, short questionnaires that screen for depression that are just as effective as more comprehensive diagnostic tools may be beneficial in improving detection rates of patients visiting a primary care setting. Objective: To develop and determine the sensitivity and specificity of a 2-Question Questionnaire (2-QQ) to screen for depression in in a suburban primary care clinic in Ragama, Sri Lanka. The purpose is to develop a short screening tool for depression that is culturally adapted in order to increase the detection of depression in the Sri Lankan patient population. Methods: This was a cross-sectional study involving two steps. Step one: verbal administration of 2-QQ to patients by their primary care physician. Step two: completion of the Peradeniya Depression Scale, a validated diagnostic tool for depression, the patient after their consultation with the primary care physician. The results from the PDS were then correlated to the results from the 2-QQ for each patient to determine sensitivity and specificity of the 2-QQ. Results: A score of 1/+ on the 2-QQ was most sensitive but least specific. Thus, setting the threshold at this level is effective for correctly identifying depressed patients, but also inaccurately captures patients who are not depressed. A score of 6 on the 2-QQ was most specific but least sensitive. Setting the threshold at this level is effective for correctly identifying patients without depression, but not very effective at capturing patients with depression. Discussion: In the context of primary care, it may be worthwhile setting the 2-QQ screen at a lower threshold for positivity (such as a score of 1 or above). This would generate a high test sensitivity and thus capture the majority of patients that have depression. On the other hand, by setting a low threshold for positivity, patients who do not have depression but score higher than 1 on the 2-QQ will also be falsely identified as testing positive for depression. However, the benefits of identifying patients who present with depression may outweigh the harms of falsely identifying a non-depressed patient. It is our hope that the 2-QQ will serve as a quick primary screen for depression in the primary care setting and serve as a catalyst to identify and treat individuals with depression.

Keywords: depression, primary care, screening tool, Sri Lanka

Procedia PDF Downloads 261

Authors: M. Sayyour, M. Abdulkareem, O. Osman, S. Salmeh

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Emphatic sounds in Arabic are /tˤ/, /sˤ/, /dˤ/, and /ðˤ/. They involve a secondary articulation in the pharynx area as opposed to their counterparts: /t/,/s/,/d/and /ð/. Although they are present in most Arabic dialects, some dialects have lost this class as a historical development, such as Maltese Arabic. It has been found that there is a difference in the pronunciation of these emphatic sounds between the two genders, arguing that males tend to produce more evident emphasis than females. This study builds on these studies by trying to investigate whether listeners perceive fully emphatic sounds as more masculine and less emphatic sounds as more feminine. Furthermore, the study aims to find out which is more important in this perception process: the emphatic consonant itself or the vowel following it. To test this, natural and manipulated tokens of two male and two female speakers were used. The natural tokens include words that have emphatic consonant and emphatic vowel and tokens that have plain consonant and plain vowel. The manipulated tokens include words that have emphatic consonant but central vowel and plain consonant followed by the same central vowel. These manipulated tokens allow us to see whether the consonant will still affect the perception even if the vowel is controlled. Another group of words that contained no emphatic sounds was used as a control group. The total number of tokens (natural, manipulated, and control) are 160 tokens. After that, 60 university students (30 males and 30 females) listened to these tokens and responded by choosing a specific character that they think is likely to produce each token. The characters’ descriptions are carefully written with two degrees of femininity and two degrees of masculinity. The preliminary results for the femininity level showed that the highest degree of femininity was for tokens that contain a plain consonant and a plain vowel. The lowest level of femininity was given for tokens that have fully emphatic consonant and vowel. For the manipulated tokens that contained plain consonant and central vowel, the femininity degree was high which indicates that the consonant is more important than the vowel, while for the manipulated tokens that contain emphatic consonant and a central vowel, the femininity level was higher than that for the tokens that have emphatic consonant and emphatic vowel, which indicates that the vowel is more important for the perception of emphatic consonants. These results are interpreted in light of feminist linguistic theories, linguistic expectations, performed gender and linguistic change theories.

Keywords: Emphatic sounds, gender studies, perception, sociophonetics

Procedia PDF Downloads 388

Authors: Tomas Makaras, Julija Razumienė, Vidutė Gurevičienė, Gintarė Sauliutė, Milda Stankevičiūtė

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Stress responses represent animal’s natural reactions to various challenging conditions and could be used as a welfare indicator. Regardless of the wide use of glucose measurements in stress evaluation, there are some inconsistencies in its acceptance as a stress marker, especially when it comes to comparison with non-invasive cortisol measurements in the fish challenging stress. To meet the challenge and to test the reliability and applicability of glucose measurement in practice, in this study, different environmental/anthropogenic exposure scenarios were simulated to provoke chemical-induced stress in fish (14-days exposure to landfill leachate) followed by a 14-days stress recovery period and under the cumulative effect of leachate fish subsequently exposed to pathogenic oomycetes (Saprolegnia parasitica) to represent a possible infection in fish. It is endemic to all freshwater habitats worldwide and is partly responsible for the decline of natural freshwater fish populations. Brown trout (Salmo trutta fario) and sea trout (Salmo trutta trutta) juveniles were chosen because of a large amount of literature on physiological stress responses in these species was known. Glucose content in fish by applying invasive and non-invasive glucose measurement procedures in different test mediums such as fish blood, gill tissues and fish-holding water were analysed. The results indicated that the quantity of glucose released in the holding water of stressed fish increased considerably (approx. 3.5- to 8-fold) and remained substantially higher (approx. 2- to 4-fold) throughout the stress recovery period than the control level suggesting that fish did not recover from chemical-induced stress. The circulating levels of glucose in blood and gills decreased over time in fish exposed to different stressors. However, the gill glucose level in fish showed a decrease similar to the control levels measured at the same time points, which was found to be insignificant. The data analysis showed that concentrations of β-D glucose measured in gills of fish treated with S. parasitica differed significantly from the control recovery, but did not differ from the leachate recovery group showing that S. parasitica presence in water had no additive effects. In contrast, a positive correlation between blood and gills glucose were determined. Parallel trends in blood and water glucose changes suggest that water glucose measurement has much potency in predicting stress. This study demonstrated that measuring β-D-glucose in fish-holding water is not stressful as it involves no handling and manipulation of an organism and has critical technical advantages concerning current (invasive) methods, mainly using blood samples or specific tissues. The quantification of glucose could be essential for studies examining the stress physiology/aquaculture studies interested in the assessment or long-term monitoring of fish health.

Keywords: brown trout, landfill leachate, sea trout, pathogenic oomycetes, β-D-glucose

Procedia PDF Downloads 180

Authors: Emilia Pietiläinen, Heikki Kyröläinen, Tommi Vasankari, Matti Santtila, Tiina Luukkaala, Kai Parkkola

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Working in the military sets special demands on physical fitness, however, reduced physical activity levels among employees in the Finnish Defence Forces (FDF), a trend also being seen among the working-age population in Finland, is leading to reduced physical fitness levels and increased risk of cardiovascular and metabolic diseases, something which also increases human resource costs. Therefore, the aim of the present study was to develop an eHealth intervention using accelerometer- smartphone app feedback technique, telephone counseling and physical activity recordings to increase physical activity of the personnel and thereby improve their health. Specific aims were to reduce stress, improve quality of sleep and mental and physical performance, ability to work and reduce sick leave absences. Employees from six military brigades around Finland were invited to participate in the study, and finally, 260 voluntary participants were included (66 women, 194 men). The participants were randomized into intervention (156) and control groups (104). The eHealth intervention group used accelerometers measuring daily physical activity and duration and quality of sleep for six months. The accelerometers transmitted the data to smartphone apps while giving feedback about daily physical activity and sleep. The intervention group participants were also encouraged to exercise for two hours a week during working hours, a benefit that was already offered to employees following existing FDF guidelines. To separate the exercise done during working hours from the accelerometer data, the intervention group marked this exercise into an exercise diary. The intervention group also participated in telephone counseling about their physical activity. On the other hand, the control group participants continued with their normal exercise routine without the accelerometer and feedback. They could utilize the benefit of being able to exercise during working hours, but they were not separately encouraged for it, nor was the exercise diary used. The participants were measured at baseline, after the entire intervention period, and six months after the end of the entire intervention. The measurements included accelerometer recordings, biochemical laboratory tests, body composition measurements, physical fitness tests, and a wide questionnaire focusing on sociodemographic factors, physical activity and health. In terms of results, the primary indicators of effectiveness are increased physical activity and fitness, improved health status, and reduced sick leave absences. The evaluation of the present scientific reach is based on the data collected during the baseline measurements. Maintenance of the studied outcomes is assessed by comparing the results of the control group measured at the baseline and a year follow-up. Results of the study are not yet available but will be presented at the conference. The present findings will help to develop an easy and cost-effective model to support the health and working capability of employees in the military and other workplaces.

Keywords: accelerometer, health, mobile applications, physical activity, physical performance

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Authors: Ayman M. Othman, Hassan Y. Ahmed, Tallat A. Ali

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Inadequate maintenance programs and funds allocated for highway networks in the developed countries have led to fast deterioration of road side elements. Therefore, this research focuses on developing a performance model for road side elements periodic maintenance activities. Road side elements that receive periodic maintenance include; earthen shoulder, road signs and traffic markings. Using the level of service concept, the developed model can determine the optimal periodic maintenance intervals for those elements based on a selected level of service suitable with the available periodic maintenance budget. Data related to time periods for progressive deterioration stages for the chosen elements were collected. Ten maintenance experts in Aswan, Sohag and Assiut cities were interviewed for that purpose. Time in months related to 10%, 25%, 40%, 50%, 75%, 90% and 100% deterioration of each road side element was estimated based on the experts opinion. Least square regression analysis has shown that a power function represents the best fit for earthen shoulders edge drop-off and damage of road signs with time. It was also evident that, the progressive dirtiness of road signs could be represented by a quadratic function an a linear function could represent the paint degradation nature of both traffic markings and road signs. Actual measurements of earthen shoulder edge drop-off agree considerably with the developed model.

Keywords: deterioration, level of service, periodic maintenance, performance model, road side element

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Authors: Aydin Sipahioglu, Gokhan Celik

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Helicopter routing problem (HRP) is finding good tours for helicopter so as to pick up and deliver personnel or material among specified nodes, mutually. It can be encountered in case of being lots of supply and demand points for different commodities and requiring delivering commodities with helicopter. For instance, to deliver personnel or material from shore to oil rig is a good example. In fact, HRP is a branch of vehicle routing problem with pickup and delivery (VRPPD). However, it has additional constraints such that fuel capacity, performance of helicopter in different altitude and temperature, and the number of maximum takeoff and landing allowed. This kind of pickup and delivery problems can be classified into 3 groups, basically. 1-1 (one to one), M-M (many to many) and 1-M-1 (one to many to one). 1-1 means each commodity has only one supply and one demand point. M-M means there can be more than one supply and demand points for each kind of commodity. 1-M-1 means commodities at depot are delivered to demand points and commodities at customers are delivered to depot. In this case helicopter takes off from its own base, complete its tour and return to its own base. In this study, we define 1-M-M-1 type HRP. That means helicopter takes off from its home base, deliver commodities among the nodes as well as between depot and customers and return to its home base. These problems have NP-hard nature. Therefore, obtaining a good solution in a reasonable time is not easy. In this study, a model is offered for 1-M-M-1 type HRP. It is shown on small scale test instances that the model can find the optimal solution.

Keywords: helicopter routing problem, vehicle routing with pickup and delivery, integer programming

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Authors: E. Bartkiene, M. Ruzauskas, V. Lele, P. Zavistanaviciute, J. Bernatoniene, V. Jakstas, L. Ivanauskas, D. Zadeike, D. Klupsaite, P. Viskelis, J. Bendoraitiene, V. Navikaite-Snipaitiene, G. Juodeikiene

Abstract:

In this study, antimicrobial nutraceuticals; gummy candies (GC) from bovine colostrum (BC), essential oils (EOs), probiotic lactic acid bacteria (PLAB), and their combinations, were developed. For antimicrobial GC preparation, heteropolysaccharide (agar) was used. The antimicrobial properties of EOs (Eugenia caryophyllata, Thymus vulgaris, Citrus reticulata L., Citrus paradisi L.), BC, L. paracasei LUHS244, L. plantarum LUHS135, and their combinations against pathogenic bacteria strains (Streptococcus mutans, Enterococcus faecalis, Staphylococcus aureus, Salmonella enterica, Escherichia coli, Proteus mirabilis, and Pseudomonas aeruginosa) were evaluated. The highest antimicrobial properties by EO’s (Eugenia caryophyllata and Thymus vulgaris) were established. The optimal ingredients composition for antimicrobial GC preparation was established, which incorporate the BC fermented with L. paracasei LUHS244 in combination with Thymus vulgaris or Eugenia caryophyllata. These ingredients showed high inhibition properties of all tested pathogenic strains (except Pseudomonas aeruginosa). Antimicrobial GC formula consisting of thyme EO (up to 0.2%) and fermented BC (up to 3%), and for taste masking, mandarin or grapefruit EOs (up to 0.2%) was used. Developed GC high overall acceptability and antimicrobial properties, thus, antimicrobial GC could be a preferred form of nutraceuticals. This study was fulfilled with the support of the LSMU-KTU joint project.

Keywords: antimicrobial activity, bovine colostrum, essential oil, gummy candy, probiotic

Procedia PDF Downloads 178

Authors: Woosik Jang, Seung H. Han, Seung Won Baek, Chan Young Park

Abstract:

Natural gas (NG) is a local energy resource that exists in certain countries, and most NG producers operate within unstable governments. Moreover, about 90% of the liquefied natural gas (LNG) market is governed by a small number of international oil companies (IOCs) and national oil companies (NOCs), market entry of second movers is extremely limited. To overcome these barriers, project viability should be assessed based on limited information at the project screening perspective. However, there have been difficulties at the early stages of projects as follows: (1) What factors should be considered? (2) How many experts are needed to make a decision? and (3) How to make an optimal decision with limited information? To answer these questions, this research suggests a LNG project viability assessment model based on the Dempster-Shafer theory (DST). Total of 11 indices for the gas field analysis and 23 indices for the market environment analysis are identified that reflect unique characteristics of LNG industry. Moreover, the proposed model evaluates LNG projects based on questionnaire survey and it provides not only quantified results but also uncertainty level of results based on DST. Consequently, the proposed model as a systematic framework can support the decision-making process from the gas field projects using quantitative results, and it is developed to a stand-alone system to enhance the practical usability. It is expected to improve the decision-making quality and opportunity in LNG projects for enterprise through informed decision.

Keywords: project viability, LNG project, enterprise information system, Dempster-Shafer Theory, strategic decision-making

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Authors: Afshin Zahedi, Keivan Jamshidi

Abstract:

This study was conducted to determine the neurotoxic effects of different doses of ACR on the thoracic axons of the spinal cord of rat. To evaluate this hypothesis in the thoracic axons, amino-cupric silver staining technique of the de Olmos was conducted to define the histopathologic characteristic (argyrophilia) of axonal damage following ACR exposure. For this purpose 60 adult male rats (Wistar, approximately 250 g) were selected. Rats were hosed in polycarbonate boxes as two per each. Randomly assigned groups of rats (10 rats per exposure group, total 5 exposure groups as A, B, C, D and E) were exposed to 0.5, 5, 50, 100 and 500 mg/kg per day×11days intraperitoneal injection (IP injection) respectively. The remaining 10 rats were housed in group (F) as control group. Control rats received daily injections of 0.9% saline (3ml/kg). As indices of developing neurotoxicity, weight gain, gait scores and landing hindlimb foot splay (LHF) were determined. Weight gains were measured daily prior to injection. Gait scoring involved observation of spontaneous open field locomotion, included evaluations of ataxia, hopping, rearing and hind foot placement, and hindlimb foot splay were determined 3-4 times per week. Gait score was assigned from 1-4. After 11 days, two rats for silver stain, were randomly selected, dissected and proper samples were collected from thoracic portion of the spinal cord of rat. Results did show no neurological behavior in groups A, B and F, whereas severe neurotoxicity was observed in groups C and D. Rats in groups E died within 1-2 hours due to severe toxemia. In histopathological studies based on the de Olmos technique no argyrophilic neurons or processes were observed in stained sections obtained from the thoracic portion of the spinal cord of rats belong to groups A, B and F, while moderate to severe argyrophilic changes were observed in different stained sections obtained from the thoracic portion of the spinal cord of rats belong to groups C and D.

Keywords: acrylamide, rat, axonopathy, argyrophily, de Olmos

Procedia PDF Downloads 344

Authors: Ziaullah, Shah Wahab Ali

Abstract:

Micro-grid equipped with heterogeneous energy resources present the idea of small scale distributed energy management (DEM). DEM helps in minimizing the transmission and operation costs, power management and peak load demands. Micro-grids are collections of small, independent controllable power-generating units and renewable energy resources. Micro-grids also motivate to enable active customer participation by giving accessibility of real-time information and control to the customer. The capability of fast restoration against faulty situation, integration of renewable energy resources and Information and Communication Technologies (ICT) make micro-grid as an ideal system for distributed power systems. Micro-grids can have a bank of energy storage devices. The energy management system of micro-grid can perform real-time energy forecasting of renewable resources, energy storage elements and controllable loads in making proper short-term scheduling to minimize total operating costs. We present a review of existing micro-grids optimization objectives/goals, constraints, solution approaches and tools used in micro-grids for energy management. Cost-benefit analysis of micro-grid reveals that cooperation among different micro-grids can play a vital role in the reduction of import energy cost and system stability. Cooperative micro-grids energy trading is an approach to electrical distribution energy resources that allows local energy demands more control over the optimization of power resources and uses. Cooperation among different micro-grids brings the interconnectivity and power trading issues. According to the literature, it shows that open area of research is available for cooperative micro-grids energy trading. In this paper, we proposed and formulated the efficient energy management/trading module for interconnected micro-grids. It is believed that this research will open new directions in future for energy trading in cooperative micro-grids/interconnected micro-grids.

Keywords: distributed energy management, information and communication technologies, microgrid, energy management

Procedia PDF Downloads 377

Authors: Lu-Yin Lin

Abstract:

The morphology of electroactive material is highly related to energy storage ability. Structure-directing agent (SDA) can design electroactive materials with favorable surface properties. Zeolitic imidazolate framework 67 (ZIF67) is one of the potential electroactive materials for energy storage devices. The SDA concept is less applied to designing ZIF67 derivatives in previous studies. An in-situ technique with ammonium fluoride (NH₄F) as SDA is proposed to produce a ZIF67 derivative with highly improved energy storage ability. Attracted by the effective in-situ technique, the NH₄F, ammonium bifluoride (NH₄HF₂), and ammonium tetrafluoroborate (NH₄BF₄) are first used as SDA to synthesize ZIF67 derivatives in one-step solution process as electroactive material of energy storage devices. The mechanisms of forming ZIF67 derivatives synthesized with different SDAs are discussed to explain the SDA effects on physical and electrochemical properties. The largest specific capacitance (CF) of 1527.0 Fg-¹ and the capacity of 296.9 mAhg-¹ are obtained for the ZIF67 derivative prepared using NH₄BF₄ as SDA. The energy storage device composed of the optimal ZIF67 derivative and carbon electrodes presents a maximum energy density of 15.1 Whkg-¹ at the power density of 857 Wkg-¹. The CF retention of 90% and Coulombic efficiency larger than 98% are also obtained after 5000 cycles.

Keywords: ammonium bifluoride, ammonium tetrafluoroborate, energy storage device, one-step solution process, structure-directing agent, zeolitic imidazolate framework 67

Procedia PDF Downloads 83

Authors: Kingsley Agyapong

Abstract:

Research conducted in recent years has delved into the concept of patient-perceived value within the context of co-creation, particularly in the realm of doctor-patient interactions within healthcare settings. However, existing scholarly discourse lacks exploration regarding the emergence of patient-derived value in the co-creation process, specifically within encounters involving patients and stakeholders such as doctors, nurses, pharmacists, and other healthcare professionals. This study aims to fill this gap by elucidating the perspectives of patients regarding the value they derive from their interactions with multiple stakeholders in the delivery of healthcare services. The fieldwork was conducted at a university clinic located in Ghana. Data collection procedures involved conducting 20 individual interviews with key informants on distinct value accrued from co-creation practices and interactions with stakeholders. The key informants consisted of patients receiving care at the university clinic during the Malaria Treatment Process. Three themes emerged from both the existing literature and the empirical data collected. The first theme, labeled as "patient value needs in co-creation," encapsulates elements such as communication effectiveness, interpersonal interaction quality, treatment efficacy, and enhancements to the overall quality of life experienced by patients during their interactions with healthcare professionals. The second theme, designated as "services that enhance patients' experience in value co-creation," pertains to patients' perceptions of services that contribute favourably to co-creation experiences, including initiatives related to health promotion and the provision of various in-house services that patients deem pertinent for augmenting their overall experiences. The third theme, titled "Challenges in the co-creation of patients' value," delineates obstacles encountered within the co-creation process, including health professionals' challenges in effectively following up with patients scheduled for review and prolonged waiting times for healthcare delivery. This study contributes to the patients' perceptions of value within the co-creation process during their interactions with service providers, particularly healthcare professionals. By gaining a deeper insight into this process, healthcare providers can enhance the delivery of patient-centered care, thereby leading to improved healthcare outcomes. The study further offers managerial implications derived from its findings, providing actionable insights for healthcare managers and policymakers aiming to optimize patient value creation in healthcare services. Furthermore, it suggests avenues for future research endeavors within healthcare settings.

Keywords: patient, healthcare, co-creation, malaria

Procedia PDF Downloads 51

Authors: Pankaj Singh Rawat, Rajeew Kumar, Pradeep Ram, Priyanka Pandey

Abstract:

Wheat is an important cereal crop for food security. Boosting the wheat production and productivity is the major challenge across the nation. Good quality of seed is required for maintaining optimum plant stand which ultimately increases grain yield. Ensuring a good germination is one of the key steps to ensure proper plant stand and moisture assurance during seed germination may help to speed up the germination. The tiny size of nanoparticles may help in entry of water into seed without disturbing their internal structure. Considering above, a laboratory experiment was conducted during 2012-13 at G.B. Pant University of Agriculture and Technology, Pantnagar, India. The completely randomized design was used for statistical analysis. The experiment was conducted in two phases. In the first phase, the appropriate concentration of nanoparticles for seed treatment was screened. In second phase seed soaking hours of nanoparticles for better seed germination were standardized. Wheat variety UP2526 was taken as test crop. Four nanoparticles (TiO₂, ZnO, nickel and chitosan) were taken for study. The crop germination studies were done in petri dishes and standard package and practices were used to raise the seedlings. The germination studies were done by following standard procedure. In first phase of the experiment, seeds were treated with 50 and 300 ppm of nanoparticles and control was also maintained for comparison. In the second phase of experiment, seeds were soaked for 4 hours, 6 hours and 8 hours with 50 ppm nanoparticles of TiO₂, ZnO, nickel and chitosan along with control treatment to identify the soaking time for better seed germination. Experiment revealed that the application of nanoparticles help to enhance seed germination. The study revealed that seed treatment with  nanoparticles at 50 ppm concentration increases root length, shoot length, seedling length, shoot dry weight, seedling dry weight, seedling vigour index I and seedling vigour index II as compared to seed soaking at 300 ppm concentration. This experiment showed that seed soaking up to 4 hr was better as compared to 6 and 8 hrs. Seed soaking with nanoparticles specially TiO₂, ZnO, and chitosan proved to enhance germination and seedling growth indices of wheat crop.

Keywords: nanoparticles, seed germination, seed soaking, wheat

Procedia PDF Downloads 231

Authors: Mohammad Syed Ali Molla, Mohammed Azim, Mohammad Esharuzzaman

Abstract:

Centrifugal-casting machine is used in manufacturing special machine components like multi-layer journal bearing used in all internal combustion engine, steam, gas turbine and air craft turboengine where isotropic properties and high precisions are desired. Moreover, this machine can be used in manufacturing thin wall hightech machine components like cylinder liners and piston rings of IC engine and other machine parts like sleeves, and bushes. Heavy-duty machine component like railway wheel can also be prepared by centrifugal casting. A lot of technological developments are required in casting process for production of good casted machine body and machine parts. Usually defects like blowholes, surface roughness, chilled surface etc. are found in sand casted machine parts. But these can be removed by centrifugal casting machine using rotating metallic die. Moreover, die rotation, its temperature control, and good pouring practice can contribute to the quality of casting because of the fact that the soundness of a casting in large part depends upon how the metal enters into the mold or dies and solidifies. Poor pouring practice leads to variety of casting defects such as temperature loss, low quality casting, excessive turbulence, over pouring etc. Besides these, handling of molten metal is very unsecured and dangerous for the workers. In order to get rid of all these problems, the need of an automatic pouring device arises. In this research work, a robot assisted pouring device and a centrifugal casting machine are designed, developed constructed and tested experimentally which are found to work satisfactorily. The robot assisted pouring device is further modified and developed for using it in actual metal casting process. Lot of settings and tests are required to control the system and ultimately it can be used in automation of centrifugal casting machine to produce high-tech machine parts with desired precision.

Keywords: bearing, centrifugal casting, cylinder liners, robot

Procedia PDF Downloads 418

Authors: Erez Yerushalmi, Sani Ziv

Abstract:

The rising demand for healthcare services, without a corresponding rise in public supply, led to a debate on whether to increase private healthcare provision - especially in hospital services and second-tier healthcare. Proponents for increasing private healthcare highlight gains in efficiency, while opponents its risk to social welfare. None, however, provide a measure of the social value and its impact on the economy in terms of a monetary value. In this paper, we impute a minimum social value of public healthcare that corresponds to indifference between gains in efficiency, with losses to social welfare. Our approach resembles contingent valuation methods that introduce a hypothetical market for non-commodities, but is different from them because we use numerical simulation techniques to exploit certain market failure conditions. In this paper, we develop a general equilibrium model that distinguishes between public-private healthcare services and public-private financing. Furthermore, the social value is modelled as a by product of healthcare services. The model is then calibrated to our unique health focused Social Accounting Matrix of Israel, and simulates the introduction of a hypothetical health-labour market - given that it is heavily regulated in the baseline (i.e., the true situation in Israel today). For baseline parameters, we estimate the minimum social value at around 18% public healthcare financing. The intuition is that the gain in economic welfare from improved efficiency, is offset by the loss in social welfare due to a reduction in available social value. We furthermore simulate a deregulated healthcare scenario that internalizes the imputed value of social value and searches for the optimal weight of public and private healthcare provision.

Keywords: contingent valuation method (CVM), general equilibrium model, hypothetical market, private-public healthcare, social value of public healthcare

Procedia PDF Downloads 152

Authors: Yassine Mohammed Benyoucef, Razin Andery Dionisovich

Abstract:

Biomimicry is an old approach, but in the scientific conceptualization is new, as an approach of innovation based on the emulation of Nature, in recent years, this approach brings many potential theories and innovations in the architecture field. Indeed, these innovations have changed our view towards other Natural organisms also to the design processes in architecture, now the use of the biomimicry approach allows the application of a great sustainable development. The Sahara area is heading towards a sustainable policy with the desire to develop this rich context in terms of architecture, because of the rapid evolution of the architectural and urban concepts and the technology acceleration in one side, and under the pressure of the architectural crisis and the accelerated urbanization in the Saharan cities on the other side, the imperatives of sustainable development, ecology, climate adaptation, energy needs, are strongly imposed. Besides that, the new architectural and urban projects in the Saharan cities are not reliable in terms of energy efficiency and design and relationship with the environment. This article discusses the using of biomimetic strategy in the sustainable development of Saharan architecture. The aim of the article is to present a synthesis of biomimicry approach and propose the biomimicry as a solution for the development of Saharan architecture which can use this approach as a sustainable and innovation strategy. The biomimicry is the solution for effective strategies of development and can have a great potential point to meet the current challenges of designing efficient for forms or structures, energy efficiency, and climate issues. Moreover, the Sahara can be a favorable soil for great changes, the use of this approach is the key for the most optimal strategies and sustainable development of the Saharan architecture.

Keywords: biomimicry, Sahara, architecture, nature, innovation, technology

Procedia PDF Downloads 197

Authors: A. Moghadasein, M. Ghasemi, S. Fazelifar

Abstract:

Aim: Chemerin is a novel adipokine that play an important role in regulating lipid metabolism and abiogenesis. Chemerin is dependent on autocrine and paracrine signals for the differentiation and maturation of fat cells; it also regulates glucose uptake in fat cells and stimulates lipolysis. It has been reported that in adipocytes, chemerin enhances the insulin-stimulated glucose and causes the phosphorylation of tyrosine in Insulin receptor substrate. According to the studies, Chemerin may increase insulin sensitivity in adipose tissue and is largely associated with Body mass index, triglycerides, and blood pressure in those with normal glucose tolerance. There is limited information available regarding the effect of exercise training on serum chemerin concentrations. The purpose of this study was to investigate the effect of endurance training on serum chemerin levels and lipids of plasma in overweight women. Methodology: This study was a quasi-experimental research with a pre-post test design. After required examination and verification of high pressure by the physician, 22 obese subjects (age: 35.64±5.55 yr, weight: 75.62±9.30 kg, body mass index: 32.4±1.6 kg/m2) were randomly assigned to aerobic training (n= 12) and control (n= 12) groups. Participants completed a questionnaire indicating the lack of sports history during the past six months, the lack of anti-hypertension drugs use, hormone therapy, cardiovascular problems, and complete stoppage of menstrual cycle. Aerobic training was performed 3 times weekly for 8 weeks. Resting levels of chemerin plasma, metabolic parameters were measured prior to and after the intervention. The control group did not participate in any training program. In this study, ethical considerations included the complete description of the objectives to the study participants, ensuring the confidentiality of their information. Kolmogorov-Smirnov and Levin test were used for determining the normal distribution of data and homogeneity of variances, respectively. Analyze of variance with repeated measure were used to investigate the changes in the intra-group and the differences in inter-group of variables. Statistical operations were performed using SPSS 16 and the significance level of the tests was considered at P < 0.05. Results: After an 8 week aerobic training, levels of chemerin plasma were significantly decreased in aerobic trained group when compared with their control groups (p < 0.05).Concurrently, levels of HDL-c were significantly decreased (p < 0.05) whereas, levels of cholesterol, TG and LDL-c, showed no significant changes (p > 0.05). No significant correlations between chemerin levels and weight loss were observed in subjects with overweight women. Conclusion: The present study demonstrated, 8 weeks aerobic training, reduced serum chemerin concentrations in overweight women. Whereas, aerobic training exercise programmers affected the lipid profile response of obese subjects differently. However further research is warranted in order to unravel the molecular mechanism for the range of responses and the role of serum chemerin.

Keywords: chemerin, aerobic training, lipid profile, obese women

Procedia PDF Downloads 492

Authors: Sercan Altundemir, Pinar Eribol, A. Kerem Uguz

Abstract:

Microfluidics systems allow many-large scale laboratory applications to be miniaturized on a single device in order to reduce cost and advance fluid control. Moreover, such systems enable to generate and control droplets which have a significant role on improved analysis for many chemical and biological applications. For example, they can be employed as the model for cells in microfluidic systems. In this work, the interfacial instability of two immiscible Newtonian liquids flowing in a microchannel is investigated. When two immiscible liquids are in laminar regime, a flat interface is formed between them. If a direct current electric field is applied, the interface may deform, i.e. may become unstable and it may be ruptured and form micro-droplets. First, the effect of thickness ratio, total flow rate, viscosity ratio of the silicone oil and ethylene glycol liquid couple on the critical voltage at which the interface starts to destabilize is investigated. Then the droplet sizes are measured under the effect of these parameters at various voltages. Moreover, the effect of total flow rate on the time elapsed for the interface to be ruptured to form droplets by hitting the wall of the channel is analyzed. It is observed that an increase in the viscosity or the thickness ratio of the silicone oil to the ethylene glycol has a stabilizing effect, i.e. a higher voltage is needed while the total flow rate has no effect on it. However, it is observed that an increase in the total flow rate results in shortening of the elapsed time for the interface to hit the wall. Moreover, the droplet size decreases down to 0.1 μL with an increase in the applied voltage, the viscosity ratio or the total flow rate or a decrease in the thickness ratio. In addition to these observations, two empirical models for determining the critical electric number, i.e., the dimensionless voltage and the droplet size and another model which is a combination of both models, for determining the droplet size at the critical voltage are established.

Keywords: droplet formation, electrohydrodynamics, microfluidics, two-phase flow

Procedia PDF Downloads 180