bluuebunny/crossref_metadata_2025 huggingface dataset:
Strong and parallel salinity‐induced phenotypic plasticity in one generation of threespine stickleback
Authors: Mazzarella A. B. , Voje K. L. , Hansson T. H. , Taugbøl A. , Fischer B.
Published: February 2015

Phenotypic plasticity is a major factor contributing to variation of organisms in nature, yet its evolutionary significance is insufficiently understood. One example system where plasticity might have played an important role in an adaptive radiation is the threespine stickleback (Gasterosteus aculeatus), a fish that has diversified after invading freshwater lakes repeatedly from the marine habitat. The parallel phenotypic changes that occurred in this radiation were extremely rapid. This study evaluates phenotypic plasticity in stickleback body shape in response to salinity in fish stemming from a wild freshwater population. Using a split‐clutch design, we detected surprisingly large phenotypically plastic changes in body shape after one generation. Fish raised in salt water developed shallower bodies and longer jaws, and these changes were consistent and parallel across families. Although this work highlights the effect of phenotypic plasticity, we also find indications that constraints may play a role in biasing the direction of possible phenotypic change. The slopes of the allometric relationship of individual linear traits did not change across treatments, indicating that plastic change does not affect the covariation of traits with overall size. We conclude that stickleback have a large capacity for plastic phenotypic change in response to salinity and that plasticity and evolutionary constraints have likely contributed to the phenotypic diversification of these fish.
Effects of weed density on the dispersal of Orius majusculus Reuter (Heteroptera Anthocoridae) within maize
Authors: Madeira F. , Pons X.
Published: February 2015

Orius majusculus Reuter (Heteroptera: Anthocoridae) is the most common and abundant generalist predator in Spanish maize crops and is sensitive to drastic changes in weed density. We carried out a 2‐year study in the NE Iberian Peninsula to examine the dispersal of O. majusculus in maize plots with moderately high and low weed density. Insects were collected using yellow sticky traps and/or a bug‐vac aspirator. Dispersal was assessed using rubidium as a marker. Dispersal rate of O. majusculus differed between sampling periods, with a maximum between the 16 unfolded leaves (V16) to grain milky (R3) maize growth stages. However, we detected no differences in the distance moved by male and females of O. majusculus from rubidium‐marked areas in plots with moderately high or low weed density suggesting that changes in weed density do not affect the dispersal of O. majusculus within a maize field.
TNFα in cerebral ischemia: another stroke against you?
Authors: Wilkins Heather M. , Swerdlow Russell H.
Published: February 2015

Read the full article ‘Rapid mitochondrial dysfunction mediates TNF‐alpha‐induced neurotoxicity' on page 443.
A Model of Mortgage Default
Authors: CAMPBELL JOHN Y. , COCCO JOÃO F.
Published: February 2015

In this paper, we solve a dynamic model of households' mortgage decisions incorporating labor income, house price, inflation, and interest rate risk. Using a zero‐profit condition for mortgage lenders, we solve for equilibrium mortgage rates given borrower characteristics and optimal decisions. The model quantifies the effects of adjustable versus fixed mortgage rates, loan‐to‐value ratios, and mortgage affordability measures on mortgage premia and default. Mortgage selection by heterogeneous borrowers helps explain the higher default rates on adjustable‐rate mortgages during the recent U.S. housing downturn, and the variation in mortgage premia with the level of interest rates.
A Comparative‐Advantage Approach to Government Debt Maturity
Authors: GREENWOOD ROBIN , HANSON SAMUEL G. , STEIN JEREMY C.
Published: February 2015

We study optimal government debt maturity in a model where investors derive monetary services from holding riskless short‐term securities. In a setting where the government is the only issuer of such riskless paper, it trades off the monetary premium associated with short‐term debt against the refinancing risk implied by the need to roll over its debt more often. We extend the model to allow private financial intermediaries to compete with the government in the provision of short‐term money‐like claims. We argue that, if there are negative externalities associated with private money creation, the government should tilt its issuance more toward short maturities, thereby partially crowding out the private sector's use of short‐term debt.
Uterine cervical cancer with brain metastasis as the initial site of presentation
Authors: Sato Yumi , Tanaka Kei , Kobayashi Yoichi , Shibuya Hiromi , Nishigaya Yoshiko , Momomura Mai , Matsumoto Hironori , Iwashita Mitsutoshi
Published: February 2015

Brain metastasis from uterine cervical cancer is rare, with an incidence of 0.5%, and usually occurs late in the course of the disease. We report a case of uterine cervical cancer with brain metastasis as the initial site of presentation. A 50‐year‐old woman with headache, vertigo, amnesia and loss of appetite was admitted for persistent vomiting. Contrast enhanced computed tomography showed a solitary right frontal cerebral lesion with ring enhancement and uterine cervical tumor. She was diagnosed with uterine cervical squamous cell carcinoma with parametrium invasion and no other distant affected organs were detected. The cerebral lesion was surgically removed and pathologically proved to be metastasis of uterine cervical squamous cell carcinoma. The patient underwent concurrent chemoradiotherapy, followed by cerebral radiation therapy, but multiple metastases to the liver and lung developed and the patient died 7 months after diagnosis of brain metastasis.
Successful management of pregnancy with very‐long‐chain acyl‐coenzyme A dehydrogenase deficiency
Authors: Yamamoto Hiroko , Tachibana Daisuke , Tajima Go , Shigematsu Yosuke , Hamasaki Takashi , Tanaka Akemi , Koyama Masayasu
Published: February 2015

Very‐long‐chain acyl‐coenzyme A dehydrogenase deficiency (VLCADD) is a rare and life‐threatening disease characterized by an enzymatic defect in the fatty acid β‐oxidation pathway. A nulliparous woman with VLCADD showed improvements in serum levels of the long‐chain acylcarnitine moiety (C14:1) during pregnancy and successfully delivered a healthy infant vaginally. Pregnancy and vaginal delivery can be successfully completed in patients with VLCADD with careful management.
Prosthodontic Implant Club at UIC, Program Description and Survey Analysis
Authors: Rynn Michelle Howard , Afshari Fatemeh S. , Schneider Justin , Yuan Judy Chia‐Chun , Harlow Rand , Knoernschild Kent L. , Campbell Stephen D. , Sukotjo Cortino
Published: February 2015

Purpose

This study aims to (1) describe the Predoctoral Implant Club at UIC (PIC‐UIC) mentoring model while providing a rationale for the program and (2) investigate PIC members’ perception about the club and prosthodontics in general via a questionnaire and focus group discussion.

Materials and Methods

A survey to investigate PIC members’ perception regarding the club was distributed at a meeting. The survey consisted of questions about the members’ prior exposure to prosthodontics, faculty, and residents; current exposure to and perceptions of prosthodontics; future outcomes from membership; and possible improvements to PIC‐UIC. Four student members of PIC‐UIC participated in a focus group discussion about their exposure to prosthodontics during each year of their training, their exposure to prosthodontics following PIC‐UIC membership, including rotations in the advanced prosthodontic clinic, mentorships by prosthodontic faculty and residents, and attendance at the American College of Prosthodontists Annual Session.

Results

Following PIC‐UIC membership, students indicated an increased exposure to prosthodontics and prosthodontic faculty. More than a third of the respondents indicated that they are “likely” to consider a prosthodontic residency after having joined PIC‐UIC. Almost two‐thirds of the respondents indicated that they would recommend PIC to students at other universities and believed their understanding of the prosthodontic specialty has increased. Students who participated in the focus group agreed they had little exposure to prosthodontics, prosthodontic faculty, and advanced restorative procedures in the beginning of their dental education. They felt that involvement in PIC‐UIC was a valuable experience that helped them consider or reinforced their decision to pursue prosthodontics as a career.

Conclusions

PIC‐UIC increased predoctoral students’ interest in prosthodontics. Involving prosthodontic faculty and residents in mentoring and educational activities was evaluated positively by students. PIC‐UIC may serve as a pipeline program for predoctoral students at other dental schools.
Mixed ancestry and admixture in Kauai's feral chickens: invasion of domestic genes into ancient Red Junglefowl reservoirs
Authors: Gering E. , Johnsson M. , Willis P. , Getty T. , Wright D.
Published: February 2015

A major goal of invasion genetics is to determine how establishment histories shape non‐native organisms' genotypes and phenotypes. While domesticated species commonly escape cultivation to invade feral habitats, few studies have examined how this process shapes feral gene pools and traits. We collected genomic and phenotypic data from feral chickens (Gallus gallus) on the Hawaiian island of Kauai to (i) ascertain their origins and (ii) measure standing variation in feral genomes, morphology and behaviour. Mitochondrial phylogenies (D‐loop & whole Mt genome) revealed two divergent clades within our samples. The rare clade also contains sequences from Red Junglefowl (the domestic chicken's progenitor) and ancient DNA sequences from Kauai that predate European contact. This lineage appears to have been dispersed into the east Pacific by ancient Polynesian colonists. The more prevalent MtDNA clade occurs worldwide and includes domesticated breeds developed recently in Europe that are farmed within Hawaii. We hypothesize this lineage originates from recently feralized livestock and found supporting evidence for increased G. gallus density on Kauai within the last few decades. SNPs obtained from whole‐genome sequencing were consistent with historic admixture between Kauai's divergent (G. gallus) lineages. Additionally, analyses of plumage, skin colour and vocalizations revealed that Kauai birds' behaviours and morphologies overlap with those of domestic chickens and Red Junglefowl, suggesting hybrid origins. Together, our data support the hypotheses that (i) Kauai's feral G. gallus descend from recent invasion(s) of domestic chickens into an ancient Red Junglefowl reservoir and (ii) feral chickens exhibit greater phenotypic diversity than candidate source populations. These findings complicate management objectives for Pacific feral chickens, while highlighting the potential of this and other feral systems for evolutionary studies of invasions.
Genetic structure, admixture and invasion success in a Holarctic defoliator, the gypsy moth (Lymantria dispar, Lepidoptera: Erebidae)
Authors: Wu Yunke , Molongoski John J. , Winograd Deborah F. , Bogdanowicz Steven M. , Louyakis Artemis S. , Lance David R. , Mastro Victor C. , Harrison Richard G.
Published: February 2015

Characterizing the current population structure of potentially invasive species provides a critical context for identifying source populations and for understanding why invasions are successful. Non‐native populations inevitably lose genetic diversity during initial colonization events, but subsequent admixture among independently introduced lineages may increase both genetic variation and adaptive potential. Here we characterize the population structure of the gypsy moth (Lymantria dispar Linnaeus), one of the world's most destructive forest pests. Native to Eurasia and recently introduced to North America, the current distribution of gypsy moth includes forests throughout the temperate region of the northern hemisphere. Analyses of microsatellite loci and mitochondrial DNA sequences for 1738 individuals identified four genetic clusters within L. dispar. Three of these clusters correspond to the three named subspecies; North American populations represent a distinct fourth cluster, presumably a consequence of the population bottleneck and allele frequency change that accompanied introduction. We find no evidence that admixture has been an important catalyst of the successful invasion and range expansion in North America. However, we do find evidence of ongoing hybridization between subspecies and increased genetic variation in gypsy moth populations from Eastern Asia, populations that now pose a threat of further human‐mediated introductions. Finally, we show that current patterns of variation can be explained in terms of climate and habitat changes during the Pleistocene, a time when temperate forests expanded and contracted. Deeply diverged matrilines in Europe imply that gypsy moths have been there for a long time and are not recent arrivals from Asia.
Cell–cell signalling promotes ferric iron uptake in Xanthomonas oryzae pv. oryzicola that contribute to its virulence and growth inside rice
Authors: Rai Rikky , Javvadi Sreegowrinadh , Chatterjee Subhadeep
Published: February 2015

Cell–cell communication mediated by diffusible signal factor (DSF) plays an important role in virulence of several Xanthomonas group of plant pathogens. In the bacterial pathogen of rice, Xanthomonas oryzae pv. oryzicola, DSF is required for virulence and in planta growth. In order to understand the role of DSF in promoting in planta growth and virulence, we have characterized the DSF deficient mutant of X. oryzae pv. oryzicola. Mutant analysis by expression analysis, radiolabelled iron uptake studies and growth under low‐iron conditions indicated that DSF positively regulates ferric iron uptake. Further, the DSF deficient mutant of X. oryzae pv. oryzicola exhibited a reduced capacity to use ferric form of iron for growth under low‐iron conditions. Exogenous iron supplementation in the rice leaves rescued the in planta growth deficiency of the DSF deficient mutant. These data suggest that DSF promotes in planta growth of X. oryzae pv. oryzicola by positively regulating functions involved in ferric iron uptake which is important for its virulence. Our results also indicate that requirement of iron uptake strategies to utilize either Fe3+ or Fe2+ form of iron for colonization may vary substantially among closely related members of the Xanthomonas group of plant pathogens.
Randomized trial investigating the safety and efficacy of influenza vaccination in patients with antineutrophil cytoplasmic antibody‐associated vasculitis
Authors: Jeffs Lisa S , Peh Chen Au , Jose Matthew D , Lange Kylie , Hurtado Plinio R
Published: February 2015

Aim

This study evaluated the safety and efficacy of influenza vaccination in patients with anti‐neutrophil cytoplasmic antibody‐associated vasculitis.

Methods

Thirty‐one patients who were in remission were randomized to receive either a trivalent influenza vaccine or no vaccine. Vaccine efficacy was assessed at 28 days. Patients were followed for 6 months for signs of reactivation of disease. In addition, 67 healthy individuals were randomized to receive either the influenza vaccine or no vaccine to assess its potential for triggering the formation of autoantibodies.

Results

Compared with patients who did not receive the vaccine, vaccinated patients achieved effective responses to all three influenza vaccine antigens. There was no significant change in levels of anti‐neutrophil cytoplasmic antibody post‐vaccination. There was no significant change in disease activity in vaccinated patients compared with non‐vaccinated patients. Among vaccinated healthy individuals, we did not observe any significant change in the level of autoantibodies measured.

Conclusion

This study shows that the administration of influenza vaccine to patients in remission with anti‐neutrophil cytoplasmic antibody‐associated vasculitis is both safe and modestly efficacious.
An Analysis of Intrinsicality
Authors: Marshall Dan
Published: February 2015

The leading account of intrinsicality over the last thirty years has arguably been David Lewis's account in terms of perfect naturalness. Lewis's account, however, has three serious problems: i) it cannot allow necessarily coextensive properties to differ in whether they are intrinsic; ii) it falsely classifies non‐qualitative properties like being Obama as non‐intrinsic; and iii) it is incompatible with a number of metaphysical theories that posit irreducibly non‐categorical properties. I argue that, as a result of these problems, Lewis's account should be rejected and replaced with an alternative account, which also analyses intrinsicality in terms of perfect naturalness, but which avoids these problems.
Secondary metabolites in plant innate immunity: conserved function of divergent chemicals
Authors: Piasecka Anna , Jedrzejczak‐Rey Nicolas , Bednarek Paweł
Published: February 2015

Plant secondary metabolites carry out numerous functions in interactions between plants and a broad range of other organisms. Experimental evidence strongly supports the indispensable contribution of many constitutive and pathogen‐inducible phytochemicals to plant innate immunity. Extensive studies on model plant species, particularly Arabidopsis thaliana, have brought significant advances in our understanding of the molecular mechanisms underpinning pathogen‐triggered biosynthesis and activation of defensive secondary metabolites. However, despite the proven significance of secondary metabolites in plant response to pathogenic microorganisms, little is known about the precise mechanisms underlying their contribution to plant immunity. This insufficiency concerns information on the dynamics of cellular and subcellular localization of defensive phytochemicals during the encounters with microbial pathogens and precise knowledge on their mode of action. As many secondary metabolites are characterized by their in vitro antimicrobial activity, these compounds were commonly considered to function in plant defense as in planta antibiotics. Strikingly, recent experimental evidence suggests that at least some of these compounds alternatively may be involved in controlling several immune responses that are evolutionarily conserved in the plant kingdom, including callose deposition and programmed cell death.

Contents

Summary
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I.
Introduction
948

II.
Phytoanticipins: the guardians that never sleep
949

III.
Phytoalexins: the troops arrive
953

IV.
In the right place at the right time
956

V.
Mode of action
958

VI.
Conclusions
960

Acknowledgements
960

References
960
Dispersal among local communities does not reduce historical contingencies during metacommunity assembly
Authors: Pu Zhichao , Jiang Lin
Published: February 2015

Ample evidence suggests that ecological communities can exhibit historical contingencies. However, few studies have explored whether differences in assembly history can generate alternative local community states in metacommunities in which local communities are linked by dispersal. In a protist microcosm experiment, we examined the influence of species colonization history on metacommunity assembly under homogeneous environmental conditions, by manipulating both the sequence of species colonization into local communities and the rate of dispersal among local communities. Whereas the role of dispersal in structuring local communities decreased over time and became non‐significant towards the end of the experiment, species colonization history significantly influenced local communities throughout the experiment. Local communities, regardless of the rate of dispersal among them, exhibited two alternative states characterized by the dominance of different species. The alternative community states, however, emerged in the absence of priority effects that were often associated with alternative community states found in other assembly studies. Rather, they were driven by variation in species interaction strength among local communities with different assembly histories. These results suggest that dispersal among local communities may not necessarily reduce the role of species colonization history in shaping metacommunity assembly, and that differences in species colonization history need to be explicitly considered as an important factor in causing heterogeneous community states in metacommunities.
Using Spatial Disease Patterns and Patient‐Level Characteristics to Describe Prevalence Elastic Behavior in Treatment for Latent Tuberculosis Infection (LTBI)
Authors: Fluegge Kyle R.
Published: February 2015

Objective

Individual adherence to a 9‐month regimen of isoniazid (9INH) for treatment of latent tuberculosis infection (LTBI) was hypothesized to reflect a prevalent elastic health behavior pattern, or prevention behavior correlated with relevant disease burden.

Method

Log‐rank tests were used to compare survival functions among raw prevalence tertiles for diseases including TB, diabetes, and obesity. Own and cross‐prevalence elasticities were calculated and spatially characterized behavioral response to diseases that may impact TB re‐infection and/or re‐activation. Discrete choice models were used to assess the significance of the spatial elasticities among an ethnically diverse clinic population of 552 patients in an urban American county in 2010.

Results

Log‐rank results revealed a statistical association between dropout and chronic disease prevalence (p < .01), but not TB prevalence (p = .13). Discrete choice models incorporating spatial elasticities and controlling for patient‐ and treatment‐level characteristics demonstrated significant associations with adherence (p < .01), an effect robust to various alternative treatment definitions.

Conclusion

Individual LTBI adherence tracks a prevalence elastic pattern that may represent a potential risk for re‐infection and re‐activation.
Serosorting Sexual Partners by Gay and Bisexual Men to Prevent HIV Infection: Implications for Public Health Clinicians
Authors: Blackwell Christopher W.
Published: February 2015

The most recent Centers for Disease Control and Prevention epidemiological statistics in the United States demonstrate that gay and bisexual men are at most risk for acquiring new HIV infections. While public health campaigns aimed at gay and bisexual males have resulted in improved HIV screening and greater awareness of the need for safer sex practices, barebacking has become a practice of increasing incidence. This act carries the highest risk of HIV transmission and acquisition; and data suggest HIV disease burden is higher among ethnic minorities. Serosorting—purposely seeking HIV serocordant partners—to help lower risk of HIV infection is common. While this can be a positive step in preventing the spread of HIV, it carries serious threats that must be acknowledged. The purpose of this article was to explore the positive and negative aspects of serosorting in the prevention of HIV, describe ways in which health care providers can approach the topic with clients, provide clinical practice implications, and suggest some direction for future research.
Measuring National Well‐Being: A UK Perspective
Authors: Everett Glenn
Published: February 2015

The Measuring National Well‐being program began in the UK in November 2010. Traditional measures of progress such as GDP have long been recognized as an incomplete picture of the state of the nation. Following a six‐month National Debate that elicited 34,000 responses, ONS developed a framework for measuring national well‐being consisting of 10 domains and 40 headline indicators. The indicators include a mixture of both subjective and objective measures. Through supplementing existing economic measures, such as GDP, with measures that reflect social and environmental well‐being, national well‐being looks at the state of the nation through a broader lens. The paper will describe the development of the framework of indicators, including developing subjective well‐being measures, and the dissemination of this information using a range of interactive tools developed for this purpose. This is a long term development program and is still in its early days of measurement. How these data are used to improve policy design, delivery, and evaluation will be important to assess the success of the program. In particular, having a more complete picture of national well‐being will lead to a better understanding of policy impacts on well‐being; better allocation of resources; more informed decisions; assessment of government performance; and international comparisons.
Gaps, ghosts and gapless relatives in spoken English
Authors: Collins Chris , Radford Andrew
Published: February 2015

This paper looks at the syntax of so‐calledgaplessrelative clauses in spoken English. §1 contrastsgap relatives(like that italicised in ‘somethingwhich I said’, in which there is a gap internally within the relative clause associated with the relativised constituent) withgaplessrelatives (like that italicised in ‘They were clowning around,which I didn't really care until I found out they had lost my file’, in which there is no apparent gap within the relative clause). In §2, we note that a number of recent analyses takewhichto function as a subordinating conjunction in gapless relatives, but we argue against this view and provide evidence that the wh‐word in such clauses is indeed a relative pronoun. In §3, we argue that the relative pronoun in gapless relatives serves as the object of a ‘silent’ preposition. In §4, we present an analysis under which a preposition can be silent when it undergoes a type of deletion operation calledGhosting. §5 discusses gapless relatives which have a Topic‐Comment interpretation, and argues for an extended Ghosting analysis under which aTPcontaining a predicate ofsayingassociated with the ghosted preposition is also ghosted. Our overall conclusion is that supposedly ‘gapless’ relatives are more properly analysed as containing a gap created by relativization of the object of a ghosted preposition.
Killer cell immunoglobulin‐like receptor (KIR) gene diversity in a population naturally exposed to malaria in Porto Velho, Northern Brazil
Authors: Perce‐da‐Silva D. S. , Silva L. A. , Lima‐Junior J. C. , Cardoso‐Oliveira J. , Ribeiro‐Alves M. , Santos F. , Porto L. C. M. S. , Oliveira‐Ferreira J. , Banic D. M.
Published: February 2015

Killer cell immunoglobulin‐like receptors (KIR) are expressed mainly in natural killer cells and specifically recognize human leukocyte antigen (HLA) class I molecules. The repertoire of KIR genes and KIR–HLA pairs is known to play a key role in the susceptibilities to and the outcomes of several diseases, including malaria. The aim of this study was to investigate the distribution of KIR genes, KIR genotypes and KIR–HLA pair combinations in a population naturally exposed to malaria from Brazilian Amazon. All 16 KIR genes investigated were present in the studied population. Overall, 46 KIR genotypes were defined. The two most common genotypes in the Porto Velho communities, genotypes 1 and 2, were present at similar frequencies as in the Americas. Principal component analysis based on the frequencies of the KIR genes placed the Porto Velho population closer to the Venezuela Mestizos, USA California hispanic and Brazil Paraná Mixed in terms of KIR gene frequencies. This analysis highlights the multi‐ethnic profile of the Porto Velho population. Most of the individuals were found to have at least one inhibitory KIR–HLA pair. Seventy‐five KIR–HLA pair combinations were identified. The KIR‐2DL2/3_HLA‐C1, KIR3DL1_HLA‐Bw4 and KIR2DL1_HLA‐C2 pairs were the most common. There was no association between KIR genes, KIR genotypes or KIR–HLA pair combinations and malaria susceptibility in the studied population. This is the first report on the distribution of KIR and known HLA ligands in the Porto Velho population. Taken together, these results should provide baseline information that will be relevant to population evolutionary history, malaria and other diseases studies in populations of the Brazilian Amazon.
Computing separable isogenies in quasi-optimal time
Authors: Lubicz David , Robert Damien
Published: February 2015

Let $A$ be an abelian variety of dimension $g$ together with a principal polarization ${\it\phi}:A\rightarrow \hat{A}$ defined over a field $k$. Let $\ell$ be an odd integer prime to the characteristic of $k$ and let $K$ be a subgroup of $A[\ell ]$ which is maximal isotropic for the Riemann form associated to ${\it\phi}$. We suppose that $K$ is defined over $k$ and let $B=A/K$ be the quotient abelian variety together with a polarization compatible with ${\it\phi}$. Then $B$, as a polarized abelian variety, and the isogeny $f:A\rightarrow B$ are also defined over $k$. In this paper, we describe an algorithm that takes as input a theta null point of $A$ and a polynomial system defining $K$ and outputs a theta null point of $B$ as well as formulas for the isogeny $f$. We obtain a complexity of $\tilde{O} (\ell ^{(rg)/2})$ operations in $k$ where $r=2$ (respectively, $r=4$) if $\ell$ is a sum of two (respectively, four) squares which constitutes an improvement over the algorithm described in Cosset and Robert (Math. Comput. (2013) accepted for publication). We note that the algorithm is quasi-optimal if $\ell$ is a sum of two squares since its complexity is quasi-linear in the degree of $f$.
Experimental Investigation of a High Head Francis Turbine During Spin-No-Load Operation
Authors: Trivedi Chirag , Cervantes Michel J. , Dahlhaug Ole G. , Gandhi B. K.
Published: February 2015

Water passes freely through a hydraulic turbine in the absence of power requirements or during maintenance of the transmission lines, spillways, or dam. Moreover, the turbine operates under no-load conditions prior to generator synchronization during startup and after the generator disconnection from the grid load for shutdown. High-velocity swirling flow during spin-no-load (SNL) induces unsteady pressure pulsations in the turbine, and these pulsations cause fatigue in the blades. To investigate the amplitude of unsteady pressure loading, transient pressure measurements were carried out in a model Francis turbine during SNL. A total of six pressure sensors were mounted inside the turbine, i.e., one in the vaneless space, three on the blade surfaces, and two in the draft tube, and three discharge conditions were investigated over the operating range of the turbine. Analysis of the unsteady pressure data showed that the runner blades experience high-amplitude pressure loading during SNL. The amplitudes at all sensor locations were high compared with those under the normal operating condition of the turbine, i.e., the best efficiency point (BEP), and increased as the discharge through the turbine increased.
Rolling-Element Bearing Heat Transfer—Part III: Experimental Validation
Authors: Hannon William M. , Barr Todd A. , Froelich Shawn T.
Published: February 2015

This paper concludes a series of papers outlining a new rolling-element bearing heat transfer model. Part I provided the model framework, Part II presented the partial differential equation (PDE) solutions, and Part III, this paper, presents full-scale test results for ball, cylindrical, spherical, and tapered rolling-element bearings. The results validate the heat partitioning equation and the predicted solid temperatures for circulating oil lubrication. In addition, sump lubrication was studied using an acrylic assembly. The results quantify what fraction of the bearing periphery is cooled by oil, as well as the flow of oil through a bearing. Finally, substantiation of the modeling assumptions is discussed.
Microwave Blade Tip Clearance Measurement System
Authors: Grzybowski Richard , Foyt George , Knoell Hartwig , Atkinson William , Wenger Josef
Published: February 2015

This paper describes the development of a Microwave Tip Clearance Measurement System for use in the gas turbine environment Applications for this sensor include basic tip clearance measurements, seal wear measurement and active blade tip clearance control in gas turbine engines. The system being developed was designed for useful operation to temperatures exceeding 1093°F, since only ceramic materials are directly exposed in the gas path. Other advantages of this microwave approach to blade tip clearance sensing include the existence of an inherent self-calibration in the sensor that permits accurate operation despite temperature variations and possible abrasion by the rotating blades. Earlier experiments designed to simulate this abrasion of the sensor head indicated that rubs as deep as 1 mm (40 mils) were easily tolerated. In addition, unlike methods based upon phase measurements, this method is very insensitive to cable vibration and length variations. Finally, this microwave technique is expected to be insensitive to fuel and other engine contamination, since it is based on the measurement of resonant frequencies, which are only slightly affected by moderate values of loss due to contamination.
Operation of Combustion Turbines on Alternate Fuel Oils
Authors: Johnson K. W.
Published: February 2015

In recent years there has been an increased interest in the burning of ash forming liquid fuel oils including applications where fuel treatment is required.

The final decision of fuel type to use depends on several economic factors. These include the delivered price, cost of fuel treatment, cost of modifying the fuel handling system, and the increased maintenance costs associated with the grade of fuel. The ultimate decision on the burning of any fuel, including those fuel oils which require treatment is generally an economic choice, rather than a technical choice. There is however a broad end user lack of knowledge and understanding of the implications of burning ash forming liquid fuel oils. There is only limited documentation available detailing the considerations required to allow the upper and lower economic factors to be bounded.

It has been demonstrated that with careful attention to the fuel treatment process and the handling and operating practices, combustion turbines can, within certain limitations, successfully burn a wide range of liquid fuels.
Gas Turbine Firing Medium BTU Gas From Gasification Plant
Authors: Zanello Piero , Tasselli Andrea
Published: February 2015

IGCC (Integrated Gasification Combined Cycle) plants for large scale power generation are becoming more and more attractive.

For a gas turbine generating set to operate on Medium BTU gas, it takes dedicated design of both engine and auxiliaries.

A new combustion section, with extensive test support, has been developed. Alternative options to reduce inlet air flow and NOx emissions have been compared and appropriate solutions adopted. All auxiliaries systems have been modified according to the gas fuel characteristics.

Integration between plant systems has been carefully evaluated and a control system implemented in order to reach maximum reliability.

The paper deals with different technical aspects of the engine as well as the plant design.
Vibration Analysis of Rotor - Coupling - Bearing System With Misaligned Shafts
Authors: Rao A. Sreenivasa , Sekhar A. S.
Published: February 2015

The shaft misalignment, even being a common fault in rotating machinery, is not sufficiently studied. The present work addresses effects of misalignment in rotating machinery. An attempt to give a theoretical model for a rotor-coupling-bearing system has been done. The rotor-bearing system including the flexible coupling is modelled using the finite elements. The reaction forces and moments developed due to flexible coupling misalignment both for parallel and angular are derived and introduced in the model. Vibration analyses such as eigen value analysis and unbalance response are carried out for the rotor system with misaligned shafts.
GE MS7001 Gas Turbine Advanced Technology Uprate
Authors: Cocca Michael A. , Stappenbeck Arthur , Van Wormer James
Published: February 2015

Today’s competitive world of Independent Power Producers and electric wheeling has increased demand for lower operating and maintenance costs and increased revenues. This need is driving gas turbine research and development. Application of advanced technology to operating units can increase output, improve total plant efficiency, increase steam production and reduce maintenance costs. Cogen Technologies is one owner that has applied advanced technology to uprate five Frame 7EA gas turbines at its Linden plant and one unit at its Camden facility. At the Linden plant, total plant efficiency was improved by more than 2%.

This paper will discuss the components included in these advanced technology uprates, the gas turbine and combined-cycle plant performance improvements that were realized, and an economic model that can be used to evaluate the potential benefits of an uprate.
Designing for High Reliability and Availability in New Combustion Turbines
Authors: McQuiggan G.
Published: February 2015

This paper will describe how Westinghouse approaches the design of new combustion turbines to ensure the same high reliability and availability as in its present products. The paper describes the risk analysis process, design verification, and methodology used in the design of the 501G combustion turbine together with Westinghouse’s design philosophy for reliable design.
The Advanced Cooling Technology for the 1500 °C Class Gas Turbines: The Steam Cooled Vanes and the Air Cooled Blades
Authors: Nomoto H. , Koga A. , Ito S. , Fukuyama Y. , Otomo F. , Shibuya S. , Sato M. , Kobayashi Y. , Matsuzaki H.
Published: February 2015

It is very essential to raise the thermal efficiency of combined cycle plants from the viewpoint of energy saving and environmental protection. Tohoku Electric Power Co., Inc. and Toshiba Corporation in Japan have jointly studied the next generation of combined cycle system using 1500 °C class gas turbine.

A promising cooling technology for the vanes using steam was developed. The blades are cooled by air, adopting the impingement cooling, the film cooling and so on. The cooling effectiveness was confirmed both for the vanes and the blades using hot wind tunnel. This paper describes the design features of the vanes and the blades, and the results of the verification tests using hot wind tunnel.
Repowering Fossil Steam Power Plants With Combustion Turbine-Based Technologies
Authors: Pace Stanley , Walters Arden
Published: February 2015

Increased competition fostered by changes in legislation governing power generation entities has engendered a need to closely assess the economics of operating older-electric generating units. Decisions must be made as to whether these units should be retired and replaced with new, greenfield generation capacity, whether capacity should be purchased from other generation companies, or whether such units should be repowered in some way. The repowering alternative has merit when economic factors and environmental considerations show it to project the least cost of electricity over other choices. The chief advantages of repowering, include use of existing real estate and infrastructure, existing transmission facilities and staffing. Since the repowered plant usually emits less stack gas pollutants per unit of energy generated then the original plant, environmental benefits can also accrue.

Various types of gas turbine based repowering options for steam electric plants are presented. All the approaches discussed involve the addition of gas turbines to the cycle and the consequent benefit of some form of combined cycle operation. This option includes boiler retirement (and replacement with combined cycle), hot or warm windbox repowering (the boiler is retained and a gas turbine topping cycle is added), feedwater heating repowering (the gas turbine exhaust heats feedwater), and site repowering (only the site infrastructure is re-used as the site for a combined cycle). Business considerations are discussed in terms of their impact on the decision to repower and technology selection. An example involving feedwater heater repowering is used to illustrate the interaction between the business and technical aspects of repowering.
Unbalance Response of a Multi-Mode Rotor Supported on Short Squeeze Film Dampers
Authors: Youssef R. , El-Shafei A.
Published: February 2015

This paper describes a fast algorithm to obtain the steady state unbalance response of a multi-mode rotor supported on short squeeze film dampers (SFDs). The presented algorithm is developed based on planar modal theory. Undamped critical speed analysis is first performed to obtain the rotor critical speeds and their associated mode shapes. The modal analysis technique is then applied to the linear part of the rotor-SFD assembly to obtain the system differential equations. The rotor is assumed to execute circular centered orbits, hence all differential equations are reduced to algebraic ones. The resulting equations are manipulated algebraically to form a polynomial in rotor rotational speed. The roots of the polynomial are found and the full unbalance response is obtained. A conventional rotor is used to describe the developed algorithm numerically. Results show that the proposed algorithm gives accurate response in comparison to that obtained by integrating the system differential equations numerically. The great advantage of the proposed algorithm is the saving in the execution time which is extremely dramatic with respect to numerical integration, in addition to other advantages such as the possibility of obtaining all solutions occurring in regions of multiple steady state. Accuracy and speed of execution are quite advantageous regarding parametric studies on multi-mode rotors. These parametric studies can help in the optimization of SFDs design.
Blade Vibrations of a High Speed Compressor Blisk-Rotor: Numerical Resonance Tuning and Optical Measurements
Authors: Frischbier J. , Schulze G. , Zielinski M. , Ziller G. , Blaha C. , Hennecke D. K.
Published: February 2015

A major challenge during the design process of a modern low aspect ratio high speed axial compressor is to find rotor blade geometries that meet both, aerodynamic and mechanical requirements. This paper deals with the mechanical design of a transonic compressor blade. In order to meet the mechanical requirements in a short development time, new methods were used: A numerical optimization tool and an optical blade vibration measurement method:

The numerical resonance tuning took advantage of a semi-automatic optimization technique, based on a Finite Element vibration anlysis tool. The intention was to find a geometry which has no critical resonances (with fundamental engine orders) within the operation range.

To verify the calculated blade natural frequencies and eigen-values standard shaker tests using a laser holography system were carried out. Blades under g-load in the running compressor were investigated with an in-house developed vibration measurement system. This system is able to measure frequencies and amplitudes of the rotor blade vibrations without blade instrumentation but small optical probes, mounted in the compressor casing. The measured resonance points are in good agreement with the predictions. All amplitudes are far below the blade fatigue limits.
The Transient Torsional Vibration Behaviour of a Turbine-Generator System Under Short Circuit Excitation
Authors: Chan Dennis S. H.
Published: February 2015

Turbine-generator systems are subjected to sudden short circuits. The sudden change of electrical characteristics in these systems can incur very high excitation torques on the components. The excitation depends on the types of short circuits and the electrical properties of the generator, etc. Transient torsional vibration due to generator short circuit is investigated in this paper. Typical short circuit excitation functions are discussed. A modern gas turbine / generator / steam turbine system is used to illustrate the effects of modelling inaccuracies and parameter variations. The acceptance standards for such transient short circuit conditions are generally based on maximum torque transmitted or some kind of allowable shear stress. They cannot be accurately predicted by models which use 1–2 disks (stations) to represent a major machine in a train. Either a more refined model or a better reduction method is needed. Flexible couplings affect the transient torsional response and they must be included in the system vibration analysis. Their influence on the peak transmitted torque has been examined. The selection of couplings for turbine-generator systems in modern combined cycle power plants should be emphasized.
Computation of Internal/Rotating Flows Using Recent CFD Techniques
Authors: Liou Meng-Sing , Kao Kai-Hsiung , Ajmani Kumud
Published: February 2015

We present two recent CFD techniques developed for numerical flux computation and grid generation. The numerical flux scheme, AUSM+, yields significant improvements over current popular schemes in terms of accuracy, simplicity of implementation, and generality to include other equations of conservation laws. The scheme has been shown to be free from inaccuracies/anomalies such as the “carbuncle phenomenon” associated with some celebrated upwind schemes. A new hybrid grid technique, termed DRAGON grid, has been developed to maximize the strengths of the Chimera grid and unstructured grid. Validation tests of these techniques and applications to rotating flows were conducted and their typical results are included in the paper.
The Negative Information Problem in Mechanical Diagnostics
Authors: Hall David L. , Hansen Robert J. , Lang Derek C.
Published: February 2015

Condition-based maintenance (CBM) is an emerging technology which seeks to develop sensors and processing systems aimed at monitoring the operation of complex machinery such as turbine engines, rotor craft drive trains, or industrial equipment. The goal of CBM systems is to determine the state of the equipment (i.e., the mechanical health and status), and to predict the remaining useful life for the system being monitored. The success of such systems depends upon a number of factors including: (1) the ability to design or use robust sensors for measuring relevant phenomena such as vibration, acoustic spectra, infrared emissions, oil debris, etc.; (2) real time processing of the sensor data to extract useful information (such as features or data characteristics) in a noisy environment and to detect parametric changes which might be indicative of impending failure conditions; (3) fusion of multi-sensor data to obtain improved information beyond that available to a single sensor; (4) micro and macro level models which predict the temporal evolution of failure phenomena; and finally, (5) the capability to perform automated approximate reasoning to interpret the results of the sensor measurements, processed data, and model predictions in the context of an operational environment. The latter capability is the focus of this paper. Although numerous techniques have emerged from the discipline of artificial intelligence for automated reasoning (e.g., rule-based expert systems, blackboard systems, case-based reasoning, neural networks, etc.), none of these techniques are able to satisfy all of the requirements for reasoning about condition-based maintenance. This paper provides an assessment of automated reasoning techniques for CBM and identifies a particular problem for CBM, namely, the ability to reason with negative information (viz., data which by it’s absence is indicative of mechanical status and health). A general architecture is introduced for CBM automated reasoning, which hierarchically combines implicit and explicit reasoning techniques. Initial experiments with fuzzy logic are also described.