Model-based design of coordinated traffic controllers

Modern transportation systems optimize traffic flows in road networks by allowing intersection-level traffic controllers to communicate and synchronize. Typically they are distributed systems, with multiple nodes (intersections) communicating with each other in real time. This paper proposes a design process for traffic coordination systems using model driven engineering (MDE), a paradigm used to design complex embedded systems in automotive and aerospace. The approach combines a conventional micro-simulator (AIMSUN) with a state of the art control modelling tool (Simulink) following a model-view-controller approach. The MDE approach allows for both micro-simulation (on a PC) and emulation (using embedded controllers). Once the model is validated, automatic code generation can be used to generate the implementation of the system on embedded devices. As a case study, the authors designed a SCATS-inspired coordinated intersection control system. To the authors' knowledge, the proposed approach is the first, fully automated approach for the design of complex intelligent transportation systems (ITS)

Effects of non-carious cervical lesion size, occlusal loading and restoration on biomechanical behavior of premolar teeth

Accepted manuscript online: 15 DEC 2015Information on fracture biomechanics has implications in materials research and clinical practice. The aim of this study was to analyze the influence of non-carious cervical lesion (NCCL) size, restorative status and direction of occlusal loading on the biomechanical behavior of mandibular premolars, using finite element analysis (FEA), strain gauge tests and fracture resistance tests.Ten buccal cusps were loaded on the outer and inner slopes to calculate the strain generated cervically. Data were collected for healthy teeth at baseline and progressively at three lesion depths (0.5 mm, 1.0 mm and 1.5 mm), followed by restoration with resin composite. The magnitude and distribution of von Mises stress and maximum principal stress were simulated at all stages using FEA, and fracture strength was also determined (n = 7 per group).There were significant effects of the lesion size and loading directions on stress, strain and fracture resistance (p<0.05). Fracture resistance values decreased with increase in lesion size, but returned to baseline with restorations.Combined assessment of computer-based and experimental techniques provide an holistic approach to characterize the biomechanical behaviour of teeth with both unrestored and restored NCCLs. This article is protected by copyright. All rights reserved.LF Zeola, FA Pereira, AC Machado, BR Reis, J Kaidonis, Z Xie, GC Townsend, S Ranjitkar, PV Soare

The feasibility of the Ages and Stages Questionnaire for the assessment of child development in a community setting in Nepal

Background: The Ages and Stages Questionnaire Third Edition (ASQ‐3) may be a feasible and cost‐effective tool to screen children's development in resource poor settings. We have assessed the feasibility of the ASQ‐3 “home procedure” when conducted by fieldworkers in a community‐based nutritional interventional trial on early child development in Nepal. Method: Six hundred children aged 6–11 months at risk of stunting were assessed by trained fieldworkers in their homes by the ASQ‐3. Three fieldworkers performed standardization exercises and were double scored with a gold standard during the study period. Intraclass correlations (ICCs) were calculated to measure the interrater agreement. The internal consistency was expressed by standardized Cronbach's alphas. The association between total ASQ score and gestation, low birth weight, and stunted children is presented to give an estimate of the construct validity of the tool. Result: Mean scores of the 600 Nepalese children were consistently lower than in the American norm sample. The ICCs from the standardization exercises were initially good to excellent but declined throughout the study period. The standardized alphas for the total score in the different age groups indicate good internal consistency but varied in the subscales. Children who were preterm, children with low birth weight, and children who were stunted scored substantially lower on the total ASQ score than those who were not. Conclusion: Although the ASQ‐3 “home procedure” is low at cost and easily accessible in a Nepalese context, the tool requires rigorous and stringent training to achieve acceptable interrater agreement. Further adjustment is required to achieve satisfactory internal consistency.acceptedVersio

Criterion for traffic phases in single vehicle data and empirical test of a microscopic three-phase traffic theory

A microscopic criterion for distinguishing synchronized flow and wide moving jam phases in single vehicle data measured at a single freeway location is presented. Empirical local congested traffic states in single vehicle data measured on different days are classified into synchronized flow states and states consisting of synchronized flow and wide moving jam(s). Then empirical microscopic characteristics for these different local congested traffic states are studied. Using these characteristics and empirical spatiotemporal macroscopic traffic phenomena, an empirical test of a microscopic three-phase traffic flow theory is performed. Simulations show that the microscopic criterion and macroscopic spatiotemporal objective criteria lead to the same identification of the synchronized flow and wide moving jam phases in congested traffic. It is found that microscopic three-phase traffic models can explain both microscopic and macroscopic empirical congested pattern features. It is obtained that microscopic distributions for vehicle speed difference as well as fundamental diagrams and speed correlation functions can depend on the spatial co-ordinate considerably. It turns out that microscopic optimal velocity (OV) functions and time headway distributions are not necessarily qualitatively different, even if local congested traffic states are qualitatively different. The reason for this is that important spatiotemporal features of congested traffic patterns are it lost in these as well as in many other macroscopic and microscopic traffic characteristics, which are widely used as the empirical basis for a test of traffic flow models, specifically, cellular automata traffic flow models.Comment: 27 pages, 16 figure

Calibrating Car-Following Models using Trajectory Data: Methodological Study

The car-following behavior of individual drivers in real city traffic is studied on the basis of (publicly available) trajectory datasets recorded by a vehicle equipped with an radar sensor. By means of a nonlinear optimization procedure based on a genetic algorithm, we calibrate the Intelligent Driver Model and the Velocity Difference Model by minimizing the deviations between the observed driving dynamics and the simulated trajectory when following the same leading vehicle. The reliability and robustness of the nonlinear fits are assessed by applying different optimization criteria, i.e., different measures for the deviations between two trajectories. The obtained errors are in the range between~11% and~29% which is consistent with typical error ranges obtained in previous studies. In addition, we found that the calibrated parameter values of the Velocity Difference Model strongly depend on the optimization criterion, while the Intelligent Driver Model is more robust in this respect. By applying an explicit delay to the model input, we investigated the influence of a reaction time. Remarkably, we found a negligible influence of the reaction time indicating that drivers compensate for their reaction time by anticipation. Furthermore, the parameter sets calibrated to a certain trajectory are applied to the other trajectories allowing for model validation. The results indicate that ``intra-driver variability'' rather than ``inter-driver variability'' accounts for a large part of the calibration errors. The results are used to suggest some criteria towards a benchmarking of car-following models

Maternal supplementation with Bacillus altitudinis spores improves porcine offspring growth performance and carcass weight

The objective of this study was to evaluate the effect of feeding Bacillus altitudinis spores to sows and/or offspring on growth and health indicators. On day (D) 100 of gestation, 24 sows were selected and grouped as: control (CON), fed with a standard diet; and probiotic (PRO), fed the standard diet supplemented with B. altitudinis WIT588 spores from D100 of gestation until weaning. Offspring (n=144) from each of the two sow treatments were assigned to either a CON (no probiotic) or PRO (B. altitudinis-supplemented) treatment for 28 days post-weaning (pw), resulting in four treatment groups: 1) CON/CON, non-probiotic supplemented sow/non-probiotic supplemented piglet; 2) CON/PRO, non-probiotic supplemented sow/probiotic-supplemented piglet; 3) PRO/CON, probiotic-supplemented sow/non-probiotic supplemented piglet; 4) PRO/PRO, probiotic-supplemented sow/probiotic-supplemented piglet. Bacillus altitudinis WIT588 was detected in the faeces of probiotic supplemented sows and their piglets, and in the faeces and intestine of probiotic-supplemented piglets. Colostrum from PRO sows had higher total solids (P=0.02), protein (P=0.04), and true protein (P=0.05), and lower lactose (P<0.01) than colostrum from CON sows. Maternal treatment improved offspring feed conversion ratio at D0-14 pw (P<0.001) and increased offspring body weight at D105 and D127 pw (P=0.01), carcass weight (P=0.05) and kill-out percentage (P<0.01). It also increased small intestinal absorptive capacity and impacted the haematological profile of sows and progeny. Little impact of post-weaning treatment was observed on any of the parameters measured. Overall, the lifetime growth benefits in the offspring of B. altitudinis-supplemented sows offer considerable economic advantages for pig producers in search of alternatives to in-feed antibiotics/zinc oxide

Predicting Inactive Conformations of Protein Kinases Using Active Structures: Conformational Selection of Type-II Inhibitors

Protein kinases have been found to possess two characteristic conformations in their activation-loops: the active DFG-in conformation and the inactive DFG-out conformation. Recently, it has been very interesting to develop type-II inhibitors which target the DFG-out conformation and are more specific than the type-I inhibitors binding to the active DFG-in conformation. However, solving crystal structures of kinases with the DFG-out conformation remains a challenge, and this seriously hampers the application of the structure-based approaches in development of novel type-II inhibitors. To overcome this limitation, here we present a computational approach for predicting the DFG-out inactive conformation using the DFG-in active structures, and develop related conformational selection protocols for the uses of the predicted DFG-out models in the binding pose prediction and virtual screening of type-II ligands. With the DFG-out models, we predicted the binding poses for known type-II inhibitors, and the results were found in good agreement with the X-ray crystal structures. We also tested the abilities of the DFG-out models to recognize their specific type-II inhibitors by screening a database of small molecules. The AUC (area under curve) results indicated that the predicted DFG-out models were selective toward their specific type-II inhibitors. Therefore, the computational approach and protocols presented in this study are very promising for the structure-based design and screening of novel type-II kinase inhibitors

Transferability of Car-Following Models Between Driving Simulator and Field Traffic

During the past few decades, there have been two parallel streams of driving behavior research: models using trajectory data collected from the field (using video recordings, GPS, etc.) and models using data from driving simulators (in which the behavior of the drivers is recorded in controlled laboratory conditions). Although the former source of data is more realistic, it lacks information about the driver and is typically not suitable for testing effects of future vehicle technologies and traffic scenarios. In contrast, driving behavior models developed with driving simulator data may lack behavioral realism. However, no previous study has compared these two streams of mathematical models and investigated the transferability of the models developed with driving simulator data to real field conditions in a rigorous manner. The current study aimed to fill this research gap by investigating the transferability of two car-following models between a driving simulator and two comparable real-life traffic motorway scenarios, one from the United Kingdom and the other one from the United States. In this regard, stimulus–response–based car-following models were developed with three microscopic data sources: (a) experimental data collected from the University of Leeds driving simulator, (b) detailed trajectory data collected from UK Motorway 1, and (c) detailed trajectory data collected from Interstate 80 in California. The parameters of these car-following models were estimated by using the maximum likelihood estimation technique, and the transferability of the models was investigated by using statistical tests of parameter equivalence and transferability test statistics. Estimation results indicate transferability at the model level but not fully at the parameter level for both pairs of scenarios

Misregulation of Scm3p/HJURP Causes Chromosome Instability in Saccharomyces cerevisiae and Human Cells

The kinetochore (centromeric DNA and associated proteins) is a key determinant for high fidelity chromosome transmission. Evolutionarily conserved Scm3p is an essential component of centromeric chromatin and is required for assembly and function of kinetochores in humans, fission yeast, and budding yeast. Overexpression of HJURP, the mammalian homolog of budding yeast Scm3p, has been observed in lung and breast cancers and is associated with poor prognosis; however, the physiological relevance of these observations is not well understood. We overexpressed SCM3 and HJURP in Saccharomyces cerevisiae and HJURP in human cells and defined domains within Scm3p that mediate its chromosome loss phenotype. Our results showed that the overexpression of SCM3 (GALSCM3) or HJURP (GALHJURP) caused chromosome loss in a wild-type yeast strain, and overexpression of HJURP led to mitotic defects in human cells. GALSCM3 resulted in reduced viability in kinetochore mutants, premature separation of sister chromatids, and reduction in Cse4p and histone H4 at centromeres. Overexpression of CSE4 or histone H4 suppressed chromosome loss and restored levels of Cse4p at centromeres in GALSCM3 strains. Using mutant alleles of scm3, we identified a domain in the N-terminus of Scm3p that mediates its interaction with CEN DNA and determined that the chromosome loss phenotype of GALSCM3 is due to centromeric association of Scm3p devoid of Cse4p/H4. Furthermore, we determined that similar to other systems the centromeric association of Scm3p is cell cycle regulated. Our results show that altered stoichiometry of Scm3p/HJURP, Cse4p, and histone H4 lead to defects in chromosome segregation. We conclude that stringent regulation of HJURP and SCM3 expression are critical for genome stability