bluuebunny/crossref_metadata_2025_split huggingface dataset:
Applications of an Inviscid Q3D Linearized Flow Solver Towards the High Operating Line Flutter Region of a Transonic Fan
Authors: Börjesson Tomas J. , Fransson Torsten H. 
Published: December 2014

The capabilities of an inviscid quasi three-dimensional linearized unstructured flow solver to correctly predict the stall flutter limit, flutter modes and critical inter-blade phase angles on a transonic rotating shroudless fan model where experimental data exist have been investigated. Three operating points were chosen for investigation at 70% and 95% speed. At 70% speed two points were investigated: one close to the torsional flutter boundary (at the intermediate operating line) and one at the flutter boundary. The 95% speed point was at the flexural flutter boundary. Steady state and unsteady calculations were made at several stream sections per operating point. At each stream section unsteady calculations were performed over the entire range of inter-blade phase angles with different mode shapes (real mode, rigid torsion and rigid bending) at different frequencies. Thus the model was “provoked” with “unphysical” mode shapes and frequencies to be compared to the unsteady solution obtained with the mode shapes and frequencies observed from the experiments. Furthermore all unsteady calculations were made with different mesh densities and solutions from different “tuned” and “untuned” steady-state solutions.
The main conclusion of the validation of the inviscid Q3D Euler model on the Fan C Model Rotating Rig is that the model generally predicts flutter, flutter modes and the critical inter-blade phase angles to be close to the experimentally determined ones.
Identification of Mistuning Characteristics of Bladed Disks From Free Response Data
Authors: Mignolet Marc P. , Rivas-Guerra Alejandro 
Published: December 2014

The focus of the present investigation is on the estimation of the dynamic properties, i.e. masses, stiffnesses, natural frequencies, mode shapes and their statistical distributions, of turbomachine blades to be used in the accurate prediction of the forced response of mistuned bladed disks. As input to this process, it is assumed that the lowest natural frequencies of the blades alone have been experimentally measured, for example in a broach block test.
Since the number of measurements is always less than the number of unknowns, this problem is indeterminate in nature. Two distinct approaches will be investigated to resolve the shortfall of data. The first one relies on the imposition of as many constraints as needed to insure a unique solution to this identification problem. Specifically, the mode shapes and modal masses of the blades are set to their design/tuned counterparts while the modal stiffnesses are varied from blade-to-blade to match the measured natural frequencies. The second approach, based on the maximum likelihood principle, yields estimates of all the structural parameters of the blades through the minimization of a specified “cost function”. The accuracy of these two techniques in predicting the forced response of mistuned bladed disks will be assessed on simple dynamic models of the blades.
Modification and Redesign of GT Components
Authors: Basu Rahul D. 
Published: December 2014

Description: Stress analysis of a GT engine fan shaft was performed for IN718 and Ti. A FE package NISA gave stiffness for unit radial and tangential loads. Results obtained with IN718 were compared with an earlier study by SNECMA. An extension of the study for weight reduction was done with Ti material parameters. The design was adapted to simplify a spring bearing mount for the HP (#3) bearing.
A convoluted spring bearing mount suggested by SNECMA was redesigned using the results for the conical fan shaft to give a more gradual stress distribution. Such a structure would be less likely to yield in LCF and catastrophic failure modes. Comparison between computed results and tabulated results for conical shells was attempted.
Results depended on loading and point of application and mounting. For instance, the fan shaft was fixed on the main rotor and a force applied to the rim and vice versa. Variation in the number of nodes and order of approximation also affected the results. Regions of maximum stress were shown in contour plots, while displacement studies gave modes of deflection.
Multienergy CT acquisition and reconstruction with a stepped tube potential scan
Authors: Shen Le , Xing Yuxiang 
Published: December 2014

Purpose:Based on an energy‐dependent property of matter, one may obtain a pseudomonochromatic attenuation map, a material composition image, an electron‐density distribution, and an atomic number image using a dual‐ or multienergy computed tomography (CT) scan. Dual‐ and multienergy CT scans broaden the potential of x‐ray CT imaging. The development of such systems is very useful in both medical and industrial investigations. In this paper, the authors propose a new dual‐ and multienergy CT system design (segmental multienergy CT, SegMECT) using an innovative scanning scheme that is conveniently implemented on a conventional single‐energy CT system. The two‐step‐energy dual‐energy CT can be regarded as a special case of SegMECT. A special reconstruction method is proposed to support SegMECT.Methods:In their SegMECT, a circular trajectory in a CT scan is angularly divided into several arcs. The x‐ray source is set to a different tube voltage for each arc of the trajectory. Thus, the authors only need to make a few step changes to the x‐ray energy during the scan to complete a multienergy data acquisition. With such a data set, the image reconstruction might suffer from severe limited‐angle artifacts if using conventional reconstruction methods. To solve the problem, they present a new prior‐image‐based reconstruction technique using a total variance norm of a quotient image constraint. On the one hand, the prior extracts structural information from all of the projection data. On the other hand, the effect from a possibly imprecise intensity level of the prior can be mitigated by minimizing the total variance of a quotient image.Results:The authors present a new scheme for a SegMECT configuration and establish a reconstruction method for such a system. Both numerical simulation and a practical phantom experiment are conducted to validate the proposed reconstruction method and the effectiveness of the system design. The results demonstrate that the proposed SegMECT can provide both attenuation images and material decomposition images of reasonable image quality. Compared to existing methods, the new system configuration demonstrates advantages in simplicity of implementation, system cost, and dose control.Conclusions:This proposed SegMECT imaging approach has great potential for practical applications. It can be readily realized on a conventional CT system.
Markerless motion tracking of lung tumors using dual‐energy fluoroscopy
Authors: Patel Rakesh , Panfil Joshua , Campana Maria , Block Alec M. , Harkenrider Matthew M. , Surucu Murat , Roeske John C. 
Published: December 2014

Purpose:To evaluate the efficacy of dual‐energy (DE) vs single‐energy (SE) fluoroscopic imaging of lung tumors using a markerless template‐based tracking algorithm.Methods:Ten representative patient breathing patterns were programmed into a Quasar™ motion phantom. The phantom was modified by affixing pork ribs to the surface, and a cedar insert with a small spherical volume was used to simulate lung and tumor, respectively. Sequential 60 kVp (6 mA) and 120 kVp (1.5 mA) fluoroscopic sequences were acquired. Frame‐by‐frame weighted logarithmic subtraction was performed resulting in a DE fluoroscopic sequence. A template‐based algorithm was then used to track tumor motion throughout the DE and SE fluoroscopy sequences. Tracking coordinates were evaluated against ground‐truth tumor locations. Fluoroscopic images were also acquired for two lung cancer patients, neither of which had implanted fiducials.Results:For phantom imaging, a total of 1925 frames were analyzed. The algorithm successfully tracked the target on 99.9% (1923/1925) of DE frames vs 90.7% (1745/1925) SE images (p < 0.01). The displacement between tracking coordinates and ground truth for the phantom was 1.4 mm ± 1.1 mm for DE vs 2.0 mm ± 1.3 mm for SE (p < 0.01). Images from two patients, one with a larger tumor and one with a smaller tumor, were also analyzed. For the patient with the larger tumor, the average displacement from physician defined ground truth was 1.2 mm ± 0.6 mm for DE vs 1.4 mm ± 0.7 mm for SE (p = 0.016). For the patient that presented with a smaller tumor, the average displacement from physician defined ground truth was 2.2 mm ± 1.0 mm for DE vs 3.2 mm ± 1.4 mm for SE (p < 0.01). Importantly, for this single patient with the smaller tumor, 15.6% of the SE frames had >5 mm displacements from the ground truth vs 0% for DE fluoroscopy.Conclusions:This work indicates the potential for markerless tumor tracking utilizing DE fluoroscopy. With DE imaging, the algorithm showed improved detectability vs SE fluoroscopy and was able to accurately track the tumor in nearly all cases.
Pharmacokinetics and Pharmacodynamics of Multiple-Dose Intravenous Nemonoxacin in Healthy Chinese Volunteers
Authors: Wu Xiao-jie , Zhang Jing , Guo Bei-ning , Zhang Ying-yuan , Yu Ji-cheng , Cao Guo-ying , Chen Yuan-cheng , Zhu De-mei , Ye Xin-yu , Wu Ju-fang , Shi Yao-guo , Chang Li-wen , Chang Yu-ting , Tsai Cheng-yuan 
Published: December 2014

ABSTRACT

This study evaluated the safety and pharmacokinetic/pharmacodynamic profiles of nemonoxacin in healthy Chinese volunteers following multiple-dose intravenous infusion once daily for 10 consecutive days. The study was composed of two stages. In the open-label stage, 500 mg or 750 mg of nemonoxacin (
n =
12 each) was administered at an infusion rate of 5.56 mg/min. In the second stage, with a randomized double-blind placebo-controlled design, 500, 650, or 750 mg of nemonoxacin (
n =
16 in each cohort; 12 subjects received the drug and the other 4 subjects received the placebo) was given at an infusion rate of 4.17 mg/min. The results showed that, in the first stage, the maximal nemonoxacin concentrations (mean ± SD) at steady state (
C
max_ss
) were 9.60 ± 1.84 and 11.04 ± 2.18 μg/ml in the 500-mg and 750-mg cohorts, respectively; the areas under the concentration-time curve at steady state (AUC
0–24_ss
) were 44.03 ± 8.62 and 65.82 ± 10.78 μg · h/ml in the 500-mg and 750-mg cohorts, respectively. In the second stage, the nemonoxacin
C
max_ss
values were 7.13 ± 1.47, 8.17 ± 1.76, and 9.96 ± 2.23 μg/ml in the 500-mg, 650-mg, and 750-mg cohorts, respectively; the AUC
0–24_ss
values were 40.46 ± 9.52, 54.17 ± 12.10, and 71.34 ± 17.79 μg · h/ml in the 500-mg, 650-mg, and 750-mg cohorts, respectively. No accumulation was found after the 10-day infusion with any regimen. The drug was well tolerated. A Monte Carlo simulation indicated that the cumulative fraction of response of any dosing regimen was nearly 100% against
Streptococcus pneumoniae
. The probability of target attainment of nemonoxacin therapy was >98% when the MIC of nemonoxacin against
S. pneumoniae
was ≤1 mg/liter. It is suggested that all of the studied intravenous nemonoxacin dosing regimens should have favorable clinical and microbiological efficacies in future clinical studies. (This study has been registered at
ClinicalTrials.gov
under registration no. NCT01944774.)
Effects of the Global Regulator CsrA on the BarA/UvrY Two-Component Signaling System
Authors: Camacho Martha I. , Alvarez Adrian F. , Gonzalez Chavez Ricardo , Romeo Tony , Merino Enrique , Georgellis Dimitris 
Published: December 2014

ABSTRACT

The hybrid sensor kinase BarA and its cognate response regulator UvrY, members of the two-component signal transduction family, activate transcription of CsrB and CsrC noncoding RNAs. These two small RNAs act by sequestering the RNA binding protein CsrA, which posttranscriptionally regulates translation and/or stability of its target mRNAs. Here, we provide evidence that CsrA positively affects, although indirectly,
uvrY
expression, at both the transcriptional and translational levels. We also demonstrate that CsrA is required for properly switching BarA from its phosphatase to its kinase activity. Thus, the existence of a feedback loop mechanism that involves the Csr and BarA/UvrY global regulatory systems is exposed.
Physiology and Substrate Specificity of Two Closely Related Amino Acid Transporters, SerP1 and SerP2, of Lactococcus lactis
Authors: Noens Elke E. E. , Lolkema Juke S. 
Published: December 2014

ABSTRACT

The
serP1
and
serP2
genes found adjacently on the chromosome of
Lactococcus lactis
strains encode two members of the amino acid-polyamine-organocation (APC) superfamily of secondary transporters that share 61% sequence identity. SerP1 transports
l
-serine,
l
-threonine, and
l
-cysteine with high affinity. Affinity constants (

K
m

) are in the 20 to 40 μM range. SerP2 is a
dl
-alanine/
dl
-serine/glycine transporter. The preferred substrate appears to be
dl
-alanine for which the affinities were found to be 38 and 20 μM for the
d
and
l
isomers, respectively. The common substrate
l
-serine is a high-affinity substrate of SerP1 and a low-affinity substrate of SerP2 with affinity constants of 18 and 356 μM, respectively. Growth experiments demonstrate that SerP1 is the main
l
-serine transporter responsible for optimal growth in media containing free amino acids as the sole source of amino acids. SerP2 is able to replace SerP1 in this role only in medium lacking the high-affinity substrates
l
-alanine and glycine. SerP2 plays an adverse role for the cell by being solely responsible for the uptake of toxic
d
-serine. The main function of SerP2 is in cell wall biosynthesis through the uptake of
d
-alanine, an essential precursor in peptidoglycan synthesis. SerP2 has overlapping substrate specificity and shares 42% sequence identity with CycA of
Escherichia coli
, a transporter whose involvement in peptidoglycan synthesis is well established. No evidence was obtained for a role of SerP1 and SerP2 in the excretion of excess amino acids during growth of
L. lactis
on protein/peptide-rich media.
The efficacy and safety of different anticoagulants on patients with severe sepsis and derangement of coagulation: a protocol for network meta-analysis of randomised controlled trials
Authors: Jiang Libing , Jiang Shouyin , Feng Xia , Ma Yuefeng , Zhang Mao 
Published: December 2014

IntroductionSepsis is the leading cause of mortality in non-cardiological critically ill patients. There are as many as 20 million cases of sepsis annually worldwide, with a mortality rate of around 35%. It has been reported that the dysregulation of haemostatic system due to the interaction between coagulation system and inflammatory response is a strong predictor of mortality in patients with severe sepsis. In this context, several anticoagulants have been evaluated in recent years. However, the results of these studies were inconsistent and even contradictory. In addition, there is insufficient evidence comparing the efficacy and safety of different anticoagulants. The purpose of our study is to carry out a systematic review and network meta-analysis comparing the efficacy and safety of different anticoagulants for severe sepsis based on existing randomised controlled trials (RCTs) and ranking these anticoagulants for practical consideration.Methods and analysisPubMed, EMBASE and Cochrane Library databases will be systematically searched for eligible studies. Randomised controlled trials (RCT) on anticoagulant therapy for severe sepsis with multiple outcome measures will be included. The Cochrane Risk of Bias Tool will be used to assess the quality of included studies. The primary outcomes are mortality and bleeding events. The secondary outcomes include the length of intensive care stay, the length of hospital stay and duration of mechanical ventilation. Direct pairwise meta-analysis (DMA), indirect treatment comparison meta-analysis (ITC) and network meta-analysis (NMA) will be conducted to compare different anticoagulants.Ethics and disseminationEthical approval is not required given that this is a protocol for a systematic review. The protocol of this systematic review will be disseminated in a peer-reviewed journal and presented at a relevant conference.Trial registration numberThis protocol has been registered in PROSPERO (http://www.crd.york.ac.uk/PROSPERO/) under registration number CRD42014013886.
Integromic Analysis of Genetic Variation and Gene Expression Identifies Networks for Cardiovascular Disease Phenotypes
Authors: Yao Chen , Chen Brian H. , Joehanes Roby , Otlu Burcak , Zhang Xiaoling , Liu Chunyu , Huan Tianxiao , Tastan Oznur , Cupples L. Adrienne , Meigs James B. , Fox Caroline S. , Freedman Jane E. , Courchesne Paul , O’Donnell Christopher J. , Munson Peter J. , Keles Sunduz , Levy Daniel 
Published: December 2014

Background—
Cardiovascular disease (CVD) reflects a highly coordinated complex of traits. Although genome-wide association studies have reported numerous single nucleotide polymorphisms (SNPs) to be associated with CVD, the role of most of these variants in disease processes remains unknown.

Methods and Results—

We built a CVD network using 1512 SNPs associated with 21 CVD traits in genome-wide association studies (at
P
≤5×10
−8
) and cross-linked different traits by virtue of their shared SNP associations. We then explored whole blood gene expression in relation to these SNPs in 5257 participants in the Framingham Heart Study. At a false discovery rate <0.05, we identified 370
cis
–expression quantitative trait loci (eQTLs; SNPs associated with altered expression of nearby genes) and 44
trans
-eQTLs (SNPs associated with altered expression of remote genes). The eQTL network revealed 13 CVD-related modules. Searching for association of eQTL genes with CVD risk factors (lipids, blood pressure, fasting blood glucose, and body mass index) in the same individuals, we found examples in which the expression of eQTL genes was significantly associated with these CVD phenotypes. In addition, mediation tests suggested that a subset of SNPs previously associated with CVD phenotypes in genome-wide association studies may exert their function by altering expression of eQTL genes (eg,
LDLR
and
PCSK7
), which in turn may promote interindividual variation in phenotypes.

Conclusions—
Using a network approach to analyze CVD traits, we identified complex networks of SNP-phenotype and SNP-transcript connections. Integrating the CVD network with phenotypic data, we identified biological pathways that may provide insights into potential drug targets for treatment or prevention of CVD.
A Systematic Relationship between the Representations of Convectively Coupled Equatorial Wave Activity and the Madden–Julian Oscillation in Climate Model Simulations
Authors: Guo Yanjuan , Waliser Duane E. , Jiang Xianan 
Published: December 2014

Abstract
The relationship between a model’s performance in simulating the Madden–Julian oscillation (MJO) and convectively coupled equatorial wave (CCEW) activity during wintertime is examined by analyzing precipitation from 26 general circulation models (GCMs) participating in the MJO Task Force/Global Energy and Water Cycle Experiment (GEWEX) Atmospheric System Study (GASS) MJO model intercomparison project as well as observations based on the Tropical Rainfall Measuring Mission (TRMM). A model’s performance in simulating the MJO is determined by how faithfully it reproduces the eastward propagation of the large-scale intraseasonal variability (ISV) compared to TRMM observations. Results suggest that models that simulate a better MJO tend to 1) have higher fractional variances for various high-frequency wave modes (Kelvin, mixed Rossby–gravity, and westward and eastward inertio-gravity waves), which are defined by the ratios of wave variances of specific wave modes to the “total” variance, and 2) exhibit stronger CCEW variances in association with the eastward-propagating ISV precipitation anomalies for these high-frequency wave modes. The former result is illustrative of an alleviation in the good MJO models of the widely reported GCM deficiency in simulating the correct distribution of variance in tropical convection [i.e., typically too weak (strong) variance in the high- (low-) frequency spectrum of the precipitation]. The latter suggests better coherence and stronger interactions between these aforementioned high-frequency CCEWs and the ISV envelope in good MJO models. Both factors likely contribute to the improved simulation of the MJO in a GCM.
Markers of endothelial function in migraine patients: Results from a bi-center prospective study
Authors: Fischer Marlene , Gaul Charly , Shanib Hind , Holle Dagny , Loacker Lorin , Griesmacher Andrea , Lackner Peter , Broessner Gregor 
Published: December 2014

Background Numerous studies suggest an increased vascular risk in patients with migraine, in particular in those with aura. A possible link between both conditions might be a dysfunction of the vascular endothelium. This observational study analyzed the endothelial markers angiopoietin-1, angiopoietin-2, Tie-2, sFlt-1 and NT-proBNP for the first time in migraineurs, patients with other primary headache disorders and healthy controls. Methods Patients with episodic migraine with and without aura, episodic cluster headache, tension-type headache and healthy controls were included. Blood samples were obtained during migraine attacks and headache-free periods in migraineurs, in and out of bout in cluster headache and during headache-free periods in tension-type headache and healthy individuals to analyze markers of endothelial function. Results No significant difference in endothelial markers between migraine, other headache disorders and healthy controls was detected. There was no significant difference between migraine attacks and headache-free intervals. Additionally, no distinction could be found between migraine with and without aura. Discussion The endothelial markers analyzed do not display a characteristic pattern in different headache disorders especially migraine compared to healthy controls. The novel findings of our study indicate that factors other than endothelial dysfunction seem to be responsible for the at least statistical association of migraine with vascular disease.
A systematic review of the incidence and prevalence of cardiac, cerebrovascular, and peripheral vascular disease in multiple sclerosis
Authors: Marrie Ruth Ann , Reider Nadia , Cohen Jeffrey , Stuve Olaf , Trojano Maria , Cutter Gary , Reingold Stephen , Sorensen Per Soelberg 
Published: December 2014

Background: Findings regarding the prevalence of vascular comorbidities in multiple sclerosis (MS) are conflicting. Objective: The objective of this review is to estimate the incidence and prevalence of vascular comorbidities and predisposing comorbidities in persons with MS and to assess the quality of the included studies. Methods: The PubMed, EMBASE, SCOPUS and Web of Knowledge databases, conference proceedings, and reference lists of retrieved articles were searched. One reviewer abstracted data using a standardized data collection form, while the second reviewer verified the abstraction. Included studies were assessed qualitatively. Quantitatively, we assessed studies using the I2 statistic, and conducted meta-analyses for population-based studies only. Results: The prevalence of hypertension and hyperlipidemia exceeded 10% in the MS population and increased with age. While the prevalence of ischemic heart disease, congestive heart failure, and stroke were less than 5% overall, the prevalence of these conditions exceeded expectations when compared to the general population. Cardiac valvular disease, however, affected the MS population less often than expected. Problems with study quality were common. Conclusion: Despite the relatively high prevalence of some vascular comorbidities in the MS population, important gaps exist in our understanding of their epidemiology. Most of our knowledge is based on studies conducted in a small number of regions.