bluuebunny/crossref_metadata_2025 huggingface dataset:
A longitudinal study of scholars attitudes and behaviors toward open‐access journal publishing
Authors: Xia Jingfeng
Published: January 2010

This research applies statistical time series analysis to examine the changing pattern of scholars' attitudes toward open‐access (OA) journal publishing from the early 1990s. By synthesizing survey results in existing studies, this research focuses on representative aspects of the attitudes and behaviors recorded through the years. It finds that although an increase in the publishing and awareness rates of scholars with regard to OA journals has been observed, scholars have been consistently concerned with the low prestige of such journals and their lack of peer review, which is not the case in practice. It is hoped that the findings will provide useful information for the improvement of OA advocacy.
Observed ENSO teleconnections with the South American monsoon system
Authors: Krishnamurthy V. , Misra Vasubandhu
Published: January 2010

This study establishes from observations that there exists a spatially coherent and seasonally persistent association of El Niño and Southern Oscillation(ENSO) with the South American monsoon variability over a large region that includes central‐east part of South America. This result is confirmed using both remote sensing data of outgoing long‐wave radiation and in situ rain gauge observations independently. This slowly varying atmospheric pattern has very high daily correlation with the sea surface temperature(SST) over the tropical Pacific and Indian Oceans. The December‐to‐March seasonal mean of the rainfall is often determined by this ENSO‐related pattern. Copyright © 2010 Royal Meteorological Society
Propagation of uncertainty from observing systems and NWP into hydrological models: COST‐731 Working Group 2
Authors: Zappa Massimiliano , Beven Keith J. , Bruen Michael , Cofiño Antonio S. , Kok Kees , Martin Eric , Nurmi Pertti , Orfila Bartlomé , Roulin Emmanuel , Schröter Kai , Seed Alan , Szturc Jan , Vehviläinen Bertel , Germann Urs , Rossa Andrea
Published: January 2010

The COST‐731 action is focused on uncertainty propagation in hydrometeorologica
l forecasting chains. Goals and activities of the action Working Group 2 are presented. Five foci for discussion and research have been identified: (1) understand uncertainties, (2) exploring, designing and comparing methodologies for the use of uncertainty in hydrological models, (3) providing feedback on sensitivity to data and forecast providers, (4) transferring methodologies among the different communities involved and (5) setting up test‐beds and perform proof‐of‐concepts. Current examples of different perspectives on uncertainty propagation are presented. Copyright © 2010 Royal Meteorological Society
A review of the road safety strategy in hong kong
Authors: Loo Becky P. Y. , Wong S. C. , Hung W. T. , Lo Hong K.
Published: January 2010

Since the mid‐1990s, the effectiveness of road safety measures in Hong Kong has been weakening. Six administrations in Australia, California, Great Britain (GB), Japan, New Zealand and Sweden are selected to help review the road safety activities in Hong Kong. Nine main components of the road safety strategy, including vision, objectives, targets, action plan, evaluation and monitoring, research and development, quantitative modeling, institutional framework and funding are summarized from the road safety strategies of these overseas administrations and compared to that of Hong Kong. It is found that Hong Kong's road safety activities have to be restructured to make significant improvement. In the future, a new approach structured by the nine different road safety components is recommended. The lessons learnt can be generalized to smooth the progress of other administrations at the Intermediate Stage towards the Advanced Stage of road safety development by using the short‐, medium‐ and long‐term approaches.
Observing freeway ramp merging phenomena in congested traffic
Authors: Sarvi Majid , Kuwahara Masao , Ceder Avishai
Published: January 2010

This work conducts a comprehensive investigation of traffic behavior and characteristics during freeway ramp merging under congested traffic conditions. 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 characteristics 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 study is undertaken to investigate traffic behavior and characteristics during the merging process under congested situations.

Extensive traffic data capturing a wide range of traffic and geometric information were collected using detectors, videotaping, and surveys at eight interchanges in Tokyo Metropolitan Expressway. Maximum discharged flow rate from the head of the queue at merging sections in conjunction with traffic and geometric characteristics were analyzed. In addition, lane changing maneuver with respect to the freeway and ramp traffic behaviors were examined. It is believed that this study provides a thorough understanding of the freeway ramp merging dynamics. In addition, it forms a comprehensive database for the development and implementation of congestion management techniques at merging sections utilizing Intelligent Transportation System.
Development of a probabilistic model to optimize disseminated real‐time bus arrival information for pre‐trip passengers
Authors: Chien Steven I‐Jy , Daripally Sunil Kumar , Kim Kitae
Published: January 2010

In the advent of Advanced Traveler Information Systems (ATIS), the total wait time of passengers for buses may be reduced by disseminating real‐time bus arrival times for the next or series of buses to pre‐trip passengers through various media (e.g., internet, mobile phones, and personal digital assistants). A probabilistic model is desirable and developed in this study, while realistic distributions of bus and passenger arrivals are considered. The disseminated bus arrival time is optimized by minimizing the total wait time incurred by pre‐trip passengers, and its impact to the total wait time under both late and early bus arrival conditions is studied. Relations between the optimal disseminated bus arrival time and major model parameters, such as the mean and standard deviation of arrival times for buses and pre‐trip passengers, are investigated. Analytical results are presented based on Normal and Lognormal distributions of bus arrivals and Gumbel distribution of pre‐trip passenger arrivals at a designated stop. The developed methodology can be practically applied to any arrival distributions of buses and passengers.
Using automatic passenger counter data in bus arrival time prediction
Authors: Chen Mei , Yaw Jason , Chien Steven I. , Liu Xiaobo
Published: January 2010

Artificial neural networks have been used in a variety of prediction models because of their flexibility in modeling complicated systems. Using the automatic passenger counter data collected by New Jersey Transit, a model based on a neural network was developed to predict bus arrival times. Test runs showed that the predicted travel times generated by the models are reasonably close to the actual arrival times.
Development of pictograms for dynamic traffic control systems in South Korea
Authors: Choi Jaisung , Tay Richard
Published: January 2010

This study developed a set of pictograms for lane control systems, to provide additional information to drivers on weather and traffic incidents. The results suggest that in the design of traffic signs, it is important to consider local context and not simply adopt standards and practices that are developed elsewhere. The differences in the social and cultural environments may affect the ease of reading and comprehension by local drivers. However, the study also showed that not all locally developed signs were rated higher for their ease of reading than others… Since some design characteristics are more salient, whereas others tend to be more dependent on the local context, it is important to conduct simple experiments and exploratory research to find the optimal designs to be used.
Multimodal, multiclass stochastic dynamic traffic assignment for evaluating information provision strategies
Authors: Lee Seungjae
Published: January 2010

A multimodal, multiclass stochastic dynamic traffic assignment model was developed to evaluate pre‐trip and enroute travel information provision strategies. Three different information strategies were examined: user optimum [UO], system optimum [SO] and mixed optimum [MO]. These information provision strategies were analyzed based on the levels of traffic congestion and market penetration rate for the information equipment. Only two modes, bus and car, were used for evaluating and calculating the modal split ratio. Several scenarios were analyzed using day‐to‐day and within day dynamic models. From the results analyzed, it was found that when a traffic manager provides information for drivers using the UO strategy and drivers follow the provided information absolutely, the total travel time may increases over the case with no information. Such worsening occurs when drivers switch their routes and face traffic congestion on the alternative route. This phenomenon is the 'Braess Paradox'.
Parking difficulty and parking information system technologies and costs
Authors: Teng Hualiang (Harry) , Qi Yi (Grace) , Martinelli David R.
Published: January 2010

Before the implementation of a parking information system, it is necessary to evaluate the parking difficulty, technology choice, and system costs. In this study, the parking problem was quantified by asking parkers to express their parking difficulties in five scaled levels from the least to the most difficult. An ordered Probit model was developed to identify the factors that influence a parker to feel the parking difficulty. The results indicate that the amount of parking information parkers had before their trips was directly related to their parking search time, which in turn, influenced their perceptions of parking difficulty. Parkers' preferences to parking information technologies were identified based on developing binary and multinomial probit models. The results indicate that personal business trips and older persons would like to use the kiosk, while the more educated and males would not. Trips with shopping and social/recreation purposes and the drivers who had visited the destination areas frequently would like to choose roadside display. Drivers who had planned their parking and had Internet access would use in‐vehicle device. The system cost was estimated based on the cost for each component of the system. The results show that providing en‐route parking search information through roadside displays is more expensive than providing pre‐trip information through a web site.
The asymmetric effects of service quality on passengers' choice of carriers for international air travel
Authors: Jou Rong‐Chang , Lam Soi‐Hoi , Kuo Chung‐Wei , Chen Chih‐Ching
Published: January 2010

The asymmetric effects of service quality on international travelers' airline choice behavior were investigated in this paper. The linear structural equation modeling system was first applied to quantify passengers' perceptions of service quality provided by airlines, which were then used as the input variables of the asymmetric response model developed to capture international travelers' airline decision. Their asymmetric responses to various service quality of airlines were assumed to be either gains or losses with respect to their reference points. The results showed that the asymmetric response model performs better than the traditional logit models that capture only symmetrical effects.
Comparative analysis of three user equilibrium models under stochastic demand
Authors: Zhou Zhong , Chen Anthony
Published: January 2010

Recent empirical studies on the value of time and reliability reveal that travel time variability plays an important role on travelers' route choice decision process. It can be considered as a risk to travelers making a trip. Therefore, travelers are not only interested in saving their travel time but also in reducing their risk. Typically, risk can be represented by two different aspects: acceptable risk and unacceptable risk. Acceptable risk refers to the reliability aspect of acceptable travel time, which is defined as the average travel time plus the acceptable additional time (or buffer time) needed to ensure more frequent on‐time arrivals, while unacceptable risk refers to the unreliability aspect of unacceptable late arrivals (though infrequent) that have a travel time excessively higher than the acceptable travel time. Most research in the network equilibrium based approach to modeling travel time variability ignores the unreliability aspect of unacceptable late arrivals. This paper examines the effects of both reliability and unreliability aspects in a network equilibrium framework. Specifically, the traditional user equilibrium model, the demand driven travel time reliability‐based user equilibrium model, and the α‐reliable mean‐excess travel time user equilibrium model are considered in the investigation under an uncertain environment due to stochastic travel demand. Numerical results are presented to examine how these models handle risk under travel time variability.
Modelling rain effects on risk‐taking behaviours of multi‐user classes in road networks with uncertainty
Authors: Shao Hu , Lam William H. K. , Tam Mei Lam , Yuan Xiao‐Ming
Published: January 2010

This paper proposes a new travel time reliability‐based traffic assignment model to investigate the rain effects on risk‐taking behaviours of different road users in networks with day‐to‐day demand fluctuations and variations in travel time. A generalized link travel time function is used to capture the rain effects on vehicle travel times and road conditions. This function is further incorporated into daily demand variations to investigate those travel time variations arising from demand uncertainty and rain condition. In view of these rain effects, road users' perception errors on travel times and risk‐taking behaviours on path choices are incorporated in the proposed model with the use of a logit‐based stochastic user equilibrium framework. This new model is formulated as a variational inequality problem in terms of path flows. A numerical example is used to illustrate the application of the proposed model for assessment of the rain effects on road networks with uncertainty.
Evaluating critical lines and stations considering the impact of the consequence using transit assignment model ‐case study of London's underground network
Authors: Shimamoto Hiroshi , Kurauchi Fumitaka , Schmöcker Jan‐Dirk , Bell Michael G H
Published: January 2010

As the problem of full transit vehicles is encountered daily by passengers in most of the big cities, previous research evaluated the consequence of overcrowding in terms of on‐board crowding and passengers not being able to board with full vehicles. The impact of overcrowding in the real world is, however, not necessarily proportional to these numbers. This paper attempts to specify the critical lines and stations of a network by considering the number of passengers failing to board and attempting to evaluate its impact on service quality and safety risks. The hypothesis is that larger stations with wider platforms can often cope better with overcrowding than smaller stations. Therefore a station size dependent satisfaction function is proposed, which takes values from 0 to 1. The method is applied to London's underground network with a number of scenarios which show critical stations in the network if delays occur.
Network reliability‐based optimal toll design
Authors: Li Hao , Bliemer Michiel C. J. , Bovy Piet H. L.
Published: January 2010

Optimal toll design from a network reliability point of view is addressed in this paper. Improving network reliability is proposed as a policy objective of road pricing. A reliability‐based optimal toll design model, where on the upper level network performance including travel time reliability is optimized, while on the lower level a dynamic user‐equilibrium is achieved, is presented. Road authorities aim to optimize network travel time reliability by setting tolls in a network design problem. Travelers are influenced by these tolls and make route and trip decisions by considering travel times and tolls. Network performance reliability is analyzed for a degradable network with elastic and fluctuated travel demand, which integrates reliability and uncertainty, dynamic network equilibrium models, and Monte Carlo methods. The proposed model is applied to a small hypothesized network for which optimal tolls are derived. The network travel time reliability is indeed improved after implementing optimal tolling system. Trips may have a somewhat higher, but more reliable, travel time.
An analysis of instability in a departure time choice problem
Authors: Iryo Takamasa
Published: January 2010

This study performs a theoretical analysis of instability in a departure time choice problem. Stability of equilibrium is an important factor for reliability of travel time. If equilibrium is not stable, travel time changes over a period of days even if demand and network performance are stable. This study examines the stability of a dynamic user equilibrium problem by using the departure time choice problem. The mechanism of day‐to‐day changes in a traveller's behaviour is determined first, and then a function that indicates dissimilarity to equilibrium is defined. The day‐to‐day changes in the dissimilarity function are mathematically examined using approximations. A numerical test is also carried out to verify the result. Results of these analyses show that there can be a case where the system does not converge to equilibrium. It is also indicated that this instability should be caused by the non‐monotonicity of the schedule cost.
Heterogeneous traffic flow modelling for an arterial using grid based approach
Authors: Gundaliya P. J. , Mathew Tom V. , Dhingra S. L.
Published: January 2010

A grid based modelling approach akin to cellular automata (CA) is adopted for heterogeneous traffic flow simulation. The road space is divided into a grid of equally sized cells. Moreover, each vehicle type occupies one or more cell as per its size unlike CA traffic flow model where each vehicle is represented by a single cell. Model needs inputs such as vehicle size, its maximum speed, acceleration, deceleration, probability constants, and arrival pattern. The position and speed of the vehicles are assumed to be discrete. The speed of each vehicle changes according to its interactions with other vehicles, following some stochastic rules depending on the circumstances. The model is calibrated and validated using real data and VISSIM. The results indicate that grid based model can reasonably well simulate complex heterogeneous traffic as well as offers higher computational efficiency needed for real time application.
Private road competition and equilibrium with traffic equilibrium constraints
Authors: Yang Hai , Xiao Feng , Huang Haijun
Published: January 2010

Toll road competition is one of the important issues under a build‐operate‐transfer (BOT) scheme, which is being encountered nowadays in many cities. When there are two or more competing firms and each firm operates a competitive toll road, their profits are interrelated due to the competitors' choices and demand inter‐dependence in the network. In this paper we develop game‐theoretic approaches to the study of the road network, on which multiple toll roads are operated by competitive private firms. The strategic interactions and market equilibria among the private firms are analyzed both in determining their supply (road capacity) and price (toll level) over the network. The toll road competition problems in general traffic equilibrium networks are formulated as an equilibrium program with equilibrium constraints or bi‐level variational inequalities. Heuristic solution methods are proposed and their convergences are demonstrated with simple network examples. It is shown that private pricing and competition can be both profitable and welfare‐improving.
Lane change algorithm for autonomous vehicles via virtual curvature method
Authors: Ho M. L. , Chan P. T. , Rad A. B.
Published: January 2010

This paper addresses the lane changing problem of autonomous vehicles when there is no road infrastructure support. The autonomous vehicle should drive from the current lane to the adjacent lane in the absence of a reference path to guide the vehicle to the new lane. We suggest an algorithm that incorporates a virtual road curvature with bicycle model for lane change guidance. As the name suggests, the virtual road curvature does not physically exist. It is a user assigned radius of a curved path which connects the current lane to the adjacent lane. Since the lateral sensor readings during lane changing maneuver are erroneous, the steering angle along with the virtual curvature is fed into a bicycle model to estimate the lateral position during the transition to the next lane. Details of the algorithm and the virtual road curvature determination are presented in the paper. In contrast to other lane changing methods, controller switching is not required and the same controller is for both lane keeping and lane changing. The algorithm is verified experimentally and the results are comparable with lane changing with physical transition lane.
Decision support for simulating the car park activity in an urban area
Authors: Boussier Jean‐Marie , Sarramia David , Estraillier Pascal
Published: January 2010

Complexity of car park activity is reproduced from a concurrent execution of behaviour of various drivers. This paper presents a step in the development of a multimodal traffic simulator based on multi‐agent paradigm and designed as a decision aid tool as well as a video game. The user‐player has the opportunity to test different scenarios. We propose an approach for designing the decision‐making rules and the learning mechanism for a car driver agent. For that, a panel of methods such as stated preference modelling, Design Of Experiments and data fusion is used. Initial behavioural models, based on similar preferences, are developed for specified categories. Each agent will adapt its behaviour after executing its learning process. Our approach can be used in order to optimize needs of road network users and those of people in charge of traffic regulation. A demonstrator has been developed to test parking policies in an urban area as well as changes of car park characteristics.
The multi‐actor, multi‐criteria analysis methodology (MAMCA) for the evaluation of transport projects: Theory and practice
Authors: Macharis Cathy , de Witte Astrid , Ampe Jeroen
Published: January 2010

In this paper the multi‐actor multi‐criteria analysis (MAMCA) method to evaluate transport projects is presented. This evaluation method specifically focuses on the inclusion of qualitative as well as quantitative criteria with their relative importance, defined by the multiple stakeholders, into one comprehensive evaluation process in order to facilitate the decision making process by the different stakeholders. The MAMCA methodology is introduced by an overview of other evaluation methods for transport projects in the past and is illustrated by means of two practical cases. The introduction will lead us to the theoretical conception of the MAMCA method where we draw the attention to the proven usefulness of the MAMCA for the evaluation of transport projects and the inclusion of different kinds of stakeholders, individuals as well as groups, into the evaluation process.
An investigation of incident frequency, duration and lanes blockage for determining traffic delay
Authors: Qi Yi (Grace) , Teng Hualiang (Harry) , Martinelli David R.
Published: January 2010

Traffic delay caused by incidents is closely related to three variables: incident frequency, incident duration, and the number of lanes blocked by an incident that is directly related to the bottleneck capacity. Relatively, incident duration has been more extensively studied than incident frequency and the number of lanes blocked in an incident. In this study, we provide an investigation of the influencing factors for all of these three variables based on an incident data set that was collected in New York City (NYC). The information about the incidents derived from the identification can be used by incident management agencies in NYC for strategic policy decision making and daily incident management and traffic operation.

In identifying the influencing factors for incident frequency, a set of models, including Poisson and Negative Binomial regression models and their zero‐inflated models, were considered. An appropriate model was determined based on a model decision‐making tree. The influencing factors for incident duration were identified based on hazard‐based models where Exponential, Weibull, Log‐logistic, and Log‐normal distributions were considered for incident duration. For the number of lanes blocked in an incident, the identification of the influencing factors was based on an Ordered Probit model which can better capture the order inherent in the number of lanes blocked in an incident. As identified in this study, rain is the only factor that significantly influenced incident frequency. For incident duration and the number of lanes blocked in an incident, various factors had significant impact. As concluded in this study, there is a strong need to identify the influencing factors in terms of different types of incidents and the roadways where the incidents occured.
Airport obstacle surfaces
Authors: Litsheim Scott , Xiao Xiaosong
Published: January 2010

The most commonly used criteria to determine complicated airport obstacle surfaces are FAR Part 77 imaginary surfaces, TERPS, and the one engine inoperative obstacle identification surface for air carriers. For each obstacle surface there are tradeoffs encountered in our practice between the obstruction penetration and extension of runway, change of flight profile, and allowable aircraft maximum payloads. For the purposes of both airport engineering and airport planning, a better understanding of these different obstacle surfaces and their application is important. In this paper, the differences and relationships between these surfaces are addressed. The conditions for the use of each criterion are discussed. In addition, the FAA's Obstruction Evaluation / Airport Airspace Analysis (OE/AAA) process is reviewed.
A two‐leveled multi‐objective symbiotic evolutionary algorithm for the hub and spoke location problem
Authors: Shin Kyoung Seok , Kim Jun Hyuk , Kim Yeo Keun
Published: January 2010

We consider a hub and spoke location problem (HSLP) with multiple scenarios. The HSLP consists of four subproblems: hub location, spoke location, spoke allocation, and customer allocation Under multiple scenarios, we aim to provide a set of well‐distributed solutions, close to the true Pareto optimal solutions, for decision makers. We present a novel multi‐objective symbiotic evolutionary algorithm to solve the HSLP under multiple scenarios. The algorithm is modeled as a two‐leveled structure, which we call the two‐leveled multi‐objective symbiotic evolutionary algorithm (TMSEA). In TMSEA, two main processes imitating symbiotic evolution and endosymbiotic evolution are introduced to promote the diversity and convergence of solutions. The evolutionary components suitable for each sub‐problem are defined. TMSEA is tested on a variety of test‐bed problems and compared with existing multi‐objective evolutionary algorithms. The experimental results show that TMSEA is promising in solution convergence and diversity.
The development of taiwan arterial traffic‐adaptive signal control system and its field test: A taiwan experience
Authors: Wu Yueh‐Tzu , Ho Chi‐Hong
Published: January 2010

This Taiwan traffic‐adaptive arterial signal control model borrowed its traffic flow framework mainly from a British traffic‐adaptive control model with a cyclic traffic progression function, i.e. SCOOT (Split Cycle Office Optimisation Technique). The new arterial control model can take into account delays of both major and minor streets and make real‐time signal timing decisions with optimal two‐way signal offsets, so as to create the best arterial signal operation performance. It has been developed to be an online real‐time software for both simulation testing and field validation. Through simulation, it was found that the performance when operating this newly developed real‐time arterial traffic‐adaptive model was significantly better than when using the optimal fixed‐time arterial timing plan. On the aspect of field testing, three signalized intersections located in East District, Tainan City, Taiwan were selected to be the test sites. Fairly good traffic control performance has been demonstrated in that it can effectively reduce travel delays of the control arterial as a whole. Additional discussions about how to combine travel delay and the total number of vehicle stops into a new control performance index have also been included to make the new traffic‐adaptive model more flexible and reasonable to meet the expectations of different driver groups in the arterial system.
Multi‐objective highway alignment optimization using a genetic algorithm
Authors: Maji Avijit , Jha Manoj K.
Published: January 2010

The available highway alignment optimization algorithms use the total cost as the objective function. This is a single objective optimization process. In this process, travel‐time, vehicle operation accident earthwork land acquisition and pavement construction costs are the basic components of the total cost. This single objective highway alignment optimization process has limited capability in handling the cost components separately. Moreover, this process cannot yield a set of alternative solutions from a single run. This paper presents a multi‐objective approach to overcome these shortcomings. Some of the cost components of highway alignments are conflicting in nature. Minimizing some of them will yield a straighter alignment; whereas, minimizing others would make the alignment circuitous. Therefore, the goal of the multiobjective optimization approach is to handle the trade‐off amongst the highway alignment design objectives and present a set of near optimal solutions. The highway alignment objectives, i.e., cost functions, are not continuous in nature. Hence, a special genetic algorithm based multi‐objective optimization algorithm is suggested The proposed methodology is demonstrated via a case study at the end.
Lottery attractiveness and presentation mode of probability and value information
Authors: Fiedler Klaus , Unkelbach Christian
Published: January 2010

The attractiveness of lotteries that vary in p (probability) and o (outcome) depends on the presentation mode of p and o information. Extending previous findings on temporally experienced p, we manipulate the numerically stated versus spatially experienced format of both p (graphical presentation of a distribution of lottery tickets in an urn) and o (distribution of money notes). Lottery attractiveness ratings were sensitive to the expected value (EV), but p received more weight than o at constant EV levels (p‐dominance). Both EV sensitivity and p‐dominance were enhanced for experienced p and numerical o. This format particularly revealed the unattractiveness of low‐p lotteries. Experiencing p was functional in terms of accuracy and high‐risk avoidance, but only when the task environments rendered p diagnostic of EV. The presentation mode manipulations did not affect the initial perception stage but the relative weighting of p and o in the final judgment integration stage. Copyright © 2010 John Wiley & Sons, Ltd.
Congenital malformations in infants born after in vitro fertilization in Sweden
Authors: Källén Bengt , Finnström Orvar , Lindam Anna , Nilsson Emma , Nygren Karl‐Gösta , Otterblad Petra Olausson
Published: January 2010

BACKGROUND:

The risk for congenital malformations is increased in infants born after in vitro fertilization (IVF). Some specific malformations appear to be more affected than others.

METHODS:

The presence of congenital malformations in 15,570 infants born after IVF with an embryo transfer between April 1, 2001, and the end of 2006 were compared with all infants born in Sweden during 2001 to 2007 (n = 689,157). Risk estimates were made after adjusting for year of birth, maternal age, parity, smoking, and body mass index. The risks of specific malformations were compared with data from a previous study (1982 to March 31, 2001) of 16,280 infants born after IVF. Different IVF methods were compared to respect to malformation risk.

RESULTS:

Increased risks of a similar magnitude were found for most cardiovascular malformations and limb reduction defects for both study periods. For neural tube defects, cardiac septal defects, and esophageal atresia, there was still an increased risk, but it was lower during the second than during the first period. For small bowel atresia, anal atresia, and hypospadias, the risk increase observed during the first study period had disappeared during the second period. An increased risk was seen for some syndromes that have been associated with imprinting errors. No difference in malformation risk according to IVF method was apparent.

CONCLUSIONS:

A slightly increased risk for congenital malformations after IVF persists. A decreasing risk is seen for some specific malformations, either true or the result of multiple testing. Birth Defects Research (Part A), 2010. © 2010 Wiley‐Liss, Inc.
Periconceptional nutrient intakes and risks of conotruncal heart defects
Authors: Shaw Gary M. , Carmichael Suzan L. , Yang Wei , Lammer Edward J.
Published: January 2010

BACKGROUND

Few inquiries into periconceptional nutrition, other than folate, and risk of heart defects exist. We investigated the observed association between conotruncal heart defects and periconceptional vitamin use, as well as potential associations with other dietary nutrients.

METHODS

Data derived from a population‐based, case‐control study of fetuses and liveborn infants among California births between July 1999 and June 2004; 76% of eligible case mothers and 77% of eligible control mothers were interviewed. Cases included 140 with d‐transposition of great arteries (dTGA), and 163 with tetralogy of Fallot (TOF). Total number of controls was 698. Use of vitamins was elicited by questionnaire for the periconceptional period. Dietary nutrient intake was elicited by a well‐known food frequency questionnaire.

RESULTS

The odds ratio for dTGA associated with supplemental vitamin use was 1.0 (95% confidence interval [CI], 0.7–1.5) and for TOF was 0.9 (95% CI, 0.6–1.3). We observed increased risks associated with lower dietary intakes of linoleic acid, total carbohydrate, and fructose for dTGA, whereas decreased risks were observed for lower intakes of total protein and methionine for TOF. Lower dietary intake of several micronutrients—namely folate, niacin, riboflavin, and vitamins B12, A, and E, even after simultaneous adjustment for other studied nutrients—was associated with increased risk of dTGA but not TOF. These associations were observed among women who did not use vitamin supplements periconceptionally. Analytic consideration of several potential confounders did not reveal alternative interpretations of the results.

CONCLUSION

Evidence continues to accumulate to show that nutrients, particularly folate, influence risks of structural birth defects. Our results extend observations that other nutrients may also be important in heart development. Birth Defects Research (Part A), 2010. © 2010 Wiley‐Liss, Inc.
An efficient computational approach for prior sensitivity analysis and cross‐validation
Authors: Bornn Luke , Doucet Arnaud , Gottardo Raphael
Published: January 2010

Prior sensitivity analysis and cross‐validation are important tools in Bayesian statistics. However, due to the computational expense of implementing existing methods, these techniques are rarely used. In this paper, the authors show how it is possible to use sequential Monte Carlo methods to create an efficient and automated algorithm to perform these tasks. They apply the algorithm to the computation of regularization path plots and to assess the sensitivity of the tuning parameter ing‐prior model selection. They then demonstrate the algorithm in a cross‐validation context and use it to select the shrinkage parameter in Bayesian regression. The Canadian Journal of Statistics 38:47–64; 2010 © 2010 Statistical Society of Canada
Increased Expression of Mineralocorticoid Receptor and 11β‐Hydroxysteroid Dehydrogenase Type 2 in Human Atria During Atrial Fibrillation
Authors: De‐An Pei , Li Li , Zhi‐Yun Xu , Jin‐Yu Huang , Zheng‐Ming Xu , Min Wang , Qiang Yao , Shi‐eng Huang
Published: January 2010

Background

Atrialfibrillation (AF) is associated with the activation of the renin‐angiotensin‐aldosterone system in the atria. It is not clear whether the expression of a mineralocorticoid receptor (MR), or 11β‐hydroxysteroid dehydrogenase type 2 (11βHSD2), conferring aldosterone specificity to the MR, in patients with AF is altered.

Hypothesis

Patients with AF may be associated with increased expression of MR and 11βHSD2 in the atria.

Methods

Atrial tissue samples of 25 patients with rheumatic heart valve disease undergoing a valve replacement operation were examined. A total of 13 patients had chronic persistent AF (>6 mo) and 12 patients had no history of AF. The MR and 11βHSD2 expression were analyzed at the mRNA and protein level. The localization of MR and 11βHSD2 in atrial tissue was performed using specific immunohistochemistry staining.

Results

The results of real‐time quantitative polymerase chain reaction (PCR) showed that AF groups, in comparison with sinus rhythm, had a higher mRNA expression level of MR or 11βHSD2 (all P < 0.01). Both the MR and 11βHSD2 protein expression level in atrial tissue were also significantly increased in patients with AF compared with patients with sinus rhythm (P < 0.05 or P < 0.01). The immunohistochemical staining of MR or 11βHSD2 demonstrated that MR and 11βHSD2 predominately located in the cytoplasm of myocardial cells in the atrium and the intensity and density of immunostaining appeared to be increased in the atria of patients with AF compared to those without AF.

Conclusions

Increasing expression of MR and 11βHSD2 in the atria during AF is one of the molecular mechanisms for development of atrial interstitial fibrosis in patients with AF. These findings may have an important impact on the treatment of AF with aldosterone antagonists. Copyright © 2010 Wiley Periodicals, Inc.
Presentation of Tako‐tsubo Cardiomyopathy in Men and Women
Authors: Kurisu Satoshi , Inoue Ichiro , Kawagoe Takuji , Ishihara Masaharu , Shimatani Yuji , Nakama Yasuharu , Kagawa Eisuke , Dai Kazuoki , Ikenaga Hiroki
Published: January 2010

Background

Recent studies have demonstrated that stress‐induced Tako‐tsubo cardiomyopathy is likely to occur in elderly female patients.

Objectives

The purpose of this study was to evaluate gender differences in the clinical characteristics of patients with Tako‐tsubo cardiomyopathy.

Methods

This study consisted of 102 patients with Tako‐tsubo cardiomyopathy. It was characterized by akinesia/hypokinesia of the mid‐to‐distal portion of the left ventricular chamber, with normokinesia/hyperkinesia of the basal portion with an ejection fraction of less than 50% on transthoracic echocardiography.

Results

There were 13 male and 89 female patients. In 10 male patients (77%), Tako‐tsubo cardiomyopathy occurred during or immediately after receiving medical treatment or examination for an underlying disease. In 9 male patients (69%), objective symptoms such as abnormality of monitoring or low blood pressure, but not subjective symptoms increased the chance of the patient being diagnosed with Tako‐tsubo cardiomyopathy. There was no significant difference in age, body weight, hypertension, or diabetes except for height between male and female patients. The incidence of in‐hospital onset was significantly higher in male patients than in female patients (77% vs 17%, P < 0.01). There was no significant difference in in‐hospital mortality (15% vs 6%, P = not significant).

Conclusions

These results suggested that physical stress might have more to do with the occurrence of Tako‐tsubo in male than female patients. Copyright © 2010 Wiley Periodicals, Inc.
Receipt of Cardiac Medications Upon Discharge Among Men and Women With Acute Coronary Syndrome and Nonobstructive Coronary Artery Disease
Authors: Ramanath Vijay S. , Armstrong David F. , Grzybowski Mary , Rahnama‐Mohagdam Sahand , Tamhane Umesh U. , Gordon Kelly , Froehlich James B. , Eagle Kim A. , Jackson Elizabeth A.
Published: January 2010

Background

Management of acute coronary syndrome (ACS) patients with nonobstructive epicardial coronary artery disease (CAD) remains poorly understood.

Hypothesis

Acute coronary syndrome patients with nonobstructive CAD are less likely to receive effective cardiac medications upon discharge from the hospital.

Methods

We identified patients hospitalized with ACS that underwent coronary angiography and had a 6‐month follow‐up. Patients were grouped by CAD severity: nonobstructive CAD (<50% blockage in all vessels) or obstructive CAD (≥50% blockage in ≥ 1 vessels). Data were collected on demographics, medications at discharge, and adverse outcomes at 6 months, for all patients.

Results

Of the 2264 ACS patients included in the study: 123 patients had nonobstructive CAD and 2141 had obstructive CAD. Cardiac risk factors including hypertension and diabetes were common among patients with nonobstructive CAD. Men and women with nonobstructive CAD were less likely to receive cardiac medications compared to patients with obstructive CAD including aspirin (87.8% vs 95.0%, P = 0.001), β‐blockers (74.0% vs 89.2%, P < 0.001), or statins (69.1% vs 81.2%, P = 0.001). No gender‐related differences in discharge medications were observed for patients with nonobstructive CAD. However, women with nonobstructive CAD had similar rates of cardiac‐related rehospitalization as men with obstructive CAD (23.3% and 25.9%, respectively).

Conclusions

Patients with nonobstructive CAD are less likely to receive evidence‐based medications compared to patients with obstructive CAD, despite the presence of CAD risk factors and occurrence of an ACS event. Further research is warranted to determine if receipt of effective cardiac medications among patients with nonobstructive CAD would reduce cardiac‐related events. Copyright © 2010 Wiley Periodicals, Inc.
Heart Rate Recovery and Oxygen Kinetics After Exercise in Obstructive Sleep Apnea Syndrome
Authors: Nanas Serafim , Sakellariou Dimitrios , Kapsimalakou Smaragda , Dimopoulos Stavros , Tassiou Antonia , Tasoulis Athanasios , Anastasiou‐Nana Maria , Vagiakis Emmanouil , Roussos Charalampos
Published: January 2010

Background

Patients who suffer from obstructive sleep apnea (OSA) have a decreased exercise capacity and abnormal autonomic nervous function. However, the kinetics of early oxygen (O2) and heart rate recovery (HRR) have not been described.

Materials and Methods

We evaluated 21 men with moderate to severe OSA (mean age: 48 ± 11 yrs, mean apnea‐hypopnea index [AHI]: 55 ± 13) and without known heart disease and 10 healthy men matched for age and body mass index (BMI; controls). Men with OSA underwent overnight polysomnography, and both groups underwent symptom‐limited incremental cardiopulmonary exercise testing (CPET). We recorded the CPET parameters including peak O2 uptake (VO2p), kinetics of early O2 recovery by the first degree slope of VO2 during the first minute (VO2/t slope), the time required for a 50% decline of VO2p during recovery (T1/2), and early heart rate recovery (HRR = HR at maximal exercise − HR at 1 min of recovery), as well as the chronotropic reserve to exercise ([CR] = [peak HR − resting HR/220 − age − resting HR] × 100). Patients with OSA had a lower VO2p (28.7 ± 4.0 vs 34.7 ± 6.2 mL/kg/min), VO2/t slope (1.04 ± 0.3 vs 1.4 ± 0.17 mL/kg/min2), and T1/2 (74 ± 10 vs 56 ± 6 sec) compared to controls (all P < 0.001). In addition, both HRR and CR were lower in the OSA group (22.0 ± 7.0 vs 31.0 ± 6.0 bpm, P:0.003, and 79.0% ± 15% vs 99.0% ± 13.0%, P:0.01, respectively).

Conclusions

Patients with OSA demonstrate reduced exercise capacity, delayed oxygen kinetics, and reduced HRR. These data point to abnormal oxygen delivery and/or oxidative function of the peripheral muscles and impaired autonomic nervous activity in OSA patients. Copyright © 2010 Wiley Periodicals, Inc.
When to Refer Patients for Catheter‐based Coronary Angiography (CBCA)
Authors: Richard Conti C.
Published: January 2010

In 2009, much was written about computed tomography (CT) angiography of the coronary circulation and little about catheter‐based coronary angiography, despite its continued use since 1958 in patients with all types of cardiac disease or potential disease. Copyright © 2010 Wiley Periodicals, Inc.
Considering contact conditions between discontinuity surfaces in extended finite element method (XFEM)
Authors: Yu T. T.
Published: January 2010

This paper presents a method of satisfying contact conditions between discontinuity surfaces in the extended finite element method. Surveys have showed that contact in the discontinuity surfaces should not be neglected in numerical simulations of cracks under alternate loadings. The contact conditions between discontinuity surfaces are expressed as linear complementary form with penalty factors, thus the nonlinear contact in the discontinuity surface is resolved with one linear complementary problem; in this case, the iterative procedure can be avoided. Numerical simulations are presented to demonstrate the accuracy and potentials of this technique. Copyright © 2009 John Wiley & Sons, Ltd.
Active and passive behaviors of soft tissues: Pelvic floor muscles
Authors: Pato M. P. M. , Areias P.
Published: January 2010

A new active‐contraction visco‐elastic numerical model of the pelvic floor (skeletal) muscle is presented. Our model includes all elements that represent the muscle constitutive behavior, contraction and relaxation. In contrast with the previous models, the activation function can be null. The complete equations are shown and exactly linearized. Small verification and validation tests are performed and the pelvis is modeled using the data from the intra‐abdominal pressure tests. Copyright © 2009 John Wiley & Sons, Ltd.
Factorized parallel preconditioner for the saddle point problem
Authors: Lazarov B. S. , Sigmund O.
Published: January 2010

The aim of this paper is to apply the factorized sparse approximate inverse (FSAI) preconditioner to the iterative solution of linear systems with indefinite symmetric matrices. Until now the FSAI technique has been applied mainly to positive definite systems and with a limited success for the indefinite case. Here, it is demonstrated that the sparsity pattern for the preconditioner can be chosen in such a way that it guarantees the existence of the factorization. The proposed scheme shows excellent parallel scalability, performance and robustness. It is applicable with short recurrence iterative methods such as MinRes and SymmLQ. The properties are demonstrated on linear systems arising from mixed finite element discretizations in linear elasticity. Copyright © 2009 John Wiley & Sons, Ltd.