Development of a Neutron Source for Therapeutic Investigations

A collimated source is being developed for possible application to neutron therapy. The source is produced by the bombardment of 40 MeV alphas on a thick Be target. Using a tissue equivalent proportional counter, dose distributions were measured along the central and lateral axes. The quality of the radiation is estimated using dosimetric calculations

Experiencing space–time: the stretched lifeworlds of migrant workers in India

In the relatively rare instances when the spatialities of temporary migrant work, workers’ journeys, and labour-market negotiations have been the subject of scholarly attention, there has been little work that integrates time into the analysis. Building on a case study of low-paid and insecure migrant manual workers in the context of rapid economic growth in India, we examine both material and subjective dimensions of these workers’ spatiotemporal experiences. What does it mean to live life stretched out, multiplyattached to places across national space? What kinds of place attachments emerge for people temporarily sojourning in, rather than moving to, new places to reside and work? Our analysis of the spatiotemporalities of migrant workers’ experiences in India suggests that, over time, this group of workers use their own agency to seek to avoid the experience of humiliation and indignity in employment relations. Like David Harvey, we argue that money needs to be integrated into such analysis, along with space and time. The paper sheds light on processes of exclusion, inequality and diff erentiation, unequal power geometries, and social topographies that contrast with neoliberalist narratives of ‘Indian shining

Assistive technology needs, access and coverage, and related barriers and facilitators in the WHO European region: a scoping review

Purpose: Globally, assistive technology (AT) is used by over 1 billion people, but the prevalence of needs and access to AT in specific countries or regions is largely unknown. This scoping review summarises the evidence available on the prevalence of needs, access and coverage of AT in the World Health Organisation European Region and the barriers and facilitators to its use. Methods: Relevant publications were identified using a combination of two strategies: 1) a systematic search for AT publications in five scientific literature databases; and 2) consultations with 76 of the Region's AT experts. Result: The search strategies yielded 103 publications, 62 of them identified by the systematic search. The included publications were predominantly from six countries, and 18 countries were unrepresented. Information on AT use for specific functional impairments was present in 57 publications: AT for hearing impairment in 14 publications; vision in 12; mobility, 12; communication, 11; self-care, 6; and cognition, 2. AT needs for vision and hearing impairment were more likely to be met (1–87% and 5–90%, respectively) compared with communication and cognition impairments (10–60% and 58%, respectively). The barriers and facilitators to AT access described were linked to accessibility, affordability and acceptability. Conclusion: Data on AT prevalence and coverage are limited in both quantity and quality. Agreed-upon definitions of functional impairment and assistive product categories and standards for data collection are needed to facilitate data comparisons and to build a more representative picture of AT needs and coverage. Implications for rehabilitation: Comprehensive and disaggregated data concerning the prevalence of needs and coverage of AT is needed to enable the development of responsive policies and actions. The literature available on the prevalence of needs and coverage of AT in the WHO European Region is primarily focussed on a small subset of countries and comparisons between studies are limited due to the use of different data collection strategies. Evidence concerning barriers and facilitators to AT access across countries is more consistent and can be organised across the key themes of accessibility, affordability and acceptability of AT. There is a need for consensus among multiple AT actors on standardised definitions for functional impairment and assistive product categories and standards for data collection to enable a more representative picture to be built of AT needs and coverage across the WHO European Region and globally

LAND USE AND TRANSIT INTEGRATION AND TRANSIT USE INCENTIVES

Planners have often looked on transportation policies as a means of controlling broad patterns of land use. It has been argued that past transportation policies have contributed to decentralization of urban activities resulting in congestion, traffic hazards, and environmental pollution. Others contend that urban land uses reflect location decisions by individual households and employers and that transportation is just one of the many factors that affect such decisions. Thus, public policies in transportation have very little opportunity to alter future land use. The exact effect of transit on the distribution of urban activities, the resulting urban structure, the level of congestion, and air quality is not fully understood. An attempt is made in this paper to document successful cases of transit and land use integration as well as the techniques used by different agencies to bring about such integration. Various studies under the Transit Cooperative Research Program on different aspects of transit and land use policies serve as the basic sources of information for this paper. Eight case studies are examined that encompass a variety of transit modes in urban North America. It is concluded that the accessibility advantages provided by transit may play a crucial role in the concentration of development and in creating economic opportunities. However, transit by itself is not sufficient to guarantee successful transit-focused development. Other major factors are supportive regional and local policies and private investment in concert with the transit program. Further, successful transit and land use integration does not necessarily imply the presence of a high-speed rail system. In a strong market, when support policies are in place, light rail and busways can also be used to channel urban growth

PROCEDURE TO EVALUATE ALTERNATIVES TO TRANSIT BUS REPLACEMENT

The addition of new buses to a transit agency\u27s fleet is a capital-intensive project. In an average year, more than 3,500 buses are purchased by Federal Transit Administration grantees. The annual cost of bus replacement easily exceeds $1 billion. A procedure to evaluate alternatives to bus replacement is presented. Two generic alternatives are identified--rehabilitation and remanufacturing. The former approach focuses on the repair of engines and machine components. The latter approach is to restore a vehicle\u27s structural integrity. The evaluation procedure is based on economic principles and quantifies the benefits and costs associated with postponing a bus replacement, either by rehabilitation or remanufacturing. A modified benefit-to-cost ratio (B/C) technique is proposed that incorporates intangible benefits and disbenefits, as well as a risk penalty associated with the extended use of an older bus. As an alternative to computing the B/C, the recommended approach is to estimate the maximum investment that can be justified in a rehabilitation or remanufacturing project using the derived benefits. An affordability index is developed that is sensitive to the risk penalty used. Numerous examples are presented to demonstrate the application of the proposed procedure. Finally, a set of guidelines is presented to assist transit agencies in determining the economic viability of postponing a new-bus purchase by rehabilitating or remanufacturing an older bus

FRAMEWORK FOR ANALYZING ALTERNATIVES TO TRANSIT BUS REPLACEMENT

The addition of new buses to the existing fleet of any transit agency is a capital-intensive project. Approximately 50,000 transit buses are in service in the United States today that were purchased primarily through federal funds. In an average year, more than 3,500 buses are purchased by grantees of the Federal Transit Administration (FTA). A recent FTA study showed that, nationwide, the total annual cost of bus replacement easily exceeds $1 billion. An analytic framework for the assessment of alternatives to bus replacement is presented in this paper. Two generic groups of alternatives are identified: rehabilitation and remanufacturing. The former focuses on the repair of engines and machine components. The latter is more concerned with restoring the structural integrity of the bus. The framework developed uses the basic principles of economics and attempts to quantify benefits and costs associated with postponing the replacement of an existing bus either by rehabilitation or by remanufacturing. The procedure incorporates intangible benefits and disbenefits, as well as a risk penalty associated with the extended use of an existing bus beyond its normal service life. A set of examples is presented to demonstrate the application of the proposed framework. The examples show that the procedure is viable and can be used to assess the economic feasibility of alternatives to bus replacement

Single-Stage Integer Programming Model for Long-Term Transit Fleet Resource Allocation

The writers present a procedure for resource allocation among transit agencies for transit fleet management, specifically focusing on the purchase of new buses and rebuilding of existing buses. The model is formulated as a nonlinear optimization problem of maximizing the total weighted average remaining life of the fleet subject to budgetary, policy, and other constraints. The problem is solved using integer programming and its application is demonstrated through a case study using actual transit fleet data from the Michigan DOT. This proposed model is an extension of earlier research on a two-stage sequential optimization method, solved by linear programming. The proposed model has a single-stage structure designed to attain a better solution by allocating resources among different improvement options and different agencies in a single step. A comparison of the results by the two methods shows that while both approaches are viable, the single-stage approach produces better results. The proposed model, as demonstrated in the case study is considered more robust, compact, efficient and suitable for both short-term and long range planning

Optimal resource allocation among transit agencies for fleet management

Most transit agencies require government support for the replacement of their aging fleet A procedure for equitable resource allocation among competing transit agencies for the purpose of transit fleet management is presented in this study The proposed procedure is a 3-dimensional model that includes the choice of a fleet improvement program, agencies that may receive them, and the timing of investments Earlier efforts to solve this problem involved the application of 1- or 2-dimensional models for each year of the planning period These may have resulted in suboptimal solution as the models are blind to the impact of the fleet management program of the subsequent years Therefore, a new model to address a long-term planning horizon is proposed. The model is formulated as a non-linear optimization problem of maximizing the total weighted average remaining life of the fleet subjected to improvement program and budgetary constraints Two variants of the problem, one with an annual budget constraint and the other with a single budget constraint for the entire planning period, are formulated. Two independent approaches, namely, branch and bound algorithm and genetic algorithm are used to obtain the solution An example problem is solved and results are discussed in details. Finally, the model is applied to a large scale real-world problem and a detailed analysis of the results is presented. (C) 2010 Elsevier Ltd

Preserving an aging transit fleet: An optimal resource allocation perspective based on service life and constrained budget

Local, county and state level transit agencies with large fleets of buses and limited budgets seek a robust fund allocation mechanism to maintain service standards. However, equitable and optimal fund allocation for purchasing, operating and maintaining a transit fleet is a complex process. In this study, we develop an optimization model for allocation of funds among different fleet improvement programs within budget constraints over the planning period. This is achieved by minimizing the net present cost (NPC) of the investment within the constraint of a minimum level of fleet quality expressed as a surrogate of the remaining life of the fleet. Integer programming is used to solve the formulated optimization problem using branch and bound algorithm. The model formulation and application are demonstrated with a real world case study of transit agencies. It is observed that minimizing NPC provides a realistic way to allocate resources between different program options among different transit agencies while maintaining a desired quality level. The proposed model is generalized and can be used as a resource allocation tool for transit fleet management by any transit agency. (c) 2012 Elsevier Ltd. All rights reserved