1,278 research outputs found

    Contrasting perceptions of an innovation in teaching civil engineering

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    The use of cardiopulmonary bypass in the extraction of intracardiac foreign bodies

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    Background:  Intracardiac foreign bodies (FBs) are uncommon and have diverse presentations. The objectives of this study were to assess the types and presentation of intracardiac FBs and to evaluate the use of cardiopulmonary bypass (CPB) in their extraction.   Methods: A retrospective descriptive study was carried out on 12 patients with a history or radiological evidence of a foreign body in the heart or the great vessels who were admitted between 2013 and 2018. Sternotomy was performed in 8 patients and left anterior thoracotomy in 4 patients. CPB was used in 4 patients with cardioplegic cardiac arrest. Aorto-bicaval cannulation was performed in 3 patients and femero-femoral bypass in 1 patient. Results: The mean age of our patients was 32.7 ±21.7 years (range 2-62 years), six were males. Six different intracardiac FBs were reported including retained bullets (n= 3), migrated catheter piece (n=3), sewing needles (n=3), displaced pacemaker lead (n= 1), circular saw (n=1) and missed pigtail catheter after pericardiocentesis (n=1). Recovery from cardiopulmonary bypass was smooth, and no hospital complications were reported. The mean duration of postoperative mechanical ventilation in all sternotomy patients was 7.8 ± 6.7 hours (5 ±2.1 in CPB patients and 10.7±8.9 in non- CPB). The duration of hospital stay in CPB cases vs. non-CPB was (5.5±1.3 vs. 5.7±0.9 days). No postoperative wound infection nor sternal dehiscence were reported. One baby who had lateral thoracotomy died on the fifth postoperative day because of severe gastroenteritis. No residual pericardial or pleural collection were reported in 6 months follow-up period. Conclusions: Retrieval of intracardiac FBs can be performed safely with low morbidity and mortality. The use of CPB did not increase morbidity or mortality. Removal of all types of intracardiac FBs is recommended to avoid complication

    Dynamics of the Phase Coupling for Flow, Heat and Mass Transfer in Conjugate Fluid/Porous Domains

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    Porous media prevail in industry e.g. heat transfer equipment, drying, food storage and several other applications. Integrated in engineering, they form conjugate Fluid/Porous domains. Physical modelling requires characterizing the microscale heat and mass (moisture) transfer interstitially within porous media and their macroscale counterparts across regional interfaces. Characterizing turbulence and its effects on phase coupling is often needed too. The modeling literature survey shows phase coupling assumptions depending on empiricism, phase equilibrium and lack of generality. Modeling of the dynamic variations for the modes of phase exchanges, i.e. heat, mass and heat accompanying mass exchanges, on both scales and generic turbulent coupling across fluid/porous interfaces are absent. Thus, the objectives of this thesis are to, i) develop a dynamic coupling model for phase heat and mass transfer in conjugate fluid/porous domains, ii) validate the model in terms of interstitial phase exchange, macroscopic interfaces and behaviors in different modes of heat and mass transfer, iii) extend the model to turbulent flows characterizing turbulence correctly for different porosities and permeabilities. The modeling process depends on a finite volume approach. Continuity, momentum, turbulence, energy and mass equations are solved in point form for fluid regions. In porous media, a volume averaged version is formulated and solved using one equation per phase e.g. fluid temperature, solid temperature, vapor in fluid mass fraction and liquid in liquid/solid mixture mass fraction. Mathematical conditions are utilised at macroscopic interfaces reconciling the point-volume form differences, to ensure continuity of conservation variables and numerical robustness. Physical phase exchange formulae and numerical implementations for macroscopic interface heat/mass and turbulence treatments are introduced. The model is validated interstitially by comparing to experiments of Coal particles drying, for macroscopic coupling by comparing to experiments and other models of apple and mineral plaster drying, respectively. The results showed good agreement for all the cases. The turbulent coupling model has been tested for a channel with porous obstruction high and low permeability cases and compared well to other studies in the literature. Finally, full turbulent flow, heat and mass transfer was tested and produced physically correct trends and contours for apple and potato slices drying

    Enhancement of circular RC columns using steel mesh as internal or external confinement under the influence of axial compression loading

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    Reinforced concrete (RC) columns cannot get supreme confinement by using the customary steel stirrups reinforcement because of the requirements for the spacing distances between the stirrups in addition to concrete continuance trouble. For this, Steel Mesh (SM) externally wrapped around the outer perimeter of the column as contributory confinement are being widely used due to its features. Limited tests focused on using SM for the internal confinement around the reinforcing cage of RC columns. Moreover, no experimental comparison was presented between RC columns internally and externally confined using SM. This paper investigates experimentally the behavior of circular RC columns confined internally or externally by SM. Six short RC columns have been subjected to axial loading until failure. The main studied parameters were SM schemes, number of SM wraps, SM position (internally or externally), and the steel stirrups existence. Results demonstrated that SM could decrease the crack opening, diminish the concrete spalling, increase the maximum failure load, and enhance the ductility, energy absorption, and column stiffness. Furthermore, the partially internal confinement using two wraps of SM around the steel ties presented the maximum capacity with reasonable ductility. In general, internally confined columns showed better behavior than the externally confined one

    Detection and localization enhancement for satellite images with small forgeries using modified GAN-based CNN structure

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    The image forgery process can be simply defined as inserting some objects of different sizes to vanish some structures or scenes. Satellite images can be forged in many ways, such as copy-paste, copy-move, and splicing processes. Recent approaches present a generative adversarial network (GAN) as an effective method for identifying the presence of spliced forgeries and identifying their locations with a higher detection accuracy of large- and medium-sized forgeries. However, such recent approaches clearly show limited detection accuracy of small-sized forgeries. Accordingly, the localization step of such small-sized forgeries is negatively impacted. In this paper, two different approaches for detecting and localizing small-sized forgeries in satellite images are proposed. The first approach is inspired by a recently presented GAN-based approach and is modified to an enhanced version. The experimental results manifest that the detection accuracy of the first proposed approach noticeably increased to 86% compared to its inspiring one with 79% for the small-sized forgeries. Whereas, the second proposed approach uses a different design of a CNN-based discriminator to significantly enhance the detection accuracy to 94%, using the same dataset obtained from NASA and the US Geological Survey (USGS) for validation and testing. Furthermore, the results show a comparable detection accuracy in large- and medium-sized forgeries using the two proposed approaches compared to the competing ones. This study can be applied in the forensic field, with clear discrimination between the forged and pristine images

    Causative organisms of pyospermia in infertile male patients

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    Background: Male urogenital tract infection is one of the most important causes of male infertility worldwide. Infection processes may lead to impairment of sperm quality, and obstruction of the seminal tract. On the light of this, there is a need to institute a microbiological intervention to detect the probable causative microbial agents.Objective: The aim of the work was to detect the common bacteria causing pyospermia in a cross-section of infertile men and the sensitive antimicrobials against these bacteria.Patients and methods: This study included 205 infertile men who were recruited from the outpatient clinic, Andrology Unit, Dermatology and Andrology & STDs Department, Mansoura University Hospital for management of infertility. Patients with grade II or grade III varicocele, more than 60-year, smoker, drug abuser and those who were treated with antibiotics during last 3 months were excluded from the study.Results: Over the period of the study, out of 205 infertile male patients with documented pyospermia, 95.6 % of semen samples revealed bacteriologic growth. It was obvious that gram positive bacteria (75.1%) were common than the gram-negative bacteria (20.5%). Six bacterial species (Staphylococcus aureus, Streptococci, Enterococci, E. coli, Klebsiella and Pseudomonas) were isolated from semen samples. The most common causative organisms were Staph. Aureus (49.3%) followed by Streptococci (22.4%) then E. Coli (8.3%), Klebsiella (8.3%) then Pseudomonas (3.9%) and finally Enterococci (3.4%).Conclusion: It could be concluded that semen analysis with peroxidase stain and semen culture are an important diagnostic tool in all patients undergoing fertility investigations to detect genitourinary infections and pyospermia

    Detection of Lying Electrical Vehicles in Charging Coordination Application Using Deep Learning

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    The simultaneous charging of many electric vehicles (EVs) stresses the distribution system and may cause grid instability in severe cases. The best way to avoid this problem is by charging coordination. The idea is that the EVs should report data (such as state-of-charge (SoC) of the battery) to run a mechanism to prioritize the charging requests and select the EVs that should charge during this time slot and defer other requests to future time slots. However, EVs may lie and send false data to receive high charging priority illegally. In this paper, we first study this attack to evaluate the gains of the lying EVs and how their behavior impacts the honest EVs and the performance of charging coordination mechanism. Our evaluations indicate that lying EVs have a greater chance to get charged comparing to honest EVs and they degrade the performance of the charging coordination mechanism. Then, an anomaly based detector that is using deep neural networks (DNN) is devised to identify the lying EVs. To do that, we first create an honest dataset for charging coordination application using real driving traces and information revealed by EV manufacturers, and then we also propose a number of attacks to create malicious data. We trained and evaluated two models, which are the multi-layer perceptron (MLP) and the gated recurrent unit (GRU) using this dataset and the GRU detector gives better results. Our evaluations indicate that our detector can detect lying EVs with high accuracy and low false positive rate

    Clinical and echocardiographic evaluation of patients undergoing total leaflets preservation during mitral valve replacement; Does it make a difference?

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    Background: The effect of anterior and posterior leaflet preservation on left ventricular function after mitral valve replacement is still the subject of ongoing research. The objective of this study is to analyze the early outcomes of total leaflets preservation compared to posterior and non-leaflet preservation during mitral valve surgery on cardiac function and dimensions measured by echocardiography and on the clinical outcomes.Methods: This prospective cohort study recruited 155 patients who had mitral valve replacement (MVR) from April 2016 to March 2018 at Assiut University Hospital. Patients were divided into three groups according to the technique of leaflets preservation; Group I (no leaflet preservation-N-MVR), Group II (total leaflet preservation- T-MVR) and Group III (posterior leaflet preservation-P-MVR). Patients who underwent redo mitral valve replacement (MVR) or those with endocarditis and had combined coronary artery bypass grafting with the MVR were excluded from the study.Results: There were nine early deaths (6%); eight patients were in Group I (N-MVR). Causes of mortality were massive intracranial hemorrhage (n= 2) and left ventricular failure (n=6). One patient died in Group III (P-MVR) from intracranial hemorrhage (1.3%). Hospital stay was significantly longer in N-MVR group compared to T-MVR and P-MVR (10.6±2.13 days in N-MVR group; p= 0.03 and 0.011 respectively). Postoperative low cardiac output occurred in all patients in N-MVR group. Left ventricular function (ejection fraction= 61.28±6.02%) and dimensions (end-diastolic diameter= 5.18±0.69 mm, end-systolic diameter= 3.58±0.78 mm) improved significantly in total leaflets preservation group.Conclusion: Leaflet preservation during mitral valve replacement was associated with improved clinical and echocardiographic outcomes. Non-leaflets preservation increased the risk of postoperative complications and length of hospital stay. Leaflet preservation is recommended as the standard approach during mitral valve replacement
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