bluuebunny/crossref_metadata_2025 huggingface dataset:
Integrated activities of two alternative sigma factors coordinate iron acquisition and uptake by Pseudomonas aeruginosa
Authors: Edgar Rebecca J. , Hampton Georgina E. , Garcia G. Patricia Casas , Maher Megan J. , Perugini Matthew A. , Ackerley David F. , Lamont Iain L.
Published: October 2017

Alternative sigma (σ) factors govern expression of bacterial genes in response to diverse environmental signals. In Pseudomonas aeruginosa σPvdS directs expression of genes for production of a siderophore, pyoverdine, as well as a toxin and a protease. σFpvI directs expression of a receptor for ferripyoverdine import. Expression of the genes encoding σPvdS and σFpvI is iron‐regulated and an antisigma protein, FpvR20, post‐translationally controls the activities of the sigma factors in response to the amount of ferripyoverdine present. Here we show that iron represses synthesis of σPvdS to a far greater extent than σFpvI. In contrast ferripyoverdine exerts similar effects on the activities of both sigma factors. Using a combination of in vivo and in vitro assays we show that σFpvI and σPvdS have comparable affinities for, and are equally inhibited by, FpvR20. Importantly, in the absence of ferripyoverdine the amount of FpvR20 per cell is lower than the amount of σFpvI and σPvdS, allowing basal expression of target genes that is required to activate the signalling pathway when ferripyoverdine is present. This complex interplay of transcriptional and post‐translational regulation enables a co‐ordinated response to ferripyoverdine but distinct responses to iron.
Development and validation of an instrument to measure nurse educator perceived confidence in clinical teaching
Authors: Nguyen Van N.B. , Forbes Helen , Mohebbi Mohammadreza , Duke Maxine
Published: October 2017

Teaching nursing in clinical environments is considered complex and multi‐faceted. Little is known about the role of the clinical nurse educator, specifically the challenges related to transition from clinician, or in some cases, from newly‐graduated nurse to that of clinical nurse educator, as occurs in developing countries. Confidence in the clinical educator role has been associated with successful transition and the development of role competence. There is currently no valid and reliable instrument to measure clinical nurse educator confidence. This study was conducted to develop and psychometrically test an instrument to measure perceived confidence among clinical nurse educators. A multi‐phase, multi‐setting survey design was used. A total of 468 surveys were distributed, and 363 were returned. Data were analyzed using exploratory and confirmatory factor analyses. The instrument was successfully tested and modified in phase 1, and factorial validity was subsequently confirmed in phase 2. There was strong evidence of internal consistency, reliability, content, and convergent validity of the Clinical Nurse Educator Skill Acquisition Assessment instrument. The resulting instrument is applicable in similar contexts due to its rigorous development and validation process.
Primulina curvituba sp. nov. (Gesneriaceae) from a limestone area in Guangxi, China
Authors: Yang Li‐Hua , Pan Bo , Kang Ming
Published: October 2017

Primulina curvituba B. Pan, L.H. Yang & M. Kang, a new species of Primulina (Gesneriaceae) from Guangxi, China, is described and illustrated. This new species is mainly diagnosed by its strongly curved corolla tube, which is a rare character in Primulina. The morphological relationship and differences between this species and its related congeners are discussed. The conservation status of P. curvituba is assessed as ‘Critically Endangered’ (CR) according to IUCN.
Bolanthus sandrasicus sp. nov. (Caryophyllaceae) from Turkey
Authors: Hamzaoğlu Ergin , Koc Murat , Büyük İlker
Published: October 2017

Bolanthus sandrasicus Hamzaoğlu & Koç sp. nov. from the Muğla province, SW Turkey, is described. This new species resembles B. thymoides Hub.‐Mor., but differs in both macromorphology and seed micromorphology. Furthermore, we investigated the phylogenetic relationships of all Bolanthus species distributed in Turkey using ITS and trnL–trnF sequence data. The results of both morphological and molecular analyses support the description of the recently discovered Muğla population as a distinct species. In addition, a diagnostic key to all Bolanthus species growing in Turkey is provided.
Studies on Schismatoglottideae (Araceae) of Borneo LV: Schismatoglottis saafiei and Schismatoglottis zainuddinii spp. nov. from Tawau Hills, Sabah
Authors: Saibeh Kartini , Boyce Peter C. , Wong Sin Yeng
Published: October 2017

Schismatoglottis saafiei Kartini, P. C. Boyce & S. Y. Wong and Schismatoglottis zainuddinii Kartini, P. C. Boyce & S. Y. Wong are described and illustrated as new species from Tawau Hills N.P., Sabah, Malaysian Borneo. Schismatoglottis zainuddinii is the first record of the Schismatoglottis Asperata clade for Sabah. Schismatoglottis saafiei belongs to a complex of species centred on S. trifasciata Hallier.f.
Daytime depression in temperature‐normalised stem CO2 efflux in young poplar trees is dominated by low turgor pressure rather than by internal transport of respired CO2
Authors: Salomón Roberto L. , De Schepper Veerle , Valbuena‐Carabaña María , Gil Luis , Steppe Kathy
Published: October 2017

Daytime decreases in temperature‐normalised stem CO2 efflux (EA_D) are commonly ascribed to internal transport of respired CO2 (FT) or to an attenuated respiratory activity due to lowered turgor pressure. The two are difficult to separate as they are simultaneously driven by sap flow dynamics.

To achieve combined gradients in turgor pressure and FT, sap flow rates in poplar trees were manipulated through severe defoliation, severe drought, moderate defoliation and moderate drought. Turgor pressure was mechanistically modelled using measurements of sap flow, stem diameter variation, and soil and stem water potential. A mass balance approach considering internal and external CO2 fluxes was applied to estimate FT.

Under well‐watered control conditions, both turgor pressure and sap flow, as a proxy of FT, were reliable predictors of EA_D. After tree manipulation, only turgor pressure was a robust predictor of EA_D. Moreover, FT accounted for < 15% of EA_D.

Our results suggest that daytime reductions in turgor pressure and associated constrained growth are the main cause of EA_D in young poplar trees. Turgor pressure is determined by both carbohydrate supply and water availability, and should be considered to improve our widely used but inaccurate temperature‐based predictions of woody tissue respiration in global models.
Understandings of psychological difficulties in people with the Huntington's disease gene and their expectations of psychological therapy
Authors: Theed Rachael , Eccles Fiona J. R. , Simpson Jane
Published: October 2017

Objectives

This study sought to investigate how people who had tested positive for the Huntington's disease (HD) gene mutation understood and experienced psychological distress and their expectations of psychological therapy.

Design

A qualitative methodology was adopted involving semi‐structured interviews and interpretative phenomenological analysis (IPA).

Method

A total of nine participants (five women and four men) who had opted to engage in psychological therapy were recruited and interviewed prior to the start of this particular psychological therapeutic intervention. Interviews were transcribed verbatim and analysed using IPA whereby themes were analysed within and across transcripts and classified into superordinate themes.

Results

Three superordinate themes were developed: Attributing psychological distress to HD: ‘you're blaming everything on that now’; Changes in attributions of distress over time: ‘in the past you'd just get on with it’; and Approaching therapy with an open mind, commitment, and hope: ‘a light at the end of the tunnel’.

Conclusion

Understandings of psychological distress in HD included biological and psychological explanations, with both often being accepted simultaneously by the same individual but with biomedical accounts generally dominating. Individual experience seemed to reflect a dynamic process whereby people's understanding and experience of their distress changed over time. Psychological therapy was accepted as a positive alternative to medication, providing people with HD with hope that their psychological well‐being could be enhanced.

Practitioner points

People with the Huntington's disease gene mutation have largely biomedical understandings of their psychological distress.

This largely biomedical understanding does not, however, preclude them for being interested in the potential gains resulting from psychological therapy.

The mechanisms of psychological therapy should be explained in detail before therapy and explored along with current attributions of distress.
Alexithymia according to Bucci's multiple code theory: A preliminary investigation with healthy and hypertensive individuals
Authors: Di Trani Michela , Mariani Rachele , Renzi Alessia , Greenman Paul Samuel , Solano Luigi
Published: October 2017

Objective

To evaluate the relation between alexithymia and Referential Activity (RA), a linguistic measure of the process by which non‐verbal emotional experience is connected to language.

Methods

The 20‐Item Toronto Alexithymia Scale (TAS‐20) and the Toronto Structured Interview for Alexithymia (TSIA) were administered to 20 postgraduate students and 15 outpatients with hypertension. The Weighted Referential Activity Dictionary (WRAD) and other linguistic measures (Reflection, Disfluency, and Somatic Sense) were applied to texts derived from the TSIA using the Discourse Attributes Analysis Program (DAAP).

Results

Multiple linear regressions performed in the whole sample showed a relation between TSIA scores and Somatic Sense. Comparing the two groups, hypertensive subjects yielded higher scores on the TSIA than the young adult sample; no differences in DAAP measures emerged. A significant negative correlation was found between the TAS‐20 Difficulty Describing Feelings score and the DAAP measure of references to body activations (Somatic Sense) both in the young adult sample and in hypertensives. In the young adult sample, negative relations emerged between different TSIA factors, WRAD score, and Somatic Sense; a positive relation with fragmented speech (Disfluency) and use of rationalization (Reflection) was also found. In hypertensive subjects, using the TSIA, a negative correlation between alexithymia and Somatic Sense and a positive correlation between alexithymia and the Mean High WRAD (a measure of intensity of engagement during the speech) were found.

Conclusion

The TSIA seems to be a more adequate instrument than the TAS‐20 to explore relations between alexithymia and RA. Results appear to suggest a complex, nonlinear relation between alexithymia and RA, presumably influenced by subject‐specific characteristics.

Practitioner points

A relation between alexithymia and RA has been proposed on theoretical grounds, but there has been minimal empirical investigation.

This was the first study to employ both a self‐report measure and a structured interview for measuring alexithymia in relation to RA.

The results of this study suggest a complex, nonlinear relation between alexithymia and RA; this finding is essentially obtained with the structured interview measure of alexithymia.

This relation is presumably influenced by subject‐specific characteristics.
Li(Ritual) in Early Confucianism
Authors: Radice Thomas
Published: October 2017

Li禮 (translated variously as “ritual”, “etiquette”, or “propriety”) plays a central role in early Confucianism, but its complexity is not always fully understood. At first glance, it may seem as iflibehaviors are merely attempts to promote conservative practices from the idealized Chinese past. However, by examining the nature and function ofli, as described theAnalects(Lunyu論語) and theXunzi荀子 (two key texts in the early Confucian tradition), it becomes overwhelmingly apparent thatliis a much more complicated phenomenon.Liactually plays key roles within the interconnected fields of Confucian ethics, religion, and politics and often adds aesthetic elements to these areas of thought. As such, it is as much a source of Confucian innovation as it is a tool for promoting reverence for the past.
Treating murine Kala‐azar with a Mayan plant induces immunochemical changes
Authors: Lezama‐Dávila C. M. , Isaac‐Márquez A. P.
Published: October 2017

Pentalinon andrieuxiiMuell Arg is a Mexican‐Central American plant anciently used by local people to treat cutaneous leishmaniasis. We evaluated a hexane extract of the root we calledPAEfor its chemical content and for its immunochemical and in vitro activity againstLeishmania donovaniand healing of experimental Kala‐azar. Chemical analysis using gas chromatography coupled to mass spectrometry (GC‐MS) identified hexadecanoic acid, hexadecanoic acid ethyl ester, 9, 12‐octadecadienoic acid ethyl ester, octadecanoic acid ethyl ester, 9‐octadecenoic acid ethyl ester and diethyl phthalate as the main compounds present inPAE. We also demonstratedPAEkills promastigotes and amastigotes in vitro and significantly reduces parasite loads in liver and spleen of infected Balb/c mice.PAEinduces expression ofNFkB/AP‐1 transcription factors and production ofIL‐2 andIFN‐γ by spleen cells ofPAEtreated but not in the untreated control mice. Furthermore, there were notIL‐6,IL‐10 norTNFproduction in macrophages treated in vitro withPAE. We developed an affordable extract ofP. andrieuxiieffective to treat experimental Kala‐azar in Balb/c mice.
Accuracy of Clinician Predictions of Future Self‐Harm: A Systematic Review and Meta‐Analysis of Predictive Studies
Authors: Woodford Rachel , Spittal Matthew J. , Milner Allison , McGill Katie , Kapur Navneet , Pirkis Jane , Mitchell Alex , Carter Gregory
Published: October 2017

Assessment of a patient after hospital‐treated self‐harm or psychiatric hospitalization often includes a risk assessment, resulting in a classification of high risk versus low risk for a future episode of self‐harm. Through systematic review and a series of meta‐analyses looking at unassisted clinician risk classification (eight studies; N = 22,499), we found pooled estimates for sensitivity 0.31 (95% CI: 0.18–0.50), specificity 0.85 (0.75–0.92), positive predictive value 0.22 (0.21–0.23), and negative predictive value 0.89 (0.86–0.92). Clinician classification was too inaccurate to be clinically useful. After‐care should therefore be allocated on the basis of a needs rather than risk assessment.
Adolescent Predictors of Incidence and Persistence of Suicide‐Related Outcomes in Young Adulthood: A Longitudinal Study of Mexican Youth
Authors: Benjet Corina , Menendez David , Albor Yesica , Borges Guilherme , Orozco Ricardo , Medina‐Mora Maria Elena
Published: October 2017

In recent years, Mexico has seen one of the largest increases in suicide rates worldwide, especially among adolescents and young adults. This study uses data from the 1,071 respondents who participated in a two‐wave longitudinal study when they were between 12 and 17 years of age, and again when they were between 19 and 26 years of age. The World Mental Health Composite International Diagnostic Interview assessed suicidal behavior and DSM‐IV mental disorders. We used Cox regressions to evaluate which sociodemographic and psychiatric factors and life events predicted the incidence and remission of suicide ideation, plan, and attempt throughout the 8‐year span. The 8‐year incidence of suicide ideation, plan, and attempt was 13.3%, 4.8%, and 5.9%, respectively. We found that the number of traumatic life events during childhood, no longer being in school, and tobacco use predicted which adolescents developed suicide behaviors as they transitioned into young adulthood. Psychiatric disorders, particularly anxiety disorders, played a larger role in the persistence of those who already had suicidal behaviors, while behavioral disorders played a role in the transition from ideation to attempt. This distinction may be useful for clinicians to assess the risk of suicide.
The Sexual Harassment–Suicide Connection in the U.S. Military: Contextual Effects of Hostile Work Environment and Trusted Unit Leaders
Authors: Griffith James
Published: October 2017

Sexual harassment has been associated with suicidal behaviors, and with the rise in suicides in the U.S. military, sexual harassment's role in suicide has been of growing interest. Lacking are studies that examine group‐ or unit‐level variables in the relationship of sexual harassment to suicidal behaviors (thoughts, plans, and attempts). In this study, survey data from soldiers (12,567 soldiers in 180 company‐sized units) who completed the Unit Risk Inventory administered during calendar year 2010 were analyzed using hierarchical linear modeling. At the individual level, sexual harassment was associated with a fivefold increase for risk of suicide. Reporting that leaders could be trusted was associated with a decreased suicide risk by about one‐third. There was no statistically significant interaction between sexual harassment and trusted leaders in predicting the suicidal behaviors. At the group level, units or companies having higher levels of sexual harassment also had soldiers three times more at risk for suicide. A cross‐leveling effect was also observed: Among units having higher levels of sexual harassment, the negative correlation (buffering effect of unit leaders on suicidal behaviors) was diminished. Implications of findings for preventing sexual harassment and suicide risk are discussed.
Fighting labor market discrimination with ban the box (BTB): Are there racial implications?
Authors: Solinas‐Saunders Monica , Stacer Melissa J.
Published: October 2017

We develop a theoretical commentary on the implementation and expansion of the ban the box (BTB) movement as a legal response to the formal and informal discrimination ex‐offenders face every day in the labor market, in particular the racial impacts of such policies. We first provide a thorough overview of the numerous laws that have created barriers to ex‐offender employment. Then we focus on the advent of BTB legislation across the U.S. and the impact these policies might have in the long run. An emphasis on the racial implications is necessary to explore the potential of BTB policies to exacerbate statistical discrimination that would marginalize young minority males with clean records. While we do not advocate the removal of BTB policies, our discussion aims to clarify the risks associated with limiting employers' access to applicants' information in the job market and to highlight the unintended consequences such policies could have on those without criminal records.
Native antimony emplaced by methane‐rich hydrothermal fluid in an orogenic fault‐zone
Authors: Jébrak Michel , Lebrun Charline , André‐Mayer Anne‐Sylvie , Simard Marjorie
Published: October 2017

Antimony‐rich gold deposits represent a subclass of orogenic hydrothermal systems. The study of the Lapa gold deposit in the Abitibi greenstone belt shows that antimony occurs during two different stages: (1) as early prograde Sb–Ni disseminated sulphides in talc schists, associated with CO2‐bearing fluids, and (2) as a late native antimony association, associated with methane‐bearing fluids indicating a reducing environment. Methane could be related to the serpentinization of the ultramafic rocks of the Piché Group hosting the Lapa deposit. Several deposits display the same methane antimony association along fault zones.
Presumed post‐traumatic ocular chondrosarcoma with intrathoracic metastases in a cat
Authors: Moreira Matheus V. L. , de Andrade Maria C. , Fulgêncio Gustavo O. , Langohr Ingeborg M. , Ecco Roselene
Published: October 2017

An indoor‐only, 5‐year‐old, spayed female domestic shorthair cat presented for an ophthalmic examination of the left eye. An intraocular tumor with secondary glaucoma and blindness was diagnosed; the globe was enucleated and sent for histopathological examination. Gross examination revealed a solid white mass filling the entire vitreous space and replacing the iris and ciliary body. The lens and retina appeared to be similarly replaced by the neoplasm. Histological examination revealed a complete loss of the internal ocular structures, with a ruptured capsule as the only remnant of the lens within an extensive malignant mesenchymal neoplastic cell proliferation. The cells were polygonal, with well‐defined cytoplasmic borders and abundant weakly basophilic cytoplasm, embedded within the islands of chondroid matrix. No neoplastic invasion of the sclera was apparent. The animal died 6 months after the enucleation due to respiratory distress. Gross examination revealed numerous firm, white to tan nodular masses with smooth to mildly irregular surfaces dispersed throughout the parietal pleura, thoracic surface of the diaphragm, tracheobronchial and mediastinal lymph nodes, pericardium, and lungs. On cross‐section, the neoplastic nodules were solid and variably translucent, resembling hyaline cartilage. Histologically, these nodules were similar to the neoplasm identified earlier in the left globe. Metastasis of post‐traumatic ocular chondrosarcoma has not yet been described in cats. This is therefore believed to be the first report of metastases of this type of neoplasm in cats. This case adds to the limited set of data on the outcome of this type of tumor.
Ex vivo comparison of single‐layer and double‐layer laparoscopic closure of equine bladders with 2 types of barbed sutures
Authors: Major Dustin S. , Duff Amy H. , Cohen Noah D. , Hardy Joanne
Published: October 2017

Objective

To compare laparoscopic single‐layer versus double‐layer closure of experimental, full‐thickness incisions in adult equine urinary bladders using unidirectional and bidirectional barbed suture.

Study design

Experimental, ex vivo, surgical study.

Sample population

Thirty adult equine cadaver urinary bladders.

Methods

Bladders were randomly divided into 5 groups (n = 6): intact controls, bladders sutured with unidirectional or bidirectional barbed suture in a single‐layer closure, and bladders sutured with unidirectional or bidirectional barbed suture in a double‐layer closure. A 5‐cm apical incision was created in each bladder assigned to a suture group, prior to closure in a laparoscopic trainer. After suturing, bursting pressures (BPs) were determined by filling the bladders with saline to failure. Continuous variables were compared among groups using generalized linear modeling with post hoc testing between groups, and categorical variables were compared using Fisher's exact test. Significance was set at P < .05.

Results

No difference in BP was detected between treatment groups, all failing at pressures lower than those of intact bladders. The 95% confidence interval for BPs exceeded a physiologically relevant threshold of 30 mm Hg after single‐layer or double‐layer closure. Irrespective of treatment group, surgical time decreased with experience, and the rate of reduction was greater for the single‐layer than the double‐layer closures.

Conclusion

In this ex vivo study, both closure techniques and both suture types appeared to be acceptable for laparoscopic closure of the urinary bladder in adult horses.
Equine chlamydiosis—An emerging infectious disease requiring a one health surveillance approach
Authors: Taylor K. A. , Durrheim D. , Heller J. , O'Rourke B. , Hope K. , Merritt T. , Freeman P. , Chicken C. , Carrick J. , Branley J. , Massey P.
Published: October 2017

Psittacosis is a rare but potentially fatal zoonosis caused by Chlamydia psittaci, an organism that is typically associated with bird contact. However C. psittaci is capable of infecting other non‐avian hosts, such as horses, sheep, cattle and goats. Stud staff and veterinarians have significant exposure to parturient animals and reproductive materials in their routine work. To investigate the zoonotic potential associated with the emergence of C. psittaci as an abortifacient agent in horses, we established a programme of joint human and animal surveillance in a sentinel horse‐breeding region in Australia. This programme comprised cross‐notification of equine cases to public health agencies, and active follow‐up of known human contacts, including stud workers, foaling staff, veterinarians and laboratory staff. We identified no confirmed cases of acute psittacosis despite intensive surveillance and testing of heavily exposed contacts; however, further work in the area is needed.
Maternal exercise modifies body composition and energy substrates handling in male offspring fed a high‐fat/high‐sucrose diet
Authors: Quiclet Charline , Dubouchaud Hervé , Berthon Phanélie , Sanchez Hervé , Vial Guillaume , Siti Farida , Fontaine Eric , Batandier Cécile , Couturier Karine
Published: October 2017

Key points

Maternal training during gestation enhances offspring body composition and energy substrates handling in early adulthood.

Offspring nutrition also plays a role as some beneficial effects of maternal training during gestation disappear after consumption of a high‐fat diet.

Maternal exercise during gestation has been reported to modify offspring metabolism and health. Whether these effects are exacerbated when offspring are receiving a high‐fat diet remains unclear. Our purpose was to evaluate the effect of maternal exercise before and during gestation on the offspring fed a high‐fat/high‐sucrose diet (HF) by assessing its body composition, pancreatic function and energy substrates handling by two major glucose‐utilizing tissues: liver and muscle. Fifteen‐week‐old nulliparous female Wistar rats exercised 4 weeks before as well as during gestation at a constant submaximal intensity (TR) or remained sedentary (CT). At weaning, pups from each group were fed either a standard diet (TRCD or CTCD) or a high‐fat/high‐sucrose diet (TRHF or CTHF) for 10 weeks. Offspring from TR dams gained less weight compared to those from CT dams. Selected fat depots were larger with the HF diet compared to control diet (CD) but significantly smaller in TRHF compared to CTHF. Surprisingly, the insulin secretion index was higher in islets from HF offspring compared to CD. TR offspring showed a higher muscle insulin sensitivity estimated by the ratio of phosphorylated protein kinase B to total protein kinase B compared with CT offspring (+48%, P < 0.05). With CD, permeabilized isolated muscle fibres from TR rats displayed a lower apparent affinity constant (Km) for pyruvate and palmitoyl coenzyme A as substrates compared to the CT group (−46% and −58%, respectively, P < 0.05). These results suggest that maternal exercise has positive effects on young adult offspring body composition and on muscle carbohydrate and lipid metabolism depending on the nutritional status.
A Three-Dimensional Agglomerate Model of an Anion Exchange Membrane Fuel Cell
Authors: Machado Bruno S. , Chakraborty Nilanjan , Mamlouk Mohamed , Das Prodip K.
Published: October 2017

In this study, a three-dimensional (3D) agglomerate model of an anion exchange membrane (AEM) fuel cell is proposed in order to analyze the influence of the composition of the catalyst layers (CLs) on overall fuel cell performance. Here, a detailed comparison between the agglomerate and a macrohomogeneous model is provided, elucidating the effects of the CL composition on the overall performance and the individual losses, the effects of operating temperature and inlet relative humidity on the cell performance, and the CL utilization by the effectiveness factor. The results show that the macrohomogeneous model overestimates the cell performance compared to the agglomerate model due to the resistances associated with the species and ionic transports in the CLs. Consequently, the hydration is negatively affected, resulting in a higher Ohmic resistance. The activation overpotential is overpredicted by the macrohomogeneous model, as the agglomerate model relates the transportation resistances within the domain with the CL composition. Despite the higher utilization in the anode CL, the cathode CL utilization shows a significant drop near the membrane–CL interface due to a high current density and a low oxygen concentration. Additionally, the influences of operating temperature and relative humidity at the flow channel inlet have been analyzed. Similar to the macrohomogeneous model, the overall cell performance of the agglomerate model is enhanced with increasing operating temperature due to the better electrochemical kinetics. However, as the relative humidity at the inlet is reduced, the overall performance of the cell deteriorates due to the poor hydration of the membrane.
The Effects of Aging and Dual Tasking on Human Gait Complexity During Treadmill Walking: A Comparative Study Using Quantized Dynamical Entropy and Sample Entropy
Authors: Ahmadi Samira , Wu Christine , Sepehri Nariman , Kantikar Anuprita , Nankar Mayur , Szturm Tony
Published: October 2017

Quantized dynamical entropy (QDE) has recently been proposed as a new measure to quantify the complexity of dynamical systems with the purpose of offering a better computational efficiency. This paper further investigates the viability of this method using five different human gait signals. These signals are recorded while normal walking and while performing secondary tasks among two age groups (young and older age groups). The results are compared with the outcomes of previously established sample entropy (SampEn) measure for the same signals. We also study how analyzing segmented and spatially and temporally normalized signal differs from analyzing whole data. Our findings show that human gait signals become more complex as people age and while they are cognitively loaded. Center of pressure (COP) displacement in mediolateral direction is the best signal for showing the gait changes. Moreover, the results suggest that by segmenting data, more information about intrastride dynamical features are obtained. Most importantly, QDE is shown to be a reliable measure for human gait complexity analysis.
The Parametric Modeling of Local Resistance and Pressure Drop in a Rotary Ball Valve
Authors: Wang Dan , Bai Changqing
Published: October 2017

In this paper, a theoretical study of ball valves is carried out for investigating the local resistance and pressure drop of ball valves in operating process. An equivalent model of ball valves is proposed based on the inherent mechanism of the resistance loss, which can be divided into three equivalent throttling components: a thick orifice, two variable-opening eccentric orifice plates, and a Z type elbow. Through analysis of the flow resistance of the three components, a general parametric modeling of ball valves is presented for the flow resistance analysis, and then an analytical formula of pressure drop is demonstrated. The results obtained from the presented model are compared with the prior test data to validate this model, and good agreement is observed. Indicate that the presented model has high accuracy in predicting the resistance and pressure loss in various openings. The results show that the influences of thin orifice plates play an important role in the total flow resistance coefficient and pressure drop, especially in the small opening. The effects of thick orifice plates and the Z type elbow gradually increased as the valve opening rises and becomes significant when the opening is more than 70%.
Contractile Smooth Muscle and Active Stress Generation in Porcine Common Carotids
Authors: Zhou Boran , Prim David A. , Romito Eva J. , McNamara Liam P. , Spinale Francis G. , Shazly Tarek , Eberth John F.
Published: October 2017

The mechanical response of intact blood vessels to applied loads can be delineated into passive and active components using an isometric decomposition approach. Whereas the passive response is due predominantly to the extracellular matrix (ECM) proteins and amorphous ground substance, the active response depends on the presence of smooth muscle cells (SMCs) and the contractile machinery activated within those cells. To better understand determinants of active stress generation within the vascular wall, we subjected porcine common carotid arteries (CCAs) to biaxial inflation–extension testing under maximally contracted or passive SMC conditions and semiquantitatively measured two known markers of the contractile SMC phenotype: smoothelin and smooth muscle-myosin heavy chain (SM-MHC). Using isometric decomposition and established constitutive models, an intuitive but novel correlation between the magnitude of active stress generation and the relative abundance of smoothelin and SM-MHC emerged. Our results reiterate the importance of stretch-dependent active stress generation to the total mechanical response. Overall these findings can be used to decouple the mechanical contribution of SMCs from the ECM and is therefore a powerful tool in the analysis of disease states and potential therapies where both constituent are altered.
A Small Deformation Thermoporomechanics Finite Element Model and Its Application to Arterial Tissue Fusion
Authors: Fankell D. P. , Regueiro R. A. , Kramer E. A. , Ferguson V. L. , Rentschler M. E.
Published: October 2017

Understanding the impact of thermally and mechanically loading biological tissue to supraphysiological levels is becoming of increasing importance as complex multiphysical tissue–device interactions increase. The ability to conduct accurate, patient specific computer simulations would provide surgeons with valuable insight into the physical processes occurring within the tissue as it is heated or cooled. Several studies have modeled tissue as porous media, yet fully coupled thermoporomechanics (TPM) models are limited. Therefore, this study introduces a small deformation theory of modeling the TPM occurring within biological tissue. Next, the model is used to simulate the mass, momentum, and energy balance occurring within an artery wall when heated by a tissue fusion device and compared to experimental values. Though limited by its small strain assumption, the model predicted final tissue temperature and water content within one standard deviation of experimental data for seven of seven simulations. Additionally, the model showed the ability to predict the final displacement of the tissue to within 15% of experimental results. These results promote potential design of novel medical devices and more accurate simulations allowing for scientists and surgeons to quickly, yet accurately, assess the effects of surgical procedures as well as provide a first step toward a fully coupled large deformation TPM finite element (FE) model.
Excitation Tests on Elbow Pipe Specimens to Investigate Failure Behavior Under Excessive Seismic Loads
Authors: Nakamura Izumi , Kasahara Naoto
Published: October 2017

The accident at the Fukushima Dai-ichi Nuclear Power Plant (NPP) resulting from the 2011 Great East Japan Earthquake raised awareness as to the importance of considering Beyond Design Basis Events (BDBE) when planning for safe management of NPPs. In considering BDBE, it is necessary to clarify the possible failure modes of structures under extreme loading. Because piping systems are one of the representative components of NPPs, an experimental investigation was conducted on the failure of a pipe assembly under simulated excessive seismic loads. The failure mode obtained by excitation tests was mainly fatigue failure. The reduction of the dominant frequency and the increase of hysteresis damping were clearly observed in high-level input acceleration due to plastic deformation, and they greatly affected the specimens’ vibration response. Based on the experimental results, a procedure is proposed for calculating experimental stress intensities based on excitation test so that they can be compared with design limitations.
Optimization of Statistical Methodologies for Anomaly Detection in Gas Turbine Dynamic Time Series
Authors: Fabio Ceschini Giuseppe , Gatta Nicolò , Venturini Mauro , Hubauer Thomas , Murarasu Alin
Published: October 2017

Statistical parametric methodologies are widely employed in the analysis of time series of gas turbine (GT) sensor readings. These methodologies identify outliers as a consequence of excessive deviation from a statistical-based model, derived from available observations. Among parametric techniques, the k–σ methodology demonstrates its effectiveness in the analysis of stationary time series. Furthermore, the simplicity and the clarity of this approach justify its direct application to industry. On the other hand, the k–σ methodology usually proves to be unable to adapt to dynamic time series since it identifies observations in a transient as outliers. As this limitation is caused by the nature of the methodology itself, two improved approaches are considered in this paper in addition to the standard k–σ methodology. The two proposed methodologies maintain the same rejection rule of the standard k–σ methodology, but differ in the portions of the time series from which statistical parameters (mean and standard deviation) are inferred. The first approach performs statistical inference by considering all observations prior to the current one, which are assumed reliable, plus a forward window containing a specified number of future observations. The second approach proposed in this paper is based on a moving window scheme. Simulated data are used to tune the parameters of the proposed improved methodologies and to prove their effectiveness in adapting to dynamic time series. The moving window approach is found to be the best on simulated data in terms of true positive rate (TPR), false negative rate (FNR), and false positive rate (FPR). Therefore, the performance of the moving window approach is further assessed toward both different simulated scenarios and field data taken on a GT.
Numerical and Experimental Investigations on Preload Effects in Air Foil Journal Bearings
Authors: Mahner Marcel , Li Pu , Lehn Andreas , Schweizer Bernhard
Published: October 2017

A detailed elastogasdynamic model of a preloaded three-pad air foil journal bearing is presented. Bump and top foil deflections are herein calculated with a nonlinear beamshell theory according to Reissner. The two-dimensional pressure distribution in each bearing pad is described by the Reynolds equation for compressible fluids. The assembly preload is calculated by simulating the assembly process of top foil, bump foil, and shaft. Most advantageously, there is no need for the definition of an initial radial clearance in the presented model. With this model, the influence of the assembly preload on the static bearing hysteresis as well as on the aerodynamic bearing performance is investigated. For the purpose of model validation, the predicted hysteresis curves are compared with measured curves. The numerically predicted and the measured hysteresis curves show a good agreement. The numerical predictions exhibit that the assembly preload increases the elastic foil structural stiffness (in particular for moderate shaft displacements) and the bearing damping. It is observed that the effect of the fluid film on the overall bearing stiffness depends on the assembly preload: For lightly preloaded bearings, the fluid film affects the overall bearing stiffness considerably, while for heavily preloaded bearings the effect is rather small for a wide range of reaction forces. Furthermore, it is shown that the assembly preload increases the friction torque significantly.
Extending “Assessment of Tesla Turbine Performance” Model for Sensitivity-Focused Experimental Design
Authors: Traum Matthew J. , Hadi Fatemeh , Akbar Muhammad K.
Published: October 2017

The analytical model of Carey is extended and clarified for modeling Tesla turbine performance. The extended model retains differentiability, making it useful for rapid evaluation of engineering design decisions. Several clarifications are provided including a quantitative limitation on the model’s Reynolds number range; a derivation for output shaft torque and power that shows a match to the axial Euler Turbine Equation; eliminating the possibility of tangential disk velocity exceeding inlet working fluid velocity; and introducing a geometric nozzle height parameter. While nozzle geometry is limited to a slot providing identical flow velocity to each channel, variable nozzle height enables this velocity to be controlled by the turbine designer as the flow need not be choked. To illustrate the utility of this improvement, a numerical study of turbine performance with respect to variable nozzle height is provided. Since the extended model is differentiable, power sensitivity to design parameters can be quickly evaluated—a feature important when the main design goal is maximizing measurement sensitivity. The derivatives indicate two important results. First, the derivative of power with respect to Reynolds number for a turbine in the practical design range remains nearly constant over the whole laminar operating range. So, for a given working fluid mass flow rate, Tesla turbine power output is equally sensitive to variation in working fluid physical properties. Second, turbine power sensitivity increases as wetted disk area decreases; there is a design trade-off here between maximizing power output and maximizing power sensitivity.
Improving the Film Cooling of a Rotor Blade Platform
Authors: Barigozzi Giovanna , Perdichizzi Antonio , Abram Roberto
Published: October 2017

This paper shows the results of an experimental activity developed in cooperation between Ansaldo Energia and the Department of Engineering and Applied Science of Bergamo University with the aim of assessing the impact of newly designed holes on the thermal protection of a rotor blade platform. The original rotor blade platform featured ten cylindrical holes located along the blade pressure side (PS). Moreover, the channel front side was cooled exploiting the seal purge flow exiting the stator to rotor interface gap. The front midchannel, and particularly the region around the interplatform gap, remained uncooled. To protect this region, two sets of cylindrical holes were designed and manufactured on a seven blade cascade model for experimental verification. Aerodynamic and thermal tests were carried out at low Mach number. To evaluate the interaction of injected flow with secondary flows a five hole probe was traversed downstream of the trailing edge plane. The thermal behavior was analyzed by using thermochromic liquid crystals technique, so to obtain film cooling effectiveness distributions. The seven-hole configuration coupled with a low blowing ratio of about 1.0 provided the best thermal protection without any impact on the aerodynamic performance.
Aeroacoustic Analysis of the Tonal Noise of a Large-Scale Radial Blower
Authors: Marsan Aurélien , Moreau Stéphane
Published: October 2017

Large-scale radial blowers are widely used in factories and are one of the main sources of noise. The present study aims at identifying the noise generation mechanisms in such a radial blower in order to suggest simple modifications that could be made in order to reduce the noise. The flow in a representative large-scale radial blower is investigated thanks to unsteady Reynolds-averaged Navier–Stokes (URANS) numerical simulations. The radiated noise is calculated, thanks to an in-house propagation code based on the Ffowcs Williams Hawkings' (FWH) analogy, SherFWH. The results highlight the main noise generation mechanisms, in particular the interaction between the rotating blades and the tongue, and the interaction between the rotating blades and the trapdoors located on the volute sidewall. Some modifications of the geometry are suggested.
Effect of a Single Leading-Edge Protuberance on NACA 634-021 Airfoil Performance
Authors: Cai Chang , Zuo Zhigang , Liu Shuhong , Maeda Takao
Published: October 2017

Leading-edge protuberances on airfoils or wings have been considered as a viable passive control method for flow separation. In this paper, the aerodynamic performance of a modified airfoil with a single leading-edge protuberance was investigated and compared with the baseline NACA 634-021 airfoil. Spalart–Allmaras turbulence model was applied for the numerical simulation. Compared to the sharp decline of baseline lift coefficient, the stall angle of the modified foil decreased and the decline of the lift coefficient became mild. The poststall performance of the modified airfoil was improved, while the prestall performance was declined. Asymmetric flows along the spanwise direction were observed on the modified airfoil, and the local region around one shoulder of the protuberance suffered from leading-edge separation at prestall angles of attack, which may be responsible for the performance decline. At poststall angles of attack, the attached flows along the peak of the protuberance with a sideward velocity component would help improving the total performance of the airfoil. Experimental visualization methods, including surface tuft and smoke flow, were performed, and the asymmetric flow pattern past the protuberance was successfully captured. This specific phenomenon may be largely related to the formation of the biperiodic condition and other complicated flow patterns induced by multiple leading-edge protuberances. The formation mechanism and suppression method of the symmetry breaking phenomenon should be investigated more deeply in the future to guide the practical application of this passive control method.
Influence of Centrifugal Forces on Oil Flow in Journal Bearing of Planetary Gear
Authors: Temis Mikhail , Lazarev Alexander
Published: October 2017

Mathematical model of oil flow in fluid film bearing in field of centrifugal forces is developed. Centrifugal forces for planet wheel bearing sliding surfaces and oil gap are formulated. This model is based on modification of two-dimensional Reynolds equation taking into account inertia centrifugal forces for oil film. Required modification of Reynolds equation is received from Navier–Stokes and continuity equations taking into account centrifugal forces acting on planet wheel bearing. Modified two-dimensional Reynolds equation is solved numerically using finite element discretization. Developed mathematical model, based on modified Reynolds equation, is verificated at comparison with solution of full Navier–Stokes equations system obtained in commercial software package. Results for pressure distribution in bearing with fixed axis and in planet wheel bearing are received and compared. The sufficient influence of centrifugal inertia forces in oil layer of planet wheel bearing on pressure distribution, bearing carrying force, and attitude angle is shown for specific shaft journal eccentricity ratio, eccentricity direction, and rotation velocity.
Numerical Simulations for the Wake Prediction of a Marine Propeller in Straight-Ahead Flow and Oblique Flow
Authors: Guilmineau E. , Deng G. B. , Leroyer A. , Queutey P. , Visonneau M. , Wackers J.
Published: October 2017

This paper presents the capability of a numerical code, isis-cfd, based on the solution of the Navier–Stokes equations, for the investigation on the hydrodynamic characteristics of a marine propeller in open water. Two propellers are investigated: the Istituto Nazionale per Studi ed Esperienze di Architectura Navale (INSEAN) E779A model in straight-ahead flow and the Potsdam Propeller Test Case (PPTC) model in oblique flow. The objectives of this study are to establish capabilities of various turbulent closures to predict the wake propeller and to predict the instability processes in the wake if it exists. Two Reynolds-averaged Navier–Stokes (RANS) models are used: the k–ω shear stress transport (SST) of Menter and an anisotropic two-equation explicit algebraic Reynolds stress model (EARSM). A hybrid RANS–large eddy simulation (LES) model is also used. Computational results for global flow quantities are discussed and compared with experimental data. These quantities are in good agreement with the measured data. The hybrid RANS–LES model allows to capture the evolution of the tip vortices. For the INSEAN E779A model, the instability of the wake is only predicted with a hybrid RANS–LES model, and the position of these instabilities is in good agreement with the experimental visualizations.