bluuebunny/crossref_metadata_2025 huggingface dataset:
Invasion of novel habitats uncouples haplo‐diplontic life cycles
Authors: Krueger‐Hadfield Stacy A. , Kollars Nicole M. , Byers James E. , Greig Thomas W. , Hammann Mareike , Murray David C. , Murren Courtney J. , Strand Allan E. , Terada Ryuta , Weinberger Florian , Sotka Erik E.
Published: June 2016

Baker's Law predicts uniparental reproduction will facilitate colonization success in novel habitats. While evidence supports this prediction among colonizing plants and animals, few studies have investigated shifts in reproductive mode in haplo‐diplontic species in which both prolonged haploid and diploid stages separate meiosis and fertilization in time and space. Due to this separation, asexual reproduction can yield the dominance of one of the ploidy stages in colonizing populations. We tested for shifts in ploidy and reproductive mode across native and introduced populations of the red seaweed Gracilaria vermiculophylla. Native populations in the northwest Pacific Ocean were nearly always attached by holdfasts to hard substrata and, as is characteristic of the genus, haploid–diploid ratios were slightly diploid‐biased. In contrast, along North American and European coastlines, introduced populations nearly always floated atop soft‐sediment mudflats and were overwhelmingly dominated by diploid thalli without holdfasts. Introduced populations exhibited population genetic signals consistent with extensive vegetative fragmentation, while native populations did not. Thus, the ecological shift from attached to unattached thalli, ostensibly necessitated by the invasion of soft‐sediment habitats, correlated with shifts from sexual to asexual reproduction and slight to strong diploid bias. We extend Baker's Law by predicting other colonizing haplo‐diplontic species will show similar increases in asexuality that correlate with the dominance of one ploidy stage. Labile mating systems likely facilitate colonization success and subsequent range expansion, but for haplo‐diplontic species, the long‐term eco‐evolutionary impacts will depend on which ploidy stage is lost and the degree to which asexual reproduction is canalized.
Primacy of lowered baseline glomerular filtration rate as a risk for incident chronic kidney disease: A longitudinal study in Japanese subjects
Authors: Miyakoshi Takahiro , Nakasone Yasuto , Sato Yuka , Yamauchi Keishi , Hashikura Rie , Takayama Masayuki , Hirabayashi Kazuko , Koike Hideo , Moriya Tatsumi , Aizawa Toru
Published: June 2016

Aim

Risk profile for incident chronic kidney disease (CKD) in Japanese subjects has not been established. Our aim was to identify risk factors for CKD in Japanese.

Methods

Consecutive 171 536 health examinees (median age 49 years and estimated glomerular filtration rate (eGFR) 78.2 mL/min per 1.73 m2) without CKD were re‐examined after a median period of 6.2 years. Results of Cox proportional hazards models in randomly assigned two thirds (Derivation cohort) were verified in the rest (Validation cohort). CKD was defined as eGFR <60 mL/min per 1.73 m2 or positive dipstick proteinuria.

Results

In the Derivation cohort, CKD developed in 1002 (5.8%) subjects. Seven variables such as lower eGFR, male gender, higher uric acid concentration, lower red cell count and higher age and systolic blood pressure were identified as significant risks for CKD, with lowered eGFR being an overwhelmingly strong risk: adjusted hazard ratio for those with the baseline eGFR <70 mL/min per 1.73 m2 was as high as 90.1. Performance of prediction of CKD by the probability on the basis of the seven risk factors combined was only marginally preferable to eGFR alone. The area under the receiver operating characteristic curve (95% CI) for the prediction was 0.846 (0.826–0.864) and 0.822 (0.802–0.840) (P < 0.01), the kappa statistic was 0.263 and 0.250 (n.s.), and the mean absolute difference between “predicted probability” and “observed” CKD was 1.4% and 1.9% (P = 0.14) by the combined model and eGFR alone, respectively.

Conclusion

Seven risk factors for incident CKD were identified in Japanese health examinees. However, lowered baseline eGFR outweighed other risks to the degree that eGFR alone was suffice for CKD prediction.
Impact of the induced organic anion transporter 1 (Oat1) renal expression by furosemide on the pharmacokinetics of organic anions
Authors: Severin María Julia , Hazelhoff María Herminia , Bulacio Romina Paula , Mamprin María Eugenia , Brandoni Anabel , Torres Adriana Mónica
Published: June 2016

Aim

Furosemide is a loop diuretic. Different authors demonstrated that continuous administration of furosemide modulates the expression of organic anion transporters. This study was undertaken to simultaneously evaluate the effects of furosemide pretreatment on organic anion transporter 1 (Oat1) and multidrug resistance protein 2 (Mrp2) renal expressions, on p‐aminohippurate (PAH) pharmacokinetics and on renal and urinary PAH levels in rats.

Methods

Male Wistar rats were treated with furosemide (6 mg/100 g body weight per day, subcutaneously, 4 days) (treated group) or saline (control group). On the fifth day, PAH was administered as a bolus infusion in the femoral vein, and plasma samples were obtained from femoral artery at different time points. PAH levels in renal tissue and urine were also assessed. Renal Oat1 and Mrp2 expressions were evaluated by western blotting.

Results

Furosemide pretreatment increased both the expression of Oat1 and Mrp2. PAH plasma concentrations decreased following a biexponential function. The furosemide‐treated group showed higher PAH plasma levels, a lower systemic clearance and elimination rate constant from the peripheral compartment, indicating that PAH renal elimination was decreased. PAH levels in renal tissue were significantly elevated and in urine appeared to be significantly lower as compared with control animals.

Conclusions

Furosemide pretreatment caused a significant decrease of PAH renal elimination, despite Oat1 and Mrp2 augmented renal expression.

The goal of the present study is the addition of important information in the wide gap of knowledge that exists about drug–drug interactions. Because of furosemide worldwide use, the data obtained are interesting and useful in terms of translation to clinical practice.
Effects of hemin on heme oxygenase‐1, gastric emptying, and symptoms in diabetic gastroparesis
Authors: Bharucha A. E. , Daley S. L. , Low P. A. , Gibbons S. J. , Choi K. M. , Camilleri M. , Saw J. J. , Farrugia G. , Zinsmeister A. R.
Published: June 2016

Background

Therapeutic options for management of diabetic gastroparesis are limited. Failure to maintain upregulation of heme oxygenase (HO1) leads to loss of interstitial cells of Cajal and delayed gastric emptying (GE) in non‐obese diabetic mice. Our hypothesis was that hemin upregulation of HO1 would restore normal GE in humans with gastroparesis.

Aims

To compare effects of hemin and placebo infusions on HO1 activity and protein, GE, autonomic function, and gastrointestinal symptoms in diabetic gastroparesis.

Methods

In a single‐center, double‐blind, placebo‐controlled, randomized clinical trial, we compared intravenous hemin, prepared in albumin, or albumin alone (placebo) in 20 patients, aged 41 ± 5 (SEM) years with diabetic gastroparesis. After infusions on days 1, 3, and 7, weekly infusions were administered for 7 additional weeks. Assessments included blood tests for HO1 protein and enzyme activity levels, GE with 13C‐spirulina breath test, autonomic functions (baseline and end), and gastrointestinal symptoms every 2 weeks.

Key Results

Nine of 11 patients randomized to hemin completed all study procedures. Compared to placebo, hemin increased HO1 protein on days 3 (p = 0.0002) and 7 (p = 0.008) and HO1 activity on day 3 (p = 0.0003) but not after. Gastric emptying, autonomic functions, and symptoms did not differ significantly in the hemin group relative to placebo.

Conclusions & Inferences

Hemin failed to sustain increased HO1 levels beyond a week and did not improve GE or symptoms in diabetic gastroparesis. Further studies are necessary to ascertain whether more frequent hemin infusions or other drugs would have a more sustained effect on HO1 and improve GE.
High‐resolution colonic motility recordings in vivo compared with ex vivo recordings after colectomy, in patients with slow transit constipation
Authors: Dinning P. G. , Sia T. C. , Kumar R. , Mohd Rosli R. , Kyloh M. , Wattchow D. A. , Wiklendt L. , Brookes S. J. H. , Costa M. , Spencer N. J.
Published: June 2016

Background

The pathogenesis of slow transit constipation (STC) remains poorly understood, with intrinsic and extrinsic abnormalities implicated. Here, we present high‐resolution colonic manometry recordings from four STC patients recorded before total colectomy, and subsequently, ex vivo, after excision.

Methods

In four female, treatment‐resistant STC patients (median age 35.5 years), a fiber‐optic manometry catheter (72 sensors spaced at 1 cm intervals) was placed with the aid of a colonoscope, to the mid‐transverse colon. Colonic manometry was recorded 2 h before and after a meal. After the colectomy, ex vivo colonic manometry was recorded in an organ bath. Ex vivo recordings were also made from colons from 4 patients (2 male; median age 67.5 years) undergoing anterior resection for nonobstructive carcinoma (‘control’ tissue).

Key Results

A large increase in ‘short single propagating contractions’ was recorded in STC colon ex vivo compared to in vivo (ex vivo 61.3 ± 32.7 vs in vivo 2.5 ± 5/h). In STC patients, in vivo, the dominant frequency of contractile activity was 2–3 cycle per minute (cpm), whereas 1‐cpm short‐single propagating contractions dominated ex vivo. This same 1‐cpm frequency was also dominant in control colons ex vivo.

Conclusions & Inferences

In comparison to control adults, the colon of STC patients demonstrates significantly less propagating motor activity. However, once the STC colon is excised from the body it demonstrates a regular and similar frequency of propagating activity to control tissue. This paper provides interesting insights into the control of colonic motor patterns.
Long‐term microbiota and virome in a Zürich patient after fecal transplantation against Clostridium difficile infection
Authors: Broecker Felix , Klumpp Jochen , Moelling Karin
Published: June 2016

Fecal microbiota transplantation (FMT) is an emerging therapeutic option for Clostridium difficile infections that are refractory to conventional treatment. FMT introduces fecal microbes into the patient's intestine that prevent the recurrence of C. difficile, leading to rapid expansion of bacteria characteristic of healthy microbiota. However, the long‐term effects of FMT remain largely unknown. The C. difficile patient described in this paper revealed protracted microbiota adaptation processes from 6 to 42 months post‐FMT. Ultimately, bacterial communities were donor similar, suggesting sustainable stool engraftment. Since little is known about the consequences of transmitted viruses during C. difficile infection, we also interrogated virome changes. Our approach allowed identification of about 10 phage types per sample that represented larger viral communities, and phages were found to be equally abundant in the cured patient and donor. The healthy microbiota appears to be characterized by low phage abundance. Although viruses were likely transferred, the patient established a virome distinct from the donor. Surprisingly, the patient had sequences of algal giant viruses (chloroviruses) that have not previously been reported for the human gut. Chloroviruses have not been associated with intestinal disease, but their presence in the oropharynx may influence cognitive abilities. The findings suggest that the virome is an important indicator of health or disease. A better understanding of the role of viruses in the gut ecosystem may uncover novel microbiota‐modulating therapeutic strategies.
Fundamentals, non‐fundamentals and the oil price changes in 2007–2009 and 2014–2015
Authors: Javan Afshin , Vallejo Carola
Published: June 2016

The fast increase in oil prices in the past 15 years and the spectacular fall in 2008 and in 2014 has led to the rethinking of supply and demand as the only determinant price. It has been observed in the last decade that large financial institutions, hedge funds, index funds and other investment funds invest billions of dollars in the futures market benefiting from the changes in oil prices. We considered the net long position of each trader category in the New York Mercantile Exchange to estimate, through the Vector Error Correction Model (VECM), the impact of each category on oil price and on volatility. Similarly, we also consider quarterly world oil demand, supply, inventories and industrial production from 1993 and 2015. The results show that fundamental variables have a strong and long‐lasting relationship with oil price. Unlike the fundamental variables, the non‐fundamental variables very quickly became stable and react in a different way when the prices of oil rise and fall. The results show that the main factor for the increase of the price in 2008 was the higher than expected demand. For the 2014 decline the VECM shows that supply is the main force behind it. The non‐fundamental variables together can explain almost 11 per cent of the variations of the price in 2008–2009. However, for the 2014–2015 period, the non‐fundamental combined explained only 5 per cent. The non‐fundamental have low share in the changes in oil price despite having a strong effect on volatility.
Successful Treatment of Keratosis Pilaris Rubra with Pulsed Dye Laser
Authors: Schoch Jennifer J. , Tollefson Megha M. , Witman Patricia , Davis Dawn M.R.
Published: June 2016

Background

Keratosis pilaris rubra is a common but rarely reported condition characterized by follicular‐based hyperkeratotic papules on a background of erythema. It can be embarrassing and symptomatic for patients, particularly adolescent boys. We sought to explore the efficacy of pulsed dye laser (PDL) in the treatment of keratosis pilaris rubra.

Methods

Eight patients were treated with PDL for keratosis pilaris rubra.

Results

All patients reported noticeable improvement after one to four treatments.

Conclusions

PDL is an effective, easily accessible, and underused therapy in the treatment of keratosis pilaris rubra.
Inguinal hernia in very low‐birthweight infants: Follow up to adolescence
Authors: Kurobe Masashi , Baba Yuji , Otsuka Masahiko
Published: June 2016

Background

This study reviewed the medical records of very low‐birthweight infants (VLBWI) followed up to adolescence, with emphasis on inguinal hernia (IH), to discuss the ideal time for IH repair in VLBWI.

Methods

Medical records from 274 VLBWI treated in the neonatal intensive care unit (NICU) between 1994 and 1999 were collected retrospectively. Outpatient data after NICU discharge were included. Additionally, a follow‐up study was undertaken via questionnaire sent to the families of VLBWI in 2011.

Results

During NICU hospitalization, IH was diagnosed in 39 of 274 VLBWI, and two developed incarceration. Thirty‐eight VLBWI were discharged with known hernia, and elective repair was performed in 19. Three developed incarceration before elective repair at the mean age of 316 days. In the remaining 18 cases of IH, spontaneous regression occurred at a mean age of 180 days and repair was not performed. New IH appeared in 25 VLBWI after NICU discharge.

Conclusions

The high incidence of IH in VLBWI was confirmed during follow up to adolescence. The rate of incarceration was low and the incidence of spontaneous regression was high. Observation up to 6 months without surgery, with the expectation of spontaneous regression, is one option to avoid unnecessary surgery, but repair should be performed before 10 months to reduce the risk of incarceration. Further large, prospective, and randomized controlled studies with a long follow up are necessary to validate the present results and to define the ideal time for IH repair in VLBWI.
Comparison of Risk Predicted by Multiple Norovirus Dose–Response Models and Implications for Quantitative Microbial Risk Assessment
Authors: Van Abel Nicole , Schoen Mary E. , Kissel John C. , Meschke J. Scott
Published: June 2016

The application of quantitative microbial risk assessments (QMRAs) to understand and mitigate risks associated with norovirus is increasingly common as there is a high frequency of outbreaks worldwide. A key component of QMRA is the dose–response analysis, which is the mathematical characterization of the association between dose and outcome. For Norovirus, multiple dose–response models are available that assume either a disaggregated or an aggregated intake dose. This work reviewed the dose–response models currently used in QMRA, and compared predicted risks from waterborne exposures (recreational and drinking) using all available dose–response models. The results found that the majority of published QMRAs of norovirus use the 1F1 hypergeometric dose–response model with α = 0.04, β = 0.055. This dose–response model predicted relatively high risk estimates compared to other dose–response models for doses in the range of 1–1,000 genomic equivalent copies. The difference in predicted risk among dose–response models was largest for small doses, which has implications for drinking water QMRAs where the concentration of norovirus is low. Based on the review, a set of best practices was proposed to encourage the careful consideration and reporting of important assumptions in the selection and use of dose–response models in QMRA of norovirus. Finally, in the absence of one best norovirus dose–response model, multiple models should be used to provide a range of predicted outcomes for probability of infection.
Climate Change Mitigation and the Collective Action Problem: Exploring Country Differences in Greenhouse Gas Contributions
Authors: Brechin Steven R.
Published: June 2016

Global climate change has become the collective action problem of our era. With the United Nations Framework Convention on Climate Change (UNFCCC) 2015COP21 Meetings in Paris as the context, the author draws upon critical mass theory (CMT) (Oliver and Marwell 1988; Oliver, Marwell, and Teixeria 1985) in an attempt to yield greater understanding of the international community's ability to achieve climate stability as a global public good. UsingCMTkey elements of collective action production functions, group heterogeneity, and interdependence, the author explores the world's collective ability to mitigate greenhouse gas (GHG) emissions at the country level. Brief examples from Belize, Central America, and other small, vulnerable nations are used to focus attention on those countries that cannot make meaningful contribution to the collection action. The findings help illustrate why climate change is such a difficult collective action problem to address, what broad strategies might be required, and how to potentially achieve more targeted distribution of international resources.
Something's gotta go, something's gotta give: completion, mirativity and transitivity in odia light verb constructions
Authors: Lemmens Maarten , Sahoo Kalyanamalini
Published: June 2016

This paper deals with asymmetric complex predicates (combining a main verb and a ‘light’ verb) in Odia, an Indo‐Aryan language. The main focus is on the two most common light verbs ‐jaa ‘go’ and ‐de ‘give’. We argue that these light verbs are constructions in their own right affecting the interpretation of the event in two ways: (i) they necessarily refer to the completion of the event (as opposed to the single verb construction) and (ii) they typically express unexpectedness or abruptness and can as such be considered a mirative construction as defined by Delancey (2012). Transitivity plays a major role not only in the distinction between ‐jaa ‘go’ and ‐de ‘give’ but also in differences of degree of completion and unexpectedness.
Peptide inhibitor of complement C1 modulates acute intravascular hemolysis of mismatched red blood cells in rats
Authors: Kumar Parvathi S. , Pallera Haree K. , Hair Pamela S. , Rivera Magdielis Gregory , Shah Tushar A. , Werner Alice L. , Lattanzio Frank A. , Cunnion Kenji M. , Krishna Neel K.
Published: June 2016

BACKGROUND

Acute hemolytic transfusion reactions have a broad clinical presentation from mild and transitory signs and symptoms to shock, disseminated intravascular coagulation, renal failure, and death. We have recently developed a rat model of acute intravascular hemolysis showing that the classical complement pathway mediates antibody‐dependent hemolysis. The objective of this study was to evaluate the role of the classical pathway inhibitor peptide inhibitor of complement C1 (PIC1) in this animal model.

STUDY DESIGN AND METHODS

Male Wistar rats received a 15% transfusion of human red blood cells (RBCs) and blood was isolated from the animals up to 120 minutes. Animals received PIC1 either 2 minutes before or 0.5 minutes after transfusion. Sham‐, vehicle‐, and cobra venom factor (CVF)‐treated animals were used as control groups with a subset of rats also receiving an equivalent dose of intravenous immunoglobulin (IVIG) before transfusion. Blood was analyzed for transfused RBC survival by flow cytometry and free hemoglobin (Hb) in isolated plasma by spectrophotometry.

RESULTS

Vehicle‐treated rats showed decreased human RBC survival and increased free Hb as expected. Rats receiving PIC1 before transfusion showed increased human RBC survival and decreased Hb similar to CVF‐treated rats. Notably, rats receiving PIC1 after initiation of transfusion showed similar decreases in hemolysis as animals receiving PIC1 before transfusion. Compared to IVIG and saline controls, PIC1‐treated animals demonstrated decreased hemolysis and protection from acute kidney injury.

CONCLUSIONS

These results demonstrate that PIC1 has efficacy in an animal model of acute intravascular hemolysis in both prevention and rescue scenarios.
Editorial practice and the progressive in Black South African English
Authors: KRUGER HAIDEE , VAN ROOY BERTUS
Published: June 2016

Innovative linguistic features occur in Outer and Expanding Circle varieties of English, leading to claims that new Englishes and learner Englishes form overlapping sets rather than discrete categories. However, less attention is given to the processes by which innovations acquire conventionalised status, in particular with regards to the role of editing of published written texts. We propose a model that incorporates both the proficiency of the writer and editorial intervention to account for the role of editing in the process of conventionalisation and legitimisation of innovative features, which is applied in a case study of the progressive aspect in Black South African English.
Juglone ameliorates skin wound healing by promoting skin cell migration through Rac1/Cdc42/PAK pathway
Authors: Wahedi Hussain M. , Park Yong U. , Moon Eun‐Yi , Kim Sun Y.
Published: June 2016

Skin cell regeneration and wound healing are key processes in the recovery from skin injuries. Rapid cell migration and regeneration of skin cells lead to faster and better healing of wounded skin. In the present study, we aimed to investigate the wound healing potential of juglone, a naturally occurring Pin1 inhibitor found in walnuts. Cultured skin cells (NHDF and HaCaT) and hairless mice were treated with juglone after wound creation to examine its effects on cell migration and wound healing rate. The expressions of cell migration related proteins (Rac1, Cdc42, and α‐PAK), collagen deposition, and angiogenesis were analyzed. Juglone treatment resulted in faster rate of growth and migration and recovered cell morphology, particularly at a concentration of 5 µM, in skin cells compared to the untreated group. In vivo experiments showed that mice treated with juglone showed faster wound healing rate with better skin morphology and collagen deposition than the vehicle group. Furthermore, juglone increased the activation and/or expression of Cdc42, Rac1, and α‐pak in HaCaT cells, and resulted in enhanced angiogenesis in endothelial cells (HUVECs). Juglone also activated MAPKs signaling by activation of ERK, JNK, and p38 proteins. Taken together, these data suggest that juglone may be a potential candidate for wound healing and skin regeneration which ameliorates wound healing mainly by promoting skin cell migration through Rac1/Cdc42/PAK pathway.
Qualitative Mobility Analysis of Wire Flexure Systems Using Load Flow Visualization
Authors: Satheeshbabu Sreeshankar , Krishnan Girish
Published: June 2016

Mobility analysis is an important step in the conceptual design of flexure systems. It involves identifying directions with relatively compliant motion (freedoms) and directions with relatively restricted motion (constraints). This paper proposes a deterministic framework for mobility analysis of wire flexure systems based on characterizing a kinetostatic vector field known as “load flow” through the geometry. A hypothesis is proposed to identify constraints and freedoms based on the relationship between load flow and the flexure geometry. This hypothesis is mathematically restated to formulate a matrix-based reduction technique that determines flexure mobility computationally. Several examples with varying complexity are illustrated to validate the efficacy of this technique. This technique is particularly useful in analyzing complex hybrid interconnected flexure topologies, which may be nonintuitive or involved with traditional methods. This is illustrated through the computational mobility analysis of a bio-inspired fiber reinforced elastomer pressurized with fluids. The proposed framework combines both visual insight and analytical rigor, and will complement existing analysis and synthesis techniques.
Vehicle Reliability Programs’ Impact on Stakeholders
Authors: Weiss Michael
Published: June 2016

The intention of this paper is to discuss the key components of reliability processes as applied to rail vehicle acquisition programs, and their effects on the ‘stakeholders’ involved. The ‘stakeholders’ identified in this context, are those that are directly involved in the new vehicle project, namely; the rail operating authority with its associated divisions, the car builder with its internal departments, equipment and system suppliers to the car builder, consultants and governing associations.
Hazmat Routing: Alternate Routing Risk Analysis
Authors: Gordon Gary A. , Young Richard R.
Published: June 2016

The railroad industry is challenged by the complexity and cost of performing the alternate route analysis as required by the Federal Railroad Administration’s (FRA) hazmat routing regulation. This is especially problematic to the regional and short line railroads for several reasons, including the unavailability of alternate routes and, as with the Class I railroads, it is a matter of cost and complexity of analysis. This research paper will look at developing a simplified risk model so as to reduce the cost and complexity of the analysis. This will be accomplished by, among other things, looking at the input parameters to the model for commonality so as to reduce the number (of input parameters) and look at three operating conditions for the analysis. They are: 1) the premise that there are available alternate routes, 2) that alternate routes may not be feasible operationally or economically and 3) that there are no alternate routes. This research and analysis will result in a model that is less complex and costly to run and address the concerns and challenges of the short line and regional railroads.
A Preliminary Methodology for Broken Rail Caused Freight Train Derailment Risk Analysis
Authors: Ben-Gera Tal , He Jiabo , Liu Xiang
Published: June 2016

This paper investigates the influence of rail age, annual traffic density, and inspection frequency on broken-rail-caused train derailment risk. First, we estimate the probability of a broken-rail-caused train derailment based on a sequence of stochastic processes including rail defect formation, growth, detection and the likelihood that a broken rail causes a derailment. In addition to derailment frequency, we also estimate derailment severity, which is measured by the average number of railcars derailed per train derailment, based on FRA-reportable train derailment data. The preliminary risk analysis model provides a quantitative approach to understand broken rail risk, and potentially aid in development of effective ways to mitigate derailment risk.
The Movement of Railroad Ties: Simulation and Field Validation
Authors: Gao Yin , Huang Hai , Liu Shushu , Stoffels Shelley M.
Published: June 2016

The railroad tie is an important component in track structure which provides lateral resistance, continuous support for rail and transfers the train load to ballast. The movement of the tie subject to train loading is usually considered as a vertical motion. However, it is believed that the real-world tie movement is not only translational but rotational due to moving load. In order to investigate the real movement of railroad ties, a train-track interaction computer program was used. The computer program includes a vehicle dynamics model and 3-D Finite Element (FE) track model. The wheel-rail contact forces were obtained from the vehicle dynamics model, and then input to FE track model to simulate the tie movement. Furthermore, the field validation was conducted at Northeast Corridor (NEC) in United States. The measuring units were mounted on the edge of ties to record the angle and acceleration change of the tie in three orthogonal directions. The data analysis showed that the field-measured translational and rotational movement of ties have good agreement with the simulation results. It is concluded that the tie movement is not only up-and-down motion under moving train load, but also comprises rotation and lateral movements.
Estimating Deterioration in the Concrete Tie-Ballast Interface Based on Vertical Tie Deflection Profile: A Numerical Study
Authors: Yu Hailing
Published: June 2016

In ballasted concrete tie track, the tie-ballast interface can deteriorate resulting in concrete tie bottom abrasion, ballast pulverization and/or voids in tie-ballast interfaces. Tie-ballast voids toward tie ends can lead to unfavorable center binding support conditions that can result in premature concrete tie failure and possible train derailment. Direct detection of these conditions is difficult. There is a strong interest in assessing the concrete tie-ballast interface conditions indirectly using measured vertical deflections.

This paper seeks to establish a link between the vertical deflection profile of a concrete tie top surface and the tie-ballast interface condition using the finite element analysis (FEA) method. The concrete tie is modeled as a concrete matrix embedded with prestressing steel strands or wires. The configurations of two commonly used concrete ties, one with 8 prestressing strands and the other with 20 prestressing wires, are employed in this study. All models are three-dimensional and symmetric about the tie center. A damaged plasticity model that can predict onset and propagation of tensile cracks is applied to the concrete material. The steel-concrete interface is homogenized and represented with a thin layer of cohesive elements sandwiched between steel and concrete elements. Strand- or wire-specific elasto-plastic bond models developed at the Volpe Center are applied to the cohesive elements to account for the interface bonding mechanisms. FE models are developed for both original and worn concrete ties, with the latter assuming hypothetical patterns of reduced cross sections resulting from abrasive interactions with the ballast. Static analyses of pretension release in these concrete ties are conducted, and vertical deflection gradients along tie lengths are calculated and shown to correspond well with the worn cross sectional patterns for a given reinforcement type.

The ballast is further modeled with Extended Drucker-Prager plasticity, and hypothetical voids are applied toward the tie ends along the concrete tie-ballast interface to simulate center binding support conditions. The distance range over which the concrete tie is supported in the center is variable and yields different center binding severity. Static simulations are completed with vertical rail seat loads applied on the concrete tie-ballast assembly. The influences of various factors on the vertical deflection profile, including tie type, vertical load magnitude, center binding severity, cross sectional material loss and prestress loss, are examined based on the FEA results.

The work presented in this paper demonstrates the potential of using the vertical deflection profile of concrete tie top surfaces to assess deteriorations in the tie-ballast interface. The simulation results further help to clarify minimum technical requirements on inspection technologies that measure concrete tie vertical deflection profiles.
Human Behavior at Railroad Grade Crossings
Authors: Kadiyala Sampath , Gubbala Phani , Schrock Steven D.
Published: June 2016

A comprehensive study is needed to address the human behavior at railroad grade crossings. Human behavior at different signs changes and it may lead to crashes. No guidance is provided in the recommendations provided by Manual on Uniform Traffic Control Devices where and when different type of signs and different combination of signs are appropriate. Crashes occur mostly when the drivers try to go through the gate or around the gate when a train is approaching. Drivers come to a complete stop at stop signs and then proceed only if a train is not coming, this may lead to a crash when they cannot accelerate in time to cross the tracks. Yield sign may have better results in this case. Cross-buck signs are same as the yield sign where drivers should slow down, look for the train and then proceed. However, people may tend to proceed without yielding as it is not as common of a sign. Hence we can say driver behavior at specific sign is important for the recommendation or the guideline to install a sign. Adopting a common sign at all grade crossings could provide enhanced consistency and reduce crashes. A literature review was done on human behavior at grade crossings and the crash rate at different types of signs. Driver behavior at the time of the crash for 15 states was studied from the Federal Railroad Administration data by reviewing detailed reasons for every crash. Driver behavior at different types of signs at the time of each crash was studied from the reviewed data and the literature review. Driver behavior at different signs was summarized.
Bond Index Numbers of Prestressed Concrete Reinforcement Wires and Their Relationships to Transfer Lengths and Pull-Out Forces
Authors: Haynes Mark D. , Wu Chih-Hang John , Arnold Matthew , Bodapati Naga Narendra B. , Beck B. Terry , Peterman Robert J.
Published: June 2016

The purpose of this research is to establish mathematical models that predicts the bond strength of a reinforcement wire in prestressed concrete members, given the known geometrical features of the wire. A total of nineteen geometrical features of the reinforcement wire were measured and extracted by a precision non-contact profilometer. With these mathematical models, prestressing reinforcement wires can now be analyzed for their bond strength without destructive testing. These mathematical models, based upon a large collection of empirical data via prestressing reinforcement wires from various wire manufacturers in US and Europe, have the potential to serve as quality assessment tools in reinforcement wire and prestressed concrete member production. Most of these models are very simple and easy to implement in practice, which could provide insight into which reinforcement wires provide the greatest bond strength and which combinations of geometrical features of the reinforcement wire are responsible for providing the bond strength.

Our various empirical models have shown that the indent side-wall angle, which is suggested by the ASTM-A881/A881M, may not be the only significant geometrical feature correlated to the transfer length and bond strengths. On the contrary, features such as the indent surface area, indent width, indent edge surface area, indent volume, and release strengths do have significant correlations with the ultimate transfer lengths of the prestressed concrete members. Extensive experiments and testing performed at the Structures Laboratory in Kansas State University, as well as field tests at Transportation Technology Center, Inc. (TTCI) and one Prestressed Concrete Railroad Tie manufacturing facility, have been used to confirm the model predictions.

In addition, our experimental results suggest that the maximum pull out force in the un-tensioned pullout testing has significant correlation with the ultimate transfer length. This finding could provide reinforcement wire manufactures with a quality assurance tool for testing their wires prior to the production.

The resultant mathematical model relating the wire geometrical features to transfer length is referred to as the Bond Index Number (BIN). The BIN is shown to provide a numerical measure of the bond strength of prestressing steel reinforcement wire, without the need for performing destructive tests with the reinforcement wire. We believe that with the BIN and the maximal pull-out forces from the un-tensioned pull-out tests, one can have better insight into the optimal reinforcement wire design by testing the performance of wires before they are put into production lines.
High-Strength Reduced-Modulus High Performance Concrete (HSRM-HPC) for Prestressed Concrete Tie Applications
Authors: Rizos Dimitrios C.
Published: June 2016

A High-Strength Reduced-Modulus High Performance Concrete (HSRM-HPC) for use in prestressed concrete rail ties has been developed by the authors. The HSRM-HPC material was originally considered for highway bridges but was rejected because of the accidental finding of the low modulus of elasticity. It is shown that the elastic modulus of the HSRM-HPC is reduced as much as 50% compared to the conventional HPC of the same strength while preserving all other properties of the conventional HPC. The use of the more flexible HSRM-HPC in concrete ties leads to reduced stress amplitudes and regularized stress fields at the rail seat area and the middle segment of the tie, which are the two most critical areas of tie failure. This work discusses the development and characterization of the HSRM HPC material, as well as current work on the performance assessment of such ties. The material development, material characterization, and performance assessment is conducted through experimental testing and computer simulations. The benefits of HSRM-HPC ties are quantified and discussed.
Effectiveness of Chemical Grouting and Stone Blowing as Remedial Measures to Mitigate Differential Movement at Railroad Track Transitions
Authors: Mishra Debakanta , Boler Huseyin , Tutumluer Erol , Hyslip James P.
Published: June 2016

Railway transitions like bridge approaches experience differential movements related to differences in track system stiffness, track damping characteristics, foundation type, ballast settlement from fouling and/or degradation, as well as fill and subgrade settlement. A recent research study at the University of Illinois has used advanced geotechnical instrumentation to identify and quantify different factors contributing to recurrent differential movement problems at three different bridge approaches along Amtrak’s Northeast Corridor (NEC) near Chester, Pennsylvania. Field instrumentation data have indicated excessive ballast movement to be the primary factor contributing to the “bump” development at these bridge approaches. Among the different remedial measures applied to mitigate the recurrent track geometry issues were: (1) Chemical Grouting, (2) Stone Blowing, and (3) Under-Tie Pads. This paper will discuss the implementation methods using track geometry records and instrumentation data, and highlight the effectiveness of chemical grouting and stone blowing to mitigate the differential movement problem at railroad bridge approaches. According to the trends in the transient ballast deformation data collected under train loading, both remedial measures were effective in significantly reducing excessive ballast deformation, which was the primary mechanism behind the bump development at these locations. Ballast degradation and presence of excessive fine particles in the ballast layer adversely affected the ability of the grout to bond with aggregate particles. A “clean” ballast layer, on the other hand, facilitated adequate bonding between the grout and ballast particles leading to significantly improved long-term track performance.
Wheel Temperature Reduction During Freight Car Braking
Authors: Stewart Monique F. , Singh Som P. , Andersen David R. , Wen Rou , Booth Graydon F.
Published: June 2016

Since the adoption of 286,000 lb gross rail load (286K GRL) car service, an increase in wheel thermal damage and shelling has been observed. This is attributed to the increased braking horsepower in 286K GRL service as compared to the 263K GRL service environment. This study investigated possible designs and methods of braking that could lead to reduced heat input to the tread of freight car wheels in order to mitigate this damage and reduce its occurrence to a level closer to that seen with 263K GRL car service.

Fifteen potential concepts to lower the thermal input to wheels and/or accelerate heat removal from the tread were identified and evaluated using the following engineering categories: simplicity of design, maintenance requirements, weight considerations, material and manufacturing costs, controllability of braking effort, and market acceptability. Five final concepts — axle-mounted disc, cheek disc, wheel rim, axle-mounted drum, and high convection coating — were developed through preliminary design and thermal analysis to confirm their effectiveness in meeting the objectives.

Four concepts for alternative braking methods — axle-mounted disc brakes, cheek disc brakes, wheel rim clasp brakes, and axle-mounted drum brakes — were analyzed in considerable detail. Of the four concepts presented, the first three appear to be feasible and would be potential candidates for further detailed investigations/evaluation.

It is shown that as the demand on railway wheels to withstand increased mechanical and thermal loads grows, there are viable braking enhancements that can help manage the stress state in freight car wheels.
Rail Surface Measurement and Multi-Scale Modeling of Wheel-Rail Contact
Authors: Alemi Mohammad Mehdi , Taheri Saied , Ahmadian Mehdi
Published: June 2016

The primary purpose of this study is to use a nano-scale optical surface profilometer to assess the feasibility of such instruments in measuring localized friction coefficient on railways, beyond what can be commonly measured by tribometers used by the railroad industry. One of the important aspects of moving freight and passengers on railways is the ability to manage and control the friction between the rails and wheels. Creating a general friction model is a challenging task because friction is influenced by various factors such as surface metrology, properties of materials in contact, surface contamination, flash temperature, normal load, sliding velocity, surface deformation, inter-surface adhesion, etc. With an increase in the number of influencing factors, the complexity of the friction model also increases. Therefore, reliable prediction of the friction, both theoretically and empirically, is sensitive to how the model parameters are measured. In this study, the surface characteristics of four rail sections are measured at 20 microns over a rectangular area using a portable Nanovea JR25 optical surface profilometer and the results were studied using various statistical procedures and Fractal theory. Furthermore, a 2D rectangular area was measured in this study because 1D height profile doesn’t capture all the necessary statistical properties of the surface. For surface roughness characterization, the 3D parameters such as root-mean-square (RMS) height, skewness, kurtosis and other important parameters are obtained according to ISO 25178 standard. To verify the statistical results and fractal analysis, a British Pendulum Skid Resistance Tester is used to measure the average sliding coefficients of friction based on several experiments over a 5 cm contact length for the four rail sections selected for the tests. The results indicate that rail surfaces with lower fractal dimension number have a lower friction. The larger fractal dimension number appears to be directly proportional to larger microtexture features, which potentially increase friction.
Rail Tank Car Total Containment Fire Testing: Results and Observations
Authors: Gonzalez Francisco , Prabhakaran Anand , Robitaille Andrew , Birk A. M. , Otremba Frank
Published: June 2016

The frequent incidences of Non-Accident Releases (NARs) of lading from tank cars have resulted in an increasing interest in transporting hazardous materials in total containment conditions (i.e., no pressure relief devices). However, the ability of tank cars to meet thermal protection requirements provided in the Code of Federal Regulations under conditions of total containment has not been established. The intent of this effort was to evaluate through a series of third-scale fire tests, the ability of tank cars to meet the thermal protection requirements under total containment conditions, with a particular focus on caustic ladings. A previous paper on this effort described the test design and planning effort associated with this research effort.

A series of seven fire tests were conducted using third scale tanks. The test fires simulated fully engulfing, hydrocarbon fueled, pool fire conditions. The initial tests were conducted with water as a lading under jacketed and non-jacketed conditions and also with different fill levels (98% full or 50% full). Additionally, two tests were conducted with the caustic, Sodium Hydroxide as the lading, each test with a different fill level. In general, the tanks with water were allowed to fail or reach near-failure conditions, whereas, the tests with the caustic lading were not allowed to proceed near failure for safety reasons. This paper describes the results and observations from the fire tests, and discusses the various factors that affected the fire test performance of the test tanks.

Review of results from the one-third scale tests, and subsequent scaling to full-scale suggest that a full-scale tank car filled with 50% NaOH solution is unlikely to meet the 100-minute survival requirement under conditions of total containment.