Search results for: analytical analysis
Commenced in January 2007
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Edition: International
Paper Count: 27874

Search results for: analytical analysis

4954 Interaction between the Rio Conventions on Climate and Biodiversity: Analysis of the Integration of Ecosystem-Based Approaches and Nature-Based Solutions into the UNFCCC

Authors: Dieudonne Mevono Mvogo

Abstract:

The Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES)-Intergovernmental Panel on Climate Change (IPCC) co-sponsored workshop report suggests that climate change and biodiversity loss are two of the most pressing issues of the Anthropocene. Research establishes the interconnection between climate change and biodiversity. On the one hand, the impact of climate change on biodiversity loss – 14 % over the past century – is projected to surpass other threats – land and sea use 34 % and direct exploitation of species 23 % – during the 21st century. Response measures to climate change also affect biodiversity negatively or positively. On the other hand, actions to halt or reverse biodiversity loss can enhance land and ocean capacity for carbon sequestration. These actions can also promote adaptation by ensuring adaptive capacity. This systemic interaction between climate change and biodiversity affects the human quality of life. The United Nations Secretariat's report entitled 'Gaps in international environmental law and environment-related instruments: towards a global pact for the environment,' released in 2018, states that cooperation and mutual support among agreements dealing with climate change, the protection of the marine environment, freshwater resources and hazardous waste are indispensable for the effective implementation of the Convention on the Biological Diversity (CBD). Since biodiversity is being lost at an alarming rate, this study aims to evaluate the cooperative framework for the coherence and coordination between climate change and biodiversity regimes to provide co-benefits for climate and biodiversity crises. It questions the potential improvement regarding integrating ecosystem-based approaches and nature-based solutions – promoted by the CBD – into the United Nations Framework Convention on Climate Change (UNFCCC).

Keywords: rio conventions, climate change, biodiversity, cooperative framework, ecosystem-based approaches, nature-based solutions

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4953 Finite Element Modelling for the Development of a Planar Ultrasonic Dental Scaler for Prophylactic and Periodontal Care

Authors: Martin Hofmann, Diego Stutzer, Thomas Niederhauser, Juergen Burger

Abstract:

Dental biofilm is the main etiologic factor for caries, periodontal and peri-implant infections. In addition to the risk of tooth loss, periodontitis is also associated with an increased risk of systemic diseases such as atherosclerotic cardiovascular disease and diabetes. For this reason, dental hygienists use ultrasonic scalers for prophylactic and periodontal care of the teeth. However, the current instruments are limited to their dimensions and operating frequencies. The innovative design of a planar ultrasonic transducer introduces a new type of dental scalers. The flat titanium-based design allows the mass to be significantly reduced compared to a conventional screw-mounted Langevin transducer, resulting in a more efficient and controllable scaler. For the development of the novel device, multi-physics finite element analysis was used to simulate and optimise various design concepts. This process was supported by prototyping and electromechanical characterisation. The feasibility and potential of a planar ultrasonic transducer have already been confirmed by our current prototypes, which achieve higher performance compared to commercial devices. Operating at the desired resonance frequency of 28 kHz with a driving voltage of 40 Vrms results in an in-plane tip oscillation with a displacement amplitude of up to 75 μm by having less than 8 % out-of-plane movement and an energy transformation factor of 1.07 μm/mA. In a further step, we will adapt the design to two additional resonance frequencies (20 and 40 kHz) to obtain information about the most suitable mode of operation. In addition to the already integrated characterization methods, we will evaluate the clinical efficiency of the different devices in an in vitro setup with an artificial biofilm pocket model.

Keywords: ultrasonic instrumentation, ultrasonic scaling, piezoelectric transducer, finite element simulation, dental biofilm, dental calculus

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4952 Bacillus thuringiensis CHGP12 Uses a Multifaceted Strategy to Suppress Fusarium Wilt of Chickpea and to Enhance the Total Biomass of Chickpea Plants

Authors: Muhammad Naveed Aslam, Rida Fatima, Anam Moosa, Muhammad Taimoor Shakeel

Abstract:

Bacillus strains produce antifungal secondary metabolites making them potential candidates for suppressing Fusarium wilt of chickpea disease. In this study, eighteen Bacillus strains were evaluated for their antagonistic effect against Fusarium oxysporum f. sp. ciceris causing Fusarium wilt of chickpea disease. In a direct antifungal assay, thirteen strains showed significant inhibition zones while the remaining five strains did not produce inhibition zones of FOC. Bacillus thuringiensis CHGP12 was the most promising strain exhibiting the highest inhibition of FOC. Antifungal lipopeptides were extracted from CHGP12 strain which showed significant inhibition of the pathogen. Liquid chromatography mass spectrometry (LCMS) analysis revealed that CHGP12 was positive for the presence of iturin, fengycin, surfactin, bacillaene, bacillibactin, plantazolicin, and bacilysin. CHGP12 was tested for biochemical determinants in an in vitro qualitative test where it showed the ability to produce lipase, amylase, cellulase, protease, siderophores, and indole 3-acetic acid (IAA). Furthermore, in a greenhouse experiment CHGP12 also showed a significant decrease in the disease severity in treated plants compared to control. Moreover, CHGP12 also exhibited a significant increase in plant growth parameters viz, root and shoot growth parameters, stomatal conductance, and photosynthesis rate. Conclusively, our findings present the promising potential of Bacillus strain CHGP12 to suppress Fusarium wilt of chickpea and to promote plant growth.

Keywords: liquid chromatography mass spectrometry, growth promotion, antagonism, hydrolytic enzymes, inhibition, lipopeptides.

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4951 Exploration of Environmental Parameters on the Evolution of Vernacular Building Techniques in East Austria

Authors: Hubert Feiglstorfer

Abstract:

Due to its location in a transition zone from the Pannonian to the pre-Alpine region, the east of Austria shows a small-scale diversity in the regional development of certain vernacular building techniques. In this article the relationship between natural building material resources, topography and climate will be examined. Besides environmental preconditions, social and economic historical factors have developed different construction techniques within certain regions in the Weinviertel and Burgenland, the two eastern federal states of Austria. But even within these regions, varying building techniques were found, due to the locally different use of raw materials like wood, stone, clay, lime, or organic fibres. Within these small-scale regions, building traditions were adapted over the course of time due to changes in the use of the building material, for example from wood to brick or from wood to earth. The processing of the raw materials varies from region to region, for example as rammed earth, cob, log, or brick construction. Environmental preconditions cross national borders. For that reason, developments in the neighbouring countries, the Czech Republic, Slovakia, Hungary and Slovenia are included in this analysis. As an outcome of this research a map was drawn which shows the interrelation between locally available building materials, topography, climate and local building techniques? As a result of this study, which covers the last 300 years, one can see how the local population used natural resources very sensitively adapted to local environmental preconditions. In the case of clay, for example, changes of proportions of lime and particular minerals cause structural changes that differ from region to region. Based on material analyses in the field of clay mineralogy, on ethnographic research, literature and archive research, explanations for certain local structural developments will be given for the first time over the region of East Austria.

Keywords: European crafts, material culture, architectural history, earthen architecture, earth building history

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4950 New Biobased(Furanic-Sulfonated) Poly(esteramide)s

Authors: Souhir Abid

Abstract:

The growing interest in vegetal biomass as an alternative for fossil resources has stimulated the development of numerous classes of monomers. Polymers from renewable resources have attracted an increasing amount of attention over the last two decades, predominantly due to two major reasons (i) firstly environmental concerns, and (ii) secondly the use of monomers from renewable feedstock is a steadily growing field of interest in order to reduce the amount of petroleum consumed in the chemical industry and to open new high-value-added markets to agriculture. Furanic polymers have been considered as alternative environmentally friendly polymers. In our earlier work, modifying furanic polyesters by incorporation of amide functions along their backbone, lead to a particular class of polymer ‘poly(ester-amide)s’, was investigated to combine the excellent mechanical properties of polyamides and the biodegradability of polyesters. As a continuation of our studies on this family of polymer, a series of furanic poly(ester-amide)s bearing sulfonate groups in the main chain were synthesized from 5,5’-Isopropylidene-bis(ethyl 2-furoate), dimethyl 5-sodiosulfoisophthalate, ethylene glycol and hexamethylene diamine by melt polycondensation using zinc acetate as a catalyst. In view of the complexity of the NMR spectrum analysis of the resulting sulfonated poly(ester-amide)s, we found that it is useful to prepare initially the corresponding homopolymers: sulfonated polyesters and polyamides. Structural data of these polymers will be used as a basic element in 1H NMR characterization. The hydrolytic degradation in acidic aqueous conditions (pH = 4,35 ) at 37 °C over the period of four weeks show that the mechanism of the hydrolysis of poly(ester amide)s was elucidated in relation with the microstructure. The strong intermolecular hydrogen bonding interactions between amide functions and water molecules increases the hydrophilicity of the macromolecular chains and consequently their hydrolytic degradation.

Keywords: furan, hydrolytic degradation, polycondensation, poly(ester amide)

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4949 Effect of Cryogenic Pre-stretching on the Room Temperature Tensile Behavior of AZ61 Magnesium Alloy and Dominant Grain Growth Mechanisms During Subsequent Annealing

Authors: Umer Masood Chaudry, Hafiz Muhammad Rehan Tariq, Chung-soo Kim, Tea-sung Jun

Abstract:

This study explored the influence of pre-stretching temperature on the microstructural characteristics and deformation behavior of AZ61 magnesium alloy and its implications on grain growth during subsequent annealing. AZ61 alloy was stretched to 5% plastic strain along rolling (RD) and transverse direction (TD) at room (RT) and cryogenic temperature (-150 oC, CT) followed by annealing at 320 oC for 1 h to investigate the twinning and dislocation evolution and its consequent effect on the flow stress, plastic strain and strain hardening rate. Compared to RT-stretched samples, significant improvement in yield stress, strain hardening rate and moderate reduction in elongation to failure were witnessed for CT-stretched samples along RD and TD. The subsequent EBSD analysis revealed the increased fraction of fine {10-12} twins and nucleation of multiple {10-12} twin variants caused by higher local stress concentration at the grain boundaries in CT-stretched samples as manifested by the kernel average misorientation. This higher twin fraction and twin-twin interaction imposed the strengthening by restricting the mean free path of dislocations, leading to higher flow stress and strain hardening rate. During annealing of the RT/CT-stretched samples, the residual strain energy and twin boundaries were decreased due to static recovery, leading to a coarse-grained twin-free microstructure. Strain induced boundary migration (SBIM) was found to be the predominant mechanism governing the grain growth during annealing via movement of high angle grain boundaries.

Keywords: magnesium, twinning, twinning variant selection, EBSD, cryogenic deformation

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4948 Evaluation of IMERG Performance at Estimating the Rainfall Properties through Convective and Stratiform Rain Events in a Semi-Arid Region of Mexico

Authors: Eric Muñoz de la Torre, Julián González Trinidad, Efrén González Ramírez

Abstract:

Rain varies greatly in its duration, intensity, and spatial coverage, it is important to have sub-daily rainfall data for various applications, including risk prevention. However, the ground measurements are limited by the low and irregular density of rain gauges. An alternative to this problem are the Satellite Precipitation Products (SPPs) that use passive microwave and infrared sensors to estimate rainfall, as IMERG, however, these SPPs have to be validated before their application. The aim of this study is to evaluate the performance of the IMERG: Integrated Multi-satellitE Retrievals for Global Precipitation Measurament final run V06B SPP in a semi-arid region of Mexico, using 4 automatic rain gauges (pluviographs) sub-daily data of October 2019 and June to September 2021, using the Minimum inter-event Time (MIT) criterion to separate unique rain events with a dry period of 10 hrs. for the purpose of evaluating the rainfall properties (depth, duration and intensity). Point to pixel analysis, continuous, categorical, and volumetric statistical metrics were used. Results show that IMERG is capable to estimate the rainfall depth with a slight overestimation but is unable to identify the real duration and intensity of the rain events, showing large overestimations and underestimations, respectively. The study zone presented 80 to 85 % of convective rain events, the rest were stratiform rain events, classified by the depth magnitude variation of IMERG pixels and pluviographs. IMERG showed poorer performance at detecting the first ones but had a good performance at estimating stratiform rain events that are originated by Cold Fronts.

Keywords: IMERG, rainfall, rain gauge, remote sensing, statistical evaluation

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4947 Spatio-Temporal Analysis of Rabies Incidence in Herbivores of Economic Interest in Brazil

Authors: Francisco Miroslav Ulloa-Stanojlovic, Gina Polo, Ricardo Augusto Dias

Abstract:

In Brazil, there is a high incidence of rabies in herbivores of economic interest (HEI) transmitted by the common vampire bat Desmodus rotundus, the presence of human rabies cases and the huge economic losses in the world's largest cattle industry, it is important to assist the National Program for Control of Rabies in herbivores in Brazil, that aims to reduce the incidence of rabies in HEI populations, mainly through epidemiological surveillance, vaccination of herbivores and control of vampire-bat roosts. Material and Methods: A spatiotemporal retrospective Kulldorff's spatial scan statistic based on a Poisson model and Monte Carlo simulation and an Anselin's Local Moran's I statistic were used to uncover spatial clustering of HEI rabies from 2000 – 2014. Results: Were identify three important clusters with significant year-to-year variation (Figure 1). In 2000, was identified one area of clustering in the North region, specifically in the State of Tocantins. Between the year 2000 and 2004, a cluster centered in the Midwest and Southeast region including the States of Goiás, Minas Gerais, Rio de Janeiro, Espirito Santo and São Paulo was prominent. And finally between 2000 and 2005 was found an important cluster in the North, Midwest and South region. Conclusions: The HEI rabies is endemic in the country, in addition, appears to be significant differences among the States according to their surveillance services, that may be difficulting the control of the disease, also other factors could be influencing in the maintenance of this problem like the lack of information of vampire-bat roosts identification, and limited human resources for realization of field monitoring. A review of the program control by the authorities it’s necessary.

Keywords: Brazil, Desmodus rotundus, herbivores, rabies

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4946 The Presence of Ochratoxin a in Breast-Milk, Urine and Serum of Lactating Women

Authors: Magdalena Twaruzek, Karolina Ropejko

Abstract:

Mycotoxins are secondary metabolites of molds. Ochratoxin A (OTA) is the most common in the Polish climate. It is produced by fungi of the genera Aspergillus and Penicillium. It is produced as a result of improper food storage. It is present in many products that are consumed both by humans and animals: cereals, wheat gluten, coffee, dried fruit, wine, grape juice, spices, beer, and products based on them. OTA is nephrotoxic, hepatotoxic, potentially carcinogenic, and teratogenic. OTA mainly enters an organism by oral intake. The aim of the study was to detect the presence of OTA in milk, urine, and serum of lactating women. A survey was also conducted regarding the daily diet of women. The research group consisted of 32 lactating women (11 were the donors from the Milk Bank in Toruń, the other 21 were recruited for this study). Results of the analysis showed the occurrence of OTA only in 3 milk samples (9.38%). The minimum level was 0.01 ng/ml, while the maximum 0.018 ng/ml and the mean 0.0013 ng/ml. Twenty-six urine samples (81.25%) were OTA positive, with minimum level 0.013 ng/ml, maximum level 0.117 ng/ml and mean 0.0192 ng/ml. Also, all 32 serum samples (100%) were contaminated by OTA, with a minimum level of 0.099 ng/ml, a maximum level of 2.38 ng/ml, and a mean of 0.4649 ng/ml. In the case of 3 women, OTA was present in all tested body fluids. Based on the results, the following conclusions can be drawn: the breast-milk of women in the study group is slightly contaminated with ochratoxin A. Ten samples of urine contained ochratoxin A above its average content in tested samples. Moreover, serum of 8 women contains ochratoxin A at a level above the average content of this mycotoxin in tested samples. The average ochratoxin A level in serum in the presented studies was 0.4649 ng/ml, which is much lower than the average serum ochratoxin A level established in several countries in the world, i.e., 0.7 ng/ml. Acknowledgment: This study was supported by the Polish Minister of Science and Higher Education under the program 'Regional Initiative of Excellence' in 2019 - 2022 (Grant No. 008/RID/2018/19).

Keywords: breast-milk, urine, serum, contamination, ochratoxin A

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4945 Engineering Thermal-Hydraulic Simulator Based on Complex Simulation Suite “Virtual Unit of Nuclear Power Plant”

Authors: Evgeny Obraztsov, Ilya Kremnev, Vitaly Sokolov, Maksim Gavrilov, Evgeny Tretyakov, Vladimir Kukhtevich, Vladimir Bezlepkin

Abstract:

Over the last decade, a specific set of connected software tools and calculation codes has been gradually developed. It allows simulating I&C systems, thermal-hydraulic, neutron-physical and electrical processes in elements and systems at the Unit of NPP (initially with WWER (pressurized water reactor)). In 2012 it was called a complex simulation suite “Virtual Unit of NPP” (or CSS “VEB” for short). Proper application of this complex tool should result in a complex coupled mathematical computational model. And for a specific design of NPP, it is called the Virtual Power Unit (or VPU for short). VPU can be used for comprehensive modelling of a power unit operation, checking operator's functions on a virtual main control room, and modelling complicated scenarios for normal modes and accidents. In addition, CSS “VEB” contains a combination of thermal hydraulic codes: the best-estimate (two-liquid) calculation codes KORSAR and CORTES and a homogenous calculation code TPP. So to analyze a specific technological system one can build thermal-hydraulic simulation models with different detalization levels up to a nodalization scheme with real geometry. And the result at some points is similar to the notion “engineering/testing simulator” described by the European utility requirements (EUR) for LWR nuclear power plants. The paper is dedicated to description of the tools mentioned above and an example of the application of the engineering thermal-hydraulic simulator in analysis of the boron acid concentration in the primary coolant (changed by the make-up and boron control system).

Keywords: best-estimate code, complex simulation suite, engineering simulator, power plant, thermal hydraulic, VEB, virtual power unit

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4944 Simulation and Analysis of Passive Parameters of Building in eQuest: A Case Study in Istanbul, Turkey

Authors: Mahdiyeh Zafaranchi

Abstract:

With rapid development of urbanization and improvement of living standards in the world, energy consumption and carbon emissions of the building sector are expected to increase in the near future; because of that, energy-saving issues have become more important among the engineers. Besides, the building sector is a major contributor to energy consumption and carbon emissions. The concept of efficient building appeared as a response to the need for reducing energy demand in this sector which has the main purpose of shifting from standard buildings to low-energy buildings. Although energy-saving should happen in all steps of a building during the life cycle (material production, construction, demolition), the main concept of efficient energy building is saving energy during the life expectancy of a building by using passive and active systems, and should not sacrifice comfort and quality to reach these goals. The main aim of this study is to investigate passive strategies (do not need energy consumption or use renewable energy) to achieve energy-efficient buildings. Energy retrofit measures were explored by eQuest software using a case study as a base model. The study investigates predictive accuracy for the major factors like thermal transmittance (U-value) of the material, windows, shading devices, thermal insulation, rate of the exposed envelope, window/wall ration, lighting system in the energy consumption of the building. The base model was located in Istanbul, Turkey. The impact of eight passive parameters on energy consumption had been indicated. After analyzing the base model by eQuest, a final scenario was suggested which had a good energy performance. The results showed a decrease in the U-values of materials, the rate of exposing buildings, and windows had a significant effect on energy consumption. Finally, savings in electric consumption of about 10.5%, and gas consumption by about 8.37% in the suggested model were achieved annually.

Keywords: efficient building, electric and gas consumption, eQuest, Passive parameters

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4943 Advanced Bio-Composite Materials Based on Biopolymer Blends and Cellulose Nanocrystals

Authors: Zineb Kassab, Nassima El Miri, A. Aboulkas, Abdellatif Barakat, Mounir El Achaby

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Recently, more attention has been given to biopolymers with a focus on sustainable development and environmental preservation. Following this tendency, the attempt has been made to replace polymers derived from petroleum with superior biodegradable polymers (biopolymers). In this context, biopolymers are considered potential replacements for conventional plastic materials. However, some of their properties must be improved for better competitiveness, especially regarding their mechanical, thermal and barrier properties. Bio-nanocomposite technology using nanofillers has already been proven as an effective way to produce new materials with specific properties and high performances. With the emergence of nanostructured bio-composite materials, incorporating elongated rod-like cellulose nanocrystals (CNC) has attracted more and more attention in the field of nanotechnology. This study is aimed to develop bio-composite films of biopolymer matrices [Carboxymethyle cellulose (CMC), Starch (ST), Chitosan (CS) and Polyvinyl alcohol (PVA)] reinforced with cellulose nanocrystals (CNC) using the solution casting method. The CNC were extracted at a nanometric scale from lignocellulosic fibers via sulfuric acid hydrolysis and then characterized using X-ray diffraction (XRD), thermogravimetric analysis (TGA), confocal microscopy, infrared spectroscopy (IR), atomic force and transmission electron microscopies (AFM and TEM) techniques. The as extracted CNC were used as a reinforcing phase to produce a variety of bio-composite films at different CNC loading (0.5-10 wt %) with specific properties. The rheological properties of film-forming solutions (FFS) of bio-composites were studied, and their relation to the casting process was evaluated. Then, the structural, optical transparency, water vapor permeability, thermal stability and mechanical properties of all prepared bio-composite films were evaluated and studied in this report. The high performances of these bio-composite films are expected to have potential in biomaterials or packaging applications.

Keywords: biopolymer composites, cellulose nanocrystals, food packaging, lignocellulosic fibers

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4942 Disentangling an Ethnographic Study of the Imagined Inca: How the Yale-Peruvian Expedition of 1911 Created an Inca Heritage

Authors: Charlotte Williams

Abstract:

Yale University Professor Hiram Bingham’s discovery of Machu Picchu in 1911 spurred an international interest in the Inca Empire, and with it, a dispute with the Peruvian government over who had rightful jurisdiction and curatorship over Inca history. By 2011, the Peruvian government initiated a legal battle for the return of artifacts that Bingham had removed from Machu Picchu, successfully returning them not to the site of Machu Picchu, but to Cusco, employing the rationale that the ancient Inca capital housed descendants of the Inca empire. This conflation of the past and present can be traced to a largely unanalyzed study that accompanied Bingham’s expedition: an ethnographic analysis of Inca descendants, which at the time portrayed indigenous Peruvian Andean peoples as remnants of a lost civilization, using Cusco as an assumed repository for people with 'Inca' characteristics. This study draws from the original Yale Peruvian Expedition archives, the Cusco Library archives, and in-depth interviews with curators of the Inca Museum and Machu Picchu Museum to analyze both the political conflict that emerged as a reaction to the ethnographic study, and how the study articulated with an inflating tourism market attempting to define what it meant to be Inca to an international public. The construction of the modern Inca as both directors of tourism management and purveyors of their archaeological material culture points to a unique case in which modern Peruvian citizens could claim heritage to an Inca past despite a lack of recognition as a legally defined group. The result has far-reaching implications, since Bingham’s artifacts returned not necessarily to a traditional nation-state, but to an imagined one, broadening the conditions under which informal repatriations can occur.

Keywords: archaeology of memory, imagined communities, Incanismo, repatriation

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4941 Development of a Program for the Evaluation of Thermal Performance Applying the Centre Scientifique et Techniques du Bâtiment Method Case Study: Classroom

Authors: Iara Rezende, Djalma Silva, Alcino Costa Neto

Abstract:

Considering the transformations of the contemporary world linked to globalization and climate changes caused by global warming, the environmental and energy issues have been increasingly present in the decisions of the world scenario. Thus, the aim of reducing the impacts caused by human activities there are the energy efficiency measures, which are also applicable in the scope of Civil Engineering. Considering that a large part of the energy demand from buildings is related to the need to adapt the internal environment to the users comfort and productivity, measures capable of reducing this need can minimize the climate changes impacts and also the energy consumption of the building. However, these important measures are currently little used by civil engineers, either because of the interdisciplinarity of the subject, the time required to apply certain methods or the difficult interpretation of the results obtained by computational programs that often have a complex and little applied approach. Thus, it was proposed the development of a Java application with a simpler and applied approach to evaluate the thermal performance of a building in order to obtain results capable of assisting the civil engineers in the decision making related to the users thermal comfort. The program was built in Java programming language and the method used for the evaluation was the Center Scientifique et Technique du Batiment (CSTB) method. The program was used to evaluate the thermal performance of a university classroom. The analysis was carried out from simulations considering the worst climatic situation of the building occupation. Thus, at the end of the process, the favorable result was obtained regarding the classroom comfort zone and the feasibility of using the program, thus achieving the proposed objectives.

Keywords: building occupation, CSTB method, energy efficiency measures, Java application, thermal comfort

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4940 Comparative Evaluation of the Effectiveness of Different Mindfulness-Based Interventions on Medically Unexplained Symptoms: A Systematic Review

Authors: R. R. Billones, N. Lukkahatai, L. N. Saligan

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Mindfulness based interventions (MBIs) have been used in medically unexplained symptoms (MUS). This systematic review describes the literature investigating the general effect of MBIs on MUS and identifies the effects of specific MBIs on specific MUS conditions. The preferred reporting items for systematic reviews and meta-analysis guidelines (PRISMA) and the modified Oxford quality scoring system (JADAD) were applied to the review, yielding an initial 1,556 articles. The search engines included PubMed, ScienceDirect, Web of Science, Scopus, EMBASE, and PsychINFO using the search terms: mindfulness, or mediations, or mindful or MBCT or MBSR and medically unexplained symptoms or MUS or fibromyalgia or FMS. A total of 24 articles were included in the final systematic review. MBIs showed large effects on socialization skills for chronic fatigue syndrome (d=0.65), anger in fibromyalgia (d=0.61), improvement of somatic symptoms (d=1.6) and sleep (d=1.12) for painful conditions, physical health for chronic back pain (d=0.51), and disease intensity for irritable bowel disease/syndrome (d=1.13). A manualized MBI that applies the four fundamental elements present in all types of interventions were critical to efficacy. These elements were psycho-education sessions specific to better understand the medical symptoms, the practice of awareness, the non-judgmental observance of the experience at the moment, and the compassion to ones’ self. The effectiveness of different mindfulness interventions necessitates giving attention to improve the gaps that were identified related to home-based practice monitoring, competency training of mindfulness teachers, and sound psychometric properties to measure the mindfulness practice.

Keywords: mindfulness-based interventions, medically unexplained symptoms, mindfulness-based cognitive therapy, mindfulness-based stress reduction, fibromyalgia, irritable bowel syndrome

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4939 Socio-Economic and Environmental Impact of Urban Sprawl: A Case Study Adigrat City, Tigray, Ethiopia

Authors: Fikre Belay Tekulu

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This thesis presents the socio-economic and environmental impacts of urban sprawl in the case of Adigrat city, Tigray Region, Ethiopia. The main objective of this research is to assess major causes, trends and socio-economic and environmental impacts of the urban sprawl of Adigrat city. The study employed both quantitative and qualitative methods as questionnaires, interviews and observation used for data collection. Simple random sampling has been used to select the participants. The land use and land cover change for agricultural land and forest and grassland resource analysis is done with the aid of GIS. Urban sprawl is mainly caused by the rapid population growth, increase in the living and property cost in the core of the city, land demand and land speculation and the growth of transport and an increase in income of people and demand of more living space. The study indicates 15726.24 hectares (515.49 per cent) of new land added to the city jurisdiction from its adjacent Gantafeshum Wereda between 1986 and 2018. The population of Adigrat city increased by 9.045 per cent per year, while the city expanded 16.01 per cent per annum and the LCR was 0.0233 hectares per person between 1986 and 2018.Built-up area increased by 35.27 per cent per annum, while agricultural land, forests and grassland cover decreased by 1.68 per cent and 1.26 per cent per annum respectively in the last thirty three years. This rapid growth of urban sprawl brought social-economic and environmental change in the city that has been observed by the city residents. Therefore, the city administration should need strong, integrated, effective and efficient work, with its neighbor rural area and also done timely preparation, implementation, supervision, and evaluation of the structural plan of the city to bring out sustainable development of the city.

Keywords: cause, , trends, urban sprawl, land use land cover, GIS

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4938 Cellular Senescence and Neuroinflammation Following Controlled Cortical Impact Traumatic Brain Injury in Juvenile Mice

Authors: Zahra F. Al-Khateeb, Shenel Shekerzade, Hasna Boumenar, Siân M. Henson, Jordi L. Tremoleda, A. T. Michael-Titus

Abstract:

Traumatic brain injury (TBI) is the leading cause of disability and death in young adults and also increases the risk ofneurodegeneration. The mechanisms linking moderate to severe TBI to neurodegeneration are not known. It has been proposed that cellular senescence inductionpost-injury could amplify neuroinflammation and induce long-term changes. The impact of these processes after injury to an immature brain has not been characterised yet. We carried out a controlled cortical impact injury (CCI) in juvenile 1 month-old male CD1 mice. Animals were anesthetised and received a unilateral CCI injury. The sham group received anaesthesia and had a craniotomy. A naïve group had no intervention. The brain tissue was analysed at 5 days and 35 days post-injury using immunohistochemistry and markers for microglia, astrocytes, and senescence. Compared tonaïve animals, injured mice showed an increased microglial and astrocytic reaction early post-injury, as reflected in Iba1 and GFAP markers, respectively; the GFAP increase persisted in the later phase. The senescence analysis showed a significant increase inγH2AX-53BP1 nuclear foci, 8-oxoguanine, p19ARF, p16INK4a, and p53 expression in naïve vs. sham groups and naïve vs. CCI groups, at 5 dpi. At 35 days, the difference was no longer statistically significant in all markers. The injury induced a decrease p21 expression vs. the naïve group, at 35 dpi. These results indicate the induction of a complex senescence response after immature brain injury. Some changes occur early and may reflect the activation/proliferation of non-neuronal cells post-injury that had been hindered, whereas changes such as p21 downregulation may reflect a delayed response and pro-repair processes.

Keywords: cellular senescence, traumatic brain injury, brain injury, controlled cortical impact

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4937 Challenging the Traditional Practice of Continuous Abscess Cavity Packing – A Single Center, Single Blind Randomized Controlled Trial

Authors: Lakmali Anthony, Bushra Oathman, Anshini Jain, Raaj Chandra

Abstract:

Introduction: Abscesses are traditionally treated by incision and drainage with the packing of the residual abscess cavity until healing. This method requires regular visits from community nurses for continuous wound packing upon discharge from the hospital and causes considerable patient discomfort. Whether abscess cavity packing offers any advantage over non-packing has not yet been adequately studied to the best of our knowledge. This study aims to determine if there are differences in clinical outcomes of time to healing, fistula formation and recurrence of abscess between abscess cavity packing vs. non-packing groups. Methods: This study was a single-center, single-blind, randomized controlled trial where patients were randomized into packing and non-packing arms. All patients over 18 years presenting to Eastern Health with an abscess requiring incision and drainage in the theatre were invited to participate. Those with underlying conditions that cause recurrent abscesses were excluded. Data were collected from December 2018 to April 2020. Results: There were 63 patients who had abscesses treated with incision and drainage that were enrolled in the study, 52 of which were suitable for analysis. Demographic characteristics were similar in both groups. The packing group had a significantly longer time to heal compared to the non-packing group. Rates of fistula formation and recurrence of abscess were low and there were no statistically significant differences between groups. The packing group had more patients with delayed healing (defined as >60 days) and required more follow-up visits compared to the non-packing group. Conclusion: This pilot study indicates that abscesses can not only be managed safely with incision and drainage alone without the need for continuous abscess cavity packing but also that non-packing may offer clinical benefits to patients with earlier healing of abscesses compared to continuous cavity packing.

Keywords: abscess packing, subcutaneous, perianal, pilonidal

Procedia PDF Downloads 38
4936 Factors Affecting Implementation of Construction Health and Safety Regulations, Their Effects and Mitigation Measures in Building Construction Project Sites of Hawassa City

Authors: Tadewos Awugchew Wudineh

Abstract:

Health and safety issues have always been a major problem and concern in the building construction industry. The health and safety regulations are stated to eliminate the potential hazards and to reduce the consequential risks. However, the importance of the regulations seems to be overlooked in building construction sites of Hawassa City. Accordingly, many companies don’t follow the regulations as construction workers are more likely to be injured and killed by construction accident than any other type of employment. This paper aimed to identify factors that affect the implementation of construction health and safety regulations, their effects and mitigation measures in building construction project sites of Hawassa City. To reach this objective, a review of literature as well as the Ethiopian construction health and safety regulations have been undertaken. Mainly a five-point Likert scale questionnaire was distributed, and statistical analysis was used to summarize, interpret the data, and to find the significances of the responses. In addition, interviews were carried out. Accordingly, the findings indicate that the top factors which affect the implementation of CHS regulations are, availability and development of a clear health and safety policy, health and safety inspections by top management, conducting health and safety training and orientation, provision of healthy and safe working environment and employment of trained safety officers. The study revealed that implementation or non-implementation of CHS regulations have effects on the worker’s productivity, job satisfaction, rate of accidents, and cost greatly. Thus, the suggestion to minimize the impact on worker’s job performance are, developing of a clear health and safety policy, management commitment towards implementation of health and safety regulations, health and safety education and training and conducting regular health and safety inspections. It was concluded from the study that good implementation of health and safety regulations are the results from administrative and management commitment which calls for more attention to be paid to improve the implementation of CHS regulations in building construction sites of Hawassa City.

Keywords: construction health and safety regulations, effects, factors, mitigation

Procedia PDF Downloads 201
4935 Effects of Tenefovir Disiproxil Fumarate on the Renal Sufficiency of HIV Positive Patients

Authors: Londeka Ntuli, Frasia Oosthuizen

Abstract:

Background: Tenefovir disiproxil fumarate (TDF) is a nephrotoxic drug and has been proven to contribute to renal insufficiency necessitating intensive monitoring and management of adverse effects arising from prolonged exposure to the drug. TDF is one of the preferred first-line drugs used in combination therapy in most regions. There are estimated 300 000 patients being initiated on the Efavirenz/TDF/Emtricitabine first-line regimen annually in South Africa. It is against this background that this study aims to investigate the effects of TDF on renal sufficiency of HIV positive patients. Methodology: A retrospective quantitative study was conducted, analysing clinical charts of HIV positive patient’s older than 18 years of age and on a TDF-containing regimen for more than 1 year. Data were obtained from the analysis of patient files and was transcribed into Microsoft® Excel® spreadsheet. Extracted data were coded, categorised and analysed using STATA®. Results: A total of 275 patient files were included in this study. Renal function started decreasing after 3 months of treatment (with 93.5% patients having a normal EGFR), and kept on decreasing as time progressed with only 39.6% normal renal function at year 4. Additional risk factors for renal insufficiency included age below 25, female gender, and additional medication. Conclusion: It is clear from this study that the use of TDF necessitates intensive monitoring and management of adverse effects arising from prolonged exposure to the drug. The findings from this study generated pertinent information on the safety profile of the drug TDF in a resource-limited setting of a public health institution. The appropriate management is of tremendous importance in the South African context where the majority of HIV positive individuals are on the TDF containing regimen; thus it is beneficial to ascertain the possible level of toxicities these patients may be experiencing.

Keywords: renal insufficiency, tenefovir, HIV, risk factors

Procedia PDF Downloads 88
4934 Estimating Water Balance at Beterou Watershed, Benin Using Soil and Water Assessment Tool (SWAT) Model

Authors: Ella Sèdé Maforikan

Abstract:

Sustained water management requires quantitative information and the knowledge of spatiotemporal dynamics of hydrological system within the basin. This can be achieved through the research. Several studies have investigated both surface water and groundwater in Beterou catchment. However, there are few published papers on the application of the SWAT modeling in Beterou catchment. The objective of this study was to evaluate the performance of SWAT to simulate the water balance within the watershed. The inputs data consist of digital elevation model, land use maps, soil map, climatic data and discharge records. The model was calibrated and validated using the Sequential Uncertainty Fitting (SUFI2) approach. The calibrated started from 1989 to 2006 with four years warming up period (1985-1988); and validation was from 2007 to 2020. The goodness of the model was assessed using five indices, i.e., Nash–Sutcliffe efficiency (NSE), the ratio of the root means square error to the standard deviation of measured data (RSR), percent bias (PBIAS), the coefficient of determination (R²), and Kling Gupta efficiency (KGE). Results showed that SWAT model successfully simulated river flow in Beterou catchment with NSE = 0.79, R2 = 0.80 and KGE= 0.83 for the calibration process against validation process that provides NSE = 0.78, R2 = 0.78 and KGE= 0.85 using site-based streamflow data. The relative error (PBIAS) ranges from -12.2% to 3.1%. The parameters runoff curve number (CN2), Moist Bulk Density (SOL_BD), Base Flow Alpha Factor (ALPHA_BF), and the available water capacity of the soil layer (SOL_AWC) were the most sensitive parameter. The study provides further research with uncertainty analysis and recommendations for model improvement and provision of an efficient means to improve rainfall and discharges measurement data.

Keywords: watershed, water balance, SWAT modeling, Beterou

Procedia PDF Downloads 23
4933 Study of a Lean Premixed Combustor: A Thermo Acoustic Analysis

Authors: Minoo Ghasemzadeh, Rouzbeh Riazi, Shidvash Vakilipour, Alireza Ramezani

Abstract:

In this study, thermo acoustic oscillations of a lean premixed combustor has been investigated, and a mono-dimensional code was developed in this regard. The linearized equations of motion are solved for perturbations with time dependence〖 e〗^iwt. Two flame models were considered in this paper and the effect of mean flow and boundary conditions were also investigated. After manipulation of flame heat release equation together with the equations of flow perturbation within the main components of the combustor model (i.e., plenum/ premixed duct/ and combustion chamber) and by considering proper boundary conditions between the components of model, a system of eight homogeneous equations can be obtained. This simplification, for the main components of the combustor model, is convenient since low frequency acoustic waves are not affected by bends. Moreover, some elements in the combustor are smaller than the wavelength of propagated acoustic perturbations. A convection time is also assumed to characterize the required time for the acoustic velocity fluctuations to travel from the point of injection to the location of flame front in the combustion chamber. The influence of an extended flame model on the acoustic frequencies of combustor was also investigated, assuming the effect of flame speed as a function of equivalence ratio perturbation, on the rate of flame heat release. The abovementioned system of equations has a related eigenvalue equation which has complex roots. The sign of imaginary part of these roots determines whether the disturbances grow or decay and the real part of these roots would give the frequency of the modes. The results show a reasonable agreement between the predicted values of dominant frequencies in the present model and those calculated in previous related studies.

Keywords: combustion instability, dominant frequencies, flame speed, premixed combustor

Procedia PDF Downloads 346
4932 A Comparative Study on Fish Raised with Feed Formulated with Various Organic Wastes and Commercial Feed

Authors: Charles Chijioke Dike, Hugh Clifford Chima Maduka, Chinwe A. Isibor

Abstract:

Fish is among the products consumed at a very high rate. In most countries of the world, fish are used as part of the daily meal. The high cost of commercial fish feeds in Africa has made it necessary the development of an alternative source of fish feed processing from organic waste. The objective of this research is to investigate the efficacy of fish feeds processed from various animal wastes in order to know whether those feeds shall be alternatives to commercial feeds. This work shall be carried out at the Research Laboratory Unit of the Department of Human Biochemistry, Faculty of Basic Medical Sciences, College of Health Sciences, Nnamdi Azikiwe University (NAU), Nnewi Campus, Anambra State. The fingerlings to be used shall be gotten from the Agricultural Department of NAU, Awka, Anambra State, and allowed to acclimatize for 14 d. Animal and food wastes shall be gotten from Nnewi. The fish shall be grouped into 1-13 (Chicken manure only, cow dung only, pig manure only, chicken manure + yeast, cow dung + yeast, pig manure + yeast, chicken manure + other wastes + yeast, cow dung + other wastes + yeast, and pig manure + other wastes + yeast. Feed assessment shall be carried out by determining bulk density, feed water absorption, feed hardness, feed oil absorption, and feed water stability. The nutritional analysis shall be carried out on the feeds processed. The risk assessment shall be done on the fish by determining methylmercury (MeHg), polycyclic aromatic hydrocarbons (PAHs), and dichloro-diphenyl-trichloroethane (DDT) in the fish. The results from this study shall be analyzed statistically using SPSS statistical software, version 25. The hypothesis is that fish feeds processed from animal wastes are efficient in raising catfish. The outcome of this study shall provide the basis for the formulation of fish feeds from organic wastes.

Keywords: assessment, feeds, health risk, wastes

Procedia PDF Downloads 64
4931 Study of Lamination Quality of Semi-Flexible Solar Modules with Special Textile Materials

Authors: K. Drabczyk, Z. Starowicz, S. Maleczek, P. Zieba

Abstract:

The army, police and fire brigade commonly use dedicated equipment based on special textile materials. The properties of these textiles should ensure human life and health protection. Equally important is the ability to use electronic equipment and this requires access to the source of electricity. Photovoltaic cells integrated with such textiles can be solution for this problem in the most of outdoor circumstances. One idea may be to laminate the cells to textile without changing their properties. The main goal of this work was analyzed lamination quality of special designed semi-flexible solar module with special textile materials as a backsheet. In the first step of investigation, the quality of lamination was determined using device equipped with dynamometer. In this work, the crystalline silicon solar cells 50 x 50 mm and thin chemical tempered glass - 62 x 62 mm and 0.8 mm thick - were used. The obtained results showed the correlation between breaking force and type of textile weave and fiber. The breaking force was in the ranges: 4.5-5.5 N, 15-20 N and 30-33 N depending on the type of wave and fiber type. To verify these observations the microscopic and FTIR analysis of fibers was performed. The studies showed the special textile can be used as a backsheet of semi-flexible solar modules. This work presents a new composition of solar module with special textile layer which, to our best knowledge, has not been published so far. Moreover, the work presents original investigations on adhesion of EVA (ethylene-vinyl acetate) polymer to textile with respect to fiber structure of laminated substrate. This work is realized for the GEKON project (No. GEKON2/O4/268473/23/2016) sponsored by The National Centre for Research and Development and The National Fund for Environmental Protection and Water Management.

Keywords: flexible solar modules, lamination process, solar cells, textile for photovoltaics

Procedia PDF Downloads 324
4930 Mental Accounting Theory Development Review and Application

Authors: Kang-Hsien Li

Abstract:

Along with global industries in using technology to enhance the application, make the study drawn more close to the people’s behavior and produce data analysis, extended out from the mental accounting of prospect theory, this paper provides the marketing and financial applications in the field of exploration and discussions with the future. For the foreseeable future, the payment behavior depends on the form of currency, which affects a variety of product types on the marketing of marketing strategy to provide diverse payment methods to enhance the overall sales performance. This not only affects people's consumption also affects people's investments. Credit card, PayPal, Apple pay, Bitcoin and any other with advances in technology and other emerging payment instruments, began to affect people for the value and the concept of money. Such as the planning of national social welfare policies, monetary and financial regulators and regulators. The expansion can be expected to discuss marketing and finance-related mental problems at the same time, recent studies reflect two different ideas, the first idea is that individuals affected by situational frames, not broad impact at the event level, affected by the people basically mental, second idea is that when an individual event affects a broader range, and majority of people will choose the same at the time that the rational choice. That are applied to practical application of marketing, at the same time provide an explanation in the financial market under the anomalies, due to the financial markets has varied investment products and different market participants, that also highlights these two points. It would provide in-depth description of humanity's mental. Certainly, about discuss mental accounting aspects, while artificial intelligence application development, although people would be able to reduce prejudice decisions, that will also lead to more discussion on the economic and marketing strategy.

Keywords: mental accounting, behavior economics, consumer behaviors, decision-making

Procedia PDF Downloads 422
4929 Occupational Stress and Lipid Profile among Drivers in Ismailia City, Egypt

Authors: Amani Waheed, Adel Mishriky, Rasha Farouk, Essam Abdallah, Sarah Hussein

Abstract:

Background: Occupational stress plays a crucial role in professional drivers' health. They are exposed to high workloads, low physical activity, high demand and low decisions as well as poor lifestyle factors including poor diet, sedentary work, and smoking. Dyslipidemia is a well-established modifiable cardiovascular risk factor. Occupational stress and other forms of chronic stress have been associated with raised levels of atherogenic lipids. Although stress management has some evidence in improving lipid profile, the association between occupational stress and dyslipidemia is not clear. Objectives: To assess the relational between occupational stress and lipid profile among professional drivers. Methodology: A cross-sectional study conducted at a large company in Ismailia City, Egypt, where, 131 professional drivers divided into 44 car drivers, 43 bus drivers, and 44 truck drivers were eligible after applying exclusion criteria. Occupational stress index (OSI), non-occupational risk factors of dyslipidemia were assessed using interview structured questionnaire. Blood pressure, body mass index (BMI) and lipid profile were measured. Results: The mean of total OSI score was 79.98 ± 6.14. The total OSI score is highest among truck drivers (82.16 ± 4.62), then bus drivers (80.26 ± 6.02) and lowest among car drivers (77.55 ± 6.79) with statistically significant. Eighty percent had Dyslipidemia. The duration of driving hours per day, exposure to passive smoking and increased BMI were the risk factors. No statistical significance between Total OSI score and dyslipidemia. Using, logistic regression analysis, occupational stress, duration of driving hours per day, and BMI were positive significant predictors for dyslipidemia. Conclusion: Professional drivers are exposed to occupational stress. A high proportion of drivers have dyslipidemia. Total OSI score doesn't have statistically significant relation with dyslipidemia.

Keywords: body mass index, dyslipidaemia, occupational stress, professional drivers

Procedia PDF Downloads 124
4928 Underground Coal Gasification Technology in Türkiye: A Techno-Economic Assessment

Authors: Fatma Ünal, Hasancan Okutan

Abstract:

Increasing worldwide population and technological requirements lead to an increase in energy demand every year. The demand has been mainly supplied from fossil fuels such as coal and petroleum due to insufficient natural gas resources. In recent years, the amount of coal reserves has reached almost 21 billion tons in Türkiye. These are mostly lignite (%92,7), that contains high levels of moisture and sulfur components. Underground coal gasification technology is one of the most suitable methods in comparison with direct combustion techniques for the evaluation of such coal types. In this study, the applicability of the underground coal gasification process is investigated in the Eskişehir-Alpu lignite reserve as a pilot region, both technologically and economically. It is assumed that the electricity is produced from the obtained synthesis gas in an integrated gasification combined cycle (IGCC). Firstly, an equilibrium model has been developed by using the thermodynamic properties of the gasification reactions. The effect of the type of oxidizing gas, the sulfur content of coal, the rate of water vapor/air, and the pressure of the system have been investigated to find optimum process conditions. Secondly, the parallel and linear controlled recreation and injection point (CRIP) models were implemented as drilling methods, and costs were calculated under the different oxidizing agents (air and high-purity O2). In Parallel CRIP (P-CRIP), drilling cost is found to be lower than the linear CRIP (L-CRIP) since two coal beds simultaneously are gasified. It is seen that CO2 Capture and Storage (CCS) technology was the most effective unit on the total cost in both models. The cost of the synthesis gas produced varies between 0,02 $/Mcal and 0,09 $/Mcal. This is the promising result when considering the selling price of Türkiye natural gas for Q1-2023 (0.103 $ /Mcal).

Keywords: energy, lignite reserve, techno-economic analysis, underground coal gasification.

Procedia PDF Downloads 28
4927 Effect of Zidovudine on Hematological and Virologic Parameters among Female Sex Workers Receiving Antiretroviral Therapy (ART) in North-Western Nigeria

Authors: N. M. Sani, E. D. Jatau, O. S. Olonitola, M. Y. Gwarzo, P. Moodley, N. S. Mujahid

Abstract:

Haemoglobin (HB) indicates anaemia level and by extension may reflect the nutritional level and perhaps the immunity of an individual. Some antiretroviral drugs like zidovudine are known to cause anaemia in People living with HIV/AIDS (PLWHA). A cross-sectional study using demographic data and blood specimen from 218 female commercial sex workers attending antiretroviral therapy (ART) clinics was conducted between December 2009 and July 2011 to assess the effect of zidovudine on haematologic and RNA viral load of female sex workers receiving antiretroviral treatment in north-western Nigeria. Anaemia is a common and serious complication of both HIV infection and its treatment. In the setting of HIV infection, anaemia has been associated with decreased quality of life, functional status, and survival. Antiretroviral therapy, particularly the highly active antiretroviral therapy (HAART), has been associated with a decrease in the incidence and severity of anaemia in HIV-infected patients who have received a HAART regimen for at least 1 year. In this study, result has shown that out of 218 patients, 26 with haemoglobin count between 5.1–10 g/dl were observed to have the highest viral load count of 300,000–350,000 copies/ml. It was also observed that most patients (190) with HB of 10.1–15.0 g/dl had viral load count of 200,000–250,000 copies/ml. An inverse relationship therefore exists, i.e. the lower the haemoglobin level, the higher the viral load count, even though the test statistics did not show any significance between the two (P=0.206). This shows that multivariate logistic regression analysis demonstrated that anaemia was associated with a CD4+ cell count below 50/µL in female sex workers with a viral load above 100,000 copies/mL who use zidovudine. Severe anaemia was less prevalent in this study population than in historical comparators; however, mild to moderate anaemia rates remain high. The study, therefore, recommends that hematological and virologic parameters be monitored closely in patients receiving first line ART regimen.

Keywords: anaemia, female sex worker, haemoglobin, Zidovudine

Procedia PDF Downloads 286
4926 The Effect of Traffic Load on the Maximum Response of a Cable-Stayed Bridge under Blast Loads

Authors: S. K. Hashemi, M. A. Bradford, H. R. Valipour

Abstract:

The Recent collapse of bridges has raised the awareness about safety and robustness of bridges subjected to extreme loading scenarios such as intentional/unintentional blast loads. The air blast generated by the explosion of bombs or fuel tankers leads to high-magnitude short-duration loading scenarios that can cause severe structural damage and loss of critical structural members. Hence, more attentions need to put towards bridge structures to develop guidelines to increase the resistance of such structures against the probable blast. Recent advancements in numerical methods have brought about the viable and cost effective facilities to simulate complicated blast scenarios and subsequently provide useful reference for safeguarding design of critical infrastructures. In the previous studies common bridge responses to blast load, the traffic load is sometimes not included in the analysis. Including traffic load will increase the axial compression in bridge piers especially when the axial load is relatively small. Traffic load also can reduce the uplift of girders and deck when the bridge experiences under deck explosion. For more complicated structures like cable-stayed or suspension bridges, however, the effect of traffic loads can be completely different. The tension in the cables increase and progressive collapse is likely to happen while traffic loads exist. Accordingly, this study is an attempt to simulate the effect of traffic load cases on the maximum local and global response of an entire cable-stayed bridge subjected to blast loadings using LS-DYNA explicit finite element code. The blast loads ranged from small to large explosion placed at different positions above the deck. Furthermore, the variation of the traffic load factor in the load combination and its effect on the dynamic response of the bridge under blast load is investigated.

Keywords: blast, cable-stayed bridge, LS-DYNA, numerical, traffic load

Procedia PDF Downloads 302
4925 Influence of Hydrophobic Surface on Flow Past Square Cylinder

Authors: S. Ajith Kumar, Vaisakh S. Rajan

Abstract:

In external flows, vortex shedding behind the bluff bodies causes to experience unsteady loads on a large number of engineering structures, resulting in structural failure. Vortex shedding can even turn out to be disastrous like the Tacoma Bridge failure incident. We need to have control over vortex shedding to get rid of this untoward condition by reducing the unsteady forces acting on the bluff body. In circular cylinders, hydrophobic surface in an otherwise no-slip surface is found to be delaying separation and minimizes the effects of vortex shedding drastically. Flow over square cylinder stands different from this behavior as separation can takes place from either of the two corner separation points (front or rear). An attempt is made in this study to numerically elucidate the effect of hydrophobic surface in flow over a square cylinder. A 2D numerical simulation has been done to understand the effects of the slip surface on the flow past square cylinder. The details of the numerical algorithm will be presented at the time of the conference. A non-dimensional parameter, Knudsen number is defined to quantify the slip on the cylinder surface based on Maxwell’s equation. The slip surface condition of the wall affects the vorticity distribution around the cylinder and the flow separation. In the numerical analysis, we observed that the hydrophobic surface enhances the shedding frequency and damps down the amplitude of oscillations of the square cylinder. We also found that the slip has a negative effect on aerodynamic force coefficients such as the coefficient of lift (CL), coefficient of drag (CD) etc. and hence replacing the no slip surface by a hydrophobic surface can be treated as an effective drag reduction strategy and the introduction of hydrophobic surface could be utilized for reducing the vortex induced vibrations (VIV) and is found as an effective method in controlling VIV thereby controlling the structural failures.

Keywords: drag reduction, flow past square cylinder, flow control, hydrophobic surfaces, vortex shedding

Procedia PDF Downloads 348