bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling Routing Behavior for Vacant Taxicabs in Urban Traffic Networks
Authors: Hu Xianbiao , Gao Song , Chiu Yi-Chang , Lin Dung-Ying
Published: October 2012

Taxicabs account for a significant portion of traffic in many Asian cities, and route choice by taxi drivers is an active research area. The routing objectives of a taxi driver vary, depending on taxi occupancy. If a taxi is occupied by customers, then a least-cost path is usually sought. Several paradigms in the literature are related to such a routing objective. However, the taxi driver's route choice behavior when a taxi is vacant is not well understood. A routing model for vacant taxis is proposed in which taxi drivers are assumed to minimize the expected search time for customers when making routing decisions at intersections. A probabilistic dynamic programming formulation of the problem and the solution algorithm are presented. A numerical analysis was conducted on a hypothetical network resembling the traffic network structure in the city of Taipei, Taiwan. The proposed model exhibited realistic and reasonable properties. This research sheds light on the routing decisions of taxi drivers and therefore directly supports areawide traffic management.
Stochastic User Equilibrium for Route Choice Model Based on Random Regret Minimization
Authors: Bekhor Shlomo , Chorus Caspar , Toledo Tomer
Published: October 2012

A static stochastic user equilibrium (SUE) problem was formulated: the mode of random regret minimization (RRM) was used for route choices. The RRM approach assumes that individuals minimize anticipated regret, rather than maximize expected utility, when choosing from alternative routes. The cost function for the RRM model is not separable, and so a variational inequality approach was adopted to formulate the problem. A path-based algorithm was applied to solve the RRM-SUE problem with the method of successive averages. Implementation of the algorithm in a real-world network is illustrated, and the trade-offs and differences between the proposed model and the SUE based on random utility models is discussed.
Evaluating Project-Based Roadway Sustainability Rating System for Public Agency Use
Authors: Muench Stephen T. , Scarsella Maleena , Bradway Margi , Hormann Liz , Cornell Lyn
Published: October 2012

Several road-owning organizations are considering the use of project-based sustainability rating systems either now or in the near future. However, there is little information on how these systems might be evaluated or best used. Experience from the Oregon Department of Transportation (DOT) represents a reasonable approach to contextualizing and evaluating such rating systems. Early support by upper management and specific direction helped the Oregon DOT develop an organizational approach to sustainability within which a rating system could be evaluated for use. The Oregon DOT's interest in project-based rating systems led to its evaluation of the Greenroads rating system and use of it on three Oregon DOT in-progress projects. The Greenroads evaluation identified 11 sustainability best practices achieved by the Oregon DOT and identified 10 more that could be achieved for low additional effort, indicating potential for improvement. Ultimately, it appears that a sustainability rating system, when used in the proper context, can provide a flexible approach for an owner agency to measure, manage, improve, and communicate sustainability at the project level.
Estimating Asset Deterioration and Life Expectancy by Using Levels of Service
Authors: Thompson Paul D.
Published: October 2012

As agencies have implemented maintenance quality assurance processes over the past 10 to 15 years, the agencies have also begun to amass valuable databases of condition and performance data, often expressed in terms of levels of service. These databases address a wide range of asset types, especially roadway and roadside features such as signs, pavement markings, traffic signals, lighting, culverts, sidewalks, and curbs. At the same time, element and condition state data have been gathered by most of the state departments of transportation for bridges and often for structures other than bridges. A few agencies have taken the next step in developing deterioration models to forecast changes in structure condition, either in the absence of maintenance activity or in response to specific agency actions or policies. The state of the practice in bridge deterioration modeling is a matter of active research but is increasingly becoming repeatable and relevant to asset management decision making. Moreover, some examples of bridge inspection and deterioration models already address a variety of nonbridge structures and a variety of performance concerns beyond physical deterioration. This study connects the level-of-service approach now frequently used in maintenance management with the quantitative forecasting of deterioration frequently used in bridge management. The result is a framework for prediction of levels of service and life expectancy that can be useful for management of all types of transportation assets.
New Methodology for Transportation Investment Decisions with Consideration of Project Interdependencies
Authors: Li Zongzhi , Kaul Hemanshu , Kapoor Sanjiv , Veliou Eirini , Zhou Bei , Lee Sang Hyuk
Published: October 2012

A new methodology for transportation project evaluation and selection explicitly addresses issues of networkwide impacts of a project and interdependencies of multiple projects. The methodology consists of two key elements: a multicommodity minimum-cost network model to estimate networkwide benefits of a single project or multiple interdependent projects and a hypergraph Knapsack model to identify the best subcollection of projects to yield maximized overall benefits. The proposed methodology is applied in a computational study with data on roadway network design, geometrics, travel demand, and traffic operations as well as the scope and costs of six major projects proposed for investment in the Loop area of Chicago, Illinois. The study reveals that the overall benefits with consideration of project networkwide impacts and their interdependencies are significantly lower by 38% to 64% as compared with those benefits established without consideration of project interdependencies, and the rate of increase in overall benefits follows a diminishing trend with higher budget levels; these findings suggest that an optimal level of investment could be established. The proposed methodology may be refined by developing a decision rule to identify a reasonably small number of subcollections of projects guaranteed to contain the optimal solution so that it could practically support large-scale transportation investment decisions.
Design and Implementation of Internet-Based Traveler Intercept Survey
Authors: Sperry Benjamin R. , Larson Shawn , Leucinger David , Janowiak Scott , Morgan Curtis A.
Published: October 2012

Traveler surveys are an integral part of supporting a data-driven transportation decision-making process. To supplement household travel surveys, transportation planners deploy traveler intercept surveys on transit vehicles or at activity centers to obtain information about users of those facilities. The use of the Internet has emerged in the past decade as the preferred medium for surveys of all types; the Internet offers several advantages over other survey modes. The design and implementation of an Internet-based traveler survey are described; the survey was used in a research study examining passengers who used a circulating shuttle bus connecting the airport terminal and the Amtrak intercity rail station at the Milwaukee General Mitchell International Airport in Wisconsin. In addition to the Internet survey, an initial interview form was used to collect basic data about the traveler and to establish the legitimacy of the Internet survey in the mind of the traveler. This process is known in the survey literature as the foot-in-the-door approach. The method used in this study resulted in a response rate of nearly 20% for the Internet survey, a respectable rate for such a survey. Transportation planners and survey designers are encouraged to consider the use of this method in future traveler intercept surveys that utilize the Internet medium.
Transferring Telephone-Based National Household Travel Survey to the Internet
Authors: Son Sanghoon , Khattak Asad , Wang Xin , Chen Ju-Yin
Published: October 2012

Transfer of the National Household Travel Survey (NHTS) and regional travel surveys to the Internet is inevitable, partly because online surveys offer an efficient means of collecting data. Behavioral surveys are increasingly being offered in multiple media and giving respondents the choice of filling out the survey by using the Internet, the telephone, or other means. This study reports experience and lessons learned from transforming the computer-assisted telephone interview methodology used for the NHTS to an Internet-based method for university students, who have ubiquitous access to the Internet. The study reflects innovations in survey research methodology in the context of surveying students at large universities in Virginia. Comparisons of two rounds of behavioral surveys conducted in 2009 and 2010 are provided, and statistical models that quantify trip underreporting are developed. In an attempt to mimic closely the NHTS instrument, the Internet instrument had a relatively high survey response burden. On the basis of analysis of trip frequencies, trip underreporting was suspected in the first round of surveys. Documented here are improvements in survey design that were intended to lower the survey response burden and reduce trip underreporting. Statistical models are estimated to quantify how changes in the instrument captured more trips. Results show that survey design improvements can encourage students to recall and report 15% to 20% more trips. The study also found that, consistent with earlier studies, discretionary trips and shorter trips were more likely to be underreported. The results from this study are valuable for future regional and national survey implementations.
Measuring Future Vehicle Preferences
Authors: Maness Michael , Cirillo Cinzia
Published: October 2012

The culmination of new vehicle technology, greater competition in energy markets, and government policies to reduce pollution and energy consumption will result in changes to the personal vehicle marketplace. To measure future vehicle preferences, stated preference (SP) surveys have been the dominant approach. Prior research has been limited to a narrow focus of accelerating respondents' hypothetical next vehicle purchasing decisions without mimicking the influence of the marketplace on these decisions. To explore marketplace influences, this study proposes to use a novel SP survey design to analyze vehicle purchasing behavior in a dynamically changing marketplace through the use of dynamic attributes and a 6-year hypothetical time window. The survey is divided into three parts: household characteristics, current vehicles, and SP. The SP section presents respondents with various hypothetical scenarios annually over a future 6-year period with one of three experiments. The experiments correspond to changing vehicle technology, fueling options, and taxation policy. Between scenarios, the vehicle, fuel, and policy attributes dynamically change to mimic marketplace conditions. A pilot web-based survey was performed during fall 2010. Mixed logit models showed that individuals responded in behaviorally realistic ways and that the survey design allowed for estimation of important parameters in vehicle choice. Respondents were able to depreciate their vehicles over the 5-year hypothetical period and place trade-offs on the features of vehicles and fuel types. The insights from the survey are also used to suggest refinements to the survey methods and areas for further research.
Evaluation of Key Design Elements of Long-Distance Survey of Front Range Travel Counts
Authors: Bricka Stacey , Sabina Erik
Published: October 2012

An evaluation of two key design aspects of a long-distance survey conducted as part of the 2009–2012 Front Range Travel Counts effort is documented. The Front Range Travel Counts project is a cooperative effort across four adjacent Colorado metropolitan regions to document travel behavior within and across regions. The effort included household, commercial vehicle, and external station surveys. Consistent with the state of the practice in the United States, the long-distance survey was administered as a supplement to the household survey sample. Respondents were asked to record all trips made to a location 50 mi or more from home during the 2-week period before the 24-h travel day. Households reporting no long-distance travel were asked to report details of their most recent long-distance trips, regardless of when the trip occurred. The analysis focuses on two design aspects: (a) the selection of a 2-week recall period, with the request for the most recent trip from those who reported zero long-distance trips, and (b) the definition of a long-distance trip. The results suggest that future surveys should use a longer recall period. In addition, the practice of asking for the most recent trip from only those respondents who reported zero long-distance trips within the recall travel period should be expanded to asking that question of all respondents. Finally, the definition as used resulted in the capture of shorter-distance trips, suggesting that refinement is needed.
Study of Blog Mining for Examination of Tourist Travel Behavior in Japan
Authors: Sasaki Kuniaki , Nishii Kazuo
Published: October 2012

The data on how travelers evaluate a specific sightseeing destination are useful for formulating tourism strategies. Making a survey is the most common way to get such data now, but the method has become difficult because travelers have become so diverse that the data are not as meaningful and substantial as they had been. To overcome this problem, Internet blogs are used: comments on sightseeing are so popular that it is easy to collect the needed data. Blog data on tourism were collected in Yatsugatake, Japan, and compared with the data obtained from ordinary questionnaire surveys to examine the features of blog data. Information from 192 blogs was collected. Analyzing the terminology used in the blogs allowed the determination of some attributes of their authors. These attributes were compared with those of questionnaire survey respondents. Although the desired information can be obtained from survey respondents, information from blogs depends on what the authors write about any destination. Nonetheless, because a blogger's destination is clear in his or her blog, the information about destinations can be used by cooccurrence analysis. With categorization of the entry tags of each blog, information about each blogger's interests can be obtained, and their preferences clearly indicate that their destination choices are closely related to their interests. In sum, although the information in blogs is subjective, if used properly the information can be effective in developing strategies for tourism by complementing data from ordinary surveys.
Dashboard Tool to Communicate Delays and Economic Cost of Delays at International Border Crossings
Authors: Rajbhandari Rajat , Saman Swapnil , Vadali Sharada , Kang Don
Published: October 2012

The development of a dashboard tool to communicate key performance measures related to the cost of delay incurred by U.S.-bound commercial vehicles at international border crossings is discussed. Various framework and implementation aspects of such a dashboard are covered. These aspects include collection and processing of delay and economic cost data, design of the dashboard interface, calculations of performance measures, and finally its intended use for stakeholders. Two sets of metrics or key performance measures are discussed within the context of international land border crossings, the first pertaining to delay measures and the second to economic costs of delay. Definitions of “true delay” at border crossings and several delay measures are given, and the development of the same at varying temporal resolutions is reviewed. On the basis of a review of previously developed dashboards, the authors believe that the current effort is the first in which highly granular delay-related intelligent transportation system data have been integrated with economic components of delay in the arena of performance measurement. Nevertheless, the research focuses on delay incurred by the freight community at international land border crossings. Finally, data gaps and other theoretical issues that need addressing in the future to advance the discussion of a delay measure and its consequences at international land border crossings are treated. Regardless of challenges concerning data, the authors believe that a significant potential exists for dashboards to enhance the planning process among stakeholders and to optimize their decision-making processes.
Aggregate Freight Generation Modeling
Authors: Oliveira-Neto Francisco Moraes , Chin Shih Miao , Hwang Ho-ling
Published: October 2012

The most comprehensive publicly available freight databases are the Commodity Flow Survey and FHWA's Freight Analysis Framework. These two sources contain the dollar value and weight of freight movements at high geographic levels, such as states or metropolitan areas. Because of the difficulty of obtaining freight data at lower geographic levels, various practitioners and researchers have suggested estimating freight models on the basis of aggregate data. Following recent practice, a methodology is presented to estimate a nationwide production and attraction model for U.S. domestic trade of goods. To this end, a Commodity Flow Survey data set provided by the U.S. Census Bureau and composed of a 2-nonconsecutive-year period (2002 and 2007) of goods movement between U.S. states for 27 industry sectors was used. The state payroll by industry sector, obtained from the County Business Patterns of the U.S. census, was the variable used to estimate freight generation models. The main objective of this study was to analyze the temporal stability and predictability of the proposed aggregate models. The results indicate that payroll alone explains a significant portion of the freight production and attraction at the state level. However, such simplification in the model process did not result in reasonable predictions of freight for a future-year horizon. It is recommended that time-dependent factors (e.g., variables related to changes in industry productivity) affecting freight demand be considered in the modeling process.
Development of Statewide Freight Flow Assignment with Freight Analysis Framework
Authors: Bujanda Arturo , Villa Juan Carlos , Williams Jon
Published: October 2012

This research presents a methodology for estimating freight flows along corridors serving international trade. A methodology for disaggregating regional flows from the FHWA Freight Analysis Framework (FAF3) to the state level was developed and applied to the state of Texas. To keep international trade moving in a timely and efficient manner, it is important to have accurate information identifying and anticipating capacity shortfalls and congestion nodes. As trade levels increase, the strain on existing infrastructure serving international trade only worsens; therefore, this information is important for improving strategic investment decisions. Findings from the literature are presented about the FAF3 structure and existing methodologies to estimate freight flows at statewide and regional levels. A methodology was developed to disaggregate national FAF3 data and then to assign and estimate the tons of international freight flows through statewide roadways and railroads. The international trade corridors in Texas are used as a case study to apply the methodology and estimate current and future freight demand. Results from the case study demonstrate encouraging findings about this methodology. Conclusions and recommendations to refine and improve this methodology and the FAF3 are provided.
Empirical Analysis of Effect of Project-Based Learning on Student Learning in Transportation Engineering
Authors: Fini Ellie H. , Mellat-Parast Mahour
Published: October 2012

The paper discusses results of an ongoing study of the effect of project-based learning on students' learning outcomes in transportation engineering, a required junior-level course in the civil engineering curriculum. The course was taught in 2008, 2009, and 2010 by the same instructor. The course was transformed from a lecture-based course into a project-based course, integrating a semester-long project as a stimulus for students' learning. To evaluate and compare the effects of lecture-based and project-based teaching approaches on students' learning, a survey instrument from the Laboratory for Innovative Technology and Engineering Education was used. The survey instrument included five constructs for measuring five different aspects of students' learning: higher-order cognitive skills, self-efficacy, ease of learning subject matter, teamwork, and communication skills. The survey of preassessment and postassessment student learning outcomes was conducted to determine the effectiveness of the project-based approach in enhancing students' learning outcomes. The results showed that the use of the project-based approach significantly improved students' ease of learning the subject matter. Project-based learning could be used as an effective teaching and learning strategy by educators to facilitate students' learning.
Field Data for Evaluating 2010 Highway Capacity Manual Operational Analysis Methodology for Interchange Ramp Terminals
Authors: Fang F. Clara , Elefteriadou Lily , Elias Aaron
Published: October 2012

Interchange ramp terminals provide connections between various highway facilities (freeway–arterial, arterial–arterial, freeway–freeway, etc.), so their efficient operation is essential. NCHRP Project 3–60 developed analysis methods for evaluating the operational performance of signalized interchange ramp terminals. Those methods were based primarily on simulated data. Further research used collected field data to evaluate the interchange analysis methodology developed under NCHRP Project 3–60 to identify application limitations and to suggest improvements. Data were collected at eight sites representing various types of interchanges with different geometric and traffic characteristics. Video cameras, mounted on existing poles on the side of the road and on nearby buildings, were used to gather traffic operation data, including demand, lane utilization, and queue length at each site. The research evaluated both individual analytic model components (such as lane utilization factors and internal queue length) and the performance of the interchange (reflected in average queue lengths and control delay). Overall, the models performed well. However, large discrepancies were observed when operating conditions of the interchange were close to capacity. The queue length prediction at the beginning of the upstream arterial or ramp phase was calibrated to modify the effective green time estimation. A new lane utilization model was based on field data for a four- or five-lane external arterial approach where the two leftmost lanes were extensions of the downstream dual left turn lanes. The findings of the work were incorporated into the 2010 Highway Capacity Manual.
Implementing Auxiliary through Lanes in Context of Highway Capacity Analysis
Authors: Bugg Zachary , Rouphail Nagui M. , Schroeder Bastian J. , Nevers Brandon
Published: October 2012

Auxiliary through lanes (ATLs) are often implemented at congested signalized intersections where fiscal and right-of-way constraints do not allow for full roadway widening. Previous research has suggested that ATLs are used significantly less than the theoretical capacity of a continuous lane. However, analysts have had little empirical basis for evaluating ATL operations in the context of the 2010 Highway Capacity Manual (HCM). Two empirical models that predict the flow in the ATL as a function of congestion and total through-movement flow are presented. A method is described for incorporating the model's findings into the HCM procedure for estimating approach capacity. The study addresses the challenges of modifying the HCM lane utilization factor and accounting for the iterative effect of actuated signal control on ATL use. The study suggests that a cyclic process can be used to balance the ATL flow with the green-to-cycle-length ratio. A method is presented for determining the upstream ATL length needed for efficient ATL operations. Two example problems illustrate the use of the new models in the context of HCM 2010.
Estimating Right-Turn-on-Red Capacity for Dual Right-Turn Lanes at Signalized Intersections
Authors: Chen Xiaoming , Qi Yi , Li Da
Published: October 2012

Dual right-turn lanes are increasingly used as a design alternative at urban intersections, primarily to accommodate high right-turn demand. For dual right-turn lanes, an accurate estimate of right-turn-on-red (RTOR) capacity can contribute to better decisions about whether RTOR should be allowed or prohibited and may lead to refined delay estimation and improved signal timing. A gap-acceptance model was formulated for predicting lane-specific RTOR capacities at dual right-turn lanes. The proposed model can represent the unequal effects of conflicting traffic streams from different cross-street lanes on RTOR capacities of dual right-turn lanes. Existing probabilistic methods were adapted to adjust RTOR capacity for shared through and right-turn lanes. Microsimulation models were developed, calibrated based on field data, and used as benchmarks to validate the proposed model. Numerical experiments indicated that the proposed model exhibits a significantly improved ability to predict RTOR capacities for dual right-turn lanes compared with the classical Harders model.
Models for Estimating Drivers following on Two-Lane Rural Highways
Authors: Rozenshtein Sofya , Polus Abishai , Cohen Moshe
Published: October 2012

Traffic performance on two-lane rural highways is commonly characterized by percent time spent following (PTSF), a parameter that determines the level of service on a road segment. Although PTSF is frequently used by transportation engineers and researchers, there is no agreement about its estimation method and values. Therefore, a study was done to calibrate and compare models of PTSF with the data collected on 25 segments of 15 two-lane highways in Israel. The study showed large differences between the collected models and previous model values. Furthermore, the study estimated traffic intensity, which was an additional characteristic of the driver-following phenomenon; this variable did not approach its expected value of 1.0. This lack of agreement between actual and expected values may result from changing driver behavior, that is, impatience as platoon lengths and delays increase. To avoid long platoons, drivers prefer to travel between them and then to perform a passing maneuver sooner than expected. This phenomenon not only reduces platoon length and delays, but also increases the risk of serious and fatal crashes.
Rationale for Incorporating Queue Discharge Flow into Highway Capacity Manual Procedure for Analysis of Freeway Facilities
Authors: Hu Jia , Schroeder Bastian J. , Rouphail Nagui M.
Published: October 2012

The freeway facilities methodology in the 2010 Highway Capacity Manual (HCM) is the only HCM methodology that encompasses undersaturated and congested flow regimes over multiple periods. However, the methodology is limited by its assumption of a fixed capacity threshold between the two flow regimes. The method does not consider the two-capacity phenomenon, which suggests that a drop in the throughput from theoretical capacity is observed after breakdown has occurred. A summary of the available literature on empirical evidence of the capacity drop under queue discharge conditions offers a theoretical evaluation of the impact on queue discharge flow based on shock wave theory relationships that form the basis of the queuing model used in the HCM freeway facilities method. Examples illustrate incorporating queue discharge into a freeway facilities analysis, and implications for practice are discussed.
Effect of Inclement Weather on Two Capacity Flows at Recurring Freeway Bottlenecks
Authors: Dehman Amjad
Published: October 2012

Inclement weather conditions are well known to reduce the capacity of freeway sections. Recent trends distinguish between definitions of two capacity regimes: free-flow capacity, defined by the prebreakdown flow (PBDF), and congested-flow capacity, defined by the queue discharge flow (QDF). The weather effect on PBDF and QDF is investigated, and weather reduction factors are proposed for use in estimating freeway bottleneck capacity for both the free-flow and congested-flow regimes. The behavior of four identified bottlenecks in the Milwaukee, Wisconsin, freeway system was analyzed under different weather conditions. More than 1,300 breakdown events were included in the analysis. Effects of rain, snow, and fog were all evaluated, with special consideration for the degree of visibility and precipitation intensity, and it was found that QDF is more sensitive to weather conditions than is PBDF. Categorizing weather variables by precipitation and visibility allowed for the development of more-accurate capacity reduction factors. Five-minute PBDF inclement weather reduction factors were statistically significantly larger than 15-min PBDF corresponding factors; however, differences between the two were very small. The refined QDF reduction factors are not only applicable at recurrent weekday freeway bottlenecks, but also may find applications at work zones and other types of bottlenecks where traffic congestion prevails.
Estimation of Capacity Drop in Highway Merging Sections
Authors: Oh Simon , Yeo Hwasoo
Published: October 2012

Capacity drop, which is defined as discharge flow drop after bottleneck activation, has been frequently observed on urban highways, especially in merging sections. Maintaining high capacity on roadways is a main concern for traffic operators, theorists, and transportation modelers. Accordingly, many researchers have investigated capacity drop, yet highway capacity and discharge flow measurement methods vary, and results are not comparable. A systematic methodology is introduced for finding capacity drops by using detector data to estimate roadway capacity and discharge flow. The impact of the number of lanes on capacity drops at merging sections on highways is investigated. Results show that capacity drop is negatively related to the number of lanes. Detailed information is analyzed for individual lanes and off-ramp effect on capacity drop. Individual lane analysis supports the negative relationship between the amount of capacity drop and the number of lanes. A decrease in capacity drop is observed when the flow ratio of the off-ramp increases.
Long-term outcome of Gamma Knife stereotactic radiosurgery for arteriovenous malformations graded by the Spetzler-Martin classification
Authors: Koltz Michael T. , Polifka Adam J. , Saltos Andreas , Slawson Robert G. , Kwok Young , Aldrich E. Francois , Simard J. Marc
Published: October 2012

Object

The object of this study was to assess outcomes in patients with arteriovenous malformations (AVMs) treated by Gamma Knife stereotactic radiosurgery (SRS); lesions were stratified by size, symptomatology, and Spetzler-Martin (S-M) grade.

Methods

The authors performed a retrospective analysis of 102 patients treated for an AVM with single-dose or staged-dose SRS between 1993 and 2004. Lesions were grouped by S-M grade, as hemorrhagic or nonhemorrhagic, and as small (< 3 cm) or large (≥ 3 cm). Outcomes included death, morbidity (new neurological deficit, new-onset seizure, or hemorrhage/rehemorrhage), nidus obliteration, and Karnofsky Performance Scale score.

Results

The mean follow-up was 8.5 years (range 5–16 years). Overall nidus obliteration (achieved in 75% of patients) and morbidity (19%) correlated with lesion size and S-M grade. For S-M Grade I–III AVMs, nonhemorrhagic and hemorrhagic combined, treatment yielded obliteration rates of 100%, 89%, and 86%, respectively; high functional status (Karnofsky Performance Scale Score ≥ 80); and 1% mortality. For S-M Grade IV and V AVMs, outcomes were less favorable, with obliteration rates of 54% and 0%, respectively. The AVMs that were not obliterated had a mean reduction in nidus volume of 69% (range 35%–96%). On long-term follow-up, 10% of patients experienced hemorrhage/rehemorrhage (6% mortality rate), which correlated with lesion size and S-M grade; the mean interval to hemorrhage was 81 months.

Conclusions

For patients with S-M Grade I–III AVMs, SRS offers outcomes that are favorable and that, except for the timing of obliteration, appear to be comparable to surgical outcomes reported for the same S-M grades. Staged-dose SRS results in lesion obliteration in half of patients with S-M Grade IV lesions.
Using a modified far-lateral approach to remove hypoglossal neurilemmomas: notes on technique
Authors: Xiao Xinru , Wu Zhen , Zhang Liwei , Jia Guijun , Tang Jie , Meng Guolu , Zhang Junting
Published: October 2012

Object

In this paper the authors describe a modified far-lateral transcondylar approach to remove hypoglossal neurilemmomas (HGNs).

Methods

Between September 2008 and June 2011, 11 consecutive patients with HGNs underwent tumor removal via a modified far-lateral transcondylar approach. The average age at presentation, tumor characteristics, cranial nerve (CN) deficits, and outcomes were assessed. The modified far-lateral transcondylar approach comprises several important steps. The first step is to remove the limited posterior aspect of the condylar facet to open the hypoglossal canal. The second step is to expose the posterior arch and the transverse process of C-1. A fat layer covers the venous plexus of the vertebral artery, and careful dissection along this surface of the fat layer is important to protect the vertebral artery from damage. The neck muscles are dissected caudally to expose the extracranial component of the tumor, which is located in front of the transverse process of C-1.

Results

Eleven cases of HGNs were treated during the study period. The mean patient age was 47.4 ± 8.9 years (range 31–59 years); there were 3 men and 8 women. The mean follow-up period was 14.1 ± 9 months. All patients presented with hypoglossal nerve deficits; other commonly observed deficits included glossopharyngeal and vestibular/cochlear nerve deficits. Gross-total resection of the tumor was achieved in 10 patients. A subtotal resection of the tumor was achieved in the remaining patient. Two patients had transient postoperative facial nerve palsies, 1 patient developed a new CN XI palsy postoperatively, and 5 patients experienced transient hoarseness and difficulty swallowing. Two patients required a tracheotomy because they demonstrated dysfunction of the caudal CNs and subsequently developed postoperative pneumonia. Postoperatively, 5 patients required the temporary placement of a nasogastric feeding tube. There were no surgery-related deaths in this series.

Conclusions

The modified far-lateral transcondylar approach is an effective treatment for HGNs, yielding a high total tumor removal rate with an acceptable rate of morbidity.
Cerebral revascularization and carotid artery resection at the skull base for treatment of advanced head and neck malignancies
Authors: Kalani M. Yashar S. , Kalb Samuel , Martirosyan Nikolay L. , Lettieri Salvatore C. , Spetzler Robert F. , Porter Randall W. , Feiz-Erfan Iman
Published: October 2012

Object

Resection of cancer and the involved artery in the neck has been applied with some success, but the indications for such an aggressive approach at the skull base are less well defined. The authors therefore evaluated the outcomes of advanced skull base malignancies in patients who were treated with bypass and resection of the internal carotid artery (ICA).

Methods

The authors retrospectively reviewed the charts of all patients with advanced head and neck cancers who underwent ICA sacrifice with revascularization in which an extracranial-intracranial bypass was used between 1995 and 2010 at the Barrow Neurological Institute.

Results

Eighteen patients (11 male and 7 female patients; mean age 46 years, range 7–69 years) were identified. There were 4 sarcomas and 14 carcinomas that involved the ICA at the skull base. All patients underwent ICA sacrifice with revascularization. One patient died of a stroke after revascularization. A second patient died of the effects of a fistula between the oral and cranial cavities (surgery-related mortality rate 11.1%). Eight months after the operation, 1 patient developed occlusion of the bypass and died. Complications associated with the bypass surgery included 1 case of subdural hematoma (SDH) with blindness, 1 case of status epilepticus, and 1 case of asymptomatic bypass occlusion (bypass-related morbidity 16.7%). Complications associated with tumor resection included 3 cases of CSF leakage requiring repair and shunting, 1 case of hydrocephalus requiring shunting, 1 case of SDH, and 1 case of contralateral ICA injury requiring a bypass (tumor resection morbidity rate 33.3%). In 1 patient treated with adjuvant therapy before surgery, the authors identified only a radiation effect and no tumor on resection. In a second patient the bypass was occluded, and her tumor was not resected. The other 16 patients underwent gross-total resection of their tumor. Excluding the surgery-related deaths, the mean and median lengths of survival in this series were 13.2 and 8.3 months, respectively (range 1.5–48 months). Including the surgery-related deaths, the mean and median lengths of survival were 11.8 and 8 months, respectively (range 17 days–48 months). At last follow-up all patients had died of cancer or cancer-related causes.

Conclusions

Despite maximal surgical intervention, including ICA sacrifice at the skull base with revascularization, patient survival was dismal, and the complication rate was significant. The authors no longer advocate such an aggressive approach in this patient population. On rare occasions, however, such an approach may be considered for low-grade malignancies.
Preoperative assessment of meningioma stiffness using magnetic resonance elastography
Authors: Murphy Matthew C. , Huston John , Glaser Kevin J. , Manduca Armando , Meyer Fredric B. , Lanzino Giuseppe , Morris Jonathan M. , Felmlee Joel P. , Ehman Richard L.
Published: October 2012

Object

The object of this study was to determine the potential of magnetic resonance elastography (MRE) to preoperatively assess the stiffness of meningiomas.

Methods

Thirteen patients with meningiomas underwent 3D brain MRE examination to measure stiffness in the tumor as well as in surrounding brain tissue. Blinded to the MRE results, neurosurgeons made a qualitative assessment of tumor stiffness at the time of resection. The ability of MRE to predict the surgical assessment of stiffness was tested using a Spearman rank correlation.

Results

One case was excluded due to a small tumor size. In the remaining 12 cases, both tumor stiffness alone (p = 0.023) and the ratio of tumor stiffness to surrounding brain tissue stiffness (p = 0.0032) significantly correlated with the surgeons' qualitative assessment of tumor stiffness. Results of the MRE examination provided a stronger correlation with the surgical assessment of stiffness compared with traditional T1- and T2-weighted imaging (p = 0.089), particularly when considering meningiomas of intermediate stiffness.

Conclusions

In this cohort, preoperative MRE predicted tumor consistency at the time of surgery. Tumor stiffness as measured using MRE outperformed conventional MRI because tumor appearance on T1- and T2-weighted images could only accurately predict the softest and hardest meningiomas.
A stroke of silence: tinnitus suppression following placement of a deep brain stimulation electrode with infarction in area LC
Authors: Larson Paul S. , Cheung Steven W.
Published: October 2012

The authors report on a case of tinnitus suppression following deep brain stimulation (DBS) for Parkinson disease. A perioperative focal vascular injury to area LC, a locus of the caudate at the junction of the head and body of the caudate nucleus, is believed to be the neuroanatomical correlate.

A 56-year-old woman underwent surgery for implantation of a DBS lead in the subthalamic nucleus to treat medically refractory motor symptoms. She had comorbid tinnitus localized to both ears. The lead trajectory was adjacent to area LC. Shortly after surgery, she reported tinnitus suppression in both ears. Postoperative MRI showed focal hyperintensity of area LC on T2-weighted images. At 18 months, tinnitus localized to the ipsilateral ear remained completely silenced, and tinnitus localized to the contralateral ear was substantially suppressed due to left area LC injury.

To the authors' knowledge, this is the first report of a discrete injury to area LC that resulted in bilateral tinnitus suppression. Clinicians treating patients with DBS may wish to include auditory phantom assessment as part of the neurological evaluation.
Ulnar nerve tuberculoma
Authors: Ramesh Chandra V. V. , Prasad Bodapati Chandramowliswara , Varaprasad Gangumolu
Published: October 2012

The authors report a very rare case of tuberculoma involving the ulnar nerve. The patient, a 7-year-old girl, presented with swelling over the medial aspect of her right forearm just below the elbow joint, with features of ulnar nerve palsy, including paresthesias along the little and ring fingers and claw hand deformity. There was a history of trauma and contact with a contagious case of tuberculosis. There were no other signs of tuberculosis. At surgical exploration the ulnar nerve was found to be thickened, and on opening the sheath there was evidence of caseous material enclosed in a fibrous capsule compressing and displacing the nerve fibers. The lesion, along with the capsule, was subtotally removed using curettage, and a part of the capsule that was densely adherent to the nerve fibers was left in the patient. Histopathological examination of the specimen was consistent with tuberculoma. The patient received adequate antitubercular treatment and showed significant improvement.
Gamma Knife surgery for a hemangioma of the cavernous sinus in a child
Authors: Murphy Rory K. J. , Reynolds Matthew R. , Mansur David B. , Smyth Matthew D.
Published: October 2012

Cavernous sinus (CS) hemangiomas are rare vascular abnormalities that constitute 0.4%–2% of all lesions within the CS. Cavernous sinus hemangiomas are high-flow vascular tumors that tend to hemorrhage profusely during resection, leading to incomplete resection and high morbidity and mortality. While Gamma Knife surgery (GKS) has proven to be an effective treatment of CS hemangiomas in the adult population, few reports of GKS for treatment of CS hemangiomas exist in the pediatric literature. Here, the authors present the first case of a 15-year-old girl with a biopsy-proven CS hemangioma who achieved complete resolution of her symptoms and a complete imaging-defined response following GKS. If suspicion for a CS hemangioma is high in a pediatric patient, GKS may be considered as an effective treatment modality, thus avoiding the morbidities of open resection.
The effect of alpha-v integrin inhibition on the malignant characteristics of medulloblastoma
Authors: Thompson Eric M. , Whitney Nathaniel L. , Wu Y. Jeffrey , Neuwelt Edward A.
Published: October 2012

Object

Hypoxia induces an aggressive phenotype in some brain tumors in part due to hypoxia-inducible factor–1α (HIF-1α) and integrin expression. The importance of hypoxia in medulloblastoma is unclear and the interaction of HIF-1α and c-Myc in medulloblastoma has not been explored. The objective of this study was to determine if hypoxia induces an aggressive phenotype in human medulloblastoma cells that constitutively express high (D283 Med) or low (DAOY) levels of c-Myc and to determine if blocking αv integrins with the monoclonal antibody intetumumab inhibits hypoxia-induced cellular stress responses.

Methods

Cells were grown at 21% and 1% O2 and in the presence or absence of intetumumab. Measures of malignancy evaluated included cell proliferation, cell migration, and expression of vascular endothelial growth factor (VEGF), αv integrins, HIF-1α, and c-Myc.

Results

Both cell lines robustly expressed αv integrins. Hypoxic DAOY cells showed significantly increased proliferation compared with normoxic controls (p < 0.05), whereas D283 Med cells did not. Both cell lines exhibited a dose-dependent decrease in proliferation when treated with intetumumab (p < 0.05). Hypoxia did not increase DAOY migration, but intetumumab significantly inhibited migration at both oxygen conditions (p < 0.05). Intetumumab significantly decreased VEGF levels in DAOY cells at both oxygen conditions (p < 0.05) and in normoxic D283 cells (p < 0.01). Neither cell line demonstrated increased HIF-1α expression in response to hypoxia. However, hypoxic D283 Med cells grown in the presence of intetumumab demonstrated significantly decreased c-Myc expression (p < 0.05).

Conclusions

Hypoxia did not clearly induce a more aggressive phenotype in medulloblastoma cells. Despite this result, intetumumab decreased medulloblastoma cell proliferation and migration and variably decreased VEGF and c-Myc expression in hypoxic conditions. Targeting αv integrins represents a promising potential adjuvant modality in the treatment of medulloblastoma, particularly subtypes that metastasize and overexpress VEGF and c-Myc.
BIOREFINERY. Pressurised hot water extraction of acetylated xylan from birch sawdust
Authors: Kilpeläinen Petri , Leppänen Kaisu , Spetz Peter , Kitunen Veikko , Ilvesniemi Hannu , Pranovich Andrey , Willför Stefan
Published: October 2012

Birch sawdust was extracted using pressurized hot water (PHW), with the ultimate aim of maximizing the yield of large and intact non-cellulosic heteropolysaccharides, i.e. hemicellulose molecules. The extractions were performed using a flow-through vessel. Effects of different extraction temperatures between 140 and 200°C were evaluated. The amount of extracted xylans, as weil as monosaccharides, increased as the temperature rose to 1 90°C, accordingly the degree of polymerization of the xylans decreased. The extracted xylans retained most of the native acetyl groups and were thereby water-soluble after the extraction. The PHW extract contained not only xylan and other hemicellulose-derived oligomers, but fragmented Iignin molecules and some extractives as well. Only trace amounts of furfurals were found in the extract at lower extraction temperatures. An optimal yield of water-soluble, polymeric xylans with the smallest amount of unwanted impurities and degradation products was thus achieved at an extraction temperature of 1 80°C using the flow-through vessel
BIOREFINERY. Nanocellulose characterization with mechanical fractionation
Authors: Tanaka Atsushi , Seppänen Veli , Houni Juha , Sneck Asko , Pirkonen Pentti
Published: October 2012

A novel fractionation method was developed to characterize nanocellulose in terms of particle size. The fractionation device ues screens or membranes with known size. The scale is in the range of micro to nano, so that NFCs can be size- or shapefractionated accordingly. The procedure is somewhat analogaus to the Sauer-MeNett fiber classifier. The reproducibility of the obtained size profile was very good. The device can also produce size specific nanocelluloses, which could be applied for scientific research purposes, e.g. nano risk assessment. Fractionation with membrane filters was able to screen out almost all particles. However, the membrane permeate contained significant amounts of dissolved substances.