bluuebunny/crossref_metadata_2025 huggingface dataset:
A Typology of Reverse Innovation
Authors: von Zedtwitz Max , Corsi Simone , Søberg Peder Veng , Frega Romeo
Published: June 2014

Reverse innovation commonly refers to an innovation initially launched in a developing country and later introduced to an advanced country. Adopting a linear innovation model with the four sequential phases of concept ideation, product development, primary target market introduction, and subsequent secondary market introduction, this study expands the espoused definition of reverse innovation beyond its market‐introduction focus with reversals in the flow of innovation in the ideation and product development phases. Recognizing that each phase can take place in different geographical locations, the paper then introduces a typology of global innovation with 16 different types of innovation flows between advanced and emerging countries, 10 of which are reverse innovation flows. The latter are further differentiated into weak and strong reverse innovation, depending on the number of innovation phases taking place in an emerging country. This analytical framework allows recasting of current research at the intersection between innovation and international business. Of the 10 reverse innovation flows, six are new and have not been covered in the literature to date. The study addresses questions of ethnocentrism and the continuity of the flow of innovation, and discusses possible extensions of the model with respect to the number of geographical categories and phases of innovation. Four research propositions highlight areas for future investigation, especially in the context of optimizing a firm's portfolio of global innovation competence and capability. The implications for management are concerned with internal and external resistance to reverse innovation. Most significantly, while greater recognition and power of innovation in formerly subordinate organizational units is inconvenient to some, the ability to leverage the potential of reverse innovation makes a firm more likely to succeed in global innovation overall.
The Emergence of Penal Extremism in California: A Dynamic View of Institutional Structures and Political Processes
Authors: Campbell Michael C.
Published: June 2014

This article examines legal and political developments in California in the 1970s and early 1980s that led to extreme changes in the state's use of imprisonment. It uses historical research methods to illustrate how institutional and political processes interacted in dynamic ways that continuously unsettled and reshaped the crime policy field. It examines crime policy developments before and after the passage of the state's determinate sentencing law to highlight the law's long-term political implications and to illustrate how it benefited interest groups pushing for harsher punishment. It emphasizes the role executives played in shaping these changes, and how the law's significance was as much political as legal because it transformed the institutional logics that structured criminal lawmaking. These changes, long sought by the law enforcement lobby, facilitated crime's politicization and ushered in a new era of frenetic and punitive changes in criminal law and punishment. This new context benefited politicians who supported extreme responses to crime and exposed the crime policy process to heightened degrees of popular scrutiny. The result was a political obsession with crime that eschewed moderation and prioritized prison expansion above all else.
Probing druggability and biological function of essential proteins in Leishmania combining facilitated null mutant and plasmid shuffle analyses
Authors: Dacher Mariko , Morales Miguel A. , Pescher Pascale , Leclercq Olivier , Rachidi Najma , Prina Eric , Cayla Mathieu , Descoteaux Albert , Späth Gerald F.
Published: June 2014

Leishmania parasites cause important human morbidity and mortality. Essential Leishmania genes escape genetic assessment by loss‐of‐function analyses due to lethal null mutant phenotypes, even though these genes and their products are biologically most significant and represent validated drug targets. Here we overcome this limitation using a facilitated null mutant approach applied for the functional genetic analysis of the MAP kinase LmaMPK4. This system relies on the episomal expression of the target gene from vector pXNG that expresses the Herpes simplex virus thymidine kinase gene thus rendering transgenic parasites susceptible for negative selection using the antiviral drug ganciclovir. Using this system we establish the genetic proof of LmaMPK4 as essential kinase in promastigotes. LmaMPK4 structure/function analysis by plasmid shuffle allowed us to identify regulatory kinase sequence elements relevant for chemotherapeutic intervention. A partial null mutant, expressing an MPK4 derivative with altered ATP‐binding properties, showed defects in metacyclogenesis, establishing a first link of MPK4 function to parasite differentiation. The approaches presented here are broadly applicable to any essential gene in Leishmania thus overcoming major bottlenecks for their functional genetic analysis and their exploitation for structure‐informed drug development.
Oil price volatility, fiscal policy and economic growth: a panel vector autoregressive (PVAR) analysis of some selected oil‐exporting African countries
Authors: Omojolaibi Joseph Ayoola , Egwaikhide Festus O.
Published: June 2014

Fiscal policy in oil‐centred economies is facing specific challenges, both in the long run, as regards intergenerational equity and fiscal sustainability, and in the short run, as regards macroeconomic stabilisation and fiscal planning. Specifically, fiscal policy in most oil‐exporting countries in Africa has been expansionary over the past years in the wake of high oil prices. Fiscal expansion has added to inflationary pressure, and monetary policy has been constrained in tackling inflation as a result of prevailing exchange rate regimes. The sharp fall in oil prices since mid‐2008 has brought to the fore a different question—whether oil exporters in Africa can sustain spending levels reached in previous years. The study makes use of quarterly data that span between 1990:q1 and 2010:q4. A panel vector autoregressive technique was employed to examine the impact of oil price volatility on economic performance of five oil‐exporting countries in Africa. The countries are Algeria, Angola, Egypt, Libya and Nigeria. In order to study the responses of shocks, the study identifies oil price volatility, real gross domestic product (real GDP), fiscal deficit, gross investment and money supply shocks by ordering the variables in this way and using a standard Choleski factorisation. The impulse response function's result shows that of all the macroeconomic variables considered, gross investment respond more effectively to oil price volatility. However, the responses of fiscal deficit, real GDP and money supply are less effective. Overall, these findings suggest that gross investment is the main route through which volatility in oil price influenced the real sector of these economies.
Moving from gas flaring to gas conservation and utilisation in Nigeria: a review of the legal and policy regime
Authors: Orji Uchenna Jerome
Published: June 2014

Nigeria is often described as ‘a gas province with significant oil accumulations’, due to her immense natural gas reserves. A large volume of Nigeria's gas reserves is found as ‘associated natural gas’ along with crude oil. In most cases, such associated gas is burnt off during oil field operations through a process that is commonly referred to as ‘gas flaring’. Recent statistics indicate that Nigeria is the second highest gas‐flaring country in the world. Gas flaring has also been a major cause of environmental pollution and a waste of non‐renewable resources that has resulted to a huge loss of revenue for the country. This article analyses the legal and policy regime to tackle gas flaring and enhance gas utilisation and re‐injection or conservation in Nigeria. It reveals several obstacles that have hindered the success of such legal and policy regimes and suggests measures to reverse the trend. The article suggests inter alia that existing legal and policy regimes to tackle gas flaring and promote gas utilisation and re‐injection have not been successful due to the absence of attractive incentives that will encourage oil‐producing companies to invest in gas utilisation or re‐injection facilities. It also suggests that the enforcement of existing anti‐gas flaring regimes has not been successful due to the absence of deterrent sanctions and also as a result of Nigeria's heavy dependence on oil revenues. The article recommends the establishment of more punitive gas flare sanctions alongside attractive fiscal incentives that will encourage oil‐producing companies to invest in gas utilisation and re‐injection facilities.
Patient and procedural characteristics for successful and failed immediate tracheal extubation in the operating room following cardiac surgery in infancy
Authors: Miller Jeffrey W. , Vu Dien , Chai Paul J. , Kreutzer Janet , Hossain Md M. , Jacobs Jeffrey P. , Loepke Andreas W.
Published: June 2014

Background

Immediate extubation in the operating room after congenital heart surgery is practiced with rising frequency at many cardiac institutions to decrease costs and complications. Infants less than one year of age are also increasingly selected for this ‘fast track’. However, factors for patient selection, success, or failure of this practice have not been well defined in this population, yet are critical for patient safety.

Objective

To identify selection criteria, patient and procedural characteristics for successful or failed very early endotracheal extubation in the operating room immediately following infant heart surgery.

Methods

A retrospective analysis was performed for 326 consecutive patients undergoing neonatal and infant heart surgery from 2009 to 2012. Extubation and reintubation data were taken from the institutional Society of Thoracic Surgeons database and patients' charts. Patient characteristics were derived using multivariable logistic regression models.

Results

Very early extubation in the operating room was performed for 130 of 326 neonates and infants (40%). Weight >4 kg, lesser procedural complexity, and absence of trisomy 21 were identified as significant predictors for attempted very early extubation. Of these patients, 12% required reintubation within 48 h following surgery, predominantly due to respiratory failure or for mediastinal re‐exploration. Greater procedural complexity was associated with failed extubations. Reintubation was associated with prolonged hospitalization.

Conclusions

Extubation immediately after infant heart surgery in the operating room can be safely achieved. However, our data suggest that patients undergoing more complex procedures should be selected more conservatively for immediate early extubation.
The Nature of Memory Traces
Authors: De Brigard Felipe
Published: June 2014

Memory trace was originally a philosophical term used to explain the phenomenon of remembering. Once debated by Plato, Aristotle, and Zeno of Citium, the notion seems more recently to have become the exclusive province of cognitive psychologists and neuroscientists. Nonetheless, this modern appropriation should not deter philosophers from thinking carefully about the nature of memory traces. On the contrary, scientific research on the nature of memory traces can rekindle philosopher's interest on this notion. With that general aim in mind, the present paper has three specific goals. First, it attempts to chart the most relevant philosophical views on the nature of memory traces from both a thematic and historical perspective. Second, it reviews critical findings in the psychology and the neuroscience of memory traces. Finally, it explains how such results lend support to or discredit specific philosophical positions on the nature of memory traces. This paper also touches upon the issues raised by recent empirical research that theories of memory traces need to accommodate in order to succeed.
‘Walter Benjamin's Philosophy of Language’
Authors: Procyshyn Alexei
Published: June 2014

In this article, I reconstruct Walter Benjamin's philosophy of language and refine the non‐predicational view of meaning often attributed to him. By situating his 1916 essay ‘On Language as Such and on the Language of Man’ within the context of his struggle with Russell's paradox and its implications for phenomenology, I show how Benjamin arrives at his conception of non‐conceptual content as an environmentally embedded affordance that is directly apprehended by appropriately situated and capable agents. This affordance‐like character of meaning explains Benjamin's account of communication, Adamic naming, and his famous distinction between linguistic and spiritual essences (sprachliche‐ and geistige Wesen). I conclude by showing why translation is central to his views on expression and communication and how it reinforces his account of language‐use.
Karma, Morality, and Evil
Authors: Burley Mikel
Published: June 2014

The doctrine of karma has been praised as a rational and morally edifying explanatory response to the existence of evil and apparent injustice in the world. Critics have attacked it as a morally misguided dogma that distorts one's vision of reality. This essay, after outlining the traditional doctrine, examines three criticisms that have been central to recent debates: firstly, that the doctrine offers no practical guidance; second, that it faces a dilemma between free will and fatalism; and third, that it involves a morally repugnant form of blaming victims for their own misfortunes. Possible responses are considered, the depth of the disagreement is highlighted, and a morally significant difference between alternative ways of articulating the belief in karma is analyzed.
Mental States, Conscious and Nonconscious
Authors: Berger Jacob
Published: June 2014

I discuss here the nature of nonconscious mental states and the ways in which they may differ from their conscious counterparts. I first survey reasons to think that mental states can and often do occur without being conscious. Then, insofar as the nature of nonconscious mentality depends on how we understand the nature of consciousness, I review some of the major theories of consciousness and explore what restrictions they may place on the kinds of states that can occur nonconsciously. I close with a discussion of what makes a state mental, if consciousness is not the mark of the mental.
Effect of Exposure to Heatwave During Blastocyst Formation on Reproductive Performance of Female Rabbits
Authors: Marco‐Jiménez F , Naturil‐Alfonso C , Peñaranda DS , Jiménez‐Trigos E , García‐Diego FJ , Vicente JS
Published: June 2014

Contents

We examined the effect of female exposure to heatwave during blastocyst formation on their reproductive performance and its effect on transcriptome in blastocyst and endometrial tissue. In this study, a total of 72 rabbit does were artificially inseminated and divided into two environmental groups 2 days later: does under conventional conditions (maintained between 14–22°C, n = 29) and does heat stressed in a climatic chamber (maintained between 32–37°C, n = 43). The heat‐stressed group were kept under these conditions for 3 days and returned to conventional conditions thereafter. Five days post‐insemination, 48 does were slaughtered to collect blastocyst and endometrium samples. mRNA transcripts from OCT‐4, VEGF, erbB3, Ifn‐ɣ, HSP70 and HSP90 were analysed by qRT‐PCR. At day 12 of gestation, 24 females were examined by laparoscopy to evaluate implanted embryos and at birth the total kits born and individual weights were recorded. Results revealed no gene expression changes in blastocyst and endometrial tissue under heatwave exposure. Moreover, our results demonstrated that rabbit embryos developed from 8–16 cells to blastocyst during a heatwave did not affect implantation rates, total number of kits born and foetal losses. In summary, these results demonstrate that heatwave period is not a critical point in the reproductive performance of rabbits during blastocyst formation.
Escalate shamefully, de‐escalate angrily or gratefully: The influence of discrete emotions on escalation of commitment
Authors: Dang Junhua , Xiao Shanshan , Liljedahl Sophie
Published: June 2014

Decision makers often tend to escalate their commitment when faced with a dilemma of whether to continue a losing course of action. Researchers recently began to investigate the influence of discrete emotions on this decision tendency. However, this work has mainly focused on negative emotions and rarely considered positive emotions, to say nothing of comparing the effects of both of them simultaneously. The current study addresses this need by presenting the results of three experiments that examined the effects of four emotions of both positive and negative valences in escalation situations. Experiment 1 investigated the relationships of three trait emotions (hope, shame, and anger) and escalation of commitment. Experiments 2 and 3 examined the effects of three induced emotions (anger, shame, and gratitude) on escalation of commitment in a student sample and an employee sample, respectively. The results revealed that the effects of discrete emotions in escalation situations are mainly due to their associated differences on the appraisal dimension of responsibility that is related to escalation situations rather than their valence. The theoretical and practical implications are discussed.
The Case for Mixed Emotions
Authors: Larsen Jeff T. , McGraw A. Peter
Published: June 2014

How do people feel when they experience bittersweet events comprised of pleasant and unpleasant aspects (e.g., good news accompanied by bad)? Just as acids immediately neutralize bases, some have suggested that bittersweet events' pleasant aspects might neutralize their unpleasant aspects, thereby resulting in fairly neutral emotional reactions. Some contemporary theorists also contend that happiness and sadness are mutually exclusive. We review research on the alternative possibility that bittersweet events can elicit pairs of opposite‐valence, mixed emotions, with particularly close attention to the growing body of evidence that people can feel happy and sad at the same time while watching films, listening to music, and experiencing meaningful endings. We also review evidence that people sometimes experience other types of mixed emotions, including disgust accompanied by amusement and fear by enjoyment. Taken together, these data indicate that positive and negative affect are separable in experience.
Role of the penetration‐resistance genes PEN1, PEN2 and PEN3 in the hypersensitive response and race‐specific resistance in Arabidopsis thaliana
Authors: Johansson Oskar N. , Fantozzi Elena , Fahlberg Per , Nilsson Anders K. , Buhot Nathalie , Tör Mahmut , Andersson Mats X.
Published: June 2014

Plants are highly capable of recognizing and defending themselves against invading microbes. Adapted plant pathogens secrete effector molecules to suppress the host's immune system. These molecules may be recognized by host‐encoded resistance proteins, which then trigger defense in the form of the hypersensitive response (HR) leading to programmed cell death of the host tissue at the infection site. The three proteins PEN1, PEN2 and PEN3 have been found to act as central components in cell wall‐based defense against the non‐adapted powdery mildew Blumeria graminis fsp. hordei (Bgh). We found that loss of function mutations in any of the three PEN genes cause decreased hypersensitive cell death triggered by recognition of effectors from oomycete and bacterial pathogens in Arabidopsis. There were considerable additive effects of the mutations. The HR induced by recognition of AvrRpm1 was almost completely abolished in the pen2 pen3 and pen1 pen3 double mutants and the loss of cell death could be linked to indole glucosinolate breakdown products. However, the loss of the HR in pen double mutants did not affect the plants' ability to restrict bacterial growth, whereas resistance to avirulent isolates of the oomycete Hyaloperonospora arabidopsidis was strongly compromised. In contrast, the double and triple mutants demonstrated varying degrees of run‐away cell death in response to Bgh. Taken together, our results indicate that the three genes PEN1, PEN2 and PEN3 extend in functionality beyond their previously recognized functions in cell wall‐based defense against non‐host pathogens.
Functional domains of the PETAL LOSS protein, a trihelix transcription factor that represses regional growth in Arabidopsis thaliana
Authors: Kaplan‐Levy Ruth N. , Quon Tezz , O'Brien Martin , Sappl Pia G. , Smyth David R.
Published: June 2014

PETAL LOSS (PTL) is a trihelix transcription factor that represses growth, especially between sepal primordia. As one of 30 trihelix proteins in Arabidopsis, it falls in the GT2 clade with duplicated trihelix DNA‐binding domains and a long α–helical central domain. PTL orthologs occur in all angiosperm genomes examined except grasses, and sequence comparisons reveal that there are two further short conserved domains at each end. GT2 itself carries two nuclear localization sequences, but PTL has an additional nuclear localization sequence (NLS). We show that PTL can act as a transcriptional activator in yeast and in planta, with the latter tested by two different functional assays. Specific deletions revealed that the activation region is C–terminal. Site‐directed mutagenesis of the DNA‐binding domains has shown that a conserved tryptophan and two downstream acidic amino acids in the second trihelix, predicted to promote folding, are each required for PTL function. Also, three basic residues in the third helix, near the DNA interaction sites, support its function. PTL was found to dimerize in yeast. This was confirmed and extended by jointly expressing differentially tagged forms of PTL in a transient expression system in Nicotiana benthamiana leaves. Cytoplasmic PTL (with mutant NLS sequences) was carried into the nucleus upon binding with nuclear‐localized PTL, providing each partner carried intact central domains. As this 90‐amino acid domain is conserved in most trihelix family members, it seems likely that they all function in dimeric form.
Relationship between urinary Tamm–Horsfall protein excretion and renal function in dogs with naturally occurring renal disease
Authors: Raila Jens , Schweigert Florian J. , Kohn Barbara
Published: June 2014

Background

Tamm–Horsfall protein (THP) is physiologically excreted in urine, but little is known about the role of THP in the diagnosis of renal disease in dogs.

Objective

The aim of this study was to evaluate to which extent naturally occurring renal disease affects the urinary excretion of THP.

Methods

Dogs were divided into 5 groups according to plasma creatinine concentration, urinary protein‐to‐creatinine ratio (UP/UC), and exogenous plasma creatinine clearance (P‐ClCr) rates: Group A (healthy control dogs; n = 8), nonazotemic and nonproteinuric dogs, with P‐ClCr rates > 90 mL/min/m2; group B (n = 25), nonazotemic and nonproteinuric dogs with reduced P‐ClCr rates (51–89 mL/min/m2); group C (n = 7), nonazotemic but proteinuric dogs with P‐ClCr rates 53–98 mL/min/m2; group D (n = 8), azotemic and borderline proteinuric dogs (P‐ClCr rates: 22–45 mL/min/m2); and group E (n = 15), azotemic and proteinuric dogs (not tested for P‐ClCr). THP was measured by quantitative Western blot analysis, and the ratio of THP‐to‐urinary creatinine (THP/UC) was calculated.

Results

The THP/UC concentrations were not different among dogs of groups A–D, but were reduced in dogs of group E (P < .001). THP/UC correlated negatively with serum creatinine (P < .01) and UP/UC (P < .01), but was not significantly associated with P‐ClCr.

Conclusions

Decreased levels of THP/UC were present in moderately to severely azotemic and proteinuric dogs. This suggests tubular injury in these dogs and that THP might be useful as urinary marker to study the pathogenesis of renal disease.
Towards a phylogenetic classification of reef corals: theIndo‐Pacific generaMerulina,GoniastreaandScapophyllia(Scleractinia,Merulinidae)
Authors: Huang Danwei , Benzoni Francesca , Arrigoni Roberto , Baird Andrew H. , Berumen Michael L. , Bouwmeester Jessica , Chou Loke Ming , Fukami Hironobu , Licuanan Wilfredo Y. , Lovell Edward R. , Meier Rudolf , Todd Peter A. , Budd Ann F.
Published: June 2014

Recent advances in scleractinian systematics and taxonomy have been achieved through the integration of molecular and morphological data, as well as rigorous analysis using phylogenetic methods. In this study, we continue in our pursuit of a phylogenetic classification by examining the evolutionary relationships between the closely related reef coral generaMerulina,Goniastrea,ParaclavarinaandScapophyllia(Merulinidae). In particular, we address the extreme polyphyly ofFavitesandGoniastreathat was discovered a decade ago. We sampled 145 specimens belonging to 16 species from a wide geographic range in theIndo‐Pacific, focusing especially on type localities, including the Red Sea, western Indian Ocean and central Pacific. Tree reconstructions based on both nuclear and mitochondrial markers reveal a novel lineage composed of three species previously placed inFavitesandGoniastrea. Morphological analyses indicate that this clade,ParagoniastreaHuang,Benzoni &Budd, gen. n., has a unique combination of corallite and subcorallite features observable with scanning electron microscopy and thin sections. Molecular and morphological evidence furthermore indicates that the monotypic genusParaclavarinais nested withinMerulina, and the former is therefore synonymised.
Cryptic species and Miocene diversification of Palaearctic naked‐toed geckos (Squamata: Gekkonidae) in the Indian dry zone
Authors: Agarwal Ishan , Bauer Aaron M. , Jackman Todd R. , Karanth Praveen
Published: June 2014

We sampled Palaearctic naked‐toed geckos from across their range in India and used two mitochondrial and two nuclear genes to reconstruct relationships within a global phylogeny. Published sequences of Peninsular Indian Hemidactylus allow us to contrast these two groups in dating analyses – providing insights into the history of the Indian dry zone. Palaearctic naked‐toed geckos first moved onto the Indian Plate in the Oligocene, with higher‐level diversification probably linked to collision of the Indian and Eurasian plates, and subsequent dispersal into‐India and diversification with increasing Miocene aridity. An independent gekkonid radiation with species in the dry zone, Hemidactylus diversified during the same period in Peninsular India. Our results demonstrate that dry zone taxa across India may date back to at least the Miocene, with a potential historical climatic barrier between the Indus and Peninsular Indian Divisions. ‘Cyrtopodion’ aravallense is revealed to be a complex with seven genetically and environmentally divergent lineages that began diversifying in the late Miocene, congruent with increased aridity in north‐western India. This discovery of cryptic diversity in the Indian dry zone represents the first terrestrial vertebrate radiation from north‐western central India and highlights how little we understand of the regions’ biodiversity, emphasizing the need for systematic geographic sampling and multiline evidence to reveal true patterns of diversity. The ancestor of ‘Cyrtopodion’ aravallense came into the nascent Indian dry zone in the Miocene and has since diversified, potentially in the absence of any sympatric scansorial rupicolous geckos. Cyrtopodion scabrum represents a unique case of commensalism and shows phylogeographic structure in its presumed native range. The taxonomic implications of our study include a number of undescribed species, recognition of ‘Cyrtopodion’ as a distinct lineage and the non‐monophyly of Altiphylax.
Numerical Analysis of the Coupled Modified van der Pol Equations in a Model of Heart Action
Authors: Zduniak Beata
Published: June 2014

In this paper, a modified van der Pol equations are considered as a description of the heart action. Wide ranges of the model parameters yield interesting qualitative results, e.g. Hopf bifurcation, Bogdanov-Takens bifurcation, transcritical and pitchfork bifurcations but also some stable solutions can be found. The physiological model works in the narrowest range of parameters which allows to obtain a stable behaviour what is important in biological problem. When some kinds of pathologies appear in the heart, it is possible to obtain chaotic behaviour. My aim is to compare the influence of these two types of coupling (unidirectional and bidirectional) on the behaviour of the van der Pol system. The coupling takes place in a system with healthy conductivity, between two nodes: SA and AV, but in some circumstances, a pathological coupling may occur in the heart. The van der Pol oscillator is a type of relaxation oscillator which can be synchronized. In this paper, synchronization properties of such a system are studied as well. For the purpose of a numerical analysis of the system in question, a numerical model was created.
Mathematical Analysis of a Size Structured Tree-Grass Competition Model for Savanna Ecosystems
Authors: Yatat Valaire , Dumont Yves , Tewa Jean Jules , Couteron Pierre , Bowong Samuel
Published: June 2014

Several continuous-time tree-grass competition models have been developed to study conditions of long-lasting coexistence of trees and grass in savanna ecosystems according to environmental parameters such as climate or fire regime. In those models, fire intensity is a fixed parameter while the relationship between woody plant size and fire-sensitivity is not systematically considered.In this paper, we propose a mathematical model for the tree-grass interaction that takes into account both fire intensity and size-dependent sensitivity. The fire intensity is modeled by an increasing function of grass biomass and fire return time is a function of climate. We carry out a qualitative analysis that highlights ecological thresholds that summarize the dynamics of the system. Finally, we develop a non-standard numerical scheme and present some simulations to illustrate our analytical results.
Engineering Studies on Joint Bar Integrity: Part II — Finite Element Analyses
Authors: Carolan Michael E. , Jeong David Y. , Perlman A. Benjamin
Published: June 2014

This paper is the second in a two-part series describing research sponsored by the Federal Railroad Administration (FRA) to study the structural integrity of joint bars. In Part I, observations from field surveys of joint bar inspections conducted on revenue service track were presented [1]. In this paper, finite element analyses are described to examine the structural performance of rail joints under various loading and tie-ballast support conditions. The primary purpose of these analyses is to help interpret and understand the observations from the field surveys.

Moreover, the finite element analyses described in this paper are applied to conduct comparative studies and to assess the relative effect of various factors on the structural response of jointed rail to applied loads. Such factors include: discrete tie support (i.e. supported joint versus suspended joint with varying spans between effective ties), bolt pattern (four versus six bolts), initial bolt tension, and easement. In addition, results are shown for 90 lb rail joined with long-toe angle bars compared to 136 lb rail joined with standard short-toe joint bars.
Empirical Modeling of a Rail Tank Car for Struck Coupler Force Estimation
Authors: Hopkins Brad M. , Maraini Dan , Seidel Andrew , Shahidi Parham
Published: June 2014

Freight rail cars may experience high input forces during a coupling event, which could potentially cause damage to the car body and/or lading. The AAR recommended practice states that cars should not be coupled at speeds greater than 4 mph. However, this recommendation is not always followed and cars are often coupled at much higher speeds. As a result, accelerometers on the car body are sometimes used to monitor impact events. Threshold levels may be set to determine if an over-speed or high-force impact event has occurred. However, a single acceleration value can be difficult to interpret because its relationship to impact force is dependent on many factors, including car type, end-of-car device type, lading type, and loading condition. Dynamic modeling and parametric studies may be used to determine these relationships which can be applied in practice.

This paper presents a study on the relationship between struck coupler force and car body acceleration for a series of impacts on a tank car in both loaded and unloaded states. For the loaded condition, the tank was filled with water. The simplest change from an unloaded tank to a loaded tank is the decrease in acceleration for a given force due to the added mass. However, there is additional complexity added to the system due to the sloshing liquid inside the tank. When attempting to model this dynamic system there is added uncertainty in struck coupler force estimation because of the non-linearity in low frequency car body oscillations. Several example data sets are presented in the time and frequency domains to illustrate this point. The data is then used to generate an empirical model using system identification techniques. The results show that the proposed model offers improved characterization of the system as compared to conventional techniques by accounting for the uncertainties introduced by the sloshing liquid in the tank. The proposed technique is computationally efficient and can potentially be implemented in real time. The model is used to estimate struck coupler force and is validated with real data.
A Spatial Geometry Approach to Variable Cross-Section Rail Modeling: Application to Switches and Turnouts
Authors: Hamper Martin B. , Ruppert Conrad , Wei Cheng , Shabana Ahmed A.
Published: June 2014

Contact between the wheel and rail can have a significant effect on the dynamics of vehicle/track interaction models. Many existing rail surface models rely on curve based geometry which may lead to some geometric inaccuracy in the case of variable cross-section rails. This investigation will focus on the development of a new spatial geometry based rail surface description which reduces this geometric inaccuracy. It has been shown in literature that certain CAD geometry types, such as B-Spline curves and surfaces, may be converted to equivalent absolute nodal coordinate formulation (ANCF) finite elements without a loss of geometric accuracy. To this end, a new ANCF surface description of variable cross-section rails is developed. This investigation also demonstrates the feasibility of using, in the future, 3D surface scanning techniques as well as profile curve measurements to develop a rail surface geometry model using the new ANCF surface which can be systematically integrated with complex multibody system (MBS) models. A realistic railroad vehicle example of a turnout, which includes variable cross-section rails, is tested for the case of the new ANCF surface. A study of the numerical results reveals the benefits of using the ANCF surface geometry developed in this investigation.
Semi-Quantitative Risk Assessment of Adjacent Track Accidents on Shared-Use Rail Corridors
Authors: Lin Chen-Yu , Saat Mohd Rapik
Published: June 2014

Safety is a high priority for any rail system, and there are several safety concerns associated with operating passenger and freight trains on shared-use rail corridors. Adjacent track accident (ATA) is one of the most important concerns. ATA refers to train accident scenarios where a derailed equipment intrudes adjacent tracks, causing operation disturbance and potential subsequent train collisions on the adjacent tracks. Other ATA scenarios include collisions between trains on adjacent tracks (raking), turnouts, and railroad crossings. Limited literature is available that addressed the risk of ATA for shared-use rail corridors. The research described in this paper presents a comprehensive risk assessment to identify factors affecting the likelihood and consequence of adjacent track accidents. A discussion on how these factors affect the probability, consequence, and how individual factor relates to each other are provided. A semi-quantitative risk analysis is developed to investigate various factors affecting train accident rate, intrusion rate, and accident consequences. This research intends to depict a high-level overview of adjacent track accidents and provides a basis for future quantitative risk analyses and risk mitigation implementations.
Rail Highway Grade Crossing Roughness Quantitative Measurement Using 3D Technology
Authors: Wang Teng (Alex) , Souleyrette Reginald R. , Lau Daniel , Xu Peng
Published: June 2014

Quality of surface is an important aspect affecting both the safety and the performance of at-grade rail-highway crossings. Roughness may increase the risk of crashes for both trains and automobiles. Varying grades in crossing profiles increase the likelihood of high-centered crossing collisions between train and truck [1]. The US DOT Railroad Highway Grade Crossing Handbook [2] suggests that rough surfaces could distract a driver’s attention from oncoming trains and that the unevenness of the crossing could result in a driver losing control of their vehicle resulting in a crash.

No quantitative method currently exists to quickly and economically assess the condition of rail crossings in order to evaluate the long term performance of crossings and set a quantitative trigger for their rehabilitation. The conventional method to measure the surface of quality of crossings is based on expert judgment, whereby crossing surfaces are classified as poor, fair or good after an inspector visits and drives over the crossing. However, actual condition of the crossing could be different from the subjective rating. Poor condition rating crossings may not always present the most cost-effective locations for preventive maintenance to lower overall life-cycle costs. Conventional ratings may derive from driving a passenger car of pickup once over the crossing. Effects of various speed, on various vehicles (suspension), and at various places (laterally) cannot be determined or even estimated except at the smoothest of crossings. A quantifiable and extensible procedure is desired.

With rapid advances in computer science, 3D sensing and imaging technologies, it seems logical that a cost-effective quantitative method could be developed to determine the need to rehabilitate rail crossings and assess long term performance. Fundamental to the quantification of crossing condition is the acquisition of an accurate 3D surface model of the crossing in its present state. This paper reports on the development of an accurate, low cost and readily deployable sensor capable of rapid collection of this 3D surface. The research is seen as a first step towards automating the crossing inspection process, ultimately leading to the quantification and estimation of future performance of rail crossing.
Effects of Ballast Degradation on Permanent Deformation Behavior From Large-Scale Triaxial Tests
Authors: Qian Yu , Tutumluer Erol , Hashash Youssef M. A. , Ghaboussi Jamshid
Published: June 2014

Consisting of large sized aggregate particles with uniform size distribution, ballast is an essential component of the track substructure to facilitate load distribution and drainage. As freight tonnage accumulates with traffic, ballast will get fouled increasingly due to either aggregate breakdown and degradation or contamination by other materials such as coal dust and subgrade soil intrusion. Fouling affects shear strength and load carrying ability of ballast layer especially under wet conditions. According to Selig and Waters [1], ballast fouling is often due to aggregate degradation, which covers up to 76% of all the fouling cases. To investigate the effects of ballast aggregate breakdown and degradation on the mechanical behavior of fouled ballast, a series of Los Angeles abrasion tests were performed in this study to generate fouled ballast materials caused by particle breakage and abrasion under a well-controlled laboratory environment. The change of particle shape properties during the Los Angeles abrasion tests was quantified and studied through image analysis technology. Large-scale triaxial tests were performed on specimens of new ballast, degraded ballast coarse particle fraction (without fines), and full gradation of degraded ballast (with fines) under repeated load application using a triaxial test device recently developed at the University of Illinois specifically for ballast size aggregate materials. The large-scale triaxial results indicated that the specimen having those degraded coarse particles yielded higher permanent deformation trends from repeated load triaxial testing when compared to the specimen with the new ballast gradation. As expected, the highest permanent deformation was obtained from the degraded ballast specimen having fine particles and the Fouling Index (FI) value of approximately 40.
A Variable No-Load Voltage Scheme for Improving Energy Efficiency in DC-Electrified Mass Transit Systems
Authors: López-López Álvaro J. , Abrahamsson Lars , Pecharromán Ramón R. , Fernández-Cardador Antonio , Cucala Paloma , Östlund Stefan , Söder Lennart
Published: June 2014

Railway mass transit systems like subways play a fundamental role in the concept of sustainable cities. In these systems, the amount of passengers strongly fluctuates along the day. Hence, in order to provide a proper service without incurring disproportionate energy consumption, operation at different traffic densities is required.

The majority of underground systems are DC-electrified. Standard DC voltages in railway systems are low for historical and safety reasons. In the rush hours, the large number of trains demanding power of the system may lead to overloaded substations and voltage dips. This problem is partially mitigated by means of substation-transformer tap regulation, which allows operators to increase the no-load voltage.

High no-load voltage has a beneficial effect at all traffic-density scenarios in terms of transmission losses. However, at the same time it effectively reduces the system’s capacity to absorb regenerated energy, which may lead to inefficient energy consumption figures during off-peak hours.

In this paper, the sensitivity of system energy consumption to no-load voltage has been analyzed. Several traffic-density scenarios in a case-study system are explored. As a result, a scheduled no-load voltage scheme is proposed for the operation of the system. This operation strategy improves energy efficiency without incurring a high investment cost. The only costs related to this proposed method are the costs of wear-and-tear in tap-changers. In case there are devices such as energy storage systems installed in the system, there would be additional operation costs related to a simultaneous update of the voltage limits for their operation.
Technology and High Reliability Organizations in Railroad Operations Safety: A Case Study of Metrolink / SCRRA and Positive Train Control (PTC) Implementation
Authors: Placencia Greg , Meshkati Najmedin , Moore James , Khashe Yalda
Published: June 2014

High-risk organizations operate technologies such as in rail transportation, aviation, or nuclear power, where failure/breakdown can initiate low-probability, high consequence events. The concept of High-Reliability Organizations (HROs) was developed to avoid or mitigate such events through proper management despite the inherent risk. The September 12, 2008, Chatsworth accident is an example of such events that HROs are designed to prevent. In that case a Metrolink commuter train and Union Pacific freight train collided when the Metrolink engineer failed to recognize and react to a stop signal as a result of texting, causing 25 deaths and 135 injuries. This incident directly resulted in the Railroad Safety Improvement Act of 2008, which mandated Positive Train Control (PTC) implementation on all Class 1 rail carriers, as well as intercity / commuter rail passenger transporters. Over the past 2 years, the USC team has observed PTC implementation at the Southern California Regional Rail Authority (SCRRA) / Metrolink. This paper examines how PTC can be an integral part in developing and promoting HRO principles within the rail industry based on those observations.
Modeling of a Roller Rig for Evaluation of Wheel/Rail Contact Mechanics
Authors: Hosseinipour Milad , Meymand Sajjad Z. , Craft Michael J. , Ahmadian Mehdi
Published: June 2014

This paper provides a detailed dynamic model of the electromechanical system for a scaled roller rig that is under construction at the Railway Technology Laboratory of Virginia Tech (RTL) for accurate study of the mechanics and dynamics at wheel-rail interface in railway vehicles. Roller rigs are critical laboratory test equipment for studying rail vehicle dynamics, either as a full railcar or single component. The controlled laboratory environment will provide a successful path for obtaining data on the mechanics and dynamics of the system, including creepage and creep forces at the wheel-rail interface under various conditions. The single-wheel scaled rig under development at RTL includes a wheel that is placed on a roller with similar profile as a U.S. 136 weight rail. The test setup allows for adjusting the wheel load, the wheel angle of attack, the rail cant, and the lateral position of the wheel with respect to the rail (including flanging). The roller and the wheel are each powered independently by two AC motors that enable controlling their relative speed to a high degree of precision, i.e., 0.1 RPM, in order for precisely controlling and simulating various creep conditions that occur in practice. An essential step for the successful design and development of the test rig is modeling the motors and the roller/wheel drivelines. The model includes the electromagnetic dynamics of the AC motors, the compliances and damping of the drivelines, the inertial properties of the motors, shafts, couplers, and the rotating wheels, in a multi-domain (electrical, magnetic, and mechanical) lumped-parameter model. The model is used to determine the damped natural frequencies of the coupled system. The results of the study indicate that the compliances of the driveline mechanics is the most critical element in maintaining a prescribed speed at the driven wheel, and also controlling the relative creep between the wheel and the simulated (round) rail.