Transient advanced mental impairment: An underappreciated morbidity after aortic surgery

AbstractObjectives: To determine the incidence, risk factors, and associated morbidity of transient advanced mental impairment (TAMI) after aortic surgery. Methods: We retrospectively studied the charts of 188 consecutive patients undergoing elective aortic reconstruction during a recent 6-year period at a university hospital. All patients were lucid on admission and nonintubated at the time of evaluation at least 2 days after operation. TAMI was defined as disorientation or confusion on 2 or more postoperative days. Preoperative, intraoperative, and postoperative clinical variables were examined statistically for associations with TAMI. Results: Fifty-three patients (28%) had development of TAMI 3.9 ± 2.8 days after operation. Stepwise logistic regression analysis selected the following independent predictors for TAMI: age >65 years (odds ratio [OR], 7.9; 95% confidence interval [CI], 2.7 to 23.7), American Society of Anesthesiology physical status classification >3 (OR, 2.8; 95% CI, 1.3 to 5.9), diabetes mellitus (OR, 3.4; 95% CI, 1.2 to 9.8), old myocardial infarction (OR, 2.4; 95% CI, 1.1 to 5.3), and hypertension (OR, 2.3; 95% CI, 1.0 to 5.3). Alcohol consumption was not significantly associated with TAMI. In the postoperative period, patients with TAMI were more likely to have hypoxia (P <.001), a need for reintubation (P <.001), pneumonia (P <.001), congestive heart failure (P =.003), and kidney failure (P =.05). In addition, patients with TAMI had a longer duration of endotracheal intubation (3.7 ± 7.8 vs 0.6 ± 1.2 days, P <.001), stay in the intensive care unit (8.9 ± 9 vs 3.9 ± 2 days, P <.001), and postoperative hospital stay (14.8 ± 11 vs 9.2 ± 5 days, P <.001) than patients without TAMI. Twenty (38%) patients with TAMI were discharged to intermediate-care facilities, compared with 11 (8%) patients without TAMI (P <.001). Postoperative variables conferring the largest relative risks for development of TAMI included oxygen saturation less than 92% (5.4), the need for reintubation (3.3), congestive heart failure (3.3), and pneumonia (3.2). TAMI, conversely, conferred the largest relative risks for development of postoperative congestive heart failure (15.3), the need for reintubation (9.3), pneumonia (7.1), and the need for ICU readmission (3.8). Conclusions: These data show that TAMI is prevalent among patients undergoing aortic reconstruction and is associated with dramatically increased morbidity and postoperative hospitalization rates. (J Vasc Surg 2002;35:376-81.

Experimental Investigation of Pipeline Emulsions Flow Behaviours

This research presents the stability and phase inversion of water-oil emulsions formed through flow shear, and the effect on flow pressure drop. Flow pressure drop profile and dissipation energy profile are established to deliberate further on this effect. The flow pressure drop profile is an important optimization tool in the industry to determine the values of flow rate and pump discharge pressure, in mitigating the unwanted formation of emulsions and higher additional pressure loss

Mechanistic-Empirical Modeling of Permanent Deformation in Asphalt Concrete Layers

Three mechanistic-empirical permanent deformation models were evaluated under Swedish conditions with respect to traffic, climate and materials using accelerated pavement testing and long-term pavement performance studies. The mechanistic-empirical pavement design guide (M E PDG), the incremental-recursive mechanistic-empirical CalME model (CalME), and the PErmanent Deformation of asphalt concrete layer for ROads (PEDRO) model generally showed both useful features and limitations. The M E PDG results were more accurate at the lowest material input data quality level (level 3) than at the highest (level 1). The main cause was probably the demonstrated inaccuracy of the predicted dynamic modulus at level 3 compared with measured level 1 results, and the M E PDG calibration at level 3. The CalME underestimated the permanent deformation in the semi-rigid section due to its response modeling sensitivity to overall pavement stiffness. Further, the results indicated that the relation between elastic and plastic material properties may change throughout the pavement life. The PEDRO model behavior due to lateral wander and observed field temperatures was reasonable. The zero shear rate viscosity assessment method for asphalt concrete, utilized in PEDRO, should be further evaluated. All models produced reasonable permanent deformation results although further validation and calibration is recommended before employment for pavement design purposes in Sweden

Experimental study of simulated micro-gravity vapor-liquid flow regimes

Space missions in the near future will require power plants and cooling systems to operate in space. Such systems will often incorporate two-phase (vapor-liquid) heat transfer loops. Heat transfer processes such as boiling and condensation involve two-phase flow and are gravity dependent. Such unit operations would, therefore, be expected to behave differently in a micro-gravitational ( micro-g ) environment. In this study, a unique approach to study the flow patterns of vapor-liquid flow on earth is presented. Simulation of a micro-g vapor-liquid flow on earth is accomplished by the use of two immiscible liquids of equal density. This equal density two-liquid system makes the buoyancy forces approach zero which is the case for real vapor-liquid flow in micro-g conditions. Water and properly selected oils are used in the experiments. In simulating micro-g vapor-liquid flow, the oil which is more viscous and more wettable liquid represents the liquid phase and water (less viscous and less wettable with respect to waxed tube surface) corresponds to the vapor phase. The experiments are carried out in a horizontal pyrex glass tube (6.1 m long and 2.54 cm ID). Data are obtained for five different fluid systems to study the effect of viscosity ratio, interfacial tension, and wettability of two fluids on flow regime boundary lines. Comparison of the simulated versus actual micro-g vapor-liquid flow regime data indicates the validity of this simulation approach. The experimental results are also compared against Taitel-Dukler and Weisman et al. model predictions under micro-g conditions. A flow regime map for vapor-liquid flow in a micro-g environment is developed for usage in designing two-phase systems in space applications. The effect of gravity on nucleate boiling is also considered. The static and dynamic forces acting on a growing vapor bubble on heating surface are evaluated and how their interaction causes the bubble to detach from the surface is presented. By using a force balance, the bubble departure radius is calculated and compared with experimental measurements from literature under micro-g conditions

Modular architecting for effects based operations

Effects Based Operations (EBO) is a way of thinking for planning, executing and assessing any operations for the effects they produce, rather than dealing with actions, targets or even objectives. The literature on EBO has been growing day by day; however, there is still a need for modeling techniques and tools that provide more efficient and effective effects based assessment, planning and analysis in order to further develop the capabilities of the operations. In this context, this thesis presents an introduction to EBO by focusing on its methodology, its challenges and also its applicability in different systems. Moreover, this thesis illustrates the importance of modular architecting in effects based planning stage --Abstract, page iii

Leptonic Decays of Heavy Quarks on the Lattice

The status of lattice calculations of heavy-light decay constants and of the $B$ parameter $B_B$ is reviewed. After describing the lattice approach to heavy quark systems, the main results are discussed, with special emphasis on the systematic errors in present lattice calculations. A detailed analysis of the continuum limit for decay constants is performed. The implications of lattice results on studies of CP violation in the Standard Model are discussed.Comment: Invited review to be published in Int. J. Mod. Phys. A, 63 pages, LaTeX, ijmpa1.sty (included), 8 postscript figure

The BG News January 30, 2004

The BGSU campus student newspaper January 30, 2004. Volume 94 - Issue 88https://scholarworks.bgsu.edu/bg-news/8225/thumbnail.jp

Modelling of Libyan crude oil using artificial neural networks

The preparation and analysis of input and model data was carried out. The importance of the correct technique of data filtering was highlighted with particular focus being emphasised on the removal of outliers in raw data. An important process in the use of Artificial Neural Network (ANN) models was identified as being the selection of the right input variables.A comparison between using factor analysis and statistical analysis in the selection of inputs and it was observed that the former gave significantly better results. The training and testing phase of Artificial Neural Network (ANN) model development was shown to be an important step in Artificial Neural Network (ANN) model development. If this phase was wrongly done then the ANN model would not be accurate in its predictions. Optimisation of the ANN model architecture was carried out with the amount of hidden layers, amount of neurons in the hidden layers, the transfer function used and the learning rate identified as key elements in obtaining an Artificial Neural Network (ANN) architecture that gave fast and accurate predictions. Fresh water addition and demulsifier addition were identified as key parameters in the economic performance of the desalting process. Due to a scarcity of water and the high cost of the demulsifier chemical it was important to try and optimise these two input variables thus reducing the cost of operations