bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimal scheduling of public transport fleet at network level
Authors: Nahry Sutanto Soehodho
Published: January 2010

This paper deals with the development of a strategic approach for optimizing the operation of public transport system that considers both user's objective and operator's objective. Passengers of public transport are assumed to seek a minimum wait time to conduct the trips, while on the other hand, operators are concerned with the efficient operation such as minimum fleet size. The average minimum wait time is to be achieved by creating an optimal despatching policy for each vehicle from the terminal. As for efficient operation the utilisation of vehicle should be maximised by having a minimum number of vehicles in operation. User's and operator's objectives are optimized within certain operational constraints such as vehicle capacity to maintain acceptable level of service. The i‐model is contructed in a bi‐level programming form in which the user's objective is minimized by dynamic programming and the operator's objective is minimized by various routing strategies. Furthermore, an algorithm and a contrived example are developed to solve and see the performance of the approach.
ITS applications in public transport: Improving the service to the transport system
Authors: Blythe Phil , Rackliff Toby , Holland Richard , Mageean Jenny
Published: January 2010

This paper examines all the disparate technologies and techniques capable of smoothing the integration of public transport modes and services at both the urban and interurban scale. The paper focuses on the application of information technology and telematics solutions which have been designed to create as seamless a journey as possible from the point of view of the transport system user. The scope of the paper is therefore deliberately wide‐ranging and includes an examination of measures as apparently unconnected as smartcard ticketing, bus priority systems, automatic vehicle locationing, trip planning and on‐board information systems as well as new public transport services offering demand responsive travel and integration with taxi services. The paper intends to show how such technological solutions can be used to increase the attractiveness and competitiveness of fixed public transport networks in comparison to the door‐to‐door flexibility of the private car.
The importance of new‐generation freight terminals for intermodal transport
Authors: Bontekoning Y. M.
Published: January 2010

Manufacturers have been promoting new terminal concepts for several years. They claim more efficient operations, shorter handling times and lower costs compared to conventional operations. However, so far no new‐generation terminals have been implemented, nor is there any intention yet to implement them. This is regrettable, because if new‐generation terminal concepts can achieve what their designers claim, these terminals could significantly improve the competitiveness of intermodal transport. It is expected that new‐generation terminals will perform particularly well in complex bundling networks such as hub and spoke, collection‐distribution and line networks. A static‐process analysis is used to evaluate the claimed terminal performances. The method incorporates the terminal function and the type of bundling network. Specific network situations have been defined for each type of bundling network. This study shows that the new concepts perform better than the reference terminal and shunting in complex bundling operations.
Evaluating commuter opinion of congestion pricing in metropolitan Seattle
Authors: Chang Kevin N. , Nihan Nancy L.
Published: January 2010

Continued growth and development in the Puget Sound region combined with existing geographic limitations have resulted in a transportation network that is at or near capacity for many hours during every weekday. Single‐occupancy vehicles (SOVs) remain the predominant mode of travel, despite a network of high‐occupancy vehicle lanes and regional transit. Given this situation, considering alternative methods to regulate traffic flow is necessary, and the implementation of a regional congestion pricing system is one such option. Although widespread throughout the world, congestion pricing has only recently been implemented in the United States.
Value of travel time: An activity‐based analysis with combined RP and SP data
Authors: Duann Liang‐Shyong , Shiaw Ming‐Shong
Published: January 2010

Under certain assumptions, values of travel time (VOT) can be divided into two parts: one associated with travel (i.e., the value of reducing travel time disutility) and the other associated with activities (the shadow price of time). The empirical results of combining RP and SP data showed that the VOT of travel was greater than that of activity. The results also showed that SP experiments that did not take or only took part of activities into consideration would underestimate VOT.
Developing freeway lane‐changing support systems using artificial neural networks
Authors: Wei Chien‐Hung
Published: January 2010

Lane‐changing involves many concerns about safety and efficiency which makes it one of the most difficult tasks of driving. It is indeed quite personal since drivers operate vehicles according to their integrated perception of comprehensive circumstances rather than individual rules. A lane‐changing decision support model is developed in this study using artificial neural networks (ANN). The advantages of the ANN approach lie in the learning capability. Due to its nature, an ANN model can consolidate various kinds of information surrounding the vehicle for the drivers and generate reliable results to help control vehicles. It then becomes a useful mechanism to assist drivers in judging current situations and making the right decisions. Several preliminary validations and comparisons are conducted with the field survey data. It is confirmed that the ANN model mimics traffic characteristics more accurately than conventional methods. This product would expedite the implementation of relevant applications in the intelligent transportation systems context. In particular, the ANN model can be adapted to individual driver characteristics. This reveals practical feasibility and significant market potential for customized in‐vehicle equipment.
A simulation model of reliable schedule design for a fixed transit route
Authors: Liu G. , Wirasinghe S. C.
Published: January 2010

This paper describes a simulation model of schedule design for a fixed transit route adopting the holding control strategy. The model is capable of determining the locations of time points and the amount of slack time allocated to each time point by minimizing the total cost associated with the schedule. The optimization is carried out through a process, which combines a heuristic search, enumeration, and population ranking and selection techniques. Examples showing applications and potential savings of the proposed model are given. It is shown that the model can serve as a practical tool for designing reliable, economical as well as operational transit schedules.
Enhanced bus operations: The Curitiba model and its applicability to China
Authors: Bell Michael G H
Published: January 2010

Buses will remain the backbone of public transport systems for some time to come because of their lower cost and higher flexibility in relation to rail transport. However, buses are perceived as being an inferior mode of public transport and do not offer as much carrying capacity as rail transport. Following the Curitiba model, this paper looks at the potential for transferring some of the key advantages of rail transport to bus operations. This involves transforming bus stops into enclosed stations, with ticket purchase and/or checking in the station and at‐grade access to vehicles. It also involves the extensive use of bus lanes. The potential contribution of transport telematics is looked at, in particular the use of smartcards for payment in a closed fare system. The potential role of the Curitiba model for China is assessed in the context of toll road construction.
Modeling urban taxi services in road networks: Progress, problem and prospect
Authors: Yang Hai , Wong K. I. , Wong S. C.
Published: January 2010

Traditionally, many economists have examined the models and economics of urban taxi services under various types of regulation such as entry restriction and price control in an aggregate way. Only recently have we modeled urban taxi services in a network context. A realistic method has been proposed to describe vacant and occupied taxi movements in a road network and taxi drivers' search behavior for customers. A few extensions have been made to deal with demand elasticity and congestion effects together with development of efficient solution algorithms. Calibration and validation of the network taxi service models have been conducted towards their practical applications. This paper presents an overview of the research that has been carried out by the authors to develop network equilibrium models and solution algorithms for urban taxi services, and offers perspectives for future researches.
Genetic algorithms approach to the problem of the automated vehicle identification equipment locations
Authors: Teodorovic Dusan , van Aerde Michel , Zhu Fulin , Dion Francois
Published: January 2010

The automated vehicle identification (AVI) equipment location problem entails determination of the best locations for the automated vehicle identification equipment. The paper attempts to solve the AVI equipment location problem as a multi‐objective optimization problem, thus determining the best locations on the basis of several criteria. The developed model is based on genetic algorithms. Testing of the model developed on the greater transportation networks is certainly one of the most important directions for the future research, as much as the development of models based on other metaheuristic approaches (Simulated Annealing, Taboo Search). The results obtained in this stage of the research are promising.
Application of genetic algorithm for scheduling and schedule coordination problems
Authors: Shrivastava Prabhat , Dhingra S. L. , Gundaliya P. J.
Published: January 2010

The problems on scheduling and schedule co‐ordination usually have conflicting objectives related to user's cost and operator's cost. Users want to spend less time to wait, transfer and travel by public buses. Operators are interested in profit making by lesser vehicle operating cost and having a minimum number of buses. As far as level of service is concerned users are interested in lesser crowing while operators are concerned with maximizing profit and thus to have higher load factors. In schedule co‐ordination problems transfer time plays an important role. Users are interested in coordinating services with in acceptable waiting time whereas operators prefer to have lesser services and want to meet higher demands, which invariably increases waiting time. These problems have multiple conflicting objectives and constraints. It is difficult to determine optimum solution for such problems with the help of conventional approaches. It is found that Genetic Algorithm performs well for such multi objective problems.
Impact of interviewing by proxy in travel survey conducted by telephone
Authors: Badoe Daniel A. , Steuart Gerald N.
Published: January 2010

Telephone‐interview surveys are a very efficient way of conducting large‐scale travel surveys. Recent advancements in computer technology have made it possible to improve upon the quality of data collected by telephone surveys through computerization of the entire sample‐control process, and through the direct recording of the collected data into a computer. Notwithstanding these technological advancements, potential sources of bias still exist, including the reliance on an adult member of the household to report the travel information of other household members.

Travel data collected in a recent telephone interview survey in the Toronto region is used to examine this issue. The statistical tool used in the research was the Analysis of Variance (ANOVA) technique as implemented within the general linear model framework in SAS. The study‐results indicate that reliance on informants to provide travel information for non‐informant members of their respective households led to the underreporting of some categories of trips. These underreported trip categories were primarily segments of home‐based discretionary trips, and non home‐based trips. Since these latter two categories of trips are made primarily outside the morning peak period, estimated factors to adjust for their underreporting were time‐period sensitive. Further, the number of vehicles available to the household, gender, and driver license status respectively were also found to be strongly associated with the underreporting of trips and thus were important considerations in the determination of adjustment factors.

Work and school trips were found not to be underreported, a not surprising result giving the almost daily repetitiveness of trips made for these purposes and hence the ability of the informant to provide relatively more precise information on them.
Multiobjective bilevel optimization for transportation planning and management problems
Authors: Yin Yafeng
Published: January 2010

Many previous studies have formulated the decision‐making problems in transportation system planning and management as single‐objective bilevel optimization models. However, real‐world decision‐making processes always have several social concerns and thus multiple objectives need to be achieved simultaneously. In most cases, these objective functions conflict with each other and are also not simple enough to be combined into a single one. Therefore it is necessary to apply multiobjective optimization to generate non‐dominated or Pareto optimal alternatives. It can be foreseen that the multiobjective bilevel modeling approach can become a powerful, and possibly interactive, decision tool, allowing the decision‐makers to learn more about the problem before committing to a final decision. Such multiobjective bilevel models are difficult to solve due to their intrinsic nonconvexity and multiple objectives. This paper consequently proposes a solution algorithm for the multiobjective bilevel models using genetic algorithms. The proposed algorithm is illustrated, using the numerical example taken from the previous study. It is found that the proposed algorithm is efficient to search simultaneously the Pareto optimal solutions.
An equity‐based passenger flow control model with application to Hong Kong‐Shenzhen border‐crossing
Authors: Yang Hai , Qiao Fengxiang
Published: January 2010

Cross‐border passengers from Hong Kong to Shenzhen by the east Kowloon‐Canton Railway (KCR) through the Lo Wu customs exceed nearly 200 thousand on a special day such as a day during the Chinese Spring Festival. Such heavy passenger demand often exceeds the processing and holding capacity of the Lo Wu customs for many hours a day. Thus, passengers must be metered off at all entrance stations along the KCR line through ticket rationing to restrain the number of passengers waiting at Lo Wu within its safe holding capacity. This paper proposes an optimal control strategy and model to deal with this passenger crowding and control problem. Because the maximum passenger checkout rate at Lo Wu is fixed, total passenger waiting time is not affected by the control strategy for given time‐dependent arriving rates at each station. An equity‐based control strategy is thus proposed to equalize the waiting times of passengers arriving at all stations at the same time. This equity is achieved through optimal allocation of the total quota of tickets to all entrance stations for each train service. The total ticket quota for each train service is determined such that the capacity constraint of the passenger queue at Lo Wu is satisfied. The control problem is formulated as a successive linear programming problem and demonstrated for the KCR system with partially simulated data.
Application of NETSIM in modeling B‐signals
Authors: Chin Hoong Chor , Cheu Ruey Long , Chandrasekar P.
Published: January 2010

NETSIM is a powerful microscopic simulation model and has been applied to numerous traffic studies. However, it appears that there are few attempts to use it to study bus operations. One of the possible reasons may be the difficulty in modeling some of the unique characteristics in bus operations. A similar challenge was faced when a recent evaluation on bus operations involving priority signals (B‐signals) was undertaken in Singapore. This paper describes the difficulties faced when NETSIM was applied in modeling bus priority signals and the techniques adopted to overcome them. This study shows that, by incorporating innovative techniques, NETSIM can be effectively used to model bus operations along with other traffic in a network.
Verification process and its application to network traffic simulation models
Authors: Horiguchi Ryota , Kuwahara Masao
Published: January 2010

This paper summarizes a standardized verification process for network traffic simulation models. After the general introduction of philosophy of verification, we explain detailed processes of the verification and its application to several well‐known simulation models. “Verification” here means several examination tests of simulation models using virtual data on a simple network so as to confirm their fundamental functions. In the course of model development, the developers have to examine whether the model performance is consistent with the specifications that they intend and also with the well‐authorized traffic engineering theory. Because of several constraints in putting the model specifications into the computer programming such as discretizing of time and space and simplifying vehicle behaviors to some degree, the intended model specifications may not be fully achieved in a computer. Therefore, we strongly recommend the verification before applying the models to a real network.
A system dynamics approach to land use / transportation system performance modeling Part II: Application
Authors: Haghani Ali , Lee Sang Y. , Byun Joon H.
Published: January 2010

This paper presents a system dynamics approach to simultaneous land use/transportation system performance modeling. A model is designed based on the causality functions and feedback loop structure between a large number of physical, socioeconomic, and policy variables. The model system consists of 7 sub‐models: population, migration of population, household, job growth‐employment‐land availability, housing development, travel demand, and traffic congestion level. The model is formulated in DYNAMO simulation language, and tested on a data set from Montgomery County, MD.

In Part I: Methodology, the overall approach and the structure of the model system is discussed and the causal‐loop diagrams and major equations are presented. In Part II: Application, the model is calibrated and tested with data from Montgomery County, MD. Least square method and overall system behavior are used to estimate the model parameters. The model is fitted with the 1970–80 data and validated with the 1980–1990 data. Robustness and sensitivities with respect to input parameters such as birth rate or regional economy growth are analyzed. The model performance as a policy analysis tool is also examined by predicting the year by year impacts of highway capacity expansion on land use and transportation system performance.

While this is a first attempt in using dynamic system simulation modeling in simultaneous treatment of land use and transportation system interactions, and model development and application are limited to some extent due to data availability, the results clearly indicate that the proposed method is a promising approach in dealing with complex urban land use/transportation modeling
Development of an object‐oriented pedestrian traffic flow simulation environment for transport terminal planning
Authors: Anagnostopoulos Dimosthenis , Karlaftis Matthew G. , Nikolaidou Mara
Published: January 2010

In recent years, simulation has become an essential tool for planning, designing, and managing terminal operations. Simulation modeling of various aspects related to the dynamic nature of the pedestrian/passenger behavior within a transport terminal can effectively assist in the analysis, evaluation, emergency response planning, and decision support phases of the terminal's operation. In this paper, the development of an object‐oriented environment that enables both the graphical description and simulation of pedestrian traffic flows at the microscopic level is discussed. The simulation environment provides generation capabilities so that a terminal station model is directly formed on the basis of preconstructed component models. Essential experimentation capabilities, including graphical representation, are provided for pedestrian‐oriented and system‐oriented measures of interest with explicit emphasis on the level of service. A case study for a 4–level station in the new Athens subway system is also used to demonstrate the potential and functionality of the simulation environment.
Discharge headway at signalized intersections in Hong Kong
Authors: Hung W. T. , Tian F. , Tong H. Y.
Published: January 2010

This paper reports the analysis and comparisons of discharge headways at 26 sites in Hong Kong. Previous studies here established good understanding of the average discharge headway under various conditions but very few studies dealt with discharge headway of individual vehicles which is a vital component in the traffic simulation at signalized intersections. This study that looked into the discharge headway of individual vehicles found that the discharge headway at different queue position follows the Type I Extreme Value Distribution. A method of estimating site‐specific parameters for this distribution has also been proposed.
Developing control strategies for freeway merging points under congested traffic situations using modeling and a simulation approach
Authors: Sarvi Majid , Kuwahara Masao , Ceder Avishai
Published: January 2010

This work focuses on developing a variety of strategies for alleviating congestion at freeway merging points as well as improving the safety of these points. On the Tokyo Metropolitan Expressway, traffic congestion frequently occurs at merging bottleneck sections, especially during heavy traffic demand. The Tokyo Metropolitan Expressway public corporation, generally applies different empirical strategies to increase the flow rate and decrease the accident rate at the merging sections. However, these strategies do not rely either on any behavioral characteristic of the merging traffic or on the geometric design of the merging segments. There have been only a few research publications concerned with traffic behavior and characteristics in these situations. Therefore, a three‐year extensive study has been undertaken to investigate traffic behavior and characteristics during the merging process under congested situations in order to design safer and less congested merging points as well as to apply more efficient control at these bottleneck sections.

Two groups of strategies were investigated in this study. The First group was related to the traffic characteristics, and the second group to the geometric characteristics. In the first group, the control strategies related to closure of freeway and ramp lanes as well as lane‐changing maneuver restriction were investigated through a simulation program, detector data, and field experiment. In the second group, the angle of convergence of the ramp with the freeway in relation to merging capacity was analyzed using a simulation program. Results suggested the potential benefits of using proposed strategies developed in this work and can serve as initial guidance for the reduction of delay and improvement of safety under congested traffic conditions.
Train scheduling simulation that minimises operational conflicts due to service constraints
Authors: Bandara J. M. S. J. , Ekanayake I. A. B.
Published: January 2010

This paper presents an attempt made to facilitate re‐scheduling of trains to minimize operational delays and accommodate uniform headways for off peak sub urban services subject to resource constraints such as locomotive availability, poor track conditions and stations without siding facilities.

The paper describes the computer simulation model designed to optimize train schedules on single‐track rail lines. Using this simulation program it is possible to plan and optimize timetables for railway networks with train runs within short time periods for both single track and double track conditions. The paper describes the capabilities of presenting the results of the simulation runs. These include the time‐distance graph, the network with train movements, dialog boxes with information about selected trains. The programme is capable of changing the starting point, departure time, train destinations and adding or deleting a stop etc. from the user interface.

Four objects of array variables are used in the simulation process to keep train and station data. Two object arrays are used for the train movements in up and down directions. The stations' data are stored in the other two object arrays. One of these arrays of stations contains all the stations of the line while the other one contains only the stations with siding facilities. A case study that covers a 61 km long single‐track line with 14 stations is presented to highlight the model capabilities.
Service effectiveness of prt vs collective ‐ corridor transport
Authors: Lowson Martin
Published: January 2010

A generalised model is used to provide estimates of overall trip times and speed for conventional corridor‐collective transport and PRT. The results demonstrate why traditional forms of transport find difficulty providing an effective service in a city. Short separations between stops are required to minimise walk times but on conventional transport this leads to significant reductions in achievable speed because of the need for frequent stops. It is also shown that there is very little benefit in service effectiveness from LRT/APM/Monorail over buses. PRT is immune to these effects. The present calculations typically show a benefit for PRT of a factor of two or greater in trip time over either bus or LRT/APM.
Special issue: Importance of public transport
Authors: Schmöcker Jan‐Dirk , Bell Michael G. H. , Lam William H. K.
Published: January 2010

The transport demand in most major cities around the world can only be met with a high‐quality public transport system. The requirements on bus, rail, underground and tram systems are manifold with reliability and efficiency as the key factors. The service operating hours and the size of the network are often extended in order to serve the needs better. Further, most metropolitan areas are trying to provide more incentives for citizens to leave the car at home and use the local transit systems instead. The reasons are well known. Not only does a public transport system only make economical sense if it is well used, but most urban areas with a high car‐dependency face at least three major problems; safety, congestion, and pollution (noise and air pollution, land separation, etc.). It is generally recognised that to decrease car usage and to increase public transport usage a stick & carrot approach is needed. The London congestion‐charging scheme is an example since all revenues collected by the scheme are put into the improvement of bus and underground services.
Walking infrastructure design assessment by continuous space dynamic assignment modeling
Authors: Hoogendoorn Serge P. , Bovy Piet. H. L. , Daamen Winnie
Published: January 2010

For the planning and design of walking infrastructure, characterized by the fact that the pedestrians can choose their paths freely in two‐dimensional space, applicability of traditional discrete network models is limited. This contribution puts forward an approach for user‐optimal dynamic assignment in continuous time and space for analyzing for instance walking infrastructure in a two‐dimensional space. Contrary to network‐based approaches, the theory allows the traffic units to choose from an infinite non‐countable set of paths through the considered space. The approach first determines the continuous paths using a path choice model. Then, origin‐destination flows are assigned and traffic conditions are calculated. The approach to determine a user‐optimal assignment is heuristic and consists of a sequence of all‐or‐nothing assignments. An application example is presented, showing dynamic user equilibrium traffic flows through a realistic transfer station. The example is aimed at illustrating the dynamic aspects of the modeling approach, such as anticipation on expected flow conditions, and predicted behavior upon catching or missing a connection.
Modeling bus drivers' aberrant behaviors and the influences on fuel and maintenance costs
Authors: Lan Lawrence W. , Kuo April Y.
Published: January 2010

Bus drivers' aberrant behaviors such as errors and violations might bring about extra fuel consumption and mechanic abrading. To investigate how the aberrant behaviors affect the fuel and maintenance costs, seven indexes are proposed and their corresponding threshold values are determined through the field experiments. Nearly six months of en route data are collected from an intercity bus route and the raw data are converted into the proposed index values by a database management system. A collinearity test is performed and three different specifications of simultaneous‐equation regression models are attempted. The results show that abnormal engine rotation, unstable speed gradient, remarkable jerk, and speeding are the four independent indexes which can significantly explain the effects of bus drivers' aberrant behaviors on fuel and maintenance costs. Based on the cost importance of these four indexes, the drivers are further clustered into five categories and some practical applications are addressed.
A multiobjective planning model for intercity train seat allocation
Authors: Chang Yu‐Hern , Yeh Chung‐Hsing
Published: January 2010

This paper presents a multiobjective planning model for generating optimal train seat allocation plans on an intercity rail line serving passengers with many‐to‐many origin‐destination pairs. Two planning objectives of the model are to maximise the operator's total passenger revenue and to minimise the passenger's total discomfort level. For a given set of travel demand, train capacity, and train stop‐schedules, the model is solved by fuzzy mathematical programming to generate a best‐compromise train seat allocation plan. The plan determines how many reserved and non‐reserved seats are to be allocated at each origin station for all subsequent destination stations on each train run operated within a specified operating period. An empirical study on the to‐be‐built Taiwan's high‐speed rail system is conducted to demonstrate the effectiveness of the model. The model can be used for any setting of travel demand and stop‐schedules with various train seating capacities.
Updating free speed models through mechanistic principles for Indian conditions
Authors: Madhu Errampalli , Reddy T. S. , Madhu S. Velmurugan
Published: January 2010

The prediction of free speeds of vehicles is an integral part of the economic appraisal of highways. It is to be noted that speeds not only govern the travel time costs, but also have major impacts on Vehicle Operating Costs (VOC). The World Bank has proposed a mechanistic free speed model based on the limiting speed concept for Highway Design and Maintenance (HDM)‐III. This model along with some refinements has been included in HDM‐4. The underlying assumption in the HDM free speed prediction model is that the free speed at any given point of time is the minimum of possible constraining speeds. This paper mainly addresses the methodology considered to update the free speed models through mechanistic principles (based on HDM‐4). This is accomplished by calibration of the model using the current data on free speeds, road and vehicle characteristics. Subsequently, the validation of the developed models has been carried out.
Effect of variable message signs on driver speed behavior on a section of expressway under adverse fog conditions—A driving simulator approach
Authors: Kolisetty V. Ganesh Babu , Iryo Takamasa , Asakura Yasuo , Kuroda Katsuhiko
Published: January 2010

Variable message signs (VMS) are used to provide dynamic information and one current application is to show different speed limits under different conditions. As speed is an important contributor to road accidents and also affects driver speed behavior, the present study focuses on how effective traffic advisory information is when helping drivers to divert from potentially dangerous conditions. Graphical representation of an Expressway section made it easy to isolate the effects of speed etc. by drivers with information provided through VMS under adverse fog conditions. Understanding and reacting to the VMS system by drivers is essential for its success. If drivers do not react by changing speed behavior then the VMS system will fail and further implementation may cease. In this paper an Analysis of Variance model, which is appropriate to the proposed experimental conditions, is used to study how subjects (drivers) will perceive provided information and also to find the effect of VMS on driver speed behavior on the simulated Expressway section.
Equity based land‐use and transportation problem
Authors: Lee Der‐Horng , Wu Lan , Meng Qiang
Published: January 2010

Due to additional trip production by land use development, the O‐D travel costs between some O‐D pairs may also change intuitively. This leads to positive and negative impacts on network users traveling between different O‐D pairs. Therefore the equity issue about the benefit distribution gained from the land‐use development problem is raised. This paper proposes an Equity based Land‐Use Transportation Problem (ELUTP) which is intended to examine the benefit distribution among the network users and the resulting equity associated with land‐use development problem in terms of the change of equilibrium O‐D travel cost. In the resulting bi‐level programming model, the upper level sub‐problem maximizes traffic production incorporating equity constraints, while the lower level sub‐problem is a combined trip distribution/assignment user equilibrium problem. Genetic algorithm based method is applied to test the models using an example network.
Korean red ginseng extract does not cause embryo‐fetal death or abnormalities in mice
Authors: Shin Sunhee , Jang Ja Young , Park Dongsun , Yon Jung‐Min , Baek In‐Jeoung , Hwang Bang Yeon , Nam Sang‐Yoon , Yun Young Won , Kim Ki‐Yon , Joo Seong Soo , Kim Yun‐Bae
Published: January 2010

BACKGROUND: Ginseng has been used for a long time and is well tolerated in humans. However, recent studies have shown that ginsenosides Rb1, Rg1, and Re exert embryotoxicity in in vitro culture systems. We investigated the effects of Korean red ginseng extract (KRGE) on embryonic implantation and fetal development in mice. METHODS: Mice were orally administered KRGE (20, 200, or 2,000 mg/kg/day) from 2 weeks before mating to gestational day (GD) 18, and implantation rate, fetal mortality, body weights, as well as external, visceral, and skeletal abnormalities were determined by Caesarean section on GD18. Ginsenosides in KRGE and in the blood of dams were identified and quantified by HPLC analysis. RESULTS: KRGE did not affect embryonic implantation and mortality as well as fetal body weights up to 2,000 mg/kg/day (≈200 times clinical doses), the upper‐limit dose recommended by the Korea Food and Drug Administration (KFDA). Although the prevalence of supernumerary ribs increased at the medium dose (200 mg/kg/day), no dose‐dependent increases in external, visceral, and skeletal abnormalities were observed. Major ginsenosides such as Rb1, Rg1, and Re were not detected in the blood of dams based on their chromatographic profiles. CONCLUSIONS: Considerable developmental toxicities of KRGE, even at the upper‐limit dose, were not observed in mice. These results might be due to the negligible blood concentrations of ginsenosides in their original forms following oral administration, suggesting that in vitro experiments to assess the effects of ginsenosides on embryotoxicity may not reliably explain the risks of ginsenosides to in vivo embryo‐fetal development. Birth Defects Res (Part B) 89:78–85, 2010. © 2010 Wiley‐Liss, Inc.
Repeat performance: how do genome packaging and regulation depend on simple sequence repeats?
Authors: Kumar Ram Parikshan , Senthilkumar Ramamoorthy , Singh Vipin , Mishra Rakesh K
Published: January 2010

Non‐coding DNA has consistently increased during evolution of higher eukaryotes. Since the number of genes has remained relatively static during the evolution of complex organisms, it is believed that increased degree of sophisticated regulation of genes has contributed to the increased complexity. A higher proportion of non‐coding DNA, including repeats, is likely to provide more complex regulatory potential. Here, we propose that repeats play a regulatory role by contributing to the packaging of the genome during cellular differentiation. Repeats, and in particular the simple sequence repeats, are proposed to serve as landmarks that can target regulatory mechanisms to a large number of genomic sites with the help of very few factors and regulate the linked loci in a coordinated manner. Repeats may, therefore, function as common target sites for regulatory mechanisms involved in the packaging and dynamic compartmentalization of the chromatin into active and inactive regions during cellular differentiation.
Nucleocytoplasmic functions of the PDZ‐LIM protein family: new insights into organ development
Authors: Krcmery Jennifer , Camarata Troy , Kulisz Andre , Simon Hans‐Georg
Published: January 2010

Recent work on the PDZ‐LIM protein family has revealed that it has important activities at the cellular level, mediating signals between the nucleus and the cytoskeleton, with significant impact on organ development. We review and integrate current knowledge about the PDZ‐LIM protein family and propose a new functional role, sequestering nuclear factors in the cytoplasm. Characterized by their PDZ and LIM domains, the PDZ‐LIM family is comprised of evolutionarily conserved proteins found throughout the animal kingdom, from worms to humans. Combining two functional domains in one protein, PDZ‐LIM proteins have wide‐ranging and multi‐compartmental cell functions during development and homeostasis. In contrast, misregulation can lead to cancer formation and progression. New emerging roles include interactions with integrins, T‐box transcription factors, and receptor tyrosine kinases. Facilitating the assembly of protein complexes, PDZ‐LIM proteins can act as signal modulators, influence actin dynamics, regulate cell architecture, and control gene transcription.
Vitamin E protects against stress‐induced gastric mucosal lesions in rats more effectively than vitamin C
Authors: Ohta Yoshiji , Imai Yoichiro , Kaida Shingo , Kamiya Yoshio , Kawanishi Minoru , Hirata Ichiro
Published: January 2010

In this study, we examined the protective effects of vitamin E (VE) against gastric mucosal lesions induced by water immersion restraint stress (WIRS) in rats in comparison with that of vitamin C (VC). The gastric mucosa of rats with 6 h of WIRS showed lesions with bleeding, decrease in nonprotein SH, VC, VE, and adherent mucus concentrations and constitutive nitric oxide synthase activity, and increase in lipid peroxide and NOx (nitrite/nitrate) concentrations and myeloperoxidase, xanthine oxidase, and inducible nitric oxide synthase activities. Either VE (0.05 or 0.5 mmol/kg) or VC (0.5 or 1.5 mmol/kg) was orally administered to rats with 6 h of WIRS just before the onset of the stress. Both doses of preadministered VE prevented gastric mucosal lesion development and attenuated all these changes in gastric mucosal components and enzymes studied, whereas only the higher dose of preadministered VC suppressed the changes in all parameters studied. These results indicate that orally administered VE protects against WIRS‐induced gastric mucosal lesions in rats more effectively than orally administered VC. These results also suggest that the administered VE protects against gastric mucosal lesions in rats with WIRS through its antioxidant and anti‐inflammatory actions in the gastric mucosa in the same way as the administered VC.
Enzyme‐instructed self‐assembly of peptide derivatives to form nanofibers and hydrogels
Authors: Gao Yuan , Yang Zhimou , Kuang Yi , Ma Man‐Lung , Li Jiayang , Zhao Fan , Xu Bing
Published: January 2010

The review describes the use of enzyme catalysis and self‐assembly, two essential and ubiquitous processes in biology, to create molecular nanofibers of peptide derivatives at the supramolecular level as potential nanomedicines and biomaterials. In particular, we discuss the use of enzymes to instruct the self‐assembly of small peptide derivatives for hydrogelation, which takes place in vitro or in vivo, extra‐ or intracellularly, as a new strategy to detect the activity of enzymes, screen enzyme inhibitors, type bacteria, develop drug delivery systems, enhance the activity and stability of enzymes, and control the fate of cells. © 2010 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 94:19–31, 2010.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
The mobility of chondroitin sulfate in articular and artificial cartilage characterized by 13C magic‐angle spinning NMR spectroscopy
Authors: Scheidt Holger A. , Schibur Stephanie , Magalhães Alvicler , de Azevedo Eduardo R. , Bonagamba Tito J. , Pascui Ovidiu , Schulz Ronny , Reichert Detlef , Huster Daniel
Published: January 2010

We have studied the molecular dynamics of one of the major macromolecules in articular cartilage, chondroitin sulfate. Applying 13C high‐resolution magic‐angle spinning NMR techniques, the NMR signals of all rigid macromolecules in cartilage can be suppressed, allowing the exclusive detection of the highly mobile chondroitin sulfate. The technique is also used to detect the chondroitin sulfate in artificial tissue‐engineered cartilage. The tissue‐engineered material that is based on matrix producing chondrocytes cultured in a collagen gel should provide properties as close as possible to those of the natural cartilage. Nuclear relaxation times of the chondroitin sulfate were determined for both tissues. Although T1 relaxation times are rather similar, the T2 relaxation in tissue‐engineered cartilage is significantly shorter. This suggests that the motions of chondroitin sulfate in natural and artificial cartilage are different. The nuclear relaxation times of chondroitin sulfate in natural and tissue‐engineered cartilage were modeled using a broad distribution function for the motional correlation times. Although the description of the microscopic molecular dynamics of the chondroitin sulfate in natural and artificial cartilage required the identical broad distribution functions for the correlation times of motion, significant differences in the correlation times of motion that are extracted from the model indicate that the artificial tissue does not fully meet the standards of the natural ideal. This could also be confirmed by macroscopic biomechanical elasticity measurements. Nevertheless, these results suggest that NMR is a useful tool for the investigation of the quality of artificially engineered tissue. © 2010 Wiley Periodicals, Inc. Biopolymers 93:520–532, 2010.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Real‐time detection of single‐living pancreatic β‐cell by laser tweezers Raman spectroscopy: High glucose stimulation
Authors: Rong Xi , Huang Shu‐Shi , Kuang Xiao‐Cong , Liu Hong
Published: January 2010

Glucose acts as a β‐cell stimulus factor and leads to cellular responses that involve a large amount of biomolecule formation, relocation, and transformation. We hypothesize that information about these changes can be obtained in real‐time by laser tweezers Raman spectroscopy. To test this hypothesis, repeated measurements designs in accordance with the application of Raman spectroscopy detection were used in the current experiment. Single rat β‐cells were measured by Raman spectroscopy in 2.8 mmol/l glucose culture medium as a basal condition. After stimulation with high glucose (20 mmol/l), the same cells were measured continuously. Each cell was monitored over a total time span of 25 min, in 5 min intervals. During this period of time, cells were maintained at an appropriate temperature controlled by an automatic heater, to provide near‐physiological conditions. It was found that some significant spectral changes induced by glucose were taking place during the stimulation time course. The most noticeable changes were the increase of spectral intensity at the 1002, 1085, 1445, and 1655 cm−1 peaks, mainly corresponding to protein and lipid. We speculate that these changes might have to do with β‐cell protein and lipid synthesis. Using laser tweezers Raman spectroscopy in combination with glucose stimulation, optical spectral information from rat β‐cells was received and analyzed. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 587–594, 2010.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
A low shear stress modular bioreactor for connected cell culture under high flow rates
Authors: Mazzei D. , Guzzardi M.A. , Giusti S. , Ahluwalia A.
Published: January 2010

A generic “system on a plate” modular multicompartmental bioreactor array which enables microwell protocols to be transferred directly to the bioreactor modules, without redesign of cell culture experiments or protocols is described. The modular bioreactors are simple to assemble and use and can be easily compared with standard controls since cell numbers and medium volumes are quite similar. Starting from fluid dynamic and mass transport considerations, a modular bioreactor chamber was first modeled and then fabricated using “milli‐molding,” a technique adapted from soft lithography. After confirming that the shear stress was extremely low in the system in the range of useful flow rates, the bioreactor chambers were tested using hepatocytes. The results show that the bioreactor chambers can increase or maintain cell viability and function when the flow rates are below 500 µL/min, corresponding to wall shear stresses of 10−5 Pa or less at the cell culture surface. Biotechnol. Bioeng. 2010; 106: 127–137. © 2010 Wiley Periodicals, Inc.