A System-of-Systems Model to Simulate the Complex Emergent Behavior of Vehicle Traffic on an Urban Transportation Infrastructure Network

Transportation agencies face escalating challenges in forecasting the traffic demand. Traditional prediction methods focused on individual transportation sectors and failed to study the inter-dependencies between the different transportation systems. Hence, there is a need for more advanced and holistic modeling techniques. To this end, this paper models and analyses an urban transportation system-of-systems incorporating seven various systems: population and GDP, CO2 emission, gasoline price and total vehicle trips, traffic demand, public and private transportation, transportation investment, and traffic congestion. Accordingly, this research simulates transportation networks as a collection of task-oriented systems that combine their resources to form a complex system with increased functionality. The goal of this paper is to understand the traffic complex behavior of urban transportation networks and to study the interdependencies between the different variables. The proposed framework could be implemented to any urban city, county, state, or country. The developed model incorporates a hybrid modeling approach that includes: logistic model, system dynamics, stochastic cellular automata, chaos theory, and Lotka-Volterra model. The final model is demonstrated using a case study. The contribution of this paper lies in modeling the transportation network as a dynamic system of systems rather than as static model as provided in previous studies

The Impact of Offsite Construction on the Workforce: Required Skillset and Prioritization of Training Needs

Offsite construction has showed great potential in addressing many of the industry\u27s problems. While multiple research efforts have been directed at examining different offsite construction aspects, few studies investigated the workforce-related aspects. Therefore, this study aims to address this knowledge gap by examining the impact of offsite construction on the workforce, as represented by the following five workforce categories: offsite, onsite, engineering and design, construction and fabrication, and administrative workforce. To this end, this paper (1) determined the impact of offsite construction on the skillset (reskilling or upskilling) and the demand (shrink or growth) for the offsite and onsite construction workforce occupations; (2) evaluated the impact of offsite construction on the technical and managerial skills of the engineering, construction, and administrative workforce occupations; and (3) identified the specific required skills that need to be incorporated into the offsite construction training programs for the workforce. The results showed that the skillsets for all offsite and onsite workforce occupations need to be upskilled. While the demand for the offsite construction workforce will increase, the demand for around 79% of the onsite workforce occupations will decrease. The findings also reflected that a total of 20 main skills are needed for the offsite construction engineering and design workforce, a total of 24 key skills are needed for the construction and fabrication workforce involved in offsite construction operations, and 22 skills are needed for the offsite construction administrative workforce. This study adds to the body of knowledge by helping offsite construction industry practitioners in workforce planning and management, in the prioritization of training needs and programs, and in identifying the required skillset to improve the quality of the workforce involved in the offsite construction operations

Quantification of the State of Practice of Offsite Construction and Related Technologies: Current Trends and Future Prospects

Although some researchers and practitioners have perceived that the current reliance on offsite construction methods is high, other studies have hypothesized that the use of offsite construction techniques is still considered to be somehow limited. To this end, this paper aims to quantify the state of practice of offsite construction in terms of current trends and future prospects for the overall industry as well as the following main sectors: industrial, building and commercial, and infrastructure. First, a questionnaire was formed, pilot-tested, distributed, and completed by 100 construction practitioners. Second, the questionnaire\u27s internal and external validity and reliability were examined using statistical analysis. Third, the research findings were validated. The results showed that the future offsite construction operations will be different from the current operations by shifting from single-trade fabrication to modularization, shifting from customized offsite construction components to standardized offsite construction components, shifting from permanent offsite construction structures to relocatable or portable offsite construction structures, and shifting the reliance on single-skilled labor to multiskilled labor. In addition, 87% of industry practitioners perceive that the future offsite construction growth rate in the coming decade will be higher than that of the previous decade. This research also showed that offsite construction will become the norm rather than the exception because (1) the current average offsite construction percentage of 33.64% will substantially grow to reach an average of 54.9% in the future, (2) the offsite construction industry will grow 4.33 times, on average, in the coming decade, (3) companies are planning to increase their offsite construction utilization rate by an average of 5.03-fold, and (4) the offsite construction automation percentage will increase by 7% in the future. The research outcomes also provided guidance on the key technologies that the industry shall currently invest in and consider leveraging in the future

Key Factors Affecting Labor Productivity in Offsite Construction Projects

Offsite construction has been shown to possess many advantages and benefits in dealing with the construction industry\u27s challenges, which include poor labor productivity. Nevertheless, all previous productivity-related research studies have focused mainly on factors impacting labor productivity in traditional stick-built construction methods. This paper filled this knowledge gap by following a multistep interrelated research methodology. First, a research team of 19 construction professionals and academics developed and distributed an industry survey to (1) quantify the likelihood of occurrence and relative impact of risk factors that adversely impact labor productivity in offsite construction projects; (2) identify and prioritize key risk factors that adversely affect labor productivity in offsite construction operations; and (3) examine how labor productivity risk factors are perceived by various project stakeholders. Second, different statistical analysis tests and methods (i.e., internal and external reliability, statistically significant differences, clustering analysis, and concordance analysis) were used to critically analyze the results and draw conclusions. Based on a total of 100 responses and 20 labor productivity risk factors, the findings reflected that the top five risk factors adversely affecting labor productivity in offsite construction projects included (1) unskilled labor and improper workforce training and development; (2) poor logistics; (3) errors, omissions, and rework; (4) work area congestion and overcrowding; and (5) insufficient coordination. Also, the findings indicated that labor productivity factors can be clustered into two groups: factors with high overall risk and factors with low overall risk on offsite construction labor productivity; 80% of the risk factors were found to fall into the first category. The results of this study also reflected the need for offsite construction companies and industry practitioners to carefully establish mitigation plans and corrective actions for the identified key risk factors adversely affecting offsite construction labor productivity. This study adds to the body of knowledge by exploring and ranking productivity factors in offsite construction projects. Ultimately, this study will help the industry and research communities better understand factors affecting offsite construction labor productivity, more effectively direct future efforts to enhance labor performance, and devise productivity improvement strategies

Management of Change Orders in Infrastructure Transportation Projects

The Illinois Department of Transportation (IDOT) will handle many upcoming projects due to the recent statewide infrastructure strategic plan and the fast-track efforts affecting many infrastructure projects amid COVID-19. Nevertheless, many change orders are anticipated to occur on IDOT\u27s projects. Thus, this paper examines the proper contractual management of changes within IDOT infrastructure transportation projects by following a research method based on the integration between a desktop analysis and a focus group analysis. The desktop analysis involved collecting information and data from existing resources, case studies, and documents related to change orders. The focus group analysis involved consulting with change order experts to verify that the outcome of each research step is useful and to validate the final outcomes of the paper. Based on 50 documented major change orders in IDOT projects and three litigated cases, two findings are provided. First, the top causes for key change orders within IDOT projects include contract administration, allowable contingencies, quantity omission or error, differing site conditions, and design changes. Second, the most critical change order related challenges within IDOT\u27s infrastructure projects include approval procedures, compensation considerations, and applicable laws. This paper offers flowcharts, synopsis of opportunities and risks, and a checklist to help the contracting parties better administer change orders. Ultimately, the contributions of this paper to the practice include: (1) minimizing the number and amount of change orders, (2) helping the contracting parties better understand how their individual responsibilities contribute to the proper processing and management of changes and variations, (3) offering contractors the ability to visualize the different steps involved in the approval of change orders, (4) assisting the project stakeholders in identifying change order-related areas for improvement, and (5) allowing project owners to better mitigate, manage, and administer the contractual aspects of change orders

Study of the effect of HFE gene mutations on iron overload in Egyptian thalassemia patients

Background: HFE gene mutations have been shown to be responsible for hereditaryhemochromatosis. Their effect on iron load in β-thalassemia patients and carriers remains controversial.Objectives: We aimed to determine the prevalence of HFE gene mutations (C282Y and H63D) in β-thalassemia patients and carriers and to investigate its effect on their serum ferritin levels.Patients and methods: A total of 100 β-thalassemia subjects; 75 patients and 25 carriers were screened for HFE gene mutations by PCR-RFLP. Serum ferritin measured by ELISA was evaluated in relation to HFE mutations.Results: Twenty-eight β-thalassemia patients (37.3%) were heterozygotes for H63D mutation (H/D), 8 (10.7%) were D/D and 39 (52%) were negative (H/H). Among carriers, 4 (16%) were D/D and 21 (84%) were H/H homozygotes. C282Y mutant allele was not detected in any of the subjects. Serum ferritin levels were significantly higher in β-thalassemia patients heterozygotes or homozygotes for H63D mutation compared to those without mutation (p= 0.000). Carriers homozygotes for H63D mutation showed significantly higher serum ferritin levels compared to those without mutation (p< 0.001).Conclusion: Homozygosity for H63D mutation tends to be associated with higher ferritin levels in beta-thalassemia patients and carriers suggesting its modulating effect on iron load in these cases

Transport Properties of Doped t-J Ladders

Conductivity and Hall coefficient for various types of t-J ladders are calculated as a function of temperature and frequency by numerical diagonalization. A crossover from an incoherent to a coherent charge dynamics is found at a temperature T_{coh}. There exists another crossover at T_{PG} below which a pseudogap opens in the optical spectra, induced by the opening of a spin gap. In the absence of the spin gap, T_{coh} and the coherent weight are suppressed especially with increasing dimensionality. On the contrary, T_{coh} is strongly enhanced by the pseudogap formation below T_{PG}, where the coherent Drude weight decreases with increasing dimensionality. The Hall coefficient shows a strong crossover at T_{PG} below which it has large amplitude for small doping concentration.Comment: 4 pages, RevTeX, 5 PostScript figure

Peri-renal adipose inflammation contributes to renal dysfunction in a non-obese prediabetic rat model: Role of anti-diabetic drugs

Diabetic nephropathy is a major health challenge with considerable economic burden and significant impact on patients’ quality of life. Despite recent advances in diabetic patient care, current clinical practice guidelines fall short of halting the progression of diabetic nephropathy to end-stage renal disease. Moreover, prior literature reported manifestations of renal dysfunction in early stages of metabolic impairment prior to the development of hyperglycemia indicating the involvement of alternative pathological mechanisms apart from those typically triggered by high blood glucose. Here, we extend our prior research work implicating localized inflammation in specific adipose depots in initiating cardiovascular dysfunction in early stages of metabolic impairment. Non-obese prediabetic rats showed elevated glomerular filtration rates and mild proteinuria in absence of hyperglycemia, hypertension, and signs of systemic inflammation. Isolated perfused kidneys from these rats showed impaired renovascular endothelial feedback in response to vasopressors and increased flow. While endothelium dependent dilation remained functional, renovascular relaxation in prediabetic rats was not mediated by nitric oxide and prostaglandins as in control tissues, but rather an upregulation of the function of epoxy eicosatrienoic acids was observed. This was coupled with signs of peri-renal adipose tissue (PRAT) inflammation and renal structural damage. A two-week treatment with non-hypoglycemic doses of metformin or pioglitazone, shown previously to ameliorate adipose inflammation, not only reversed PRAT inflammation in prediabetic rats, but also reversed the observed functional, renovascular, and structural renal abnormalities. The present results suggest that peri-renal adipose inflammation triggers renal dysfunction early in the course of metabolic disease.This study was supported by American University of Beirut Faculty of Medicine Medical Practice Plan grant #320148 granted to AFE. The funding body had no role in the design of the study or collection, analysis, and interpretation of data or in writing the manuscript

Absence of association between behavior problems in childhood and hypertension in midlife

Background It is known that behavior in childhood is associated with certain physical and mental health problems in midlife. However, there is limited evidence on the role of childhood behavior problems in the development of hypertension in adulthood. The present study aimed to examine whether behavior problems in childhood influenced the risk of hypertension in midlife in the United Kingdom 1958 birth cohort. Methods The 1958 British birth cohort comprised 17,638 individuals born in the first week of March 1958 in the United Kingdom. Behavior problems were assessed at 7, 11, and 16 years of age by parents and teachers. At age 45, blood pressure was measured and hypertension was recorded if blood pressure was ≥140/90 mm Hg or if the participants were informed by their health professionals that they had high blood pressure. Behavioral information was reported according to the Rutter Children's Behaviour Questionnaire (RCBQ) and the Bristol Social Adjustment Guide (BSAG). Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to examine behavior problems in childhood in relation to hypertension at 45 years of age according to logistic regression analysis, with adjustment for sex, social class in childhood and adulthood, childhood cognition, birth weight, gestational age at birth, body mass index (BMI), smoking, alcohol consumption, and physical activity. Results Behavior problems reported by parents at 7, 11, and 16 years were not associated with hypertension in midlife (OR, 0.93; 95% CI, 0.81, 1.07; OR, 0.95; 95% CI, 0.81, 1.11; OR, 0.98; 95% CI, 0.85, 1.12, respectively). Similarly, teacher-reported behavior problems at 7, 11, and 16 years were not associated with hypertension in midlife (OR, 0.92; 95% CI, 0.72, 1.18; OR, 0.92; 95% CI, 0.84, 1.02; OR, 1.03; 95% CI, 0.92, 1.15, respectively). Further separate analyses showed similar results for males and females. Conclusion There is no association between behavior problems in childhood and hypertension in midlife

Non-Fermi liquid regime of a doped Mott insulator

We study the doping of a Mott insulator in the presence of quenched frustrating disorder in the magnetic exchange. A low doping regime $\delta<J/t$ is found, in which the quasiparticle coherent scale is low : $\epsilon_F^* = J (\delta/\delta^*)^2$ with $\delta^*=J/t$ (the ratio of typical exchange to hopping). In the ``quantum critical regime'' $\epsilon_F^*<T<J$, several physical quantities display Marginal Fermi Liquid behaviour : NMR relaxation time $1/T_1\sim const.$, resistivity $\rho_{dc}(T) \propto T$, optical lifetime \tau_{opt}^{-1}\propto \omega/\ln(\omega/\epstar) and response functions obey $\omega/T$ scaling, e.g. $J\sum_q \chi''(q,\omega) \propto \tanh (\omega/2T)$. In contrast, single-electron properties display stronger deviations from Fermi liquid theory in this regime with a $\sqrt{\omega}$ dependence of the inverse single-particle lifetime and a $1/\sqrt{\omega}$ decay of the photoemission intensity. On the basis of this model and of various experimental evidence, it is argued that the proximity of a quantum critical point separating a glassy Mott-Anderson insulator from a metallic ground-state is an important ingredient in the physics of the normal state of cuprate superconductors (particularly the Zn-doped materials). In this picture the corresponding quantum critical regime is a ``slushy'' state of spins and holes with slow spin and charge dynamics responsible for the anomalous properties of the normal state.Comment: 40 pages, RevTeX, including 13 figures in EPS. v2 : minor changes, some references adde