bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal Conductivity of Molten B2O3, B2O3–SiO2, Na2O–B2O3, and Na2O–SiO2 Systems
Authors: Kim Youngjae , Morita Kazuki
Published: February 2015

With the aid of the transient hot‐wire method, the thermal conductivity of molten B2O3, B2O3–SiO2, Na2O–SiO2, and Na2O–B2O3 systems was measured along with their temperature and composition. It was observed that the thermal conductivity of pure B2O3 increased with temperature, until about 1400 K, and then decreased subsequently. Using the MAS‐NMR, 3Q‐MAS, and Raman spectroscopy, the structure of B2O3 and SiO2 in the B2O3–SiO2 system was confirmed. Findings show that an addition of B2O3 into the pure SiO2 system causes a significant decrease in thermal conductivity, due to the formation of boroxol rings. The thermal conductivity of the Na2O–SiO2 system was measured and its phonon mean free path was calculated. In addition, a positive linear relation between viscosity and thermal conductivity was observed. In the Na2O–B2O3 system, it was found that a change in the relative fraction of 4‐coordinated boron has an influence on the thermal conductivity when the concentration of Na2O is between 10 and 30 mol%, in which case the tetraborate unit is dominant.
The influence of authentic leadership and empowerment on nurses’ relational social capital, mental health and job satisfaction over the first year of practice
Authors: Read Emily A. , Laschinger Heather K.S.
Published: February 2015

Aims

To examine a theoretical model testing the effects of authentic leadership, structural empowerment and relational social capital on the mental health and job satisfaction of new graduate nurses over the first year of practice.

Background

Relational social capital is an important interpersonal organizational resource that may foster new graduate nurses’ workplace well‐being and promote retention. Evidence shows that authentic leadership and structural empowerment are key aspects of the work environment that support new graduate nurses; however, the mediating role of relational social capital has yet to be explored.

Design

A longitudinal survey design was used to test the hypothesized model.

Methods

One hundred ninety‐one new graduate nurses in Ontario with <2 years of experience completed mail surveys in January–March 2010 and 1 year later in 2011. Path analysis using structural equation modelling was used to test the theoretical model.

Results

Participants were mostly female, working full time in medicine/surgery or critical care. All measures demonstrated acceptable reliability and validity. Path analysis results supported our hypothesized model; structural empowerment mediated the relationship between authentic leadership and nurses’ relational social capital, which in turn had a negative effect on mental health symptoms and a positive effect on job satisfaction. All indirect paths in the model were significant.

Conclusion

By creating structurally empowering work environments, authentic leaders foster relational social capital among new graduate nurses leading to positive health and retention outcomes.
Intralocus tactical conflict: genetic correlations between fighters and sneakers of the dung beetle Onthophagus taurus
Authors: Buzatto B. A. , Kotiaho J. S. , Tomkins J. L. , Simmons L. W.
Published: February 2015

Males and females differ in their phenotypic optima for many traits, and as the majority of genes are expressed in both sexes, some alleles can be beneficial to one sex but harmful to the other (intralocus sexual conflict; ISC). ISC theory has recently been extended to intrasexual dimorphisms, where certain alleles may have opposite effects on the fitness of males of different morphs that employ alternative reproductive tactics (intralocus tactical conflict; ITC). Here, we use a half‐sib breeding design to investigate the genetic basis for ISC and ITC in the dung beetle Onthophagus taurus. We found positive heritabilities and intersexual genetic correlations for almost all traits investigated. Next, we calculated the intrasexual genetic correlation between males of different morphs for horn length, a sexually selected trait, and compared it to intrasexual correlations for naturally selected traits in both sexes. Intrasexual genetic correlations did not differ significantly between the sexes or between naturally and sexually selected traits, failing to support the hypothesis that horns present a reduction of intrasexual genetic correlations due to ITC. We discuss the implications for the idea of developmental reprogramming between male morphs and emphasize the importance of genetic correlations as constraints for the evolution of dimorphisms.
Conservation of multivariate female preference functions and preference mechanisms in three species of trilling field crickets
Authors: Blankers T. , Hennig R. M. , Gray D. A.
Published: February 2015

Divergence in mate recognition systems among closely related species is an important contributor to assortative mating and reproductive isolation. Here, we examine divergence in male song traits and female preference functions in three cricket species with songs consisting of long trills. The shape of female preference functions appears to be mostly conserved across species and follows the predictions from a recent model for song recognition. Multivariate preference profiles, combining the pulse and trill parameters, demonstrate selectivity for conspecific pulse rates and high trill duty cycles. The rules for integration across pulse and trill timescales were identical for all three species. Generally, we find greater divergence in male song traits than in associated female preferences. For pulse rate, we find a strong match between divergent male traits and female peak preferences. Preference functions for trill parameters and carrier frequency are similar between species and show less congruence between signal and preference. Differences among traits in the degree of trait–preference (mis)match may reflect the strength of preferences and the potential for linkage disequilibrium, selective constraints and alternative selective pressures, but appear unrelated to selection for mate recognition per se.
Which risk‐adjustment index performs better in predicting 30‐day mortality? A systematic review and meta‐analysis
Authors: Yang Mo , Mehta Hemalkumar B. , Bali Vishal , Gupta Parul , Wang Xin , Johnson Michael L. , Aparasu Rajender R.
Published: February 2015

Rationale, aims and objectives

Individual comparisons of the performance of risk‐adjustment indices have been widely conducted. Few reviews have been conducted to summarize the performance of different risk‐adjustment indices. A 30‐day mortality rate is widely used to evaluate the quality of care in hospitals by federal agencies like the Centers for Medicare and Medicaid Services. This study examined relative performance of risk‐adjustment indices that predict 30‐day mortality.

Methods

Databases including Medline, PubMed and PsycINFO were searched for studies that compared risk‐adjustment indices. The search protocol included comparative studies in which the performance of risk‐adjustment indices were compared across any defined cohort to compare 30‐day mortality, including mortality within 30 days and intensive care unit mortality, which lasts less than 30 days. Data were extracted using a structured form and abstract data included author and publication year, population studied (including location, sample size, study time period), comparison indices, outcome studied, results and conclusions from the results. A meta‐analytical approach was used to summarize all the studies. Scaled ranking score was used to estimate the relative superiority of any given risk‐adjustment indices. A hypergeometric test was carried out to evaluate the performance of risk‐adjustment measures.

Results

Out of 2805 studies identified, 23 studies met the eligibility criteria. Main risk‐adjustment indices used for comparison included Acute Physiology and Chronic Health Evaluation, Sequential Organ Failure Assessment score, Charlson co‐morbidity index, Model for End‐Stage Liver Disease score and Simplified Acute Physiology Score (SAPS). Based on scaled ranking score, SAPS performed best (score 0.510) among all the risk‐adjustment indices. However, based on hypergeometric test, the five measures performed equally well.

Conclusions

Although all the selected risk‐adjustment indices perform equally well, SAPS seems better than other indices for short‐term mortality
based on scaled ranking score.
An extragonadal teratoma in a female cynomolgus monkey (Macaca fascicularis)
Authors: Schelling S.H. , Morton D.
Published: February 2015

Extragonadal teratomas have not been reported in nonhuman primates. A female cynomolgus monkey, a vehicle control in an exploratory toxicity study, was necropsied. Microscopic examination of an extragonadal mass in the animal's craniodorsal retroperitoneum revealed a teratoma. This is the first report of an extragonadal teratoma in a nonhuman primate.
Risk factors for adenomyosis, leiomyoma and concurrent adenomyosis and leiomyoma
Authors: Güzel Ali İrfan , Akselim Burak , Erkılınç Selçuk , Kokanalı Kuntay , Tokmak Aytekin , Dolmuş Başar , Doğanay Melike
Published: February 2015

Aim

To evaluate the risk factors for adenomyosis, leiomyoma and concomitant adenomyosis and leiomyoma in patients with treatment‐resistant menometrorrhagia.

Methods

A retrospective study was conducted on 129 women who underwent abdominal hysterectomy for treatment‐resistant menometrorrhagia. The patients were divided into four groups according to the postoperative histopathology: concomitant adenomyosis and leiomyoma (n = 33), adenomyosis only (n = 26), leiomyoma only (n = 48) and controls (n = 22). Patients without any organic uterine pathology constituted the control group.

Results

Age at menarche was higher in the concomitant adenomyosis and leiomyoma group compared to the adenomyosis only group (P = 0.006). The mean age (P = 0.007), age at menarche (P = 0.001) and gravidity (P = 0.001) were higher in the concomitant adenomyosis and leiomyoma group compared to the leiomyoma only group. Preoperative hemoglobin was lower in the concomitant adenomyosis and leiomyoma, adenomyosis only, and leiomyoma only groups than the control group (P < 0.008). On receiver operating characteristic analysis, hemoglobin <10.9 mg/dL had a sensitivity and specificity of 77% and 70%, respectively, in discrimination of any uterine organic pathology, including adenomyosis only, leiomyoma only, and concomitant adenomyosis and leiomyoma, from the control group. Patients in the adenomyosis group were older (OR, 1.20; 95%CI: 1.05–1.50) and had a lower age at menarche (OR, 0.42; 95%CI: 0.19–0.89) than the other groups.

Conclusions

Preoperative anemia may be a useful predictor of adenomyosis. Older patients, and patients who had a lower age at menarche, were also more likely to have adenomyosis.
Umbilical cord milking reduces need for red cell transfusions and improves neonatal adaptation in preterm infants: Meta‐analysis
Authors: Dang Dan , Zhang Chuan , Shi Shan , Mu Xin , Lv Xiaoming , Wu Hui
Published: February 2015

Aim

To assess effects of umbilical cord milking (UCM) on early blood pressure stabilization, hemoglobin (Hb), as well as incidence of transfusion and complications in preterm infants.

Methods

This meta‐analysis was conducted by searching the Pubmed, EMBASE and Cochrane Library (until July 2014) databases. Any clinical trials, including randomized control trials, comparing UCM to immediate cord clamping (ICC) were analyzed.

Results

Six studies were included in this meta‐analysis. In total, 292 preterm infants were treated with UCM, while 295 received ICC. Compared to ICC, UCM increased initial Hb significantly by 1.84 g/dL (weighted mean difference; 95%CI: 0.91–2.76; P < 0.0001) and decreased the incidence of transfusion with a pooled risk ratio of 0.74 (95%CI: 0.61–0.90; P = 0.002). Incidence of necrotizing enterocolitis (NEC), intraventricular hemorrhage (IVH) and mortality were significantly lower with UCM compared with ICC. Apgar score and temperature were not significantly different between the two groups.

Conclusions

By facilitating the early stabilization of blood pressure, UCM at preterm birth was found to be comparatively safe and associated with lower blood transfusion exposure and lower incidence of IVH, NEC and death.
Prenatal findings and epimutations for paternal uniparental disomy for chromosome 14 syndrome
Authors: Watanabe Takafumi , Go Hayato , Kagami Masayo , Yasuda Shun , Nomura Yasuhisa , Fujimori Keiya
Published: February 2015

The phenotypes associated with paternal uniparental disomy for chromosome 14 (UPD(14)pat) are clinically distinctive and caused by genetic alterations at the 14q32.2 imprinted region. Here we describe prenatal and neonatal findings in a case of epimutation associated with UPD(14)pat‐like phenotype. A 25‐year‐old Japanese woman was referred to hospital at 32 weeks of gestation for management of threatened premature delivery. Fetal ultrasound and magnetic resonance imaging showed a narrow thorax and polyhydramnios. At 35 weeks of gestation, emergency cesarean section was performed and placentomegaly was identified. Physical examination of the neonate indicated a small narrow thorax, diastasis recti, and dysmorphic facial features that included hirsute forehead, broad flat nasal bridge, micrognathia, small ears, and a long protruding philtrum. Genetic analysis identified epimutation at the intergenic differentially methylated region (IG‐DMR) and at MEG3‐DMR.
What is the role of matrix metalloproteinase‐2 in placenta percreta?
Authors: Kocarslan Sezen , Incebıyık Adnan , Guldur Muhammet Emin , Ekinci Turan , Ozardali Hasan Ilyas
Published: February 2015

Aim

This study compared the placental expression of the matrix metalloproteinase‐2 (MMP‐2) enzyme, which is thought to play a key role in the penetration of trophoblastic cells, in third‐trimester placenta percreta (PP) patients with that of women with normal pregnancies.

Methods

Twenty‐five pregnant subjects who underwent cesarean section due to PP and 25 term pregnant subjects who underwent cesarean section for obstetric reasons were included in the study. Demographic data, pathology reports, and histopathological samples were examined. Blocks containing samples of placenta underwent immunohistochemical analysis using the MMP‐2 antibody. Immunohistochemical expression of placental samples obtained from both groups was examined and compared.

Results

There were no statistically significant differences in the demographic data (P > 0.05). With regard to immunohistochemistry, cytoplasmic staining of trophoblastic cells was considered immunohistochemically positive. In the PP tissue samples, positive MMP‐2 staining was detected as follows: 0 immunoreactivity, one patient (4%); 1(+), six patients (24%); 2(+), seven patients (28%); and 3(+), 11 patients (44%). In the term pregnant placental tissue samples, positive MMP‐2 staining was detected in five patients (20%) at 0 immunoreactivity, 12 (48%) at 1(+) immunoreactivity, five (20%) at 2(+) immunoreactivity, and three patients (12%) at 3(+) immunoreactivity. Immunohistochemical expression was significantly different between the PP and normal term pregnancy placental tissues (P = 0.02).

Conclusion

The stronger expression of the MMP‐2 enzyme in the PP as compared to the normal placental tissue suggests that this enzyme may be an effective mediator in the pathogenesis of PP.
Heterogeneity of Multiple Sclerosis White Matter Lesions Detected With T2*‐Weighted Imaging at 7.0 Tesla
Authors: Yao Bing , Ikonomidou Vasiliki N. , Cantor Fredric K. , Ohayon Joan M. , Duyn Jeff , Bagnato Francesca
Published: February 2015

BACKGROUND AND PURPOSE

Postmortem studies in multiple sclerosis (MS) indicate that in some white matter lesions (WM‐Ls), iron is detectable with T2*‐weighted (T2*‐w), and its reciprocal R2* relaxation rate, magnetic resonance imaging (MRI) at 7.0 Tesla (7T). This iron appears as a hyperintense rim in R2* images surrounding a hypointense core. We describe how this observation relates to clinical/radiological characteristics of patients, in vivo.

METHODS

We imaged 16 MS patients using 3T and 7T scanners. WM‐Ls were identified on T1‐w/T2‐w 3T‐MRIs. Thereafter, WM‐Ls with a rim of elevated R2* at 7T were counted and compared to their appearance on conventional MRIs.

RESULTS

We counted 36 WM‐Ls presenting a rim of elevated R2* in 10 patients. Twenty‐three (64%) lesions coincided with focal WM‐Ls on T2‐w MRIs; 13 (36%) coincided with only portions of larger lesions on T2‐w images; and 20 (56%) corresponded to a hypointense chronic black hole. WM‐Ls presenting a rim of elevated R2* were seen in both relapsing‐remitting patients with low disability and in those with long‐standing secondary progressive MS.

CONCLUSIONS

WM‐Ls with a contour of high R2* are present at different MS stages, potentially representing differences in the contribution of iron in MS disease evolution.
Magnetic Resonance Fiber Tracking in a Neonate with Hemimegalencephaly
Authors: Re Thomas J , Scarciolla Laura , Takahashi Emi , Specchio Nicola , Bernardi Bruno , Longo Daniela
Published: February 2015

A magnetic resonance diffusion fiber tracking study in neonate diagnosed with left hemisphere hemimegalencephaly is presented. Despite diffuse morphologic deformities identified in conventional imaging, all major pathways were identifiable bilaterally with minor aberrations in vicinity of morphologic lesions.
THE SLX MODEL
Authors: Halleck Vega Solmaria , Elhorst J. Paul
Published: February 2015

We provide a comprehensive overview of the strengths and weaknesses of different spatial econometric model specifications in terms of spillover effects. Based on this overview, we advocate taking the SLX model as point of departure in case a well‐founded theory indicating which model is most appropriate is lacking. In contrast to other spatial econometric models, the SLX model also allows for the spatial weights matrix W to be parameterized and the application of standard econometric techniques to test for endogenous explanatory variables. This starkly contrasts commonly used spatial econometric specification strategies and is a complement to the critique of spatial econometrics raised in a special theme issue of the Journal of Regional Science (Volume 52, Issue 2). To illustrate the pitfalls of the standard spatial econometrics approach and the benefits of our proposed alternative approach in an empirical setting, the Baltagi and Li (2004) cigarette demand model is estimated.
Use of a Psychometric Instrument as a Referral Process for the Required Level of Specialization of Health and Social Services
Authors: Tremblay Audrée , Morin Diane
Published: February 2015

In Québec, services of people with intellectual disability (ID) are divided into three levels of care based on the World Health Organization model. Currently, no standardized tool is used to assess the level of specialization of care required by persons with ID in the province despite the Ministry of Social and Health Services' reference framework, which stipulates that services should be fair and easily accessible to all. The present study examined potential tools to address this situation. The scores on the Supports Intensity Scale‐French version (SIS‐F), Adaptive Behavior Assessment System‐II, and Scales of Independent Behavior‐Revised (SIB‐R) (Part 2) of 30 participants with ID were examined in conjunction with the required level of specialization of services, as determined by an expert committee. Scores on these scales were not linearly related to the required level of care. This indicates that scores cannot be used to determine if a person needs services from the primary, secondary, or tertiary care facility. However, significant differences were observed between the primary and tertiary levels on the Exceptional Behavioral Support Needs scale of the SIS‐F and the SIB‐R Part 2. The study shows that the expert committee was more successful in making this determination than a standardized instrument. The instruments used in the present study, not designed for this purpose, were insufficient. Nonetheless, results underline the importance of factoring in challenging behaviors in the assessment of service needs.
A genetic component of extinction risk in mammals
Authors: Polishchuk Leonard V. , Popadin Konstantin Y. , Baranova Maria A. , Kondrashov Aleksey S.
Published: February 2015

Genetic factors may play an important role in species extinction but their actual effect remains poorly understood, particularly because of a strong and potentially masking effect expected from ecological traits. We investigated the role of genetics in mammal extinction taking both ecological and genetic factors into account. As a proxy for the role of genetics we used the ratio of the rates of nonsynonymous (amino acid changing) to synonymous (leaving the amino acid unchanged) nucleotide substitutions,Ka/Ks. Because most nonsynonymous substitutions are likely to be slightly deleterious and thus selected against, this ratio is a measure of the inefficiency of selection: if large (but less than 1), it implies a low efficiency of selection against nonsynonymous mutations. As a result, nonsynonymous mutations may accumulate and thus contribute to extinction. As a proxy for the role of ecology we used body massW, with which most extinction‐related ecological traits strongly correlate. As a measure of extinction risk we used species’ affiliation with the five levels of extinction threat according to the IUCN Red List of Threatened Species. We calculatedKa/Ksfor mitochondrial protein‐coding genes of 211 mammalian species, each of which was characterized by body mass and the level of threat. Using logistic regression analysis, we then constructed a set of logistic regression models of extinction risk on ln(Ka/Ks) and lnW. We found thatKa/Ksand body mass are responsible for a 38% and a 62% increase in extinction risk, respectively. Given that the standard error of these values is 13%, the contribution of genetic factors to extinction risk in mammals is estimated to be one‐quarter to one‐half of the total of ecological and genetic effects. We conclude that the effect of genetics on extinction is significant, though it is almost certainly smaller than the effect of ecological traits.

Synthesis

Mutation provides the material for evolution. However, most mutations that play a role in evolution are slightly deleterious and thus may contribute to extinction. We assess the role of mitochondrial DNA mutations in mammalian extinction risk and find it to be one‐quarter to one‐half of the total of mutation and body mass effects, where body mass represents an integral measure of extinction‐related ecological traits. Genetic factors may be all the more important, because ecological traits associated with large body mass would both promote and protect from extinction, while mutation accumulation caused by low effective population size seems to have no counterbalance.
Disentangling direct and indirect effects of a legume shrub on its understorey community
Authors: Michalet Richard , Brooker Rob W. , Lortie Christopher J. , Maalouf Jean‐Paul , Pugnaire Francisco I.
Published: February 2015

Direct and indirect interactions among plants contribute to shape community composition through above‐ and belowground processes. However, we have not disentangled yet the direct and indirect soil and canopy effects of dominants on understorey species. We addressed this issue in a semi‐arid system from southeast Spain dominated by the legume shrub Retama sphaerocarpa. During a year with an exceptionally dry spring, we removed the shrub canopy to quantify aboveground effects and compared removed‐canopy plots to open plots between shrubs to quantify soil effects, both with and without watering. We added a grass removal treatment in order to separate direct from indirect shrub effects and quantified biomass, abundance, richness and composition of the forb functional group. With watering, changes in forb biomass were primarily driven by indirect shrub effects, with contrasting negative soil and positive aboveground indirect effects; changes in forb abundance and composition were more influenced by direct shrub soil effects with contrasting species composition between open and Retama patches. As community composition was different between open and Retama patches the indirect effects of Retama on forb species did not concern forbs from the open community but forbs from Retama patches. Indirect effects are, thus, important at the functional group level rather than at the species level. Without watering, there were no significant interactions. Changes in species richness between treatments were weak and seldom significant. We conclude that shrub effects on understorey forbs are primarily due to their influence on soil properties, directly affecting forb species composition but indirectly affecting the biomass of the forbs of the Retama patches, and only with sufficient water.
Duration of colonization and interactions between early and late colonists determine the effects of patch colonization history on patch biodiversity
Authors: Amoroso Natalie , Chalcraft David R.
Published: February 2015

Patches can vary in their colonization history as the result of many factors, including differences in patch size and isolation, which alter the timing and duration in which one or more species colonize a patch. Prior work has found that the particular time that a species colonizes a patch can affect the performance of co‐occurring species, but it is less clear whether it affects the biodiversity of the patch. Our objective was to evaluate how two components of colonization history affect biodiversity – the total duration of the colonization window in which a predator is able to colonize the patch and the particular time in the patch's colonization history (i.e. early versus late in community development) that colonization by a predator occurs. We conducted an experiment to examine how the duration and timing in which predatory dragonflies colonize recently filled ephemeral ponds affects insect biodiversity. Dragonfly colonization history had an important effect on insect biodiversity. Ponds with a longer colonization history by dragonflies had fewer insect morphotypes than ponds with a shorter colonization history. The timing of dragonfly colonization (i.e. early versus late in community development) had no effect on the number of insect morphotypes present despite altering both the rate of dragonfly metamorph production and the abundance of larval dragonflies present at the end of the study. The effect of duration of long‐term dragonfly colonization on biodiversity stemmed from early colonists weakening the influence of later colonists on insect biodiversity. Though colonization by dragonflies reduced adult insect abundance, differences in the time in which dragonflies colonized ponds had no effect on total insect abundance. Moreover, differences in patch biodiversity appears to be affected more by variation in the duration a patch was colonized by a predator than variation in the time in which a patch was colonized by a predator.
Biotic invasions can alter nutritional composition of zooplankton communities
Authors: Kratina Pavel , Winder Monika
Published: February 2015

Ecologists and ecosystem managers often base their understanding of trophic dynamics on consumer and resource biomass. However, the factors that alter the relative nutritional value of resources are often poorly understood, despite their potential to decouple trophic interactions. Recent population declines in pelagic fishes of the upper San Francisco Estuary were not accompanied by an equivalent decrease in zooplankton biomass, which are the main resource for the fish and their larvae. It was hypothesized that changes in zooplankton nutritional conditions following the establishment of invasive species caused food‐quality related limitations for these higher‐order consumers. Using stable isotopes, elemental stoichiometry and fatty acid analyses for all dominant invasive and native zooplankton taxa and seston, we characterized the plankton community structure in the estuary and demonstrated taxon‐specific differences in their nutritional value. We then quantified the temporal dynamics in meso‐zooplankton proportions of docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), polyunsaturated fatty acids (PUFA), and ratio of n3:n6 fatty acids. We found temporal increase in the community‐level DHA, n3 to n6 fatty acid ratio, decrease in the community‐level EPA and PUFA in the brackish water region, but no change in the bulk PUFA proportions in the freshwater region of the estuary. These changes were caused mainly by declines of native cladocerans that are rich in EPA and by an increase in the dominance of invasive taxa with high DHA concentrations, similar to that of native taxa. Although we showed temporal shifts in individual fatty acid classes, the proportion of the essential fatty acids remained relatively high, suggesting that nutritional prey availability for fish remained unchanged with the shift in species composition. We argue that the nutritional content of resource communities should be considered when analyzing the long‐term trophic dynamics and designing effective management and restoration strategies.
Human leukocyte antigen‐G polymorphism influences the age of onset and autoantibody status in rheumatoid arthritis
Authors: Mariaselvam C. M. , Chaaben A. B. , Salah S. , Charron D. , Krishnamoorthy R. , Tamouza R. , Negi V. S.
Published: February 2015

The study was conducted to investigate the frequency of three gene polymorphisms in the 3′‐untranslated region (3′‐UTR) of human leucocyte antigen‐G (HLA‐G) gene in south Indian patients with rheumatoid arthritis (RA) and analyze their influence on disease susceptibility, phenotype and treatment response. HLA‐G 14 bp insertion (Ins)/deletion (del) (rs66554220), HLA‐G +3142G>C (rs1063320) and +3187A>G (rs9380142) polymorphism was analyzed in 221 RA patients and 200 healthy controls. Frequency of HLA‐G genotypes or alleles did not differ between patients and controls. Analysis based on rheumatoid factor (RF) status revealed that the frequency of allele ‘A’ (rs9380142) was significantly higher in RF‐positive than in RF‐negative patients [84% vs 74%, Yates‐corrected P value (Pc) = 0.04, odds ratio (OR) = 1.8, 95% confidence interval (CI) = 1.0–3.2]. A similar difference was maintained in RF‐positive female patients than their RF‐negative counterparts (83% vs 71%, Pc = 0.02, OR = 1.9, 95% CI = 1.0 to 3.4) and between RF‐positive and RF‐negative young onset RA (YORA) patients (84% vs 73%, Pc = 0.03, OR = 1.9, 95% CI = 1.0–3.2), suggesting that rs9380142 polymorphism influenced RF status. The 14 bp Ins allele of rs66554220 was significantly more prevalent in RF‐positive YORA than in RF‐positive late onset RA (LORA) patients (51% vs 25%, P = 0.03, OR = 3.1, 95% CI = 1.1–9.8). Frequency of the four major haplotypes [InsGA (48%), DelGA (22%), DelCG (18%), DelCA (9.7%)] observed did not differ between cases and controls. HLA‐G does not appear to be a risk factor for development of RA in south Indian Tamils but may act as a genetic modifier of clinical phenotype in terms of autoantibody production, gender preference and age at disease onset.
Factors associated with delivery outside a health facility: cross‐sectional study in rural Malawi
Authors: Mazalale Jacob , Kambala Christabel , Brenner Stephan , Chinkhumba Jobiba , Lohmann Julia , Mathanga Don P. , Robberstad Bjarne , Muula Adamson S. , De Allegri Manuela
Published: February 2015

Objective

To identify factors associated with delivery outside a health facility in rural Malawi.

Method

A cross‐sectional survey was conducted in Balaka, Dedza, Mchinji and Ntcheu districts in Malawi in 2013 among women who had completed a pregnancy 12 months prior to the day of the survey. Multilevel logistic regression was used to assess factors associated with delivery outside a facility.

Results

Of the 1812 study respondents, 9% (n = 159) reported to have delivered outside a facility. Unmarried women were significantly more likely [OR = 1.88; 95% CI (1.086–3.173)] to deliver outside a facility, while women from households with higher socio‐economic status [third‐quartile OR = 0.51; 95% CI (0.28–0.95) and fourth‐quartile OR = 0.48; 95% CI (0.29–0.79)] and in urban areas [OR = 0.39; 95%‐CI (0.23–0.67)] were significantly less likely to deliver outside a facility. Women without formal education [OR 1.43; 95% CI (0.96–2.14)] and multigravidae [OR = 1.14; 95% CI (0.98–1.73)] were more likely to deliver outside a health facility at 10% level of significance.

Conclusion

About 9% of women deliver outside a facility. Policies to encourage facility delivery should not only focus on health systems but also be multisectoral to address women's vulnerability and inequality. Facility‐based delivery can contribute to curbing the high maternal illness burden if authorities provide incentives to those not delivering at the facility without losing existing users.
Menstrual cycle phase does not affect sympathetic neural activity in women with postural orthostatic tachycardia syndrome
Authors: Stickford Abigail S.L. , VanGundy Tiffany B. , Levine Benjamin D. , Fu Qi
Published: February 2015

Key points

Women with the postural orthostatic tachycardia syndrome (POTS) report fluctuations in orthostatic tolerance throughout the menstrual cycle.

The mechanism(s) underlying blood pressure control across the menstrual cycle in women with POTS are unknown.

The findings of the present study indicate that the menstrual cycle does not affect muscle sympathetic nerve activity but modulates blood pressure and vasoconstriction in POTS women during orthostatic stress.

Factors other than sympathetic neural activity are likely responsible for the symptoms of orthostatic intolerance across the menstrual cycle in women with POTS.

Patients with the postural orthostatic tachycardia syndrome (POTS) are primarily premenopausal women, which may be attributed to female sex hormones. We tested the hypothesis that hormonal fluctuations of the menstrual cycle alter sympathetic neural activity and orthostatic tolerance in POTS women. Ten POTS women were studied during the early follicular (EF) and mid‐luteal (ML) phases of the menstrual cycle. Haemodynamics and muscle sympathetic nerve activity (MSNA) were measured when supine, during 60 deg upright tilt for 45 min or until presyncope, and during the cold pressor test (CPT) and Valsalva manoeuvres. Blood pressure and total peripheral resistance were higher during rest and tilting in the ML than EF phase; however, heart rate, stroke volume and cardiac output were similar between phases. There were no mean ± SD differences in MSNA burst frequency (8 ± 8 EF phase vs. 10 ± 10 bursts min–1 ML phase at rest; 34 ± 15 EF phase vs. 36 ± 16 bursts min–1 ML phase at 5 min tilt), burst incidence or total activity, nor any differences in the cardiovagal and sympathetic baroreflex sensitivities between phases under any condition. The incidence of presyncope was also the same between phases. There were no differences in haemodynamic or sympathetic responses to CPT or Valsalva. These results suggest that the menstrual cycle does not affect sympathetic neural activity but modulates blood pressure and vasoconstriction in POTS women during tilting. Thus, factors other than sympathetic neural activity are probably responsible for the symptoms of orthostatic intolerance across the menstrual cycle in women with POTS.
A Novel Proximity Probe Unaffected by Shaft Electromagnetic Properties
Authors: Hastings Michael M. , Jensen Henrik B.
Published: February 2015

Non-contact eddy-current displacement transducers, or proximity probes as they are popularly known, have always played an important role in monitoring the condition of a variety of machines, and will remain doing so for years to come. Although immensely useful for detecting a wide range of machine faults by simply monitoring the shaft position and vibration, there are definite limitations to the traditional probe systems due to the aging technology. Some of these problems are the probe driver sensitivity to the probe coil parameters, the shaft’s electromagnetic properties, and the capacitance of the cable it is attached to. Since each probe driver has to be individually calibrated to a specific probe tip diameter, a specific kind of shaft material and a specific cable length, it is easy to imagine that stocking such dedicated drivers can be expensive for large applications. But what is even more costly than this is the risk of reduced monitoring reliability due to an incorrectly selected or calibrated driver. As a result of this, a new proximity probe system recently has been designed and tested that uses a simple yet innovative principle that makes it insensitive to shaft material electromagnetic properties, can accommodate different cable lengths without recalibration, and yet still can fulfil all the installation, application, and performance expectations of a traditional probe.
Technology Development Programs for the Advanced Turbine Systems Engine
Authors: Diakunchak Ihor S. , Bannister Ronald L. , Huber David J. , Roan D. Frank
Published: February 2015

This paper describes the technologies that are being developed or extended beyond the current state-of-the-art to achieve Advanced Turbine Systems (ATS) Program goals. The Westinghouse ATS plant is an advanced closed-loop enoled combined cycle, based on an advanced gas turbine engine incorporating novel design concepts and enhancements of existing technologies. The ATS engine is a fuel-flexible design operating nn natural gas with provisions fnr future conversion to coal or biomass fuels. It is based nn proven concepts employed in 501F and 501G engines. To achieve the required performance and reliability the engine will include closed-loop steam cooling, advanced materials and coatings, and enhanced component performance. To minimize NOx emissions, an ultra-low NOx combustion system will be incorporated. To ensure technical success, development programs are being conducted on the following: closed-loop steam cooling, advanced materials and coatings, component aerodynamic performance, flow visualization, optical diagnostics, combustion generated noise, and catalytic combustion.
H Gas Turbine Combined Cycle Technology and Development Status
Authors: Corman James C.
Published: February 2015

A revolutionary step has been taken in the development of the Next Advance in Power Generation Systems — “H” Technology Combined Cycle. This new gas turbine combined cycle system increases thermal performance to the 60% level by increasing gas turbine operating conditions to 2600°F (1430°C) at a pressure ratio of 23 to 1. This represents a significant increase in operating temperature for the gas turbine. However, the potential for single digit NOx levels (based upon 15% O2 in the exhaust) has been retained. The combined effect of performance increase and environmental control is achieved by an innovative closed loop steam cooling system which tightly integrated the gas turbine and steam turbine cycles.

Although a significant advance has been taken in performance, the new power generation system has been configured with a substantial number of proven concepts and technology programs are ongoing to validate the new features. The technical activities which support the introduction of the new turbine system have reached a point in the development cycle where the results are integrated into the design methods. This has permitted the “H” Technology to achieve a design readiness status and the first unit will be under test in late 1997.
Investigation of Hydrodynamic Forces on Rotating and Whirling Centrifugal Pump Impellers
Authors: Fongang R. , Colding-Jørgensen J. , Nordmann R.
Published: February 2015

A 2-dimensional fluid model is developed to investigate the hydrodynamic forces exerted on a rotating impeller caused by the impeller-fluid-volute interaction in a centrifugal pump. In this model, the impeller periphery and the volute contour are replaced by a distribution of unsteady vortices. The impeller center is assumed to execute a whirling motion about the rotor center. This is an improvement of the earlier quasisteady flow model of Colding-Jørgensen (1980) where the impeller was taken as a single vortex-source point. The forces can be presented as a sum of a steady and an unsteady part. The rotordynamic coefficients are deduced from the unsteady forces decomposed into radial and tangential components relative to the orbit described by the impeller center. In comparison to most of the theoretical and experimental results found in the literature, the model seems to give good prediction. It appears clearly from this analysis that, under certain operating conditions, the fluid forces on the impeller have a destabilizing effect on the pump rotor.
Wake Mixing in Axial Flow Compressors
Authors: Adamczyk John J.
Published: February 2015

Over the years it has been speculated that the performance of multi-stage axial flow compressors is enhanced by the passage of a wake through a blade row prior to being mixed-out by viscous diffusion. The link between wake mixing and performance depends on the ability to recover the total pressure deficit of a wake by a reversible flow process. This paper shows that such a process exists, it is unsteady, and is associated with the kinematics of the wake vorticity field. The analysis shows that the benefits of wake total pressure recovery can be estimated from linear theory and quantified in terms of a volume integral involving the deterministic stress and the mean strain rate. In the limit of large reduced frequency the recovery process is shown to be a direct function of blade circulation. Results are presented which show that the recovery process can reduce the wake mixing loss by as much as seventy percent. Under certain circumstances this can lead to nearly a point improvement in stage efficiency, a nontrivial amount.
Simple Instrumentation Rake Designs for Gas Turbine Engine Testing
Authors: Smout Peter D. , Cook Steven C.
Published: February 2015

The determination of gas turbine engine performance relies heavily on intrusive rakes of pilot tubes and thermocouples for gas path pressure and temperature measurement. For over forty years, Kiel-shrouds mounted on the rake body leading edge have been used as the industry standard to de-sensitise the instrument to variations in flow incidence and velocity. This results in a complex rake design which is expensive to manufacture, susceptible to mechanical damage, and difficult to repair.

This paper describes an exercise aimed at radically reducing rake manufacture and repair costs. A novel ’common cavity rake’ (CCR) design is presented where the pressure and/or temperature sensors are housed in a single slot let into the rake leading edge. Aerodynamic calibration data is included to show that the performance of the CCR design under uniform flow conditions and in an imposed total pressure gradient is equivalent to that of a conventional Kiel-shrouded rake.
The Effects of Engine Degradation on Creep - Using a Transient Engine Simulation
Authors: Little P. Darrin , Singh Riti
Published: February 2015

The aero-gas turbine has undergone significant development to improve the thrust to weight ratio. These developments have increased the engine’s capability to withstand elevated temperatures which corresponds to both improved performance and increases in hot section creep. In addition, as the engine’s condition degrades over time, the gas generator’s rotational speed, free body stresses, and the hot gas temperature are further increased. To maximize the potential safe life of an engine and reduce operating costs, understanding the effects of engine component degradations on component life is essential. This paper examines the effects of engine degradation on the failure mechanism of creep, and presents a method in which the metal temperatures can be tied to transient parameters. The use of transient parameters enables engine stresses and temperatures to be determined at any operating point, which is essential for military aircraft engines.
Quasi-Three-Dimensional and Three-Dimensional Flow Calculation in a Francis Turbine
Authors: Sallaberger Manfred J.
Published: February 2015

The complex three-dimensional flow in the wicket gate and the runner of a Francis turbine is investigated by applying both a quasi-three-dimensional and a three-dimensional computational method. The computations were conducted on a double grid containing the stationary wicket gate and the rotating runner. The equations for inviscid and incompressible flow are solved, assuming that the relative flow field in the runner is stationary. In the quasi-three-dimensional method the governing equations are solved on stream surfaces using a Finite-Element-Method. In the three-dimensional method, the equations of continuity and motion are solved by a Finite-Volume technique using Denton’s code for incompressible flow. Both methods are used in order to compute the flow in a Francis-runner of high specific speed at the operating point of optimum efficiency. The results of the calculations are compared with measurements taken at the draft-tube inlet. Differences between results of computations and measurements are presented.
Three-Dimensional Inverse Method for Turbomachinery Blading Design
Authors: Demeulenaere Alain , Van den Braembussche René
Published: February 2015

An iterative procedure for 3D blade design is presented. The three-dimensional blade shape is modified using a physical algorithm, based on the transpiration model. The transpiration flux is computed by means of a modified Euler solver, in which the target pressure distribution is imposed along the blade surfaces. Only a small number of modifications is needed to obtain the final geometry.

The method is based on a high resolution three-dimensional Euler solver. An upwind biased evaluation of the advective fluxes allows for a very low numerical entropy generation, and sharp shock capturing.

The method is first validated, by redesigning an existing geometry, starting from a different one. It is further used to redesign a transonic compressor blade, to achieve, for the same mass flow and outlet flow angle, a shock free deceleration along the suction side. The last example concerns the design of a low aspect ratio turbine blade, with a positive compound lean to reduce the intensity of the passage vortices. The final blade is designed for an optimized pressure distribution, taking into account the forces resulting from the blade lean angle.
The Generation of 3D, Stretched, Viscous Unstructured Meshes for Arbitrary Domains
Authors: Dawes W. N.
Published: February 2015

This paper presents a procedure which cao generate highly stretched, unstructured, viscous meshes for essentially arbitrary three dimensional configurations. The procedure is based on a combination of the ideas behind Delaunay and moving front methodologies. Examples are presented for a variety of turbomachinery types of flow to demonstrate the potency of the new approach. Recent enhancements to the author’s flow solver are also briefly described.