Dynamics Of Water In Aircraft Fuel Tanks During Flight Maneuvers

The goal of the current research is to study the dynamics of water in fuel tanks during flight maneuvers. The study was motivated by the fact that airplane fuel tanks can be exposed to extremely low temperatures, whereby water can nucleate and freeze, in turn causing the fuel lines to clog. Therefore, ice formation in the fuel system may lead to aviation safety issues. Different scenarios were considered which influence the movement of water and kerosene in a fuel tank. A test rig was constructed to replicate airplane motions when taking off, landing, and turning. Computer-simulated experiments were performed to replicate airplane motions under roll maneuvers and when turning right or left. The computer model required the a priori knowledge of interfacial properties of water in kerosene. These properties were experimentally measured and were used as input data for the computer simulation. The surface tension of water was confirmed as 72.9 mN/m, and the surface tension of water in kerosene (the interfacial tension between kerosene and water) was measured as 6.78 mN/m. The contact angle of water in kerosene on aluminum and plexiglass was measured as 114.9º and 121.1º, respectively. The contact angle of water in the air on aluminum and plexiglass was measured to be 49.6º and 64.6º, respectively. The experimental simulations showed that water took 114.9 seconds to clear the fuel line port while the tank was in a takeoff mode, compared to 121.8 seconds while the tank was in landing mode. The time taken for water to clear the fuel line decreased before it increased when the tank inclination was changed from 0 to 30º. In addition, the volume of water remaining in the fuel tank decreased as the tilt angle was increased. The computer-simulated experiments were performed for an airplane undergoing right and left banking motion in addition to roll motions. The results showed that the resultant acceleration vector and magnitude had a significant influence on the local composition and movement of water in the fuel tank

Adhesion Molecule Expression and Cellular Infiltrate Within Gingival Tissue

The development of gingival inflammation is not well understood, despite many years of investigation. Accordingly, the main aims of this thesis were, to study the immune and inflammatory cellular infiltrate during the development of gingival inflammation and to examine the effect of proinflammatory cytokines on adhesion molecule expression using gingival organ culture. Two studies were performed which utilised the experimental gingivitis model. In the model, experimental gingival inflammation was induced in two groups of healthy volunteers by withdrawing oral hygiene procedures and allowing plaque to accumulate undisturbed for 21-days and 10-days. Tissue for analysis was obtained from the experimental gingivitis studies and from patients undergoing routine periodontal treatment. Immunohistology and computerised image planimetry were employed for assessing changes within periodontal cellular infiltrate and adhesion molecules; and a bioassay was used to assess changes in the levels of interleukin-1. Initial studies showed that a single staining avidin-biotin-complex method utilising peroxidase as the substrate, gave the optimal immunohistological staining procedure. Clinical parameters during the experimental gingivitis studies changed as expected, with the 10-day study demonstrating minimal changes and the 21-day study showing large increases as expected. The 10-day study was aimed at analysing changes during very early 'histological' inflammation and the 21-day study during 'clinically detectable' inflammation. The cytokine, interleukin-1 was demonstrated in crevicular fluid during the 21-day study in healthy human volunteers. A sensitive and specific bioassay allowed detection of biologically active interleukin-1 in inflamed gingiva. Interleukin-1 levels increased rapidly with plaque accumulation and in advance of the subsequent gingival inflammation, peaking within 7 days of the start of gingivitis. Monoclonal antibodies to CD1a (specific for Langerhans cells and thymocytes) and HLA-DR (class II major histocompatibility antigens - (MHC)) were used to identify Langerhans cells within gingival biopsies taken every 7 days of the 21-day study and every 3 days of the 10-day study. HLA-DR antibody stained dendritic cells within the oral epithelium which were morphologically identical to the CDla+ Langerhans cells. During the 10-day study the number of CDla+ Langerhans cells and HLA-DR+ Langerhans cells did not change with time. However, within the 21-day study. Class II MHC Langerhans cell numbers rose and plateaued between day 7 and 14, then decreased to baseline by day 21. As plaque accumulated and inflammation developed there was an initial increase, followed by a decrease in CDla+ Langerhans cells. It was hypothesised that this may reflect the antigen presenting and migrating role of Langerhans cells to lymph nodes. The cellular infiltrate of gingival tissue was also analysed and it was found that all of the cell types studied (neutrophils; T-cells and T-cell subsets i.e. helper, suppressor, naive and memory) were present in varying quantities. Periodontal cellular infiltrate was seen within healthy tissue and within experimentally inflamed gingival tissue; and demonstrated preferential accumulation in the connective tissue subjacent to the junctional epithelium. Higher numbers of memory-T cells than naive-T cells were found within healthy gingival tissue; with subsequent inflammation development their was no change in memory-T cells numbers, with a simultaneous decrease in the number of naive-T cells. This suggests that the naive-T cells were maturing into memory-T cells, and in turn are maintaining the numbers of memory-T cells within the gingival tissue. Vascular endothelium expressed ELAM-1 (endothelial cell leukocyte adhesion molecule-1), VCAM-1 (vascular cell adhesion molecule-1) and ICAM-1 (intercellular adhesion molecule-1) both in clinically 'healthy' tissue (day 0) and in experimentally inflamed tissue (day 3 to 10 and day 7 to 21). Positive vessels were found mainly in the connective tissue subjacent to the junctional epithelium where the highest numbers of T cells (CD11a+) and neutrophils were also seen

Generating spiky solutions of Einstein field equations with the Stephani transformation

The Geroch/Stephani transformation is a solution-generating transformation, and may generate spiky solutions. The spikes in solutions generated so far are either early-time permanent spikes or transient spikes. We want to generate a solution with a late-time permanent spike. We achieve this by applying the Stephani transformation with the rotational Killing vector field of the locally rotationally symmetric Jacobs solution. The late-time permanent spike occurs along the cylindrical axis. The generated solution also features a rich variety of transient structures. We introduce a new technique to analyse these structures. Our findings lead us to discover a transient behaviour, which we call the overshoot transition

Cylindrical spikes

The Geroch/Stephani transformation is a solution-generating transformation, and may generate spiky solutions. The spikes in solutions generated so far are either early-time permanent spikes or transient spikes. We want to generate a solution with a late-time permanent spike. We achieve this by applying Stephani's transformation with the rotational Killing vector field (KVF) of the locally rotationally symmetric Jacobs solution. The late-time permanent spike occurs along the cylindrical axis. Using a mixed KVF, the generated solution also features a rich variety of transient structures. We introduce a new technique to analyse these structures. Our findings lead us to discover a transient behaviour, which we call the overshoot transition. These discoveries compel us to revise the description of transient spikes

A Novel Method for Dynamic Multicriteria Decision Making with Hybrid Evaluation Information

How to select the most desirable pattern(s) is often a crucial step for decision making problem. By taking uncertainty as well as dynamic of database into consideration, in this paper, we construct a dynamic multicriteria decision making procedure, where the evaluation information of criteria is expressed by real number, intuitionistic fuzzy number, and interval-valued intuitionistic fuzzy number. During the process of algorithm construction, the evaluation information at all time episodes is firstly aggregated into one, and then it is transformed into the unified interval-valued intuitionistic fuzzy number representational form. Similar to most multicriteria decision making approaches, the TOPSIS method is applied in the proposed decision making algorithm. In particular, the distance between possible patterns and the ideal solutions is defined in terms of cosine similarity by considering all aspects of the unified evaluation information. Experimental results show that the proposed decision making approach can effectively select desirable pattern(s)

Managing social networking stress: the role of self-management in reducing social media exhaustion and improving higher education employee performance

This study investigates the significance of self-management in academic staff stress management related to social networking sites (SNS). It emphasizes particularly on reducing social media exhaustion and increasing job effectiveness. The research applies the stressor-strain-outcome theory and the Smart PLS (partial least squares) analytical approach to examine data from 391 respondents. The study’s goal is to provide empirical data on the efficacy of self-control management in reducing SNS stress and its effects on academic staff’s psychological wellbeing and job performance. Data is collected by survey using online email platforms among academic employees, and the collected data is examined utilizing the Smart PLS approach. This approach allows for an investigation of the proposed links and their statistical importance. This research’s ramifications are important for academic institutions since its results can help academic personnel effectively cope with SNS-related stress. Academic employees can better limit their SNS usage and avoid social media tiredness by promoting self-control management practices. As a result, academic employees’ job performance and overall wellbeing may increase. The study’s findings help to comprehend how self-management might reduce SNS stress and improve staff performance in the academic sector

Malignant middle cerebral artery infarction following subacute subdural hematoma: A case report and literature review

Background: Subacute subdural hematomas (ASDH) are only treated surgically when they cause mass effect significant enough to give symptoms. Rarely, sub-ASDH may cause enough pressure to result in a malignant middle cerebral artery (MCA) territory infarction. Decompressive craniectomy (DC) is the last resort to reduce intracranial pressure following malignant MCA infarction. Herein, we review the literature and describe a case of MCA/posterior cerebral artery (PCA) territories infarction following drainage of a sub-ASDH that was treated with DC with good outcome. Case Description: We report a case of malignant right-sided MCA/PCA infarction in a 62-year-old man who presented with progressive headache following a cycling incident leading to a head injury. Initial CT head demonstrated a small right ASDH. He had no neurological deficit, headache settled on analgesia, and there was no expansion of the SDH on the repeat CT; therefore, he was managed conservatively. He was admitted 6-days later with worsening headaches and hyponatremia. Repeat CT revealed an increase in size of the hematoma and mass effect leading to a mini-craniotomy and evacuation of hematoma. He developed left-sided hemiplegia, slurred speech and hyponatremia, and CT head demonstrated a right-sided MCA/PCA infarction with significant mass effect. He underwent emergent DC and subsequent cranioplasty and ultimately recovered to mRS of 2. Conclusion: SDH are frequent neurosurgical entities. Malignant MCA/PCA strokes following mini-craniotomies are rare but need to be considered especially during the consent process

Strokectomy for malignant middle cerebral artery infarction: experience and meta-analysis of current evidence

Strokectomy means surgical excision of infarcted brain tissue post-stroke with preservation of skull integrity, distinguishing it from decompressive hemicraniectomy. Both can mitigate malignant middle cerebral artery (MCA) syndrome but evidence regarding strokectomy is sparse. Here, we report our data and meta-analysis of strokectomy compared to hemicraniectomy for malignant MCA infarction. All malignant MCA stroke cases requiring surgical intervention in a large tertiary centre (January 2012–December 2017, N = 24) were analysed for craniotomy diameter, complications, length of follow-up and outcome measured using the modified Rankin score (mRS). Good outcome was defined as mRS 0–3 at 12 months. In a meta-analysis, outcome from strokectomy (pooled from our cohort and published strokectomy studies) was compared with hemicraniectomy (our cohort pooled with published DECIMAL, DESTINY and HAMLET clinical trial data). In our series (N = 24, 12/12 F/M; mean age: 45.83 ± 8.91, range 29–63 years), 4 patients underwent strokectomy (SC) and 20 hemicraniectomy (HC). Among SC patients, craniotomy diameter was smaller, relative to HC patients (86 ± 13.10 mm, 120 ± 4.10 mm, respectively; p = 0.003), complications were less common (25%, 55%) and poor outcomes were less common (25%, 70%). In the pooled data (N = 41 SC, 71 HC), strokectomy tended towards good outcome more than hemicraniectomy (OR 2.2, 95% CI 0.99–4.7; p = 0.051). In conclusion, strokectomy may be non-inferior, lower risk and cost saving relative to hemicraniectomy sufficiently to be worthy of further investigation and maybe a randomised trial

Role of OmpA2 surface regions of Porphyromonas gingivalis in host-pathogen interactions with oral epithelial cells

Outer membrane protein A (OmpA) is a key outer membrane protein found in Gram-negative bacteria that contributes to several crucial processes in bacterial virulence. In Porphyromonas gingivalis, OmpA is predicted as a heterotrimer of OmpA1 and OmpA2 subunits encoded by adjacent genes. Here we describe the role of OmpA and its individual subunits in the interaction of P. gingivalis with oral cells. Using knockout mutagenesis, we show that OmpA2 plays a significant role in biofilm formation and interaction with human epithelial cells. We used protein structure prediction software to identify extracellular loops of OmpA2, and determined these are involved in interactions with epithelial cells as evidenced by inhibition of adherence and invasion of P. gingivalis by synthetic extracellular loop peptides and the ability of the peptides to mediate interaction of latex beads with human cells. In particular, we observe that OmpA2-loop 4 plays an important role in the interaction with host cells. These data demonstrate for the first time the important role of P. gingivalis OmpA2 extracellular loops in interaction with epithelial cells, which may help design novel peptide-based antimicrobial therapies for periodontal disease