Open Access. Powered by Scholars. Published by Universities.®
- Discipline
-
- Urban Studies and Planning (886)
- Urban Studies (793)
- Business (769)
- Engineering (744)
- Physical Sciences and Mathematics (677)
-
- Civil and Environmental Engineering (412)
- Operations and Supply Chain Management (388)
- Economics (365)
- Computer Sciences (279)
- Infrastructure (261)
- Transportation Engineering (252)
- Environmental Sciences (205)
- Public Policy (161)
- Mathematics (148)
- Law (142)
- Political Science (138)
- Analysis (137)
- Civil Engineering (134)
- Operations Research, Systems Engineering and Industrial Engineering (130)
- Sociology (125)
- Economic Policy (118)
- Environmental Policy (106)
- Marketing (98)
- Sustainability (95)
- International and Area Studies (92)
- Policy Design, Analysis, and Evaluation (91)
- Models and Methods (89)
- Institution
-
- Portland State University (974)
- World Maritime University (855)
- San Jose State University (570)
- Singapore Management University (323)
- Wayne State University (206)
-
- Old Dominion University (150)
- University of Nevada, Las Vegas (119)
- University of Texas at El Paso (68)
- University of North Florida (66)
- University of Texas at Arlington (44)
- University of Massachusetts Boston (39)
- University of Nebraska at Omaha (37)
- Walden University (36)
- University of South Florida (34)
- Embry-Riddle Aeronautical University (33)
- Purdue University (32)
- University of Colorado Law School (26)
- University of Nebraska - Lincoln (22)
- Clemson University (21)
- Western Kentucky University (21)
- City University of New York (CUNY) (18)
- University of Arkansas, Fayetteville (18)
- SIT Graduate Institute/SIT Study Abroad (16)
- University of Kentucky (15)
- University of New Orleans (15)
- Claremont Colleges (13)
- University of New Hampshire (13)
- University of Michigan Law School (11)
- University of Central Florida (9)
- University of Denver (9)
- Keyword
-
- Transportation (226)
- Transportation -- Planning (138)
- Urban transportation (82)
- Equity (68)
- Etc. – Periodicals (59)
-
- Etc. – Periodicals; Logistics -- Florida – Jacksonville -- Societies (59)
- Etc. – Periodicals; University of North Florida -- Societies (59)
- Etc. – Periodicals; University of North Florida -- Students – Periodicals; College student newspapers and periodicals -- Florida – Jacksonville; Transportation -- Florida – Jacksonville -- Societies (59)
- TLS Newsletter -- Archives; University of North Florida. Transportation & Logistics Society – Periodicals; University of North Florida. Transportation and Logistics Flagship Program -- Societies (59)
- Economics (52)
- Public transit (50)
- Faculty (44)
- Traffic safety (41)
- Intelligent transportation systems (39)
- Transportation planning (38)
- Public transportation (36)
- Transit-oriented development (36)
- Transportation and state (36)
- Infrastructure (35)
- Bicycle commuting (33)
- Safety (33)
- Singapore (33)
- Transit (32)
- Transportation -- Oregon -- Planning (32)
- Travel time (Traffic engineering) (32)
- Traffic congestion (31)
- Pedestrians (29)
- Aviation (28)
- Urban transportation -- Planning (28)
- Geographic information systems (27)
- Publication Year
- Publication
-
- World Maritime University Dissertations (711)
- Mineta Transportation Institute (537)
- PSU Transportation Seminars (236)
- TREC Final Reports (223)
- Journal of Transportation Management (203)
-
- Research Collection School Of Computing and Information Systems (203)
- TREC Project Briefs (99)
- Center for Urban Studies Publications and Reports (85)
- TREC Webinar Series (71)
- Open Access Theses & Dissertations (68)
- Transportation & Logistics Society Newsletter (59)
- Dissertations and Theses (52)
- UNLV Theses, Dissertations, Professional Papers, and Capstones (49)
- Urban Studies and Planning Faculty Publications and Presentations (46)
- CTEDD Final Project Reports - Archive (44)
- Civil and Environmental Engineering Faculty Publications and Presentations (42)
- Research Collection School Of Economics (35)
- Walden Dissertations and Doctoral Studies (34)
- Maritime Safety & Environment Management Dissertations (Dalian) (32)
- Faculty Books and Monographs (31)
- Research Collection College of Integrative Studies (29)
- Research Collection Lee Kong Chian School Of Business (29)
- MARENER 2017 (25)
- ShipArc 2015 Conference (25)
- Journal of Public Transportation (22)
- Civil & Environmental Engineering Theses & Dissertations (19)
- Electronic Theses and Dissertations (19)
- Reports (18)
- TriMet Collection (18)
- Publications (17)
- Publication Type
- File Type
Articles 241 - 270 of 4092
Full-Text Articles in Transportation
Charting A Sustainable Course Beyond Carbon : A Critical Carbon-Water-Energy Assessment Of Net-Zero Shipping Scenarios With Synthetic Fuels And Ghc Offsetting, Alexandre Bellot
Charting A Sustainable Course Beyond Carbon : A Critical Carbon-Water-Energy Assessment Of Net-Zero Shipping Scenarios With Synthetic Fuels And Ghc Offsetting, Alexandre Bellot
World Maritime University Ph.D. Dissertations
This thesis extends the scope of IMO maritime decarbonization studies by incorporating cradle-to-grave approaches. This study advocates for an approach incorporating cradle-to-grave resource efficiency and carbon neutrality, assessing cumulative energy demand and net freshwater withdrawal as key sustainability metrics. The thesis specifically addresses the question of the sustainability of decarbonization strategies centred on substituting fossil fuels with synthetic alternatives and offsetting the remaining carbon footprint. Advanced ship energy modelling: The thesis first introduces a ship energy model capable of evaluating ships’ fuel consumption with various propulsion and energy generation options. The model simulates energy transfers across a concept ship’s systems, …
Improving Onboard Training For Deck Cadets : An Analysis Through The Lens Of Learning Theories, Yusuke Mori
Improving Onboard Training For Deck Cadets : An Analysis Through The Lens Of Learning Theories, Yusuke Mori
World Maritime University Ph.D. Dissertations
As a critical component of skill development and identity construction for prospective seafarers, onboard training has played a central role in Maritime Education and Training (MET). Each Maritime Education and Training Institution (METI) implements distinct onboard training arrangements based on its environmental, socio-cultural, and historical context, as well as the learning theories that inform its approach. However, the absence of a rigorous examination of the factors influencing national variations in onboard training creates challenges in establishing legal norms at the international level. Furthermore, the literature has identified a wide range of issues and challenges in the implementation of onboard training, …
Conceptual Critical Success Factors Model On Infrastructure Sustainability Rating System For California Construction Projects, Joseph J. Kim, Jose A. Arroyo-Turcios
Conceptual Critical Success Factors Model On Infrastructure Sustainability Rating System For California Construction Projects, Joseph J. Kim, Jose A. Arroyo-Turcios
Mineta Transportation Institute
This report addresses the sensitivity and reliability of the sustainability rating systems by comparing each category’s verified scores with its respective submitted scores to evaluate how points are awarded for infrastructure projects, examine which categories present the most challenges for verification, and identify the best category for verification in the sustainability rating system. The authors conducted three analyses using credit score data obtained from fourteen actual civil infrastructure projects certified under Envision. First, the Natural World category had the highest average score from the submitted and verified data. Pairwise comparisons using t-tests indicate that the mean value of one category …
Developing A Roadmap For Green Port In Timor-Leste, Emanuel Da Silva Maia
Developing A Roadmap For Green Port In Timor-Leste, Emanuel Da Silva Maia
World Maritime University Dissertations
No abstract provided.
Seasonal Pollen Increases Traffic Fatalities In The United States, Monica Deza
Seasonal Pollen Increases Traffic Fatalities In The United States, Monica Deza
Population Health Research Brief Series
Traffic fatalities are the among the leading causes of death in the United States. Motor vehicle crash death rates have declined overall in the U.S. in recent decades, but there is substantial variation in rates across the country. Due to climate change, exposure to pollen has increased in various parts of the U.S. The antihistamine response triggered by pollen can result in poor physical and cognitive symptoms, thus impacting an individual’s ability to drive and increasing the risk of motor vehicle fatalities. This brief summarizes findings from a study that used data from the National Allergy Bureau (NAB) Pollen and …
Piloting A Zero-Emission Delivery Zone In Downtown Portland, Art Pearce, Sarah Pullman, Jacob Sherman
Piloting A Zero-Emission Delivery Zone In Downtown Portland, Art Pearce, Sarah Pullman, Jacob Sherman
PSU Transportation Seminars
The Portland Bureau of Transportation (PBOT) was awarded a nearly $2 million Strengthening Mobility and Revolutionizing Transportation (SMART) Grant by the US Department of Transportation (USDOT) in Fall 2023 to pilot the country’s first regulated Zero-Emission Delivery Zone in downtown Portland and test digital infrastructure tools. This project will test an innovative set of incentives and regulations to better understand what technology and strategies municipalities can use to support and reduce greenhouse gas emissions in the freight sector.
While other cities in the United States have piloted voluntary Zero-Emission Delivery Zones (ZEDZs) to encourage the transition of commercial fleets to …
Breaking The Yoke: A Systematic Unmasking Of Challenges To Sustainable Rural Development In South Sudan, Gai Chol Paul
Breaking The Yoke: A Systematic Unmasking Of Challenges To Sustainable Rural Development In South Sudan, Gai Chol Paul
Journal of Sustainable Social Impact
South Sudan, a young nation grappling with the legacy of protracted conflict, faces significant challenges in fostering sustainable rural development. While the immense potential of its vast agricultural lands remains largely untapped, the persistent triple threat of insecurity, deficient infrastructure, and the absence of robust government policy actively hinders progress. The ongoing armed conflict, characterized by inter-communal violence and sporadic attacks, casts a long shadow over rural areas in South Sudan. Thus, I developed this mixed-method multiple-case study, grounded in the sustainable livelihoods framework, to explore challenges that hinder sustainable rural development in South Sudan. I collected data through document …
Active Transportation Term Guide, Kalonni Steib
Active Transportation Term Guide, Kalonni Steib
Capstone Projects and Master's Theses
The Monterey County Health Department, through its Planning, Evaluation, and Policy (PEP) Department, is dedicated to promoting health equity by implementing strategic plans, aligning performance standards with national accreditation, and addressing social and environmental policies. Serving underserved and unincorporated communities, PEP focuses on overcoming language barriers in Monterey County, which has a significant Hispanic and Latino population. This project aimed to develop a bilingual glossary of active transportation terms to enhance communication between the community and government agencies. Implemented over three to six months, the glossary was piloted for feedback and updates. The project successfully identified key transportation terms and …
Practice Unveils Weaknesses: Analysing The Implementation Of Regulations On Seafarers’ Work/Rest Hours, Bikram S. Bhatia
Practice Unveils Weaknesses: Analysing The Implementation Of Regulations On Seafarers’ Work/Rest Hours, Bikram S. Bhatia
World Maritime University Ph.D. Dissertations
Seafarers’ fatigue risk management is rooted in regulations on manning and work/rest hours. These regulations establish a minimum fatigue management standard achieved through work/rest hours compliance. Seafarers must maintain daily records of their work/rest hours and report any non-compliance to their company. However, adjustments to these records have been reported in the literature. Such malpractice obscures instances of non- compliance and hinders the feedback necessary for resolving these issues, including flag State review and amendments to minimum safe manning documents. It compromises the integrity of fatigue risk management and underscores the need for further research.
This study examined the implementation …
Establishing A Robust Decision Framework To Support Transportation Planning Decisions And Accommodate Connected And Autonomous Transportation Alternatives, Bobby Cottam
Graduate Theses and Dissertations
Transportation planning involves complex decisions to provide high-quality transportation systems involving multiple stakeholders with numerous competing interests, on top of that they are trying to improve the quality and reliability of those systems on shrinking budgets. This decision is further complicated by the advent of new transportation methods e.g., ride-hailing and the promise of connected and autonomous vehicles (CAVs). While the actual short-term impact of these technologies is uncertain, they will most certainly have a significant impact within the 20-year planning horizon that transportation planners typically consider. These technologies are also blurring the lines between traditionally separate modes of transportation; …
Modeling And Regulating A Ride-Sourcing Market Integrated With Vehicle Rental Services, Dong Mo, Hai Wang, Zeen Cai, W. Y. Szeto, Xiqun (Michael) Chen
Modeling And Regulating A Ride-Sourcing Market Integrated With Vehicle Rental Services, Dong Mo, Hai Wang, Zeen Cai, W. Y. Szeto, Xiqun (Michael) Chen
Research Collection School Of Computing and Information Systems
With the popularity of on-demand ride services worldwide, ride-sourcing platforms must maintain an adequate fleet size and cope with growing travel demand. Recently, platforms have attempted to provide vehicle rental services to drivers who do not own cars, then recruited them to provide on demand ride services. This helps lower the entry barrier for drivers and offers another profitable business for platforms. From the government's perspective, however, it is challenging to coordinately regulate a ride-sourcing business and vehicle rental business. This paper proposes a bi-level optimization model to investigate how the government regulates the ride-sourcing market integrated with vehicle rental …
Uncovering Electric Vehicle Ownership Disparities Using K-Means Clustering Analysis: A Case Study Of Austin, Texas, Seung Jun Choi, Junfeng Jiao
Uncovering Electric Vehicle Ownership Disparities Using K-Means Clustering Analysis: A Case Study Of Austin, Texas, Seung Jun Choi, Junfeng Jiao
Research Collection College of Integrative Studies
Transportation electrification is promoted for its environmental and energy efficiency benefits. However, recent studies examining electric vehicle (EV) adoption have revealed complex patterns influenced by race and income disparities. These studies, primarily based on surveys, often overlook regional ownership variations and built environment measures linked to urban form. Our study addresses this gap by analyzing actual EV registration data with spatial details using hot spot and K-means clustering analyses. The analysis results revealed a pronounced East–West divide in EV adoption. In West Austin, clusters indicate a higher number of EVs, greater energy consumption, and residents who are predominantly White, with …
Consistent Vmt Mapping And Modeling In California: How Can We Better Assess The Vmt Impacts Of State And Local Transportation Projects?, Serena E. Alexander, Shams Tanvir, Syed Tanvir Ahmed, Annie Jones
Consistent Vmt Mapping And Modeling In California: How Can We Better Assess The Vmt Impacts Of State And Local Transportation Projects?, Serena E. Alexander, Shams Tanvir, Syed Tanvir Ahmed, Annie Jones
Mineta Transportation Institute
Despite California’s ambitious target to achieve carbon neutrality by 2045, the state is not reducing greenhouse gas (GHG) emissions from personal vehicle travel, and per capita Vehicle Miles Traveled (VMT) and GHG emissions continue to increase. One central challenge of climate planning facing California is the lack of consistent methods to measure the VMT impacts of transportation projects. Using both qualitative and quantitative data, this research answers the question: “What are the advantages and limitations of existing VMT calculators to determine the climate impacts of transportation projects to help meet California’s climate goals?” Research methods included: (1) a quantitative analysis …
Developing An Roi Assessment Model For Employee Development Programs Implemented By California Transit Agencies, Tyler Reeb, Susan Gallagher
Developing An Roi Assessment Model For Employee Development Programs Implemented By California Transit Agencies, Tyler Reeb, Susan Gallagher
Mineta Transportation Institute
The objective of this research is to determine the extent to which transit agencies in California are implementing Return on Investment (ROI) assessments or otherwise evaluating the value and effectiveness of the employee development programs they administer, what cost and performance data they collect and track, and what resources or support are needed to support ROI assessment efforts. Transit agencies will necessarily incur expenses in efforts to improve the recruitment, retention, and morale of employees, but will struggle to solicit adequate funding unless they are able to demonstrate the value of such efforts to a broader audience. Thus, developing and …
The Indirect Benefits Of A Transit Apprenticeship And Its Potential Value As A Flexible Postsecondary Pathway, Kathleen F. Mcconnell, Priya Raman
The Indirect Benefits Of A Transit Apprenticeship And Its Potential Value As A Flexible Postsecondary Pathway, Kathleen F. Mcconnell, Priya Raman
Mineta Transportation Institute
The transit sector has begun to embrace apprenticeships as a worthwhile training model. Apprenticeships may also address young people’s interest in career advancement opportunities, an additional benefit to the transit sector as it replaces an aging workforce and resolves other recruitment challenges. Apprenticeships that emphasize both technical and soft skills invest in career advancement by offering employees the chance to develop “cross-cutting competencies.” A highly developed model of this approach is found in the Santa Clara Valley Transportation Authority Joint Workforce Initiative (JWI), which formally recognizes skills acquisition with accredited certificates. Further development of this model would find support in …
Experimental Investigations Of Wind Shear From Passing A Vehicle, Hamid Rahai, Assma Begum, Jeremy Bonifacio, Ryan Moffit
Experimental Investigations Of Wind Shear From Passing A Vehicle, Hamid Rahai, Assma Begum, Jeremy Bonifacio, Ryan Moffit
Mineta Transportation Institute
Wind energy can be harnessed for various commercial and transportation-related applications. This study assessed experimentally the potential of capturing wind energy from the passage of vehicles for electric power generation. Both wind tunnel experiments and field tests were performed. The wind tunnel experiments were performed in an open-circuit low-speed wind tunnel at a free-stream mean velocity of 23 m/s. Five PVC pipes placed adjacent to the wind-blowing domain were used to simulate the columns under a freeway overpass. A scaled Ahmad body (simplified car body model) was used as the vehicle. The spanwise distance between the Ahmad body and the …
Right Turn On Red: Energy-Saving Measure Or Unsafe Maneuver?, Bruce Appleyard, Anurag Pande, Joseph Gibbons, Shams Tanvir, Megan Honey, Nell Ahangarfabrik, Mario Carbajal, Madison Swayne
Right Turn On Red: Energy-Saving Measure Or Unsafe Maneuver?, Bruce Appleyard, Anurag Pande, Joseph Gibbons, Shams Tanvir, Megan Honey, Nell Ahangarfabrik, Mario Carbajal, Madison Swayne
Mineta Transportation Institute
There is a growing interest in prohibiting right turn on red (RTOR) policies in the name of pedestrian and bicycle safety but there is not enough research on the subject to help agencies make informed decisions. When Congress passed the Energy Policy and Conservation Act of 1975, they included a provision requiring states to permit right turns on red lights as an energy-saving measure to receive federal assistance for mandated conservation programs. Since 1980, all states have permitted right turns on red as a general rule. More research is needed to help guide state policies that can support jurisdictions in …
An Assessment Of The Viva Callesj Event In San Jose, Richard Kos, Adam Cohen
An Assessment Of The Viva Callesj Event In San Jose, Richard Kos, Adam Cohen
Mineta Transportation Institute
This report evaluates the Viva CalleSJ event held in San Jose, California, on September 8, 2024. As a celebrated open-streets initiative, Viva CalleSJ temporarily transformed six miles of city streets into car-free zones to encourage active transportation, foster community engagement, and support local businesses. This assessment employed a mixed-methods approach, including participant surveys, interviews with stakeholders, and observational analysis. Key findings highlighted the event’s success in attracting a diverse audience, promoting physical activity, and driving economic benefits. Over 50% of attendees arrived by bicycle, and 77.7% planned to spend money at the event, averaging $54.23 per participant. Community-building impacts were …
Zero-Emission Buses In The Us: Understanding And Addressing Market And Policy Challenges, Leah Foecke, Zachary Karson, Thomas Tiberghien
Zero-Emission Buses In The Us: Understanding And Addressing Market And Policy Challenges, Leah Foecke, Zachary Karson, Thomas Tiberghien
Mineta Transportation Institute
As the US public transportation sector accelerates its shift from fossil fuels to zero-emission alternatives, transit agencies and transit bus manufacturers alike face significant uncertainty and instability. This report provides policymakers with updated insights into the US transit bus market, focusing on key industry dynamics, financial challenges with zero-emission bus (ZEB) acquisition, technological obstacles in deployment, and regulatory issues. The research relies on interviews with stakeholders, a detailed review of existing literature, and an analysis of US public transit data. Key findings reveal ongoing challenges related to costs, supply, reliability, and workforce development, all of which hinder the adoption of …
Ev Charging At Multifamily Properties: Moving Beyond Barriers, Whit Jamieson, Anna Guida, Connor Herman
Ev Charging At Multifamily Properties: Moving Beyond Barriers, Whit Jamieson, Anna Guida, Connor Herman
PSU Transportation Seminars
Transportation is the top contributor of greenhouse gas emissions in the US and light-duty vehicles are the #1 contributor to transportation emissions. Mass adoption of electric vehicles (EVs) is key in the fight toward a more sustainable future, but there are several factors that have delayed our transition to EVs.
EV charging at home is the most convenient and cost-effective charging option for EV drivers, but people living in multifamily housing face serious barriers to accessing home charging. During this session, we will explore why EV charging at multifamily housing is critical to mass adoption of EVs, barriers to charging …
Bike Buses: An Evaluation Of An Emerging Active Transportation To School Intervention, Evan Howington, Nathan Mcneil, John Macarthur
Bike Buses: An Evaluation Of An Emerging Active Transportation To School Intervention, Evan Howington, Nathan Mcneil, John Macarthur
TREC Faculty and Staff Publications
Bike buses are a relatively new form of active transportation to school (ATS) that have primarily emerged in Europe and the United States. A form of coordinated, group bike riding along a defined route to school, bike buses are an outgrowth of Safe Routes to School interventions in North America that seek to reverse the declining rates of walking and biking to school among children. Our initial phase of research included a literature review of social and environmental factors affecting ATS in the contemporary North American context, and two convenience surveys of bike bus coordinators and parent participants. This initial …
Addressing Transportation Emissions Through State Climate And Energy Policy, Amy Schlusser
Addressing Transportation Emissions Through State Climate And Energy Policy, Amy Schlusser
PSU Transportation Seminars
Oregon has adopted policies to reduce greenhouse gas emissions from the energy and transportation sectors. This presentation will provide some background on these policy frameworks and explore how these policies impact transportation fuels and the transportation sector more broadly.
Fast-Tracking Transit: Unveiling Portland's First Bus Rapid Transit Line And Signal Optimization Strategies, Mark Haines, Jesse Stemmler
Fast-Tracking Transit: Unveiling Portland's First Bus Rapid Transit Line And Signal Optimization Strategies, Mark Haines, Jesse Stemmler
PSU Transportation Seminars
This presentation on the Division Transit Project will provide an overview of the project elements including roadway design, bus station design, traffic signal timing and operations and the Next Gen Transit Signal Priority (TSP) system. We will discuss some lessons learned and provide before and after results from the project.
Competencies Required For Simulation Instructors In Maritime Education And Training, Ryo Hiwatashi
Competencies Required For Simulation Instructors In Maritime Education And Training, Ryo Hiwatashi
World Maritime University Dissertations
No abstract provided.
Research Into Renewable Energy Technology, Energy Carriers And The Path To A Low-Carbon Future For Suriname, Bryan Michel Ristie
Research Into Renewable Energy Technology, Energy Carriers And The Path To A Low-Carbon Future For Suriname, Bryan Michel Ristie
World Maritime University Dissertations
No abstract provided.
Assessment Of Underwater Radiated Noise And The Application Of Particular Sensitive Sea Areas To Limit Its Impact On Marine Life : Case Study On Development Of Underwater Noise Management System For The North Western Mediterranean Pssa, Brian Musinguzi
World Maritime University Dissertations
No abstract provided.
The Role Of The Philippine Coast Guard Toward Sustainable Coastal And Marine Tourism In Relation To United Nations Sustainable Development Goals, Kimmy Carrie Necesario
The Role Of The Philippine Coast Guard Toward Sustainable Coastal And Marine Tourism In Relation To United Nations Sustainable Development Goals, Kimmy Carrie Necesario
World Maritime University Dissertations
No abstract provided.
Digitalization Effects On Women Seafarers In The Era Of Maritime Autonomous Surface Ship (Mass), Taiwo Oluwatosin Olajide
Digitalization Effects On Women Seafarers In The Era Of Maritime Autonomous Surface Ship (Mass), Taiwo Oluwatosin Olajide
World Maritime University Dissertations
No abstract provided.
Acci̇Dental Oi̇L Polluti̇On From Tankers İN The Caspi̇An Sea : Problem Causes And Lessons Learned, Emin Sadirov
Acci̇Dental Oi̇L Polluti̇On From Tankers İN The Caspi̇An Sea : Problem Causes And Lessons Learned, Emin Sadirov
World Maritime University Dissertations
No abstract provided.
Ilegal, Unreported And Unregulated (Iuu) Fishing During Port State Control Inspections : : How To Enhance The Implementation Of Fao, Ilo, And Imo Instruments In A Joint Effort To Facilitate Inter-Institutional Coordination To Combat Iuu Fishing During Port State Control Inspections, José Miguel Jaramillo Mendoza
World Maritime University Dissertations
No abstract provided.