bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatial Methodology for Assessing Distribution of Transportation Project Impacts with Environmental Justice Framework
Authors: Klein Nicholas
Published: January 2008

Given the importance of transportation planning and the heavy investment in transportation made in metropolitan regions across the country, there is insufficient analysis of the distribution of investments and transportation project impacts. Methods of analysis in the academic arena and in practice by metropolitan planning organizations (MPOs) are not adequate to describe the distribution of impacts or the cumulative nature of these impacts on local populations across a region. Although transportation planners evaluate specific project benefits and burdens and perform some regional distribution analyses, a thorough and scientific analysis of the impacts throughout a region is not currently performed. The project described here offers new methods for the evaluation of transportation project impacts by combining geographic information system practices with spatial analysis techniques to bring additional analytic capabilities to the process. Although this project does not address all of the shortcomings of the current methods, the analysis is a significant improvement over the existing descriptive methods used by MPOs. This project adds to the understanding of the distribution of transportation project impacts by demonstrating a flexible method of analysis of the cumulative impacts of transportation policies on communities over time.
Gender and the Automobile
Authors: Vance Colin , Iovanna Rich
Published: January 2008

With a focus on individual motorists in car-owning households in Germany, this analysis econometrically investigates the determinants of automobile travel for nonwork service activities against the backdrop of two questions: (a) Does gender play a role in determining the probability of car use and the distance driven? and (b) If so, how is this role mitigated or exacerbated by other socioeconomic attributes of the individual and the household in which he or she resides? Drawing on a panel of data collected between 1996 and 2003, Heckman's sample selection model is specified to control for biases that otherwise could arise from the existence of unobservable variables that determine both the discrete and the continuous choices pertaining to car use. The results indicate that although women, on average, undertake more nonwork travel than men, they undertake less such travel by car, implying a greater reliance on other modes. Moreover, employment status, age, the number of children, automobile availability, and the proximity to public transit are all found to have significantly different effects on the probability of nonwork car travel between men and women but—with the exception of automobile availability—not on the distance driven. Taken together, these results suggest that policies targeted at reducing automobile dependency and associated negative externalities, such as congestion, are unlikely to have uniform effects across the sexes. These findings have implications for both policy evaluation and travel demand forecasting.
Mode Choice Behavior of Elderly Travelers in Honolulu, Hawaii
Authors: Lucas Tara Y. I. , Archilla Adrian Ricardo , Papacostas C. S.
Published: January 2008

A literature review of studies that focused on the travel behavior of older people suggested that the following factors affected travel behavior: age, gender, medical condition, ability to drive, cost of a trip, residential location (suburb versus city), trip purpose, day of the week, time of day, income, and availability of a private vehicle. This study estimated two discrete-choice multinomial logit models of mode choice by using data from a household interview survey conducted by the Oahu Metropolitan Planning Organization, Hawaii. In addition to traveler and trip attributes, the models included certain travel time and cost variables. The estimation data contained data for trips made by both elderly and nonelderly people. These models suggest that being elderly, retired, or both, has a negative effect on driving, being a passenger, and walking, as compared with taking transit. Use of the estimated models to perform sensitivity analyses also is illustrated. This analysis helped to visualize the finding that being elderly and the costs of driving and out-of-vehicle transit are more important determinants of shifts away from driving and toward the use of transit than travel time changes.
Development and Evaluation of Speed-Activated Sign to Reduce Speeds in Work Zones
Authors: Mattox James H. , Sarasua Wayne A. , Ogle Jennifer H. , Eckenrode Ryan T. , Dunning Anne
Published: January 2008

Excessive speed is one of the most significant factors contributing to work zone crashes, which, along with work zone fatalities, have increased substantially in the past decade. From the beginning of 2000 to the end of 2003, the number of work zone crashes in South Carolina nearly tripled. In 2005, the South Carolina Department of Transportation initiated a research project to evaluate speed reduction measures in work zones. Through an in-depth literature review of speed control techniques for work zones, it was found that innovative technologies are often too expensive and thus impractical for large-scale implementation. There is a need for less-expensive technologies that are effective in reducing speeds in work zones. Development and evaluation of a speed-activated sign are discussed. Data were collected in work zones on two-lane primary and secondary highways in South Carolina, and the effectiveness of the speed-activated sign was evaluated on the basis of changes in mean speeds, 85th-percentile speeds, and percentages of vehicles exceeding the speed limit. Mean speed reductions ranged from 2 to 6 mph (3.2 to 9.7 km/h) with an average reduction of 3.3 mph (5.3 km/h). This average reduction improved to 4.1 mph (6.6 km/h) at sites where more than 50% of the vehicles were speeding before a sign was introduced. Further research was conducted with two speed-activated signs on a multilane divided highway and an Interstate freeway where similar speed reductions were experienced. From this study, researchers recommend that the speed-activated sign be used in short-term work zones.
Driver Understanding of Sequential Portable Changeable Message Signs in Work Zones
Authors: Ullman Brooke R. , Ullman Gerald L. , Dudek Conrad L. , Williams Alicia A.
Published: January 2008

Results of a Texas Transportation Institute driving simulator study are presented. The study's focus was the ability of motorists to capture and process information on two portable changeable message signs (PCMS) used in sequence (i.e., one PCMS following another along the edge of the roadway such that each PCMS contains part of a single message). The purpose of the PCMS is to convey information about upcoming traffic situations. Results indicate the need to keep messages at or below the four-unit maximum recommended in existing guidelines. It was found that presenting five units of information on sequential PCMS resulted in low comprehension rates, below what would be acceptable for highway applications. However, by keeping the message length to four units, it appears that the use of the sequential PCMS will result in comprehension rates comparable with those obtained by presenting the same information at a single location on a large dynamic message sign. Comprehension may be enhanced by repeating one line of the message on both PCMS used in a given sequence.
Evaluation of Alternative Dates for Advance Notification on Portable Changeable Message Signs in Work Zones
Authors: Ullman Gerald L. , Ullman Brooke R. , Dudek Conrad L.
Published: January 2008

Results of a laptop-based human factors study of alternative formats of presenting notice of future roadwork messages on portable changeable message signs (PCMS) in highway work zones are documented. A total of 192 participants across Texas were shown a series of different two-phase messages for a fixed period of time and asked questions by test administrators to determine comprehension and recall of the information presented in each message. Participants were also asked to indicate their preferred format for presenting such information on a PCMS. On the basis of these studies, it is recommended that messages that require the display of calendar dates for future roadwork and other traffic control activities use a message format consisting of the three-character abbreviation of the month (e.g., APR for April) in conjunction with the date. When future work activities span several days in the same month, the month needs to be noted only once in the message (i.e., APR 21–23) rather than repeating the month (i.e., APR 21-APR 23).
Work Zone Crashes Involving Traffic Control Devices, Safety Features, and Work Vehicles and Equipment
Authors: Bryden James E.
Published: January 2008

Examinations were made of 461 work zone crashes involving Category 3 and Category 4 work zone safety features, portable traffic signs, and work vehicles and equipment. Category 3 devices include crash attenuators and temporary traffic barriers. Category 4 devices include trailer-mounted arrow panels, changeable message signs, and light towers. Crash data reported here, compiled from recent New York State Department of Transportation construction projects, show that portable signs and Category 4 devices are involved in a small number of crashes and rarely result in injuries to vehicle occupants or workers. The use of traffic barriers or attenuators to reduce crash frequency and severity involving these devices is not indicated, because severity rates on temporary barriers and work zone attenuators are higher than on the devices they would be used to protect. Both work zone attenuators and temporary barriers were involved in a substantial number of crashes and injuries. These crashes emphasize the importance of deploying the devices according to accepted work zone practices and limiting their use to situations in which they are warranted to protect more serious hazards. Worker injuries reported in a number of these crashes emphasize the importance of safe work practices such as restraint use by vehicle occupants, even at slow speeds in work zones, and effective separation of workers from traffic in work zones.
Wet Night Visibility of Pavement Markings
Authors: Gibbons Ronald B. , Hankey Jonathan
Published: January 2008

Fifty-three participants evaluated the visibility of four different pavement marking materials under a simulated rain system operating at 0.8 in. (20 mm) of rain per hour at night while driving a vehicle on a closed test track. The conditions tested include a variable lighting condition, glare, pavement types, and two different vehicle types. The evaluation consisted of determining the detection distance of a start or an end point of a white 4-in. edge line. Results showed that lighting improved visibility and mitigated the effects of glare. Results also showed that the wet retroreflective tape provided the longest visibility distance, followed by equivalent performance of profile thermoplastic; large glass beads with standard paint provided the shortest visibility distance. The detection distance was compared with the retroreflective performance of the pavement marking technology. It was found that a log-linear relationship exists between the retroreflectivity and the detection distance. It was also found that the level of retroreflectivity provided by the materials tested did not provide adequate visibility distance for a sedan with a 2-s visibility time at speeds greater than 45 mph.
Evaluating the Retroreflectivity of Pavement Marking Materials under Continuous Wetting Conditions
Authors: Pike Adam M. , Hawkins H. Gene , Carlson Paul J.
Published: January 2008

Wet weather performance of pavement markings has received increased emphasis with the availability of new products designed specifically to improve nighttime visibility in wet weather conditions. Procedures for measuring the performance of these and standard marking materials are found in ASTM E1710, E2176, and E2177, which describe retroreflectivity measurement in dry, continuous wetting, and recovery conditions, respectively. Research comparing the retroreflectivity values measured for 18 different marking samples in 14 measurement conditions is described. Each sample was measured according to the three ASTM procedures, plus an additional 11 rates of continuous wetting. In addition, analysis was done of 20 years of Texas rainfall data to gain an understanding of the relationships between actual rainfall rates and the rates specified in E2176. Findings indicate that while the allowable rainfall rate in E2176 ranges from 6 to 14 in./h, 88% of rainfall events produced maximum rates less than 0.75 in./h. A wide variability was found in the retroreflectivity values of materials as a function of the wet condition. For most markings, the retroreflectivity level decreases as the rainfall rate increases, but changes in retroreflectivity were not consistent for the different samples. Also, an analysis of the effect of cross slope on wet retroreflectivity measurements indicated that it has a major impact on the measured values. Findings suggest that the range of conditions permitted by E2176 brings into question the ability to use this procedure to compare material retroreflectivity in a standardized manner.
Characterization and Mitigation of Temperature Sensitivity within Mobile Retroreflectometer Unit
Authors: Fletcher James , Philpott Aaron , Choubane Bouzid , Holzschuher Charles
Published: January 2008

Mobile retroreflectometers have demonstrated great potential as a tool to assess the retroreflectivity of pavement markings, on both project and network levels. Such devices can collect and process much more data than their handheld predecessors can. However, studies have shown concerns with repeatability and reproducibility. Successful integration of pavement marking retroreflectivity readings into a pavement management system hinges on the accuracy of the collected data. Previous research has centered on data collection techniques to minimize error (collection frequency, averaging), but little research has focused on the technology and the components making measurement possible. Results were summarized for the characterization and the mitigation of a temperature sensitivity uncovered during the Florida Department of Transportation's evaluation of a mobile retroreflectometer unit. During routine data collection, offsets in the measured retroreflectivity were observed between results from repeat runs on the same section. A strong correlation was observed between the temperature of the device and measured retroreflectivity. More specifically, as the temperature within the device increased from 20°C to 40°C, a 30% increase in measured retroreflectivity resulted. Testing revealed that the optical filters operating outside their manufacturer-specified temperature range were primarily responsible for the temperature sensitivity. The response of the filter set over a broad range of temperatures was characterized, and a compensation algorithm was created to reduce system error. A thermoelectric cooler was incorporated to regulate the internal temperature of the retroreflectometer. With these modifications, a temperature sensitivity of ±3% resulted over a temperature range of 20°C.
Finite Element Modeling of Stresses inside a Raised Pavement Marker during Tire–Marker Impacts
Authors: Zhang Yunlong , Agrawal Ravi P. , Schrock Steven D. , Tong Jiaxin
Published: January 2008

Retroreflective raised pavement markers (RRPMs) supplement other pavement markings to provide guidance to road users. The poor durability of many RRPMs in the field indicates a need to develop improved laboratory testing procedures. This requires identifying critical locations and magnitudes of stresses inside the markers during the tire–marker impacts that happen on roads. The goal of this research was to investigate stresses inside an RRPM model under tire–marker impact and to analyze the effect of external factors. Tire–marker impacts were modeled and simulated through the use of the finite element tools Hypermesh and LS-DYNA. The simulated critical locations and estimates of magnitudes of stresses inside the markers were identified. According to the simulations, the critical stresses lie on the top edges of the marker, perpendicular to the traffic direction. It was found that the stresses increase inside the markers as the tire load is increased. In addition, relatively high stresses were seen as the location of the impact moves away from the center of the marker. The angle of impact was found to affect the tensile stresses inside the markers, with higher angles causing greater tensile stresses. On the basis of the simulations, no consistent effect of the tire speed was found on the stresses inside the markers. These findings point toward requirements for improved testing standards. It is believed that a laboratory procedure that can replicate these internal stresses should result in a test with the ability to predict actual field performance more accurately.
Enhancing Road Weather Information through Vehicle Infrastructure Integration
Authors: Petty Kevin R. , Mahoney William P.
Published: January 2008

Vehicle infrastructure integration (VII) represents a concept with the potential to aid in the reduction of weather-related accidents on U.S. roadways while increasing surface transportation mobility and efficiency. Technological advancements in the automotive and telecommunications industries have resulted in the ability of vehicles to acquire and use high temporal- and spatial-resolution information associated with environmental and roadway conditions. VII would enable vehicle-to-vehicle and vehicle-to-infrastructure communications through dedicated short-range communications (wireless radio communication at 5.9 GHz). This capability could potentially serve as a means of gathering and distributing vehicle data in support of applications and products designed to diagnose and predict road weather conditions. It is believed that the inclusion of VII-enabled data in road weather applications will improve weather and road condition analyses and forecasts. A summary is given of vehicle data elements that are likely to contribute to development and improvement of road weather products. A synopsis of probable VII product enhancements is provided, along with examples of how vehicle data can be used in the application development process. Developing a broad understanding of how to use vehicle data properly will require a significant amount of research. Research needs aimed at addressing the technical issues and barriers associated with the use of VII-enabled data are discussed.
Optimal Allocation of Multiple Emergency Service Resources for Protection of Critical Transportation Infrastructure
Authors: Huang Yongxi , Fan Yueyue , Cheu Ruey Long
Published: January 2008

Optimal deployment of limited emergency resources in a large area is of interest to public agencies at all levels. In this paper, the problem of allocating limited emergency service vehicles including fire engines, fire trucks, and ambulances among a set of candidate stations is formulated as a mixed integer linear programming model, in which the objective is to maximize the service coverage of critical transportation infrastructure (CTI). On the basis of this model, the effects of demand at CTI nodes and of transportation network performance on the optimal coverage of CTI are studied. In addition, given a fixed total budget, the most efficient distribution of investment among the three types of emergency service vehicles is identified. To cope with the uncertainty involved in some of the model parameters such as traffic network performance, formulations based on various risk preferences are proposed. The concept of regret is applied to evaluate the robustness of proposed resource allocation strategies. The applicability of the proposed methodologies to high-density metropolitan areas is demonstrated through a case study that uses data from current practice in Singapore.
Optimizing Protective Measures with Respect to Multiple Hazards
Authors: Murray-Tuite Pamela M.
Published: January 2008

In the past century, more than a thousand attacks targeted the transportation system or used it as a weapon. In the latter case, terrorists transformed the transportation system into a delivery system for vehicular bombs targeting structural assets. The most effective protection against this threat is the erection of barriers to create sufficient distance between the asset and the avenue of attack. However, these barriers often impede traffic flow and degrade evacuation and other emergency response times. Thus, although they reduce a network's risk from one type of event, the protective measures increase risk from other hazards. This paper examines the trade-offs between protective measures that limit vehicle access to structures and the benefits of a fully operational transportation system in evacuation scenarios. A framework containing a linear integer program is presented to select optimally a vector of active and passive security measures while ensuring emergency transportation connectivity and mobility, a sufficient benefit-cost ratio, budget compliance, and workforce availability. Application of the framework to a sample network indicated that the protective measures induced more risk than they alleviated. These results are specific to the network and scenarios evaluated. However, security professionals, planners, and government decision makers can use the methodology presented in this paper to evaluate their networks and area-specific hazards in order to make better-informed security choices that consider all representative events simultaneously rather than in isolation.
Emergency Logistics Issues Affecting the Response to Katrina
Authors: Holguín-Veras José , Pérez Noel , Ukkusuri Satish , Wachtendorf Tricia , Brown Bethany
Published: January 2008

Extreme events pose serious logistical challenges to emergency and aid organizations active in preparation, response, and recovery operations, because the disturbances they produce have the potential to turn normal conditions suddenly into chaos. Under these conditions, delivering critical supplies (e.g., food, water, medical supplies) becomes an extremely difficult task because of the severe damage to the physical and virtual infrastructure and the limited or nonexistent transportation capacity. In this context, the recovery process is made more difficult by the prevailing lack of knowledge about the nature and challenges of emergency supply chains. As a result, the design of reliable emergency logistics systems is hampered by lack of knowledge about how formal and informal (emergent) supply chains operate and interact; methods to analyze and coordinate the flows of priority and nonpriority goods; and, in general, scientific methods to analyze logistics systems under extreme conditions. This paper describes the key logistical issues that plagued the response to Hurricane Katrina. The logistical failures following Katrina, which in August 2005 devastated the U.S. Gulf Coast, provide an example of the need to improve the efficiency of supply chains to the site of an extreme event. The paper is based on public accounts of the event and interviews conducted during a number of field visits to the Katrina-affected area in the aftermath of the event, as part of a research project funded by the National Science Foundation.
Molecular imaging of reduced renal uptake of radiolabelled [DOTA0,Tyr3]octreotate by the combination of lysine and Gelofusine in rats
Authors: Bernard B. F. , Breeman W. A. P. , Forrer F. , de Blois E. , Hoppin J. , Gotthardt M. , Boerman O. C. , Krenning E. P. , de Jong M. , Rolleman E. J.
Published: January 2008

Aim: In peptide receptor radionuclide therapy (PRRT) using radiolabelled somatostatin analogues, kidney uptake of radiolabelled compound is the major dose-limiting factor. We studied the effects of Gelofusine (20 mg) and lysine (100 mg) and the combination of both after injection of therapeutic doses of radiolabelled [DOTA0,Tyr3]octreotate (60 MBq 111In or 555 MBq 177Lu labelled to 15 μg peptide) in male Lewis rats. Methods: Kidney uptake was measured by single photon emission computed tomography (SPECT) scans with a four-headed multi-pinhole camera (NanoSPECT) at 24 h, 5 and 7 days p. i. and was quantified by volume of interest analysis. For validation the activity concentration in the dissected kidneys was also determined ex vivo using a gamma counter and a dose calibrator. Results: Gelofusine and lysine both reduced kidney uptake of [177Lu-DOTA0,Tyr3]octreotate significantly by about 40% at all time points. The combination of Gelo - fusine and lysine resulted in a 62% inhibition of kidney uptake (p < 0.01 vs. lysine alone). A weak but significant dose-response relationship for Gelofusine, but not for lysine, was found. In a study with [111In-DOTA0,Tyr3]octreotate, conclusions drawn from NanoSPECT data were confirmed by biodistribution data. Conclusions: We conclude that rat kidney uptake of radiolabelled somatostatin analogues can be monitored for a longer period in the same animal using animal SPECT. Gelofusine and lysine had equal potential to reduce kidney uptake of therapeutic doses of [177Lu-DOTA0,Tyr3]octreotate. The combination of these compounds caused a significantly larger reduction than lysine or Gelofusine alone and may therefore offer new possibilities in PRRT. The NanoSPECT data were validated by standard biodistribution experiments.
Somatostatin receptor scintigraphy in advanced renal cell carcinoma
Authors: Gauler T. , Görges R. , Bauer S. , Stergar H. , Antoch G. , Bockisch A. , Schütte J. , Freudenberg L. S.
Published: January 2008

Aims: Objective of this prospective study was to evaluate the role of somatostatin receptor scintigraphy (SRS) in advanced renal cell carcinoma (RCC) with respect to potential therapy with somatostatin analogue (SST-A) and to assess the response rate under therapy with SST-A. Patients, methods: 16 patients with documented progression of histologically confirmed advanced RCC were included. Planar whole-body SRS was performed 4, 24 and 48h post i.v. injection of 175–200 MBq 111In-pentetreoide. 5 and 25 h p.i. SPECT of thorax and abdomen were performed. Documentation of somatostatin receptor expression via SRS in >50% of known tumour lesions was the criteria for treatment start with SST-A (Sandostatin LAR®-Depot 30mg i.m. every four weeks). Results: In 9/16 of the patients SRS showed at least one metastasis with moderate (n = 5) or intense (n = 4) tracer uptake. Lesion-based SRS evaluation showed only 12.1% (20/165) of all metastases. Most false-negative lesions were located in the lungs. In two patients, the majority of the known metastases was SRS positive and these patients received SST-A therapy. The first radiographic evaluation after a twomonth interval showed progressive disease in both patients. Conclusions: We conclude that SRS is of limited value in staging of advanced RCC. In our patients SST-A did not result in a growth control of RCC. Consequently, the use of SST-A in advanced RCC seems to be no relevant therapeutic option.
Factors affecting the specific activity of [18F]fluoride from a [18O]water target
Authors: Preusche S. , Mäding P. , Zessin J. , Steinbach J. , Füchtner F.
Published: January 2008

Aim: Characterisation of the influence of different polymeric tube materials of a water target system, used for the production of 18F activity, on the specific activity of radiotracers. Material, methods: Target water samples taken from different locations of the 18F water target system of a Cyclone® 18/9 cyclotron, equipped with Teflon® (PTFE) or polypropylene (PP) tubes, were analyzed for non-radioactive [19F]fluoride content. [19F]Fluoride content was measured by ion chromatography (IC20, Dinoex) with suppressed conductivity detection. Both the ion chromatographic results and the amount of 18F activity produced were used for the calculation of the specific activity (SA) of [18F]fluoride at the start of the labelling synthesis. To check these results, the SA of the labelled receptor ligand [18F]ZK811460 was also determined by using the different tubing materials. Results: Dose-exposed PTFE tubes of the target dispensing (loading) system were identified to be a major source of [19F]fluoride contamination. Conclusion: By replacing PTFE tubes of the target dispensing system with PP tubes, the content of 19F was reduced considerably resulting in an increase of SA of the radiotracer [18F]ZK811460 by factor of two.
Demonstration of angiogenesis and the effect on an antiangiogenetic therapy with 99mTc labeled erythrocytes
Authors: Bodenstein C. , Senekowitsch-Schmidtke R. , Weber W. A. , Zengel P.
Published: January 2008

Aim: To evaluate, whether scintigraphic studies with radiolabeled erythrocytes may be used to demonstrate the formation of new vessels during angiogenesis and if an effect on antiangiogenetic therapy could be detected. Methods: As an angiogenesis model we used the ingrowth of blood vessels in matrigel, subcutaneously injected into mice. In order to measure the relative blood volume in the matrigel non-invasively, mouse erythrocytes were labeled with Technetium-99m DTPA. The amount of activity in the matrigel was measured 30 minutes after injection of the radiolabeled erythrocytes with a gammacamera (in-vivo) and a gammacounter (ex-vivo). These results were correlated with the concentration of hemoglobin in the matrigel and the immunhistochemically evaluated density of blood vessels. The influence of the angiogenesis stimulating growth factor (bFGF) and the antiangiogenetic effect of the cyclooxigenase type 2 inhibitor (COX-2) NS398 were tested. Results: There was a close correlation between the activity concentration in the matrigel and the hemoglobin content. Treatment with bFGF significantly increased the activity concentration from 1.74% ± ID/g to 4.06% ± 0.36 (p < 0.01), whereas treatment with NS398 significantly inhibited tracer uptake from 2.83% ID/g ± 0.33 to 0.87% ID/g ± 0.12 (p < 0.01). Conclusion: These results demonstrate the feasibility of using 99mTc labelled erythrocytes for scintigraphic imaging to assess the effects of angiogenesis stimulating and inhibiting interventions noninvasively.
Survey of management of solitary thyroid nodules in Germany
Authors: Wegscheider K. , Vaupel R. , Schmidt M. , Schicha H. , Dietlein M.
Published: January 2008

Aim: To compare the opinions of practitioners in primary care with those of thyroid specialists in Germany on the management of solitary thyroid nodules (Papillon 2005). Methods: Questionnaires were filled in by 2,191 practitioners and 297 thyroid specialists between June 1 and September 30, 2005. The test cases and their modifications described a solitary thyroid nodule of 2–3 cm with different levels of thyroid function and a hypoechogenic nodule of 1 cm in diameter. Results: TSH determination and sonography were found to be standard procedures, followed by scintigraphy (selected by 84.7% of practitioners and 95.1% of specialists, p < 0.001) and fine needle aspiration cytology (54.5% of practitioners, 57.4% of specialists). For a hypoechogenic nodule calcitonin determination was advocated by 54.0% of endocrinologists and by 32.2% of nuclear medicine physicians (p < 0.001). A euthyroid solitary thyroid nodule would be treated medically by 77.8% of practitioners and by 85.7% of specialists, the combination of levothyroxine and iodine being clearly preferred (60.9% of practitioners and 67.1% of specialists). For a hyperfunctioning nodule the preference of radioiodine therapy was significantly higher in the specialist group (88.8%) than among the practitioners (52.2%). Conclusions: The main differences of opinion between practitioners and specialists focused on calcitonin screening and referral to radioiodine therapy.
Is there a role for scintigraphic imaging of bone manifestations in Gaucher disease?
Authors: Kohlfürst S. , Gallowitsch H. J. , Kresnik E. , Lind P. , Mehta A. B. , Hughes D. A. , Mikosch P.
Published: January 2008

Gaucher disease is the most prevalent inherited, lysosomal storage disease and is caused by deficient activity of the enzyme β-glucocerebrosidase. Bone and bone marrow alterations are frequent in the most prevalent non-neuronopathic form of Gaucher disease. Imaging of bone manifestations in Gaucher disease is performed by a variety of imaging methods, conventional X-ray and MRI as the most frequently and most important ones. However, different modalities of scintigraphic imaging have also been used. This article gives an overview on scintigraphic imaging with respect to bone manifestations in Gaucher disease discussing the advantages and limitations of scintigraphic imaging in comparison to other imaging methods.
Assembly Language
Authors: King Willis
Published: January 2008

An assembly language is a symbolic representation of a corresponding machine language. Whereas a machine language program consists of bit patterns, an assembly language program consists of alphanumeric names (symbols), numbers, and other special characters. The names describe operations to be performed (mnemonics) as well as storage locations and registers from which data (operands) are to be fetched or stored. While the machine language instruction is the only instruction a computer can “understand,” it is very difficult for humans to write a program using pure machine language directly. Assembly language was the first step taken some 60 years ago to facilitate programming and it led to the development of more powerful programming languages (higher level languages).
Automatic Test Generation
Authors: Belfore Lee A.
Published: January 2008

Automatic test generation (ATG) is an essential component in any test strategy. ATG automates the process of finding good tests, which allows the designer to focus on higher level aspects of the test architecture. ATG has a theoretic basis in the Boolean algebra and the logic circuits used to represent and implement, respectively functions in digital systems. Sequential tests complicate the testing process and are handled in one of two ways. First, the sequential machine is unrolled symbolically, which gives it the appearance of a combinational machine. Second, the circuit may be modified to allow for easier and more effective testing. Technology trends continue to present challenges for ATG. These challenges drive an active research community that search for problems associated with the progression of technology that makes testing approaches either more difficult or not effective, intellectual property cores whose internals may not be available to the test designer, and high levels of abstraction used typically in modern design methodologies.
Coordination and Synchronization: Designing Practical Detectors for Large‐Scale Distributed Systems
Authors: Gupta Indranil
Published: January 2008

Online detectors are important to achieving coordination and synchronization in large‐scale distributed applications that run in peer‐to‐peer systems, the Grid, PlanetLab, and large‐scale, enterprise‐like server farms. Detectors can be used to monitor the up/down status of hosts, the malicious behavior among processes, and the availability behavior among hosts, and to estimate the number of hosts in a distributed system. We discuss a variety of online detectors that exist for these different problems with an emphasis on practical solutions that satisfy two characteristics: They have been implemented and validated in experimental evaluation or practice, and they are based on novel ideas and on strong theory. The goal of this article is to enable practitioners to understand these protocols so they can be implemented easily or adapted for various distributed systems. This article aims to provide the starting researcher an overvew, and a good feel for the area of detectors to enable additional learning in this interesting field.
Evolutionary Learning
Authors: Dracopoulos Dimitris C.
Published: January 2008

This article describes the use of evolutionary computing techniques in machine learning tasks. The different categories of evolutionary computation are outlined: emphasis is given in the description of how these can be applied to problems that require learning. Learning algorithms that do not involve evolutionary algorithms are not included, but references in which the reader can find detailed information about such nonevolutionary learning approaches are provided.
High‐Level Synthesis
Authors: Damaj Issam
Published: January 2008

Hardware synthesis is a general term used to refer to the processes involved in automatically generating a hardware design from its specification. High‐level synthesis (HLS) could be defined as the translation from a behavioral description of the intended hardware circuit into a structural description similar to the compilation of programming languages (such as C and Pascal into assembly language. The chained synthesis tasks at each level of the design process include system synthesis, register‐transfer synthesis, logic synthesis, and circuit synthesis. The development of hardware solutions for complex applications is no more a complicated task with the emergence of various HLS tools. Many areas of application have benefited from the modern advances in hardware design, such as automotive and aerospace industries, computer graphics, signal and image processing, security, complex simulations like molecular modeling, and DND matching. The field of HLS is continuing its rapid growth to facilitate the creation of hardware and to blu more and more the border separating the processes of designing hardware and software.
Knowledge Management Application
Authors: K. Maier Ronald
Published: January 2008

Information and communication technologies (ICT) that support the handling of knowledge in organizations have been discussed for a long time. From the 1950s to the 1980s, systems that apply artificial intelligence (AI) technologies had a powerful impact on the conceptualization of knowledge, not only in the discipline computer science, but also in fields such as management science, organization science, or psychology. However, many business organizations that attempt to implement these technologies were frustrated by their comparably high complexity and the difficulties of applying them to business challenges. Thus, AI technologies survived only in specific application fields. In the 1990s, after a period of high attention to the increase of efficiency, organizations were faced with the transformation of the economy into a knowledge economy and its challenges to increase significantly the speed of innovation and to improve the way organizations handle (distributed) knowledge. For those countries that do not have (anymore) the possibility to exploit some form of natural resources, it is knowledge that creates wealth. Organizations strive to increase productivity of
knowledge work
. Knowledge work is creative work, it solves ill‐structured problems in complex domains with high variety and many exceptions, and thus it requires a high level of skills and expertise from employees. The challenge is to design, implement, and maintain an organizational and ICT environment conducive for this type of work. The importance of knowledge work can be underlined by a recent study that showed that most jobs created in the United States between 1990 and 2000 in fact are jobs in the knowledge work sector (1).
Data Storage on Magnetic Disks
Authors: Piramanayagam S. N.
Published: January 2008

Hard disk drives (HDDs) have been used as storage devices in computers for more than 50 years. Although the first HDD of 1956, which was three to four times bigger than a fridge, had a capacity of 5 × 10
6
bytes, recent HDDs that are as big as a paperback book have a capacity of 1 × 10
12
bytes. In addition to capacity, HDDs can also outdo their competitors in terms of price. Because of cost and capacity advantage, HDDs have also found a significant place in the consumer electronic devices, such as in video cameras and video recorders that require huge storage requirements. Entry of HDDs in consumer electronic devices was possible because of the tremendous progress that was made in almost all the technologies associated with the HDDs. This article will provide an overview of HDDs, with more emphasis on the magnetic disks that store the information.
Microprogramming
Authors: Bomar Bruce W.
Published: January 2008

The microprogrammed approach to implementing control state machines has been used widely since the early 1960s and has the advantages of structured programming and fixed timing characteristics. With microprogramming, state machine changes require only a change in memory contents, so the rate at which the controller can be
clocked does not change no matter how significant the program change. This approach is in contrast to the standard state machine approach with state transitions described in a hardware description language like VHDL or Verilog, where design changes can dramatically impact the logic equations, amount of combinational logic, and clock frequency. This article introduces the microprogramming technique and presents a microprogrammed control unit that has been tailored to implementation in field programable gut arrays. The sequencer presented supports both nested subroutines and nested loops and can operate in both pipelined and non‐pipelined modes. Althouse not attractive for a small number of states, the microprogrammed approach has significant advantages for complex controllers with a large number of states.
Mixed Integer Programming
Authors: Wolsey Laurence A.
Published: January 2008

A linear mixed integer program is an optimization problem in which a nonempty subset of integer variables (unknowns) and a subset of real‐valued (continuous) variables exist, the constraints are all linear equations or inequalities, and the objective is a linear function to be minimized (or maximized). After presenting several practical applications of mixed integer programming, we describe the main classes of algorithms, branch‐and‐bound and branch‐and‐cut, that are used to solve this hard class of problems. Considerable attention is paid to ways to improve solution times, involving preprocessing, reformulation with cuts and/or new variables, and heuristics.
Multigrid Methods
Authors: Mijalković Slobodan Ž. , Mihajlović Milan D.
Published: January 2008

Numerical modeling of important phenomena and processes in science and engineering has emerged in recent years as an alternative to the experimental approach. The ever‐increasing computer speed and storage capabilities enable modeling of large‐scale problems in continuum mechanics, electromagnetism, quantum physics, and other important areas. To perform the modeling task efficiently, sophisticated algorithms and numerical techniques for the solution of the underlying models are essential. Such models are expressed frequently as mathematical equations. To represent a continuous mathematical model on a computer, which operates on discrete binary‐coded data, a mathematical procedure referred to as the discretization needs to be deployed. A common result of the discretization procedure is a system of linear or non linear equations that needs to be solved. Numerical modeling of complex systems frequently requires the solution of large systems of equations (numbering several million). Such systems need to be solved repeatedly, as part of an iterative procedure, such as linearization, time‐stepping, optimization, or inverse problems. This reason is why the solution of linear systems is a crucial phase of the overall numerical modeling process. As a result, substantial research effort has been devoted to the development of effective numerical algorithms for the solution of linear systems.

This article describes an important class of iterative algorithms for the solution of linear systems, referred to as multigrid (MG) methods. MG was developed originally in the context of the solution of discretized differential equations, with the aim to overcome the difficulties that standard iterative solvers encounter in this context. Over time, MG methods have evolved into an independent field of research, which has a major impact on many scientific and engineering disciplines. In this article, we present a brief review of MG and its applications to some realistic problems from numerical modeling practice.
Object‐Oriented Databases
Authors: Bertino Elisa , Guerrini Giovanna
Published: January 2008

Object‐oriented databases result from the integration of database technology with the object‐oriented paradigm developed in the programming languages and software engineering areas. They have been developed to meet the requirements imposed by applications characterized by highly structured data, long transactions, data types for storing images and texts, and nonstandard, application‐specific operations. Examples of such applications, which have requirements and characteristics different from those typical of traditional database applications for business and administration, are design and manufacturing systems (CAD/CAM, CIM), scientifical and medical databases, geographic information systems, and multimedia databases.

In this article, we discuss object‐oriented databases, with a focus on data model and query language aspects.
Parallel Architectures
Authors: Alaghband Gita
Published: January 2008

A general overview of parallel computer architectures is presented. Various types are introduced by applying the main concepts of replication and overlap to achieve concurrency in computer architectures. Distinguishing features, applicability, and issues related to each major parallel architecture type are described. A more detailed discussion for each architecture category is covered in dedicated individual articles in this encyclopedia.
Peer‐to‐Peer Communication
Authors: Guo Lei , Zhang Xiaodong
Published: January 2008

This article presents the basic principle of peer‐to‐peer communications and representative peer‐to‐peer systems.
Software Safety
Authors: Kornecki Andrew J.
Published: January 2008

Safety is a property of a system that ensures it will provide harmless operation. Safe systems do not jeopardize human life, endanger property, or put the environment at risk. Because of the progress'of technology and the proliferation of computers in everyday life, modern systems are increasingly software intensive. Computers control everything possible from microwave covens to complex weapon systems. Certainly, software may introduce safety risks because of nature of the system that it controls. When systems experience failures because of faulty software—and this failure leads to safety violations—serious questions are raised. Despite the risks, software increasingly is making its way into safety‐critical systems.

Software must be evaluated early for its contribution to the safety of the system: during the concept phase and before the acquisition or development of the software. The term “software safety” is related to the software‐focused features and measures that provide assurance that (a) a system performs predictably under normal and abnormal conditions and (b) the probability of unintended events is minimized. consequences are controlled. The discipline of software safety is the systematic approach to identifying, analyzing, and tracking hazardous functions implemented by software, as well as software‐based mitigation and control of hazards to ensure safer software operation within a system.

The article describes the concepts and methods related to software safety: hazards, risks, fault tolerance, error propagations and handling, safety in the development lifecycle, safety requirements, design methodologies, implementation considerations, verification and validation, standards, and certification.