Adjustment factors for MEPDG pavement responses considering three- dimensional analysis and wide-base tire

The Mechanistic-Empirical Pavement Design Guide (MEPDG) provides a superior methodology as compared to its predecessor in the design and analysis of pavement structures. The mechanistic (MEDPG analysis) calculates critical pavement responses due to pavement-tire interactions. On the other hand, the empirical part refers to the prediction of pavement distress propagation over time using transfer functions. Transfer functions link critical pavement responses to particular pavement distresses. Although MEPDG analysis provides a theoretically framework for pavement simulations, its limitations and simplifications may produce inaccurate pavement response calculations. In contrast, finite element (FE) analysis has proven capable of overcoming these limitations by simulating pavement more realistically in terms of material characterization and loading conditions. However, the high computational cost of the FE analysis precludes its use as a pavement analysis engine within the MEPDG’s framework. Therefore, this study suggests two adjustment factors based on FE analysis to bridge the gap between reality and MEPDG analysis. The first adjustment factor—developed utilizing 480 cases performed in ABAQUS and considering similar material properties and pavement structure—converts pavement responses obtained from dual tire assembly (DTA) loading to new generation wide base tire (NG-WBT) loading. The second adjustment factor—developed from running 336 cases in MEPDG and FE analyses using compatible input parameters—accounts for the limitations of MEPDG analysis regarding the material characterization and loading conditions. The simulated cases were selected to capture extreme conditions—e.g., thick and thin pavement structures with strong and weak material properties—so that extrapolation could be avoided during the implementation of the equations. The adjustment factors revealed that NG-WBT produces higher responses than DTA, which can cause greater pavement damage. Additionally, MEPDG analysis fails to capture the effect of non-uniformity and the three dimensionality of contact stress on pavement response. The discrepancy becomes significant; especially for the pavement responses near the pavement surface, such as tensile strain at the AC surface and vertical shear strain within the AC layer, that are believed to cause top-down cracking

Sinus Node Dysfunction as the First Manifestation of Left Ventricular Noncompaction with Multiple Cardiac Abnormalities

AbstractLeft ventricular noncompaction (LVNC) is a genetically heterogenous form of cardiomyopathy which may remain undiagnosed till adulthood due to the late presentation of typical symptoms such as dyspnea, congestion, ventricular arrhythmias and thromboembolism. Symptomatic bradycardia secondary to persistent sinus node dysfunction is very rare. Coexistent cardiac defects are common in children however in adults the disease is usually in isolated form. Here, we present a case of twenty-three year-old female LVNC patient with patent ductus arteriosus, bicuspid aortic valve and persistent sinus node dysfunction who presented with dizziness as the first manifestation of the disease

Incisional hernia as an unusual cause of hepatic encephalopathy in a 62-year-old man with cirrhosis: a case report

<p>Abstract</p> <p>Introduction</p> <p>Hepatic encephalopathy may be initiated by many factors such as gastrointestinal bleeding, infections, fluid and electrolyte disturbances. Hypokalemia is one of the most commonly encountered electrolyte abnormalities causing hepatic encephalopathy in patients with cirrhosis.</p> <p>Case presentation</p> <p>We present the case of a 62-year-old Caucasian man with decompensated liver cirrhosis having multiple episodes of hepatic encephalopathy precipitated by vomiting. He had an incisional hernia at the right lumbar region. A barium contrast study of the small intestine and magnetic resonance imaging showed that the hernial sac included gastric antrum and bowel. We observed that hepatic encephalopathy coincided with hypokalemia as a result of a large volume of vomiting triggered by the collapsed hernial sac. Hepatic encephalopathy was resolved by administration of intravenous potassium.</p> <p>Conclusion</p> <p>This case illustrates that a hernia causing a large volume of vomiting may be a precipitant factor in the development of hepatic encephalopathy.</p

Development of Adjustment Factors for MEPDG Pavement Responses Utilizing Finite-Element Analysis

The Mechanistic-empirical pavement design guide (MEPDG) provides theoretically superior methodology, as compared with its predecessor, for the design and analysis of pavement structures. The mechanistic part refers to simulating pavement–tire interaction to calculate critical responses within pavement. The empirical part means prediction of pavement distress propagation over time using transfer functions that link a critical pavement response to a particular pavement distress. The mechanistic part of MEPDG simulates tire–pavement interaction in three steps: subdivision of pavement layers; complex modulus calculation at the middepth of each sublayer, considering velocity and temperature; and running the multilayered elastic theory (MLET) software, JULEA. Although MEDPG has a grounded methodology for pavement analysis, it has a number of limitations and unrealistic simplifications that result in inaccurate response predictions. These limitations are primarily related to the pavement analysis approach used in the MEPDG framework, MLET. By contrast, finite-element (FE) analysis has proven to be a promising numerical approach for overcoming these limitations and simulating pavement more accurately and realistically. Although comparison of MLET with FE analysis has been studied, the difference between FE and MEPDG simulations has not been quantified. This study fills that gap by developing linear equations that connect pavement responses produced by these two approaches to pavement analysis. The equations are developed for ten different pavement responses, using a total of 336 cases simulated using FE and MEPDG analyses. The cases modeled in simulations were selected to capture extreme conditions, i.e., thick and thin pavement structures with strong and weak material properties. The equations developed can help pavement researchers understand quantitatively the effect of MEPDG limitations. In addition, the equations may be used as adjustment factors for MEPDG to compute pavement responses more realistically without using computationally expensive approaches, such as FE analysis

Five Methods of Breast Volume Measurement: A Comparative Study of Measurements of Specimen Volume in 30 Mastectomy Cases

Background To compare breast volume measurement techniques in terms of accuracy, convenience, and cost. Methods Breast volumes of 30 patients who were scheduled to undergo total mastectomy surgery were measured preoperatively by using five different methods (mammography, anatomic [anthropometric], thermoplastic casting, the Archimedes procedure, and the Grossman-Roudner device). Specimen volume after total mastectomy was measured in each patient with the water displacement method (Archimedes). The results were compared statistically with the values obtained by the five different methods. Results The mean mastectomy specimen volume was 623.5 (range 150–1490) mL. The breast volume values were established to be 615.7 mL (r = 0.997) with the mammographic method, 645.4 mL (r = 0.975) with the anthropometric method, 565.8 mL (r = 0.934) with the Grossman-Roudner device, 583.2 mL (r = 0.989) with the Archimedes procedure, and 544.7 mL (r = 0.94) with the casting technique. Examination of r values revealed that the most accurate method was mammography for all volume ranges, followed by the Archimedes method. Conclusion The present study demonstrated that the most accurate method of breast volume measurement is mammography, followed by the Archimedes method. However, when patient comfort, ease of application, and cost were taken into consideration, the Grossman-Roudner device and anatomic measurement were relatively less expensive, and easier methods with an acceptable degree of accuracy

Impact of Wide-Base Tires on Pavements: A National Study

This paper summarizes a multi-year effort comparing the new-generation wide-base tires (NG-WBT) and dual-tire assembly from a holistic point of view. The tires were compared considering not only pavement damage but also environmental impact. Numerical modeling, prediction methods, experimental measurements, and life-cycle assessment were combined to provide recommendations about the use of NG-WBT. A finite element (FE) approach considering variables that are usually omitted in the conventional analysis of flexible pavement was used for modeling pavement structures combining layer thickness, material properties, tire load, tire-inflation pressure, and pavement type (interstate and low volume). A prediction tool, ICT-Wide, was developed based on an artificial neural network to obtain critical pavement responses in cases excluded from the FE analysis matrix. Based on the bottom-up fatigue cracking, permanent deformation, and international roughness index, the life-cycle energy consumption, cost, and green-house gas emissions were estimated. To make this research useful for state departments of transportation and practitioners, a modification to AASHTOware is proposed to account for NG-WBT. The revision is based on two adjustment factors, one accounting for the discrepancy between the AASHTOware approach and the FE model of this study, and the other addressing the impact of NG-WBT. Although greater pavement damage may result from NG-WBT, for the analyzed cases, the extra pavement damage may be outweighed by the environmental benefits when NG-WBT market penetration is considered

Optimal Pavement Design and Rehabilitation Planning Using a Mechanistic-Empirical Approach

This paper presents the development of a pavement design and rehabilitation optimization decision-making framework based on Mechanistic-Empirical (ME) roughness transfer models. The AASHTOWare Pavement ME Design (the software of Pavement ME Design) is used to estimate pavement deterioration based on the combined effects of permanent deformation, fatigue, and thermal cracking. The optimization problem is first formulated into a mixed-integer nonlinear programming model to address the predominant trade-off between agency and user costs. To deal with the complexity associated with the pavement roughness transfer functions in the software and to use the roughness values as input to the optimization framework, a dynamic programming subroutine is developed for determining the optimal rehabilitation timing and asphalt concrete design thickness. An application of the proposed model is demonstrated in a case study. Managerial insights from a series of sensitivity analyses on different unit user cost values and model comparisons are presented

Predictive value of admission red cell distribution width-platelet ratio for no-reflow phenomenon in acute ST segment elevation myocardial infarction undergoing primary percutaneous coronary intervention

Background: The red cell distribution width–platelet ratio (RPR), a novel inflammatory marker is currently used to predict inflammation in chronic diseases. It may be associated with adverse outcomes among artery disease but its prognostic value in ST-segment elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention (PCI) has not been fully investigated. There is no data regarding the association between RPR and in-hospital major adverse cardiovascular events (MACEs). This study evaluated the relations between pre-procedural RPR and the in-hospital and long-term outcomes in STEMI patients undergoing primary PCI. Methods: This study included 580 STEMI patients (77% men, mean age: 59 ± 12 years). The patients were divided into two groups according to thrombolysis in myocardial infarction (TIMI) flow grades after primary PCI. No-reflow was defined as a post-PCI TIMI flow grade of 0, 1 or 2 (group 1). Angiographic success was defined as TIMI flow grade 3 (group 2). Results: Whole blood cell count, neutrophil and lymphocyte percentages, red cell distribution width, platecrit, neutrophil–lymphocyte ratio (NLR) and RPR values were higher among patients with no-reflow. On multivariate analysis, pain to balloon time, multivessel disease, TIMI thrombus grade, tirofiban, aspirin, previous coronary artery disease, NLR, platecrit and RPR remained independent predictors of no-reflow after primary PCI. Patients in no-reflow group tended to be higher percent in-hospital MACE, including nonfatal myocardial infarction and cardiovascular mortality compared to the reflow patients. Conclusions: Admission NLR, platecrit and RPR are independent correlates of no-reflow and in-hospital MACEs among patients with STEMI undergoing primary PCI.

Development of Overweight Vehicle Permit Fee Structure in Illinois

Permits are one of the most effective and common tools for state agencies to regulate the operation of overweight and oversize vehicles by ensuring the safety of passenger and freight traffic and minimizing damage to pavements and bridges while promoting commerce and the safe movement of goods and services. Although the State of Illinois uses a relatively comprehensive permit system, many of its parts have not been revised for more than 30 years. Therefore, the objective of this study was to revise the current permit system by evaluating up-to-date impacts of overweight vehicles. In this study, impacts of overweight (OW) vehicles were evaluated in three aspects (bridge, pavement, and traffic safety) and individual fees were developed for each. The most recent databases on infrastructure condition and state-of-the-art prediction/ classification algorithms were employed to produce the realistic and up-to-date assessment of OW vehicles' impact. Finally, a combined permit fee was recommended as a function of miles to be traveled, as well as axle and weight information, by aggregating the calculated individual fees.IDOT-R27-152Ope

Recent trends in soft-tissue infection imaging.

This article discusses the current techniques and future directions of infection imaging with particular attention to respiratory, central nervous system, abdominal, and postoperative infections. The agents currently in use localize to areas of infection and inflammation. An infection-specific imaging agent would greatly improve the utility of scintigraphy in imaging occult infections. The superior spatial resolution of (18)F-fluorodeoxyglucose positron emission tomography ((18)F-FDG-PET) and its lack of reliance on a functional immune system, gives this agent certain advantages over the other radiopharmaceuticals. In respiratory tract infection imaging, an important advancement would be the ability to quantitatively delineate lung inflammation, allowing one to monitor the therapeutic response in a variety of conditions. Current studies suggest PET should be considered the most accurate quantitative method. Scintigraphy has much to offer in localizing abdominal infection as well as inflammation. We may begin to see a gradual increase in the usage of (18)F-FDG-PET in detecting occult abdominal infections. Commonly used modalities for imaging inflammatory bowel disease are scintigraphy with (111)In-oxine/(99m)Tc-HMPAO labeled autologous white blood cells. The literature on central nervous system infection imaging is relatively scarce. Few clinical studies have been performed and numerous new agents have been developed for this use with varying results. Further studies are needed to more clearly delineate the future direction of this field. In evaluating the postoperative spine, (99m)Tc-ciprofloxacin single-photon emission computed tomography (SPECT) was reported to be \u3e80% sensitive in patients more than 6 months after surgery. FDG-PET has also been suggested for this purpose and may play a larger role than originally thought. It appears PET/computed tomography (CT) is gaining support, especially in imaging those with fever of unknown origin or nonfunctional immune systems. Although an infection-specific agent is lacking, the development of one would greatly advance our ability to detect, localize, and quantify infections. Overall, imaging such an agent via SPECT/CT or PET/CT will pave the way for greater clinical reliability in the localization of infection