bluuebunny/crossref_metadata_2025_split huggingface dataset:
Understanding Stray Current Mitigation, Testing and Maintenance on DC Powered Rail Transit Systems
Authors: Memon Saud 
Published: November 2013

All direct current traction power systems using rails for return of traction current have a level of current leakage. This leakage of current is dependent on both design and operating factors affecting the efficiency of the rail return path and is referred to as stray current. Stray currents have been detected since the first electric railways were placed into operation during the latter half of the nineteenth century and have serious effects on utility structures and the neighboring infrastructure at large. Stray currents can create safety hazards thereby rendering the design of stray current mitigation an important element of the overall design of a rail transit system.
Like any other design/construction project, a baseline survey is an important and significant step in the data collection and fact finding process for a light rail system. Such a survey would aid in finding the soil resistivity data and the results of the stray current levels on existing buried metal utilities. Similarly defining the design criteria for stray current mitigation, monitoring, and testing for a new light rail design project is also important. Most of the design criteria for the older rail transit systems have been developed as an aftermath of the corrosion problem and/or after the design of new extension to the system. Some older transit systems still do not have a specified design or mitigation criteria for stray current, and corrosion issues are handled as they surface and are prioritized based on severity. In the absence of guidelines, it is hard to understand the reasoning behind the limiting criteria suggested in the transit agency manuals particularly when there is no record of testing or soil resistivity investigation. For these older transit systems the limiting criterion was developed based on the information from other transit services. Having applicable design criteria for stray current control and mitigation will help standardize the process for the transit and will lower the cost of mitigation.
This paper has been written by a Civil Engineer with an effort to understand the source and the scientific reasoning behind the limiting values suggested by the transit agencies associated with stray current testing procedures and its control. In order to understand the limited stray current corrosion criteria and the respective testing, various transit agencies were interviewed. These interviews were supplemented by a thorough review of the respective transit agency criteria manual/guidelines (where such information was available and accessible). Critical evaluations of the testing procedures were conducted to analyze if these tests and mitigation methods were effective.
A Study on Determination of Electrical Impedance and Frequency Characteristics of a Subway System Using Finite Element Analysis
Authors: Deleanu Sorin , Carpenter David C. 
Published: November 2013

The paper provides a description of the analysis of a subway system (track-in-tunnel) by using FEM analysis and comparing to classical analytical approaches by Carson, Pollaczek, Bickford and Tylavsky.
Reviews of methods to determine self and mutual impedance for electrified railroads are provided. These methods include frequency response and are directly applicable to a three-rail track DC track system.
The analytic impedance models are built on Carson-Pollaczek–Bickford equations, adjusted by Tylavsky, for two situations: when the ground is perfectly insulated and when considering the earth return current. For the latter, the authors assume a return current path only through the tunnel concrete structure below the railway track support structure. The model is extended by considering the effects of the soil beneath under tunnel as a conductor.
The solution of finite element method (FEM) applied for the determination of impedance for the three-rail track subway train configuration, modeled and examined, consists of computational analysis based upon minimizing the energy of electromagnetic field.
The paper continues by examining the frequency effects on the track and system. The track/trolley model developed by Tylavsky was modified such that the trolley feeder is provided by the power rail and used to calculate the return current through the traction rails. The subway train, supplied with a rectified DC power, is subjected to a significant harmonic content, which may affect the signal and control circuits.
Both experimental data and preliminary analytical and numerical calculations are presented, showing the variation of resistances and inductances of the running track with the current magnitude and frequency response. In the study, a large frequency range was considered (15Hz to 5000Hz) in order to cover all of the significant frequencies used for control and signal systems in common tracks configurations, and for which measurements have been carried. It is then shown that the power and signaling characteristics of the modeled system can predict the magnitude of the perturbation current for different values of frequency. The current density profile is illustrated for the case of a concrete tunnel structure in a subway application.
The last section consists of a discussion regarding future developments and further work.
Consequences of Failed Track Circuits on Conventional Signaling System in CBTC Projects
Authors: Diemunsch Kenneth M. , Reitz Daniel J. 
Published: November 2013

In recent years, many rapid mass transit agencies have chosen Communication Based Train Control (CBTC) technology to refurbish their signaling system or to equip a new line. CBTC technology is a type of Automatic Train Control (ATC) that allows transit agencies to increase nominal throughput and to improve safety. The main functions of CBTC are described in [1.] and [2.].
This technology can operate without fixed wayside track detectors such as track circuits. However, track circuit equipment continues to be implemented on the tracks and in the equipment rooms. For authorities under the Federal Railroad Administration, current regulations require use of track circuit but the main functional reason is to have a backup system in case of CBTC failure. Most transit agencies decide to include track circuit occupied and vacant status into the CBTC system in order to enhance safety. How to enhance safety and keep train operation efficient during track circuit failure is a challenge for CBTC projects.
This paper discusses the relationship between the CBTC and the conventional interlocking system when track circuit failure occurs. The analysis in this paper applies to both relay and solid state interlocking systems as both technologies have to deal with the same impact under this scenario. The method of detection of track circuit failure by the CBTC system and the possible restrictions on CBTC train operation are not presented. The paper focuses on the interface between the CBTC and the signaling system. It begins by introducing the different types of track circuit failures and their consequences on conventional signaling system to address and compare multiple scenarios. Then, the paper discusses how the CBTC system can affect the conventional signaling system equipment, such as signals and train stops, once it has detected a track circuit failure. Transit agencies’ different possible approaches to manage track circuits failures within the context of an operating CBTC system are explained.
The Application of Track Spectrum Applying to Track Dynamic Analysis
Authors: Li Cheng-hui , Chen Bo-jing , Liu Yu-tao , Dai Feng 
Published: November 2013

The track irregularity is the primary cause to induce the vibration of the wheel-rail system. With the statistical characteristics of track irregularity, the track spectrum is widely applied to the track dynamic analysis. The track spectrum and its application are discussed in this paper mainly from the three aspects as follows.
1. Due to the multiple types of track structure, the statistical features of the track irregularity are varying, thus the original type and wavelength of the track spectrum cannot interpret the current situation.
2. As for the track dynamic analysis, because of the lack of the important short wave track irregularity spectrum, the track high-frequency vibration can hardly be further analysed with the existing track spectrum.
3. When the track irregularity in time domain included in the track spectrum for track dynamic analysis is used, there exists the problem that the amplitude of responses tends to be smaller than the actual situation.
To sum up, this paper further put forward some suggestions about optimizing the test work of the supplementary track spectrum and reasonably utilizing the track spectrum.
Selected In-Track Applications and Performances of Hot-Mix Asphalt Trackbeds
Authors: Rose Jerry G. 
Published: November 2013

The use of a layer of asphalt within railway trackbeds has steadily grown since the early 1980s in the United States. Its primary use has been for maintenance and rehabilitation applications in existing tracks, particularly at special trackworks, to improve trackbed performance, and to a lesser extent for new trackbed applications where the projected long-term performance of the asphalt trackbed is anticipated to be economically justified. Normally the asphalt layer is 6 in. (150 mm) thick, placed on a prepared subgrade or granular subballast, and is subsequently topped with a layer of typical ballast. Accepted highway/railway construction practices are adhered to, including adequate preparation and compaction of the support layers. In addition, surface and sub-surface drainage aspects are evaluated on a site-specific basis and improvements are specified based on accepted engineering practices. This application does not deviate significantly from conventional all-granular trackbed designs, except the asphalt layer is substituted for a portion of the thickness of the granular subballast and ballast support materials.
Described herein are 1) typical trackbed designs, 2) in-track applications, and 3) long-term performance evaluations for various types of major applications on several U.S. Class I railroads, namely NS, UP, CSX, and BNSF, and a limited number of Shortline railroads. Specifically addressed are rehabilitation applications for special trackworks — tunnel floors/approaches, wheel impact load detectors, bridge approaches, rail-highway crossings, turnouts, rail crossings, and rail crossovers — plus descriptions for a limited number of new double-tracking open-track installations. Brief descriptions are provided for international applications in six countries.
Particular detail is given to factors affecting the economic justification for utilizing this technology based on long-term performances and historical evaluations of numerous installations. Details are provided relative to unique conditions and logistics related to the application of the layer of asphalt within the trackbed support for the special trackworks and selected open-track installations. Several specific installations are highlighted.
HIV prevalence and related risk behaviours among female sex workers in Iran: results of the national biobehavioural survey, 2010
Authors: Sajadi Leily , Mirzazadeh Ali , Navadeh Soodabeh , Osooli Mehdi , Khajehkazemi Razieh , Gouya Mohammad Mehdi , Fahimfar Noushin , Zamani Omid , Haghdoost Ali-Akbar 
Published: November 2013

ObjectivesTo determine the prevalence of HIV and related behavioural risks among Iranian female sex workers (FSW) via the first national biobehavioural surveillance survey.MethodsIn 2010, 1005 FSW were approached and 872 recruited using facility-based sampling from 21 sites in 14 cities in Iran. We collected dried blood samples and conducted face-to-face interviews using a standardised questionnaire. Data were weighted based on the response rate and adjusted for the clustering effect of the sampling site. Adjustment was performed by weighting based on the sampling fraction of each site using a prior estimate of its total size of the FSW population.ResultsThe prevalence of HIV infection (95% CI) was 4.5% (2.4 to 8.3) overall, 4.8% (2.2 to 9.8) among those who had reported a history of drug use and 11.2% (5.4 to 21.5) among those who had a history of injection drug use. The frequencies of condom use in the last sexual act with paying clients and non-paying partners were 57.1% and 36.3%, respectively. Any drug use was reported by 73.8% of participants, and among this subgroup, 20.5% had a history of injection drug use.ConclusionsThe prevalence of HIV was considerable among FSW particularly those who had a history of drug injection. A combination of prevention efforts addressing unsafe sex and injection are needed to prevent further transmission of HIV infection.
Transitioning to Independence and Maintaining Research Careers in a New Funding Climate: American Society of Preventive Oncology Junior Members Interest Group Report
Authors: Hamilton Jada G. , Birmingham Wendy C. , Tehranifar Parisa , Irwin Melinda L. , Klein William M.P. , Nebeling Linda , Chubak Jessica 
Published: November 2013

Abstract
The American Society of Preventive Oncology (ASPO) is a professional society for multi-disciplinary investigators in cancer prevention and control. The ASPO Junior Members Interest Group promotes the interests of predoctoral, postdoctoral, and junior faculty members within the Society, and provides them with career development and training opportunities. To this end, as part of the 37th ASPO Annual Meeting held in Memphis, Tennessee in March 2013, the Junior Members Interest Group organized a session designed to address issues faced by early-career investigators as they navigate the transition to become an independent, well-funded scientist with a sustainable program of research in the current climate of reduced and limited resources. Four speakers were invited to provide their complementary but distinct perspectives on this topic based on their personal experiences in academic, research-intensive positions and in federal funding agencies. This report summarizes the main themes that emerged from the speakers' presentations and audience questions related to mentoring; obtaining grant funding; publishing; developing expertise; navigating appointments, promotion, and tenure; and balancing demands. These lessons can be used by early-career investigators in cancer prevention and control as they transition to independence and build programs of fundable research. Cancer Epidemiol Biomarkers Prev; 22(11); 2138–42. ©2013 AACR.
Durable Antibody Responses Following One Dose of the Bivalent Human Papillomavirus L1 Virus-Like Particle Vaccine in the Costa Rica Vaccine Trial
Authors: Safaeian Mahboobeh , Porras Carolina , Pan Yuanji , Kreimer Aimee , Schiller John T. , Gonzalez Paula , Lowy Douglas R. , Wacholder Sholom , Schiffman Mark , Rodriguez Ana C. , Herrero Rolando , Kemp Troy , Shelton Gloriana , Quint Wim , van Doorn Leen-Jan , Hildesheim Allan , Pinto Ligia A. ,   for the CVT Group
Published: November 2013

Abstract
The Costa Rica HPV16/18 Vaccine Trial (CVT) showed that four-year vaccine efficacy against 12-month HPV16/18 persistent infection was similarly high among women who received one, two, or the recommended three doses of the bivalent HPV16/18 L1 virus-like particle (VLP) vaccine. Live-attenuated viral vaccines, but not simple-subunit vaccines, usually induce durable lifelong antibody responses after a single dose. It is unclear whether noninfectious VLP vaccines behave more like live-virus or simple-subunit vaccines in this regard. To explore the likelihood that efficacy will persist longer term, we investigated the magnitude and durability of antibodies to this vaccine by measuring HPV16- and HPV18-specific antibodies by VLP-ELISA using serum from enrollment, vaccination, and annual visits through four years in four vaccinated groups; one-dose (n = 78), two-doses separated by one month (n = 140), two doses separated by six months (n = 52), and three scheduled doses (n = 120, randomly selected). We also tested enrollment sera from n = 113 HPV16- or HPV18 L1-seropositive women prevaccination, presumably from natural infection. At four years, 100% of women in all groups remained HPV16/18 seropositive; both HPV16/18 geometric mean titers (GMT) among the extended two-dose group were non-inferior to the three-dose group, and ELISA titers were highly correlated with neutralization titers in all groups. Compared with the natural infection group, HPV16/18 GMTs were, respectively, at least 24 and 14 times higher among the two-dose and 9 and 5 times higher among one-dose vaccinees. Antibody levels following one-dose remained stable from month 6 through month 48. Results raise the possibility that even a single dose of HPV VLPs will induce long-term protection. Cancer Prev Res; 6(11); 1242–50. ©2013 AACR.
Frontal Theta Oscillatory Activity Is a Common Mechanism for the Computation of Unexpected Outcomes and Learning Rate
Authors: Mas-Herrero Ernest , Marco-Pallarés Josep 
Published: November 2013

Abstract
In decision-making processes, the relevance of the information yielded by outcomes varies across time and situations. It increases when previous predictions are not accurate and in contexts with high environmental uncertainty. Previous fMRI studies have shown an important role of medial pFC in coding both reward prediction errors and the impact of this information to guide future decisions. However, it is unclear whether these two processes are dissociated in time or occur simultaneously, suggesting that a common mechanism is engaged. In the present work, we studied the modulation of two electrophysiological responses associated to outcome processing—the feedback-related negativity ERP and frontocentral theta oscillatory activity—with the reward prediction error and the learning rate. Twenty-six participants performed two learning tasks differing in the degree of predictability of the outcomes: a reversal learning task and a probabilistic learning task with multiple blocks of novel cue–outcome associations. We implemented a reinforcement learning model to obtain the single-trial reward prediction error and the learning rate for each participant and task. Our results indicated that midfrontal theta activity and feedback-related negativity increased linearly with the unsigned prediction error. In addition, variations of frontal theta oscillatory activity predicted the learning rate across tasks and participants. These results support the existence of a common brain mechanism for the computation of unsigned prediction error and learning rate.
Different Brains Process Numbers Differently: Structural Bases of Individual Differences in Spatial and Nonspatial Number Representations
Authors: Krause Florian , Lindemann Oliver , Toni Ivan , Bekkering Harold 
Published: November 2013

Abstract
A dominant hypothesis on how the brain processes numerical size proposes a spatial representation of numbers as positions on a “mental number line.” An alternative hypothesis considers numbers as elements of a generalized representation of sensorimotor-related magnitude, which is not obligatorily spatial. Here we show that individuals' relative use of spatial and nonspatial representations has a cerebral counterpart in the structural organization of the posterior parietal cortex. Interindividual variability in the linkage between numbers and spatial responses (faster left responses to small numbers and right responses to large numbers; spatial–numerical association of response codes effect) correlated with variations in gray matter volume around the right precuneus. Conversely, differences in the disposition to link numbers to force production (faster soft responses to small numbers and hard responses to large numbers) were related to gray matter volume in the left angular gyrus. This finding suggests that numerical cognition relies on multiple mental representations of analogue magnitude using different neural implementations that are linked to individual traits.
Two new species of Armascirus (Acari: Prostigmata: Cunaxidae) from Slovakia
Authors: KALÚZ Stanislav , VRABEC MICHAL 
Published: November 2013

Two new mite species from Central Europe, viz. Armascirus fendai sp. nov. and Armascirus masani sp. nov. (Acari: Prostigmata, Cunaxidae) are described and figured. The keys to the known species (females and males) of the genus Armascirus are given.
The Influence of Recurrent Modes of Climate Variability on the Occurrence of Winter and Summer Extreme Temperatures over North America
Authors: Loikith Paul C. , Broccoli Anthony J. 
Published: November 2013

AbstractThe influence of the Pacific–North American (PNA) pattern, the northern annular mode (NAM), and the El Niño–Southern Oscillation (ENSO) on extreme temperature days and months over North America is examined. Associations between extreme temperature days and months are strongest with the PNA and NAM and weaker for ENSO. In general, the association with extremes tends to be stronger on monthly than daily time scales and for winter as compared to summer. Extreme temperatures are associated with the PNA and NAM in the vicinity of the centers of action of these circulation patterns; however, many extremes also occur on days when the amplitude and polarity of these patterns do not favor their occurrence. In winter, synoptic-scale, transient weather disturbances are important drivers of extreme temperature days; however, many of these smaller-scale events are concurrent with amplified PNA or NAM patterns. Associations are weaker in summer when other physical mechanisms affecting the surface energy balance, such as anomalous soil moisture content, also influence the occurrence of extreme temperatures.
How do Tropical Temperate Troughs Form and Develop over Southern Africa?
Authors: Macron Clémence , Pohl Benjamin , Richard Yves , Bessafi Miloud 
Published: November 2013

Abstract
This paper aims at separating the respective influences of tropical and midlatitude variability on the development and life cycle of tropical temperate troughs (TTTs) over southern Africa in austral summer (November–February). Cluster analysis is applied to 1971–2000 40-yr ECMWF Re-Analysis (ERA-40) daily outgoing longwave radiation (OLR) anomalies to identify TTTs and monitor tropical convection. The same analysis applied to the zonal wind stretching deformation at 200 hPa (ZDEF) characterizes midlatitude transient perturbations. Results based on the comparison between these two classifications first confirm that midlatitude baroclinic waves are a necessary condition for TTT development, but they are not sufficient. Roughly 40% of those occurring in austral summer are associated with a TTT. They tend to be stronger than the baroclinic waves not associated with TTT development. In the tropics, additional conditions needed to form a TTT consist of an excess of latent energy over the Mozambique Channel, mostly because of moisture advections and convergence from the Atlantic and Indian Oceans. Taken together, these conditions are highly favorable for deep atmospheric convection over and near southern Africa and seem to explain a large fraction of TTT variability.