bluuebunny/crossref_metadata_2025 huggingface dataset:
Commentary: Physical health outcomes and health care have improved so much, so why is child mental health getting worse? Or is it? A commentary on Collishaw (2015)
Authors: Verhulst Frank
Published: February 2015

The frequency of problems in children and adolescents varies between times within populations in the same geographical area. It has often been suggested that problems in children and adolescents have increased and that present‐day youth fare less well than youth in the past. These concerns are fed by the assumed negative impact of societal change on individual development. It has been 20 years since (Rutter and Smith, 1995. Psychosocial disorders in young people: Time trends and their causes. Chicester: Wiley) published their findings on child and adolescent problem behaviors that occur at different points in time in western societies in the latter part of the 20th century. They concluded that, despite a lack of rigorous epidemiological data, there was some evidence for a secular increase in adolescents’ conduct problems, substance abuse, depression and suicide. Fergusson argued that factors implied by Rutter and Smith as risks for adjustment problems, such as changes in social, economic, educational, family and other structures associated with child rearing and child development, may equally well lead to positive developments. He argued that increasing social diversity may lead to increasing variability in adolescent adjustment patterns with on the one end increasing numbers of young people showing psychopathology (as was shown by Rutter and Smith) and on the other end increasing numbers of young people who show responsible prosocial behaviors. However, there were no data available to test the possibility that social change has had both positive and detrimental effects for adolescents. Rutter and Smith's review also made clear that there were numerous methodological obstacles hampering firm conclusions about secular changes in rates of disorder that may well reflect changes in diagnostic criteria, use of mental health services, or record keeping such as police or suicide records. Twenty years ago, few epidemiological comparisons were available in which changes in problems in representative samples of children and adolescents from western societies at different points in time were assessed with similar standardized procedures. This situation has changed drastically over the last couple of years. In the current Annual Research Review, Collishaw gives an impressively thorough overview of studies published over the last two decades on secular trends in child and adolescent mental health with an emphasis on studies that compare rates of child and adolescent problems over time in one geographically defined population. The review also raises a number of issues related to existing time‐trend research worth mentioning…
Editorial: Capturing the dynamics of development and psychopathology: from neural circuits to global trends
Authors: Fearon Pasco
Published: February 2015

Every year, the Journal of Child Psychology and Psychiatry dedicates an entire issue to state‐of‐the‐art reviews of the science underpinning our field, conducted by leading international experts. Like last year, the Editors sought to bring together a wide range of topics and thinkers covering many of the major themes that define contemporary child psychology and psychiatry. As always, the result is a veritable treasure trove of data and ideas on some of the most important topics of our times. For the second year running, we also invited commentaries from world‐leading experts to accompany each review, and in every case the reviews and their commentaries create a fascinating, forward‐looking dialogue about the hurdles that have been overcome, and the challenges that lie ahead. As you read the articles in the this year's Annual Research Review issue, many common threads will no doubt strike you. To my mind, one notable feature of all the articles was the extent to which elegant research designs, and innovations in technology, have been, and will always be, the key to unlocking some of the central puzzles we are faced with when trying to elucidate the mechanisms of child psychopathology: the innovative use of MRI to reveal the complex structural and functional networks of neuronal organization (Vertes & Bulmore); the importance of well‐chosen quasi‐experiments to reveal the distinctive sequelae of adverse early care (Zeanah & Gleason), or throw light on the very earliest neurodevelopmental processes implicated in ASD and ADHD (Johnson, Gliga, Jones & Charman); the enormous value of consistent measurement and rigorous epidemiological sampling for charting, and understanding, variations in child psychopathology across nations (Polanczyk, Salum, Sugaya, Caye & Rohde), over the lifespan (Costello & Maughan), and over social periods (Collishaw); the use of rare genetic syndromes for disentangling the common and distinct developmental mechanisms involved in ADHD and other neurodevelopmental disorders (Scerif & Baker), and the major contribution of high‐density genotyping, next‐generation sequencing and large‐scale international collaborative consortia for revealing the hidden heritability problem and pointing to some of the ways it can be tackled (Kiser, Rivero & Lesch). I was also struck by the fact all the authors showed a great willingness to embrace complexity ….
Oral mixing ability and cognition in elderly persons with dementia: A cross‐sectional study
Authors: Weijenberg R. A. F. , Lobbezoo F. , Visscher C. M. , Scherder E. J. A.
Published: February 2015

Masticatory performance has been positively associated with cognitive ability in both animals and healthy humans. We hypothesised that there would also be a positive correlation between masticatory performance and cognition in older persons suffering from dementia. Older persons suffering from dementia (n = 114) and receiving institutionalised care were studied in a cross‐sectional design. The assessments included masticatory performance, which was measured objectively with a two‐colour gum mixing ability test, and cognition, which was assessed with a multidomain neuropsychological test battery. Significant relationships were observed between masticatory performance and general cognition and between masticatory performance and verbal fluency. Hierarchical regression analysis revealed that the correlation with general cognition was influenced by the scores for dependency in activities of daily living. The association between verbal fluency and masticatory performance was not significantly affected by secondary variables. An unexpected limitation of this study was the high dropout rate for the mixing ability test. The clinical implications of these findings are profound; care professionals should endeavour to maintain and stimulate mastication in older persons with dementia in an attempt to preserve cognition.
Histiocytic Sarcoma with Central Nervous System Involvement in Dogs: 19 Cases (2006–2012)
Authors: Mariani C.L. , Jennings M.K. , Olby N.J. , Borst L.B. , Brown J.C. , Robertson I.D. , Seiler G.S. , MacKillop E.
Published: February 2015

Background

Reports of histiocytic sarcoma (HS) involving the central nervous system (CNS) are sparse and consist mainly of case reports describing 1–3 animals.

Objective

The objective of this study was to report the signalments, clinical signs, clinicopathologic and diagnostic imaging findings, treatment, and outcome of a series of dogs withHSandCNSinvolvement.

Animals

Nineteen dogs withHSexamined at veterinary referral hospitals.

Methods

Retrospective case series. Medical records were reviewed and cases with a histopathological diagnosis ofCNS HSwere included in the study. Diagnostic imaging studies of theCNSwere evaluated and histopathologic samples were reviewed to confirm the diagnosis.

Results

Retrievers andPembrokeWelshCorgis were overrepresented in this cohort of dogs. Tumors involved the brain in 14 dogs and the spinal cord in 5. In 4 dogs,HSwas part of a disseminated, multiorgan process whereas it appeared confined to theCNSin 15 dogs. Diagnostic imaging had variable appearances although extraaxial masses predominated in the brain. There was meningeal enhancement in all dogs that was often profound and remote from the primary mass lesion. Pleocytosis was present in all dogs withCSFevaluation. Median survival was 3 days.

Conclusions and Clinical Importance

Breed predispositions appear to vary from reports ofHSin other organ systems. Some unique imaging and clinicopathologic characteristics, particularly brain herniation, profound meningeal enhancement, and pleocytosis in combination with 1 or more mass lesions, might help to differentiate this neoplasm from others involving theCNS, although this requires further study.
Can light intensity cause shifts in natural product and bacterial profiles of the sponge Aplysina aerophoba?
Authors: Sacristán‐Soriano Oriol , Banaigs Bernard , Becerro Mikel A.
Published: February 2015

The potential role of microbial consortia on sponge chemistry is well known. However, how environmental factors affect microbial and chemical profiles and how these shifts affect the sponge holobiont are far from being understood. This study experimentally investigated the effect of light on both the concentration of secondary metabolites and the bacterial assemblages of the sponge Aplysina aerophoba. We quantified major brominated alkaloids (BAs) using a high‐performance liquid chromatography system coupled with a UV‐detector and analysed sponge‐associated bacteria using denaturing gradient gel electrophoresis of 16S rRNA gene amplicons. We identified distinct chemical and bacterial profiles between the ectosome and the choanosome of A. aerophoba. The abundance of most secondary metabolites increased regardless of the illumination regime. We found that the probability of occurrence of three microbial phylotypes (operational taxonomic units 84, 86 and 87) was strongly associated with increasing concentrations of three brominated compounds (aerophobin‐1, aplysinamisin‐1 and isofistularin‐3). Although the role of these bacteria remains uninvestigated, these associations between natural products and specific microbial phylotypes outline further hypotheses that will improve our understanding of the organization and functioning of these complex host–symbiont interactions.
Geoecohydrological mechanisms couple soil and leaf water dynamics and facilitate species coexistence in shallow soils of a tropical semiarid mixed forest
Authors: Rodríguez‐Robles Ulises , Arredondo J. Tulio , Huber‐Sannwald Elisabeth , Vargas Rodrigo
Published: February 2015

Trees growing on shallow rocky soils must have exceptional adaptations when underlying weathered bedrock has no deep fractures for water storage. Under semiarid conditions, hydrology of shallow soils is expected to decouple from plant hydrology, as soils dry out as a result of rapid evaporation and competition for water increases between coexisting tree species.

Gas exchange and plant–water relations were monitored for 15 months for Pinus cembroides and Quercus potosina tree species in a tropical semiarid forest growing on c. 20‐cm‐deep soils over impermeable volcanic bedrock.

Soil and leaf water potential maintained a relatively constant offset throughout the year in spite of high intra‐annual fluctuations reaching up to 5 MPa. Thus, hydrology of shallow soils did not decouple from hydrology of trees even in the driest period. A combination of redistribution mechanisms of water stored in weathered bedrock and hypodermic flow accessible to oak provided the source of water supply to shallow soils, where most of the actively growing roots occurred.

This study demonstrates a unique geoecohydrological mechanism that maintains a tightly coupled hydrology between shallow rocky soils and trees, as well as species coexistence in this mixed forest, where oak facilitates water access to pine.
Seeing without knowing: task relevance dissociates between visual awareness and recognition
Authors: Eitam Baruch , Shoval Roy , Yeshurun Yaffa
Published: February 2015

We demonstrate that task relevance dissociates between visual awareness and knowledge activation to create a state of seeing without knowing—visual awareness of familiar stimuli without recognizing them. We rely on the fact that in order to experience a Kanizsa illusion, participants must be aware of its inducers. While people can indicate the orientation of the illusory rectangle with great ease (signifying that they have consciously experienced the illusion's inducers), almost 30% of them could not report the inducers’ color. Thus, people can see, in the sense of phenomenally experiencing, but not know, in the sense of recognizing what the object is or activating appropriate knowledge about it. Experiment 2 tests whether relevance‐based selection operates within objects and shows that, contrary to the pattern of results found with features of different objects in our previous studies and replicated in Experiment 1, selection does not occur when both relevant and irrelevant features belong to the same object. We discuss these findings in relation to the existing theories of consciousness and to attention and inattentional blindness, and the role of cognitive load, object‐based attention, and the use of self‐reports as measures of awareness.
Partial migration to seasonally‐unstable habitat facilitates biological invasions in a predator‐dominated system
Authors: Bajer Przemyslaw G. , Parker James E. , Cross Timothy K. , Venturelli Paul A. , Sorensen Peter W.
Published: February 2015

Although partial migration, a phenomenon in which some individuals in a population conduct seasonal migrations while others remain resident, is common among animals, its importance in facilitating biological invasions has not been demonstrated. To illustrate how partial migration might facilitate invasions in spatially complex habitats, we developed an individual‐based model of common carp Cyprinus carpio in systems of lakes and winterkill‐prone marshes in the Upper Mississippi River Basin (UMRB). Our model predicted that common carp are unable to become invasive in lakes of the UMRB unless they conduct partial migrations into winterkill‐prone marshes in which recruitment rates are high in the absence of native predators that forage on carp eggs and larvae. Despite low dispersal rates of juveniles and higher mortality rates of migrants, partial migration was adaptive across a wide range of migration rates and winterkill frequencies. Partial migration rates as low as 10% and winterkill occurrence as infrequent as once in 20 years were sufficient to cause invasiveness because of carp's reproductive potential and longevity. Consistent with the results of our model, empirical data showed that lake connectivity to winterkill‐prone marshes was an important driver of carp abundance within the study region. Our results demonstrate that biological invasions may be driven by a small, migratory contingent of a population that exploits more beneficial reproductive habitats.
Zero‐Fluoroscopy Ablation of Accessory Pathways in Children and Adolescents: CARTO3 Electroanatomic Mapping Combined with RF and Cryoenergy
Authors: Scaglione Marco , Ebrille Elisa , Caponi Domenico , Siboldi Alessandra , Bertero Giovanni , Di Donna Paolo , Gabbarini Fulvio , Raimondo Cristina , Di Clemente Francesca , Ferrato Paolo , Marasini Maurizio , Gaita Fiorenzo
Published: February 2015

Background

Fluoroscopic catheter ablation of cardiac arrhythmias in pediatric patients exposes the patients to the potential risk of radiation considering the sensitivity of this population and its longer life expectancy. We evaluated the feasibility, safety, and efficacy of accessory pathway (AP) ablation guided by CARTO3 electroanatomic mapping (EAM) system with both cryoenergy and radiofrequency (RF) energy in order to avoid x‐ray exposure in pediatric patients.

Methods

We included 44 patients (mean age: 13.1 ± 3.3 years); nine of 44 presented concealed AP. An electrophysiological study with a three‐dimensional EAM reconstruction was performed in every patient with a venous transfemoral direct right atrium approach or an arterial transfemoral retrograde approach to reach the mitral annulus. In two patients with left‐sided AP, the ablation was performed via a patent foramen ovale.

Results

A total of 47 APs were present, left sided in 45% (21/47) of cases (15 lateral, one anterior, three posteroseptal, and two posterolateral) and right sided in 55% (26/47; one anterior, three anterolateral, one posterolateral, three lateral, five para‐Hisian, 12 posteroseptal, and one anteroseptal). Ablation without the use of fluoroscopy was successfully performed in every patient (33 with RF and in 11 with cryoenergy). No complication occurred. At a mean follow‐up of 16.0 ± 11.7 months, we observed seven recurrences, three of them successfully re‐ablated without fluoroscopy. In one case cryoablation of a para‐Hisian AP was ineffective in the long term.

Conclusions

Three‐dimensional EAM allowed a safe and effective fluoroless AP ablation procedure in a pediatric population both with RF and cryoenergy.
Long‐term efficacy of bevacizumab and irinotecan in recurrent pediatric glioblastoma
Authors: Umeda Katsutsugu , Shibata Hirofumi , Saida Satoshi , Hiramatsu Hidefumi , Arakawa Yoshiki , Mizowaki Takashi , Nishiuchi Ritsuo , Adachi Souichi , Heike Toshio , Watanabe Ken‐Ichiro
Published: February 2015

A 5‐year‐old boy with glioblastoma relapsed soon after postoperative irradiation in combination with temozolomide. Second‐line chemotherapy was also ineffective; therefore, the bevacizumab and irinotecan were given after a third gross‐total resection of the tumor. Treatment was interrupted for 1 month due to development of posterior reversible encephalopathy syndrome, but was re‐initiated at a lower dose of bevacizumab with prolonged intervals between treatments. The patient was alive and disease free 2 years after initial diagnosis. Bevacizumab and irinotecan are a promising regimen for pediatric cases of recurrent glioblastoma after gross‐total resection, although the optimal treatment schedule must be determined on a patient‐by‐patient basis.
Membranous nephropathy presenting with nephrotic syndrome in a child with thalassemia major
Authors: Yavuz Sevgi , Anarat Ali , Bayazıt Aysun Karabay , Karagun Barbaros Şahin , Yılmaz Sema , Kılınc Yurdanur , Gonlusen Gulfiliz , Kuyucu Yurdun
Published: February 2015

Few data on the renal effects of thalassemia syndrome are available in the literature. Recent clinical studies identified proximal tubular damage and glomerular filtration abnormalities in thalassemia. Iron‐chelating agents might be nephrotoxic as well, but proven glomerular injury, either due to anemia or chelating therapy, has not previously been demonstrated in thalassemia patients. Here, we report the first thalassemia patient presenting with nephrotic syndrome to be diagnosed with membranous nephropathy in the literature.
Effectiveness of professional training in bereavement care: Survey of Japanese pediatricians supporting families who have lost a child
Authors: Setou Noriko , Sakaguchi Yukihiro , Kurokawa Kayoko , Takada Satoshi
Published: February 2015

Background

The aim of this study was to assess the effectiveness of professional training in bereavement care.

Method

We mailed a questionnaire to 554 Japanese pediatricians. It asked about demographic characteristics, personal support experiences, professional training, psychological distress, recognition of high risk after a child's death, and eight items relating to awareness in bereavement care. We divided the subjects into two groups based on the presence or absence of professional training and compared them on the basis of each item (χ2 test), and conducted logistic regression analysis.

Results

Of the 239 respondents, 193 (80.8%) had performed bereavement care. The final number included in the analysis was 175, after excluding responses with missing data. A total of 46 respondents (26.3%) had attended bereavement care training. The subjects who had had training were more likely to recognize those at high risk for poor psychological recovery, have information about support groups, have a desire to study bereavement care, and understand the necessity of cooperation with mental health specialists.

Conclusion

Many pediatricians had personally provided support for the bereaved. On logistic analysis, it was considered that four factors (recognition of high risk for poor recovery, information about support, desire to study, and cooperation with professionals) were significantly associated with the professional training. There were no significant differences, however, in psychological distress, helplessness, and fatigue. Training programs related to stress management must be improved for pediatricians who feel high levels of psychological distress.
Depletion from Self‐Regulation: A Resource‐based Account of the Effect of Value Incongruence
Authors: Deng Hong , Wu Chia‐Huei , Leung Kwok , Guan Yanjun
Published: February 2015

Value incongruence between employees and organizations has been identified as a negative work condition. An attitude‐based account suggests that value incongruence gives rise to negative attitudes toward organizations and thus causes low performance. To complement this mechanism, we propose a resource‐based account based on ego‐depletion theory, which suggests that value incongruence consumes an individual's regulatory resources and leads to low work performance. In support of this view, results from 2 survey studies and a vignette experiment reveal that value incongruence is positively associated with ego depletion, which in turn is negatively related to work performance. The mediation effect of ego depletion is independent of the attitude‐based mechanism as represented by job satisfaction and affective commitment. Consistent with the affective consistency perspective, the relationship between value incongruence and ego depletion is stronger among employees high in positive affectivity and weaker among employees high in negative affectivity. The corresponding moderated mediation analysis shows that the indirect effects of value incongruence on work performance through ego depletion vary as a function of positive and negative affectivity. This investigation unravels the self‐regulatory consequence of value incongruence and shows that the resource‐based mechanism of value incongruence operates differentially as a function of dispositional affectivity.
Fluorescence Properties of Diphenylthiazolo[4,5‐b]pyrazines Tuned by Donor‐Acceptor Substituent Effects
Authors: Nakagawa Tatsuki , Yamaji Minoru , Maki Shojiro , Niwa Haruki , Hirano Takashi
Published: February 2015

Fluorescence properties of 2,6‐ and 2,5‐diphenylthiazolo[4,5‐b]pyrazine (TPy) derivatives having an electron‐donating substituent (methoxy and dimethylamino) on the 6‐ and 5‐phenyl groups were studied. It was found that 2,6‐diphenyl derivatives fluoresce more efficiently than 2,5‐diphenyl derivatives. Furthermore, a 2,6‐diphenyl derivative having an additional cyano group on the 2‐phenyl ring was an excellent fluorophore showing a wide solvatochromism with great fluorescence yields. Based on the obtained spectroscopic data and mechanistic explanations concerning the substituent effects on the fluorescence properties, useful information on designing new TPy fluorophores is provided.
Exosome‐transported microRNAs of helminth origin: new tools for allergic and autoimmune diseases therapy?
Authors: Siles‐Lucas M. , Morchon R. , Simon F. , Manzano‐Roman R.
Published: February 2015

Chronic diseases associated with inflammation show fast annual increase in their incidence. This has been associated with excessive hygiene habits that limit contacts between the immune system and helminth parasites. Helminthic infections induce regulation and expansion of regulatory T cells (Treg) leading to atypical Th2 type immune responses, with downregulation of the inflammatory component usually associated with these type of responses. Many cells, including those of the immune system, produce extracellular vesicles called exosomes which mediate either immune stimulation (DCs) or immune modulation (T cells). The transfer of miRNAs contained in T‐cell exosomes has been shown to contribute to downregulate the production of inflammatory mediators. It has been recently described the delivery to the host–parasite interface of exosomes containing miRNAs by helminths and its internalization by host cells. In this sense, helminth microRNAs transported in exosomes and internalized by immune host cells exert an important role in the expansion of Treg cells, resulting in the control of inflammation. We here provide relevant information obtained in the field of exosomes, cell–cell communication and miRNAs, showing the high potential of helminth miRNAs delivered in exosomes to host cells as new therapeutic tools against diseases associated with exacerbated inflammatory responses.
Heterologous expression of mitochondria‐targeted microbial nitrilase enzymes increases cyanide tolerance in Arabidopsis
Authors: Molojwane E. , Adams N. , Sweetlove L. J. , Ingle R. A.
Published: February 2015

Anthropogenic activities have resulted in cyanide (CN) contamination of both soil and water in many areas of the globe. While plants possess a detoxification pathway that serves to degrade endogenously generated CN, this system is readily overwhelmed, limiting the use of plants in bioremediation. Genetic engineering of additional CN degradation pathways in plants is one potential strategy to increase their tolerance to CN. Here we show that heterologous expression of microbial nitrilase enzymes targeted to the mitochondria increases CN tolerance in Arabidopsis. Root length in seedlings expressing either a CN dihydratase from Bacillus pumilis or a CN hydratase from Neurospora crassa was increased by 45% relative in wild‐type plants in the presence of 50 μm KCN. We also demonstrate that in contrast to its strong inhibitory effects on seedling establishment, seed germination of the Col‐0 ecotype of Arabidopsis is unaffected by CN.
A Study of Separable Solutions of a Generalized Burgers Equation
Authors: Rao Ch. Srinivasa , Nath Smriti
Published: February 2015

This paper concerns the separable solutions of a generalized Burgers equation. Existence of separable solutions to the generalized Burgers equation is proved under certain conditions. A careful numerical study shows that these separable solutions of the generalized Burgers equation describe the large time asymptotic behavior of solutions of initial boundary value problems.
Factors related to receipt of dental care in Eastern Iowa nursing facilities
Authors: Ghazal Tariq S. , Caplan Daniel J. , Cowen Howard J. , Oliveira Deise
Published: February 2015

Objective:

To assess factors related to nursing facility residents’ receipt of dental treatment when it was offered on site.

Methods:

Screening forms that included demographic, general, and dental health information were obtained from residents of 10 nursing facilities in Eastern Iowa, and their dental procedure history for up to 7 years after screening was recorded. Residents were grouped as having received either no procedures; diagnostic procedures only; or nondiagnostic procedures.

Results:

Of the 586 residents, the mean age was 83.8 years at screening and 31.3% were edentulous. The odds of receiving nondiagnostic procedures were lower among residents who were older (OR = 0.98, 95%CI 0.96–0.99) or edentulous (OR = 0.31, 95%CI 0.20–0.46), compared to those who received no dental procedures.

Conclusions:

Those who were older or edentulous had lower odds of receiving nondiagnostic dental procedures. Well‐designed prospective cohort studies are needed to better evaluate barriers to receipt of dental treatment among the institutionalized elderly.
Surface Trafficking of APP and BACE in Live Cells
Authors: Bauereiss Anna , Welzel Oliver , Jung Jasmin , Grosse‐Holz Simon , Lelental Natalia , Lewczuk Piotr , Wenzel Eva M. , Kornhuber Johannes , Groemer Teja W.
Published: February 2015

Amyloid‐β (Aβ)‐peptide, the major constituent of the plaques that develop during Alzheimer's disease, is generated via the cleavage of Aβ precursor protein (APP) by β‐site APP‐cleaving enzyme (BACE). Using live‐cell imaging of APP and BACE labeled with pH‐sensitive proteins, we could detect the release events of APP and BACE and their distinct kinetics. We provide kinetic evidence for the cleavage of APP by α‐secretase on the cellular surface after exocytosis. Furthermore, simultaneous dual‐color evanescent field illumination revealed that the two proteins are trafficked to the surface in separate compartments. Perturbing the membrane lipid composition resulted in a reduced frequency of exocytosis and affected BACE more strongly than APP. We propose that surface fusion frequency is a key factor regulating the aggregation of APP and BACE in the same membrane compartment and that this process can be modulated via pharmacological intervention.
High‐Resolution Membrane Capacitance Measurements for Studying Endocytosis and Exocytosis in Yeast
Authors: Carrillo Lucia , Cucu Bayram , Bandmann Vera , Homann Ulrike , Hertel Brigitte , Hillmer Stefan , Thiel Gerhard , Bertl Adam
Published: February 2015

With patch‐clamp recording, we detect in yeast protoplasts individual exo‐ and endocytotic events as discrete steps in membrane capacitance. The high‐resolution data show that exo‐ and endocytotic vesicles undergo, similar to other eukaryotes, permanent and transient fusion/fission with a bias for transient events. The electrical data are a good representation of the membrane dynamics of a growing yeast cell.
21RST CENTURY: “The Game against Nature”
Authors: Lane Jan-Erik
Published: February 2015

When a decision-maker faces a choice between alternatives of action in a situation of uncertainty, one speaks of a “game against Nature” when he/she faces no interaction with another player or group. In the process of global warming, mankind is the one player facing two alternatives: resilience or precaution. Not knowing fully the consequences of the increase in the emission of greenhouse gases on climate change or the implications of climate change for biological and social system, what action to take? If there were a global benevolent rule, he/she may decide to avoid the worst outcome. But global ecological policy-making requires the coordination among a large number of players, which open up the possibility of reneging as well as carries heavy transaction costs.
Stall Inception and Development in an Axial Flow Aeroengine
Authors: Wilson Alexander G. , Freeman Chris
Published: February 2015

This paper describes the phenomenon of stall and surge in an axial flow aeroengine using fast response static pressure measurements from the compressor of a Rolls-Royce VIPER engine. It details the growth of flow instability at various speeds, from a small zone of stalled fluid involving only a few blades into the violent surge motion of the entire machine.

Various observations from earlier theoretical and compressor rig results are confirmed by these new engine measurements. The main findings are as follows:

1. The point of stall inception moves rearwards as engine speed increases, and is shown to be simply related to the axial matching of the compressor.

2. The final unstable operation of the machine can be divided into rotating stall at low speed and surge or multiple surge at high speed.

3. The inception process is independent of whether the final unstable operation is rotating stall or multiple surge.

4. Stall/surge always starts as a circumferentially small flow disturbance, rotating around the annulus at some fraction of rotor speed.
Predictions of 3-D Steady and Unsteady Inviscid Transonic Stator/Rotor Interaction With Inlet Radial Temperature Non-Uniformity
Authors: Saxer André P. , Giles Michael B.
Published: February 2015

Numerical predictions of 3-D inviscid, transonic steady and periodic unsteady flow within an axial turbine stage are analyzed in this paper. As a first case, the unsteady effects of the stator trailing edge shock wave impinging on the downstream rotor are presented. Local static pressure fluctuations up to 60% of the inlet stagnation pressure are observed on the rotor suction side. The second case is an analysis of the rotor-relative radial secondary flow produced by a spanwise parabolic non-uniform temperature profile at the stator inlet. The generation of local hot spots is observed on both sides of the rotor blade behind the passing shock waves. The magnitude of the unsteady stagnation temperature fluctuations is larger than the time-averaged rotor inlet disturbance. In both cases, steady, unsteady and time-averaged solutions are presented and compared. From these studies, it is concluded that the steady-state solution in static pressure matches well with the time-averaged periodic unsteady flow field. However, for the stagnation temperature distribution only the trend of the time-averaged solution is modeled in the steady-state solution.
Control Requirements for the RB 211 Low Emission Combustion System
Authors: Corbett Nicholas C. , Lines Norman P.
Published: February 2015

The RB 211 DLE series staged, pre-mix, lean burn combustor, demands total integration of control system and combustion hardware.

The controls design process is described from the conception of the Engine Management System (EMS), which provides protection and control in separate environments, through to implementation of engine development testing.

The process of devising an acceptable fuelling strategy to each combustion stage is discussed. This identified the requirements for the computation of complex routines in order to control combustion zone temperatures.

The sensitivity of the control design to external conditions of humidity, ambient temperature and fuel composition are explored.

Extensive simulation was used to determine necessary instrumentation accuracies.

The paper concludes with a review of the development testing and the final control system configuration.
Design Considerations of a Versatile Simulator for High Bypass Turbofans
Authors: Balan Chellappa
Published: February 2015

The continuing requirements for performance improvement of higher thrust turbofans is met by increased bypass ratios. The trend towards higher bypass ratios and relatively large diameter low pressure ratio fans require innovative design approaches which include shorter inlets, slimmer nacelles, shorter fan ducts and exhaust systems, and possible elimination of thrust reverser. The success of this new generation of high bypass ducted turbofans depends on understanding the acoustic impact from reduced treatment areas, inlet-fan coupling and operability, as well as overall system performance. To achieve these goals a versatile scale model propulsion simulator large enough to operate as a fan rig, yet small enough to be installed in a wind tunnel for evaluating overall acoustic, operability, and system performance was developed. The criteria of designing such a simulator and its capabilities are discussed in this paper.
Design and Experimental Characterization of a Non Intrusive Measurement System of Rotating Blade Vibration
Authors: Nava P. , Paone N. , Rossi G. L. , Tomasini E. P.
Published: February 2015

A measurement system for non-intrusive monitoring of rotating blade vibration in turbomachines based on fiber optic sensors is presented.

The design of the whole system is discussed; the development of special purpose sensors, their interfacing to the data acquisition system and the signal processing are outlined.

The processing algorithms are tested by software simulation for several possible blade vibrations.

Experimental tests performed on different bladed rotors are presented. Results are compared to simultaneous strain gauge measurements.
Control-Oriented High-Frequency Turbomachinery Modeling: Single-Stage Compression System 1D Model
Authors: Badmus O. O. , Chowdhury S. , Eveker K. M. , Nett C. N.
Published: February 2015

In this paper, a 1D unsteady compressible viscous flow model of a generic compression system previously developed by the authors is applied to a multi-stage axial compressor experimental rig configured for single–stage operation. The required model parameters and maps are identified from experimental data. The resulting model is an explicit system of 9 first order ODE’s. The model inputs are compressor speed, nozzle area, compressor discharge bleed area, plenum bleed area, inlet total pressure and entropy, and nozzle and bleed exit static pressures. The model and experimental data are compared with respect to both open–loop uncontrolled and closed–loop controlled behaviors. These comparisons focus on i) forced transients and ii) global nonlinear dynamics and bifurcations. In all cases the comparison between the model and experimental data is excellent. Of particular interest is the ability of the model, which does not include any hysteretic maps, to predict experimentally observed hysteresis with respect to the onset and cessation of surge. This predictive capability of the model manifests itself as the coexistence of a stable equilibrium (rotating stall) and a stable periodic solution (surge) in the model at a single fixed set of system input values. Also of interest is the fact that the controllers used for closed–loop comparisons were designed directly from the model with no a posteriori tuning of controller parameters. Thus, the excellent closed–loop comparisons between the model and experimental data provide strong evidence in support of the validity of the model for use in direct model based controller design. The excellent agreement between the model and experimental data summarized above is attributed in large part to the use of effective lengths within the model, as functions of axial Mach number and nondimensional compressor rotational speed, as prescribed by the modeling technique. The use of these effective lengths proved to be far superior to the use of physical lengths. The use of these effective lengths also provided substantial improvement over the use of physical lengths coupled with fixed first order empirical lags, as proposed by other authors for the modeling of observed compressor dynamic lag. The overall success of this model is believed to represent a positive first step toward a complete experimental validation of the approach to control–oriented high–frequency turbomachinery modeling being developed by the authors.
Investigation of Through-Flow Hypothesis in a Turbine Cascade Using a 3D Navier-Stokes Computation
Authors: Perrin G. , Leboeuf F.
Published: February 2015

The results of a computation, performed with a three-dimensional Navier-Stokes computation at ONERA, have been averaged in the blade-to-blade direction; the spatial fluctuations around the averaged flow variables have also been determined. It has then been possible to estimate all terms in the average components of the momentum equations. The comparison of the two-dimensional balances of these three equations shows that the shear stress play a minor role in the momentum balance, except on the dissipation of the passage vortex kinetic energy downstream of the blade trailing edges. The kinetic energy of the spanwise component of the velocity spatial fluctuations has a very strong influence on the radial pressure gradient; it introduces a convection effect. This is a key effect for all these balances.
Dynamic Analysis of Squeeze Film Damper Supported Rotors Using Equivalent Linearization
Authors: El-Shafei A. , Eranki R. V.
Published: February 2015

The technique of equivalent linearization is presented in this paper as a powerful technique to perform nonlinear dynamic analysis of squeeze film damper (SFD) supported rotors using linear rotordynamic methods. Historically, it is customary to design squeeze film dampers (SFDs) for rotordynamic analysis by assuming circular centered orbits, which is convenient in making the nonlinear damper coefficients time independent and thus can be used in an iterative approach to determine the rotor dynamic characteristics. However, the general synchronous orbit is elliptic in nature due to possible asymmetry in the rotor support. This renders the nonlinear damper coefficients time dependent which would require extensive numerical computation using numerical integration to determine the rotor dynamic characteristics. Alternatively, it is shown that the equivalent linearization, which is based on a least square squares approach, can be used to obtain time independent damper coefficients for SFDs executing eccentric elliptic orbits which are nonlinear in the orbit parameters. The resulting equivalent linear forces are then used in an iterative procedure to obtain the unbalance response of a rigid rotor-SFD system. Huge savings over numerical integration are reported for this simple rotor. The technique can be extended to be used in conjunction with currently available linear rotordynamic programs to determine the rotor dynamic characteristics through iteration. It is expected that for multi-rotor multi-bearing systems this technique will result in even more economical computation.
Modeling of Flexible Rotor Machines Supported With Hydrostatic Bearings
Authors: Headifen R. N. , Weldon W. F.
Published: February 2015

In this paper a method is described that takes the nonlinear dynamic stiffness and damping coefficients for multiple hydrostatic bearings and incorporates them into a rotordynamic FEM model for a rotating machine. A Newton-Raphson iteration scheme is presented that uses updated bearing coefficients at every iteration to the solution. A non-linear computer program was written using the method described which models transient and synchronous response and calculates damped eigenvalues.
A Study of the Influence of Rubbing on the Dynamics of a Flexible Disk Rotor System
Authors: Wu Fangsheng , Flowers George T.
Published: February 2015

This study is concerned with investigating the influence of lateral disk flexibility on the dynamics of a rotor system experiencing rub. A rotating, flexible continuous disk/shaft model was developed and the dynamical behavior of this system with and without rubbing was studied. The model developed in this study is similar to the Jeffcott rotor model except that the disk is treated as a laterally flexible continuous circular plate. The motion of the disk was transformed from physical coordinates to a set of generalized coordinates under which the generalized motion was uncoupled and the responses were calculated. Then the inertial moment acting on the shaft was computed and introduced into the governing equations of the shaft motion.

Direct integration and the harmonic balance method were used to study the steady state motion of the system. A number of parameter variation studies were performed for varied rub clearances and disk mass influence ratios. The system responses to the rub, its occurrence and development, and the global stability of the observed responses were studied.

The results show that rub can be classified into two types: light rub and heavy rub, and the light rub has the forms of forward, backward, or mixed whirling motion. The results also show that the disk flexibility may alter the critical speed to some degree and may also significantly affect the amplitude and stability of the rotor vibration.
Active Control of Surge in Multi-Stage Axial-Flow Compressors
Authors: Escuret J. F. , Elder R. L.
Published: February 2015

This paper deals with a theoretical study of the active control of purely axial 1D instabilities in multi-stage axial-flow compressors. The paper briefly considers the development of a suitable surge model and continues with the derivation of a controller using linear optimal control theory. The controller is specifically designed to suppress the instabilities predicted by the linearised form of the surge model. The control technique involves a bleed being dynamically varied in response to fluctuations of variables. It is found that a stabilising optimal controller can always be obtained. The second part of the paper presents a non-linear simulation of the surge prediction model with the linear controller, using a 4th order Runge-Kutta scheme. This demonstrates how some non-linearities in the flow model can affect the controller operation. It is also shown that, the amplitudes and the frequency response required of the actuator to retain stability can exceed the practical limitations.
A Methodology for the Design of Automated Gas Turbine Diagnostic Systems
Authors: Loukis E. , Mathioudakis K. , Papailiou K.
Published: February 2015

A methodology for the design of automated diagnostic systems for Gas Turbines is presented. The first stage of the proposed methodology consists in an initial selection of instruments and measuring positions on the engine, based on a basic knowledge of the engine itself and previous experience, as well as modelling capabilities of the phenomena happening in it. It is followed by a stage of “learning” experiments. One purpose of these experiments is to provide measurement data, on which a final selection of instruments will be based. The instruments most suitable for the fault cases of interest are selected, according to the diagnostic potential they offer. Another purpose is to develop procedures of automated fault diagnosis. The necessary background information for the later exploitation of the system is also established. The applicability of the entire methodology is demonstrated for the case of designing a blade fault diagnostic system for an Industrial Gas Turbine.
The Experimental Investigations on the Compressor Cascades With Leaned and Curved Blade
Authors: Shang Erbing , Wang Z. Q. , Su J. X.
Published: February 2015

This paper presents the results of the experimental investigations on the effects of leaned and curved blade of plane axial compressor cascade. The ink trace method has been used for the surface flow visualization. The five-hole probe measurements are performed at the cascade exit 12.5 percent chord downstream, and the static pressure distributions are measured on the endwalls and blade surfaces.
Effectiveness of the Gas Turbine Endwall Fences in Secondary Flow Control at Elevated Freestream Turbulence Levels
Authors: Chung J. T. , Simon T. W.
Published: February 2015

A secondary flow management technique which employs a boundary layer fence on the endwall of a gas turbine passage is evaluated under freestream turbulence conditions that are representative of turbine conditions. A turbulence generator, which was able to reproduce the characteristics of the combustor exit flow, was used. The horseshoe and passage vortices observed in previous tests with low turbulence level remain coherent and strong within the cascade passage when the intensity is elevated to 10 percent. A boundary layer fence on the endwall remains effective in changing the path of the horseshoe vortex and reducing the Influence of the vortex on the flow near the suction wall at the high freestream turbulence level. The fence is more effective in reducing the secondary flow for the high turbulence case than for a low TI case, probably because the vortex which has been deflected into the core flow diffuses and dissipates faster in the more turbulent flow. The fence decreases aerodynamic losses for streamlines within the core of the channel flow.
A Reduction Method for Stability and Dynamic Response Analysis of Nonlinear Mechanical Systems
Authors: Jean An-Nan , Shiau Ting-Nung
Published: February 2015

The stability, transient response, and steady state response of nonlinear mechanical systems is studied using reduction method. The steady state periodic response is investigated using the harmonic balance method. An implicit integration method for predicting transient response is proposed. The stability of the steady state periodic response is studied using Floquet theory. A reduction is introduced to analyze the system dynamic behaviors in modal coordinates to reduce the working space. The method reduces the system degrees of freedom to only those coordinates related to the system nonlinear components. The merit of the method is demonstrated by an example of flexible rotor system with nonlinear bearing supports.