bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantitative Study on Equivalent Roughness Conversion Coefficient and Roughness Effect of Centrifugal Compressor
Authors: Tang Yonghong , Xi Guang , Wang Zhiheng , Tian Yubao 
Published: September 2019

Abstract
Applying an appropriate roughness model is one of the most effective ways to improve the accuracy of the numerical simulation for centrifugal compressors, and it is also the key to the study of surface deterioration such as compressor fouling and corrosion. The basis for using the roughness model is to determine the conversion relation between physical roughness and equivalent roughness. In this paper, numerical and experimental studies on the roughness conversion relation for the centrifugal compressors were performed by means of a unique self-developed “pseudo front stage (PFS)” device. An equivalent roughness conversion coefficient of 8.5 was determined on the basis of fitting performance of the U-bend and return channel model. The validity of the conversion coefficient in improving the performance prediction accuracy of the centrifugal compressors was verified by three centrifugal compressor models. The concept of weighted average roughness was proposed to quantify the roughness sensitivity and roughness level of the centrifugal compressor. Quantitative research on the roughness effect of centrifugal compressors indicated that the peak efficiency degradation due to the roughness effect in the compressors was linearly associated with the logarithm of the relative roughness when the impeller of the centrifugal compressor was in the hydraulically rough regime. Doubling or halving the roughness value of all components of a centrifugal compressor in the hydraulically rough flow regime will result in a change in the peak efficiency of the compressor by about 1.72%.
Advanced Natural Circulation Reduced-Order Model With Inclined Channel for Low Pressure Conditions
Authors: Manthey René , Knospe Alexander , Lange Carsten , Schuster Christoph , Hurtado Antonio 
Published: September 2019

Abstract
Natural circulation with two-phase flow is a nonlinear dynamical systems, which can show a very complex and strange behavior under specific conditions. The application of stability analysis requires a large computational effort and is cumbersome in case of prediction the dynamical behavior by system codes alone. Therefore, model-order reduction techniques are used to compensate this disadvantage by coupling with a bifurcation code such as MatCont. A reduced-order model is derived by employing the proper orthogonal decomposition (POD) to analyze the stability landscape of a low pressure natural circulation system representing passive safety systems such as the containment cooling condenser. The required full-order model contains a classical natural circulation loop with a heated section and a riser. The two-phase region is modeled by a drift–flux mixture model. The reliability of the full-order model is investigated by comparison with a reference model by the validated system code ATHLET.
A Coupled Overset Mesh and Hybridizable Discontinuous Galerkin Algorithm for Pseudo-Compressible Flow
Authors: Kauffman Justin A. , Pitt Jonathan S. 
Published: September 2019

Abstract
A previously presented overset mesh enabled hybridizable discontinuous Galerkin (HDG) finite element method is extended in this work to an isentropic compressible (pseudo-compressible) fluid. This formulation is a first-principles approach and is complementary to the augmented Lagrangian approach that was utilized in the previous HDG incompressible Navier–Stokes formulations which eliminate the global pressure field. This is the first original presentation combining overset meshes, HDG, and fluid flow, specifically isentropic flow for low Mach number applications. Verification of the code implementation of the proposed overset-HDG formulation is performed via the method of manufactured solutions (MMS) on a successively refined overset mesh configuration containing five meshes, and for order k=1,…,4, Lagrange polynomial elements in both two and three dimensions. Optimal order convergence, k + 1, can be observed in all fields for both the two- and three-dimensional simulations, for each mesh. A two-dimensional benchmark problem is also presented to enable code-to-code comparison as a preliminary validation exercise.
Verification of Stress-Intensity Factor Solutions by Uncertainty Quantification
Authors: Sobotka James C. , Craig McClung R. 
Published: September 2019

AbstractThis paper summarizes an emerging process to establish credibility for surrogate models that cover multidimensional, continuous solution spaces. Various features lead to disagreement between the surrogate model's results and results from more precise computational benchmark solutions. In our verification process, this disagreement is quantified using descriptive statistics to support uncertainty quantification, sensitivity analysis, and surrogate model assessments. Our focus is stress-intensity factor (SIF) solutions. SIFs can be evaluated from simulations (e.g., finite element analyses), but these simulations require significant preprocessing, computational resources, and expertise to produce a credible result. It is not tractable (or necessary) to simulate a SIF for every crack front. Instead, most engineering analyses of fatigue crack growth (FCG) employ surrogate SIF solutions based on some combination of mechanics, interpolation, and SIF solutions extracted from earlier analyses. SIF values from surrogate solutions vary with local stress profiles and nondimensional degrees-of-freedom that define the geometry. The verification process evaluates the selected stress profiles and the sampled geometries using the surrogate model and a benchmark code (abaqus). The benchmark code employs a Python scripting interface to automate model development, execution, and extraction of key results. The ratio of the test code SIF to the benchmark code SIF measures the credibility of the solution. Descriptive statistics of these ratios provide convenient measures of relative surrogate quality. Thousands of analyses support visualization of the surrogate model's credibility, e.g., by rank-ordering of the credibility measure.
Lagrangian Analysis of Flame Dynamics in the Flow Field of a Bluff Body-Stabilized Combustor
Authors: Premchand C. P. , George Nitin B. , Raghunathan Manikandan , Unni Vishnu R. , Sujith R. I. , Nair Vineeth 
Published: September 2019

Abstract
Experiments are performed in a partially premixed bluff body-stabilized turbulent combustor by varying the mean flow velocity. Simultaneous measurements obtained for unsteady pressure, velocity, and heat release rate are used to investigate the dynamic regimes of intermittency (10.1 m/s) and thermoacoustic instability (12.3 m/s). Using wavelet analysis, we show that during intermittency, modulation of heat release rate occurring at the acoustic frequency fa by the heat release rate occurring at the hydrodynamic frequency fh results in epochs of heat release rate fluctuations where the heat release rate is phase locked with the acoustic pressure. We also show that the flame position during intermittency and thermoacoustic instability are essentially dictated by saddle point dynamics in the dump plane and the leading edge of the bluff body.
Vulnerable Locations on the Head to Brain Injury and Implications for Helmet Design
Authors: Fanton Michael , Sganga Jake , Camarillo David B. 
Published: September 2019

Abstract
In studying traumatic brain injury (TBI), it has been long hypothesized that the head is more vulnerable to injury from impacts in certain directions or locations, as the relationship between impact force and the resulting neurological outcome is complex and can vary significantly between individual cases. Many studies have identified head angular acceleration to be the putative cause of brain trauma, but it is not well understood how impact location can affect the resulting head kinematics and tissue strain. Here, we identify the susceptibility of the head to accelerations and brain strain from normal forces at contact points across the surface of the skull and jaw using a three-dimensional, 20-degree-of-freedom rigid-body head and cervical spine model. We find that head angular acceleration and brain tissue strain resulting from an input force can vary by orders of magnitude based on impact location on the skull, with the mandible as the most vulnerable region. Conversely, head linear acceleration is not sensitive to contact location. Using these analyses, we present an optimization scheme to distribute helmet padding thickness to minimize angular acceleration, resulting in a reduction of angular acceleration by an estimated 25% at the most vulnerable contact point compared to uniform thickness padding. This work gives intuition behind the relationship between input force and resulting brain injury risk, and presents a framework for developing and evaluating novel head protection gear.
Injuries in elite women’s ski jumping: surveillance through the 2017–18 FIS World Cup season
Authors: Stenseth Oleane Marthea Rebne , Barli Sindre Fløtlien , Martin Richard Kyle , Engebretsen Lars 
Published: September 2019

ObjectivesTo describe the incidence, type, aetiology and severity of injuries sustained by the International Ski Federation World Cup level female ski jumpers during the 2017–18 season.DesignProspective cohort study.MethodsSixty-seven female ski jump athletes from 16 countries were followed throughout the 17-week winter season. Preseason baseline demographic data and injury history were recorded via questionnaire. Prospective biweekly reports and retrospective end-of-season interviews provided data on all injuries requiring medical attention.ResultsSeventeen injuries were recorded, corresponding to an incidence of 25.4 injuries/100 athletes/season. The incidence of time-loss and severe injuries were found to be 17.9 and 4.5, respectively. The knee was the most common site of injury (4/17; 23.5%). Fourteen injuries occurred on the ski jump hill and crash-landing was the most common mechanism of injury (10/14; 71%). Eighty-five per cent of all moderate and severe injuries occurred in snow or windy conditions. Length of jumps resulting in injury averaged 83.7% (95% CI 72.9% to 94.4%) of hill size. Moderate injuries causing 8–28 days absence from training activities were most common (7/17; 41%) and there were three severe injuries necessitating >4 weeks absence.ConclusionInjuries among elite female ski jumpers are common and the majority are acute, resulting in time loss from training and competition. The knee was the most common site of injury and poor weather conditions may be a risk factor. Future studies are needed to identify risk factors for injury and to guide injury prevention initiatives.
Midbrain MRI assessments in progressive supranuclear palsy subtypes
Authors: Picillo Marina , Tepedino Maria Francesca , Abate Filomena , Erro Roberto , Ponticorvo Sara , Tartaglione Salvatore , Volpe Giampiero , Frosini Daniela , Cecchi Paolo , Cosottini Mirco , Ceravolo Roberto , Esposito Fabrizio , Pellecchia Maria Teresa , Barone Paolo , Manara Renzo 
Published: September 2019

ObjectivesTo explore the role of the available midbrain-based MRI morphometric assessments in (1) differentiating among progressive supranuclear palsy (PSP) subtypes (PSP Richardson’s syndrome (PSP-RS), PSP with predominant parkinsonism (PSP-P) and the other variant syndromes of PSP (vPSP)), and (2) supporting the diagnosis of PSP subtypes compared with Parkinson’s disease (PD) and healthy controls (HC).MethodsSeventy-eight patients with PSP (38 PSP-RS, 21 PSP-P and 19 vPSP), 35 PD and 38 HC were included in the present analysis. Available midbrain-based MRI morphometric assessments were calculated for all participants.ResultsCurrent MRI midbrain-based assessments do not display an adequate sensitivity and specificity profile in differentiating PSP subtypes. On the other hand, we confirmed MR Parkinsonism Index (MRPI) and pons area to midbrain area ratio (P/M) have adequate diagnostic value to support PSP-RS clinical diagnosis compared with both PD and HC, but low sensitivity and specificity profile in differentiating PSP-P from PD as well as from HC. The same measures show acceptable sensitivity and specificity profile in supporting clinical diagnosis of vPSP versus HC but not versus PD. Similar findings were detected for the newer MRPI and P/M versions.ConclusionsFurther studies are warranted to identify neuroimaging biomarkers supporting the clinical phenotypic categorisation of patients with PSP. MRPI and P/M have diagnostic value in supporting the clinical diagnosis of PSP-RS.Classification of evidenceThis study provides class III evidence that available MRI midbrain-based assessments do not have diagnostic value in differentiating the Movement Disorder Society PSP subtypes.
A semi-analytical model of heat transfer and pressure drop in annular flow regime for flow boiling in a horizontal microtube at uniform heat flux
Authors: Younes Amen , Hassan Ibrahim , Kadem Lyes 
Published: September 2019

A semi-analytical model for predicting heat transfer and pressure drop in annular flow regime for saturated flow boiling in a horizontal microtube at a uniform heat flux has been developed based on a one-dimensional separated flow model. More than 600 two-phase heat transfer, 498 two-phase pressure drop, and 153 void fraction experimental data points for annular flow regime were collected from the literature to validate the present model. The collected data were recorded for various working fluids, R134a, R1234ze, R236fa, R410a, R113, and CO2, for round macro- and microsingle horizontal tubes with an inner diameter range of 0.244 mm ≤ Dh ≤ 3.1 mm, a heated length to diameter ratio of 90 ≤ Lh/Dh ≤ 2000, a saturation temperature range of –10 ≤ Tsat ≤ +50 °C, and liquid to vapor density ratios in the range 6.4 ≤ ρf/ρg ≤ 188. The model was tested for laminar and turbulent flow boiling conditions corresponding to an equivalent Reynolds number, 1900 ≤ Reeq ≤ 48 000, and confinement number, 0.27 ≤ Cconf ≤ 3.4. Under the annular flow regime, the present model predicted the collected data of the heat transfer, pressure drop, and void fraction with mean absolute errors (MAE) of 18.14%, 23.02%, and 3.22%, respectively.
Strong cosmic censorship under quasinormal modes of non-minimally coupled massive scalar field
Authors: Gwak Bogeun 
Published: September 2019

Abstract
We investigate the strong cosmic censorship conjecture in lukewarm Reissner–Nordström–de Sitter black holes (and Martínez–Troncoso–Zanelli black holes) using the quasinormal resonance of non-minimally coupled massive scalar field. The strong cosmic censorship conjecture is closely related to the stability of the Cauchy horizon governed by the decay rate of the dominant quasinormal mode. Here, dominant modes are obtained in the limits of small and large mass black holes. Then, we connect the modes by using the WKB approximation. In our analysis, the strong cosmic censorship conjecture is valid except in the range of the small-mass limit, in which the dominant mode can be assumed to be that of the de Sitter spacetime. Particularly, the coupling constant and mass of the scalar field determine the decay rate in the small mass range. Therefore, the validity of the strong cosmic censorship conjecture depends on the characteristics of the scalar field.
Synthesis of Nb-doped TiO2films on rigid and flexible substrates at low temperature
Authors: Safeen Kashif , Micheli V. , Bartali R. , Gottardi G. , Safeen Akif , Ullah Hafeez , Laidani N. 
Published: September 2019

In this work, an attempt has been made to compare the physical properties of conductive films of Nb-doped TiO2deposited on Kapton polyimide, glass and silicon substrates. Thin films were deposited by radio frequency sputtering at room temperature and subsequently characterized using X-ray diffraction, X-ray photoelectron spectroscopy, UV-VIS-NIR spectroscopy and Hall Effect measurement. Structurally, the films grown on the flexible substrate exhibit more strain and had inferior crystallinity (crystallite size [Formula: see text]13.8 nm) compared to the films deposited on glass and silicon substrates (crystallite size [Formula: see text]27 nm). The film on glass had a resistivity value around [Formula: see text] while the resistivity of the films grown on polyimide was found about five-fold higher. Furthermore, the films deposited on glass substrate showed optical transparency of [Formula: see text]80% in the visible range (400–750 nm). The inferior electrical transport properties of the films grown on polyimide were correlated with the poor crystallinity and cracks induced during the annealing process. Furthermore, various possible routes have been discussed to improve crystallinity and control cracks in the films.
Measured with Sperm Chromatin Dispersion (SCD) Technique: Will DNA Integrity in Spermatozoa Increase After Micronutrient Supplementation? Comparative Controlled Study
Authors: Eidenberger Fiona , Huber Kim-Lien , Fuchs Patricia , Simkovicova Nikola , Imhof Martin 
Published: September 2019

Background: An elevated DNA Fragmentation Index (DFI) has been associated with male infertility; therefore measuring the sperm nuclear DNA integrity appears to be useful in predicting the ability of spermatozoa to fertilize oocytes.Aim: To evaluate the effect of micronutrient supplementation over DFI values in subfertile men.Methods: This was a retrospective/comparative study that included a total of 306 subfertile males consulting the clinic from March 2011 to November 2017, who had performed the Sperm Chromatin Dispersion test (SCD) — a method used to detect DNA fragmentation — along with the initial semen analysis. Of the included population, [Formula: see text] 146 had received two daily oral capsules of a standardized combined micronutrient compound ([Formula: see text], Lenus Pharma, Vienna, Austria) for three months plus lifestyle change (study group). Each capsule contains L-carnitine, L-arginine, coenzyme Q10, zinc, vitamin E, folic acid, glutathione and selenium. Those who did not receive the active treatment ([Formula: see text] 160) but only engaged with lifestyle changes were considered controls. The SCD test was performed in both groups at baseline and after 3 months.Results: For the first statistical analysis, patients with an initial mean DFI of >15% were considered ([Formula: see text] 66 [37 were study and 29 were controls]). After 3 months, both groups displayed a significant decrease of mean DFI values. However, this decrease was more evident in the study group as compared to controls (10.54% vs. 14.48%, [Formula: see text] 0.05; [Formula: see text] 0.013). For the second statistical approach the entire population was considered ([Formula: see text] 306). After 3 months, only the study group displayed a significant decrease of the mean initial DFI value (10.16% to 6.49%, [Formula: see text] < 0.0001); decrease that was more evident as compared to controls (6.49% vs. 8.82%, [Formula: see text] 0.05; [Formula: see text] 0.000020).Conclusions: Among subfertile men with a DFI >15%, both regimes significantly decreased sperm DNA fragmentation; however, when any baseline DFI value was considered, only treatment with the active standardized micronutrient compound achieved a significant better result.
Ushering in Liquid Biopsy for the Microsatellite Status: Advantages and Caveats
Authors: Wang Linghua , Ajani Jaffer A. 
Published: September 2019

AbstractMicrosatellite instable tumors often respond to immune checkpoint blockade (ICB), however, tumor tissue is unavailable/insufficient in some patients. Two groups are reporting a blood-based assessment of the microsatellite status validated in tumor tissue and by clinical benefit in patient receiving ICB. Both approaches are highly appealing with a few caveats.See related articles by Georgiadis et al., p. 7024, and Willis et al., p. 7035
Distinct Transcriptional Programming Drive Response to MAPK Inhibition in BRAFV600-Mutant Melanoma Patient-Derived Xenografts
Authors: Feng Tianshu , Golji Javad , Li Ailing , Zhang Xiamei , Ruddy David A. , Rakiec Daniel P. , Geyer Felipe C. , Gu Jane , Gao Hui , Williams Juliet A. , Stuart Darrin D. , Meyer Matthew J. 
Published: September 2019

Abstract
Inhibitors targeting BRAF and its downstream kinase MEK produce robust response in patients with advanced BRAFV600-mutant melanoma. However, the duration and depth of response vary significantly between patients; therefore, predicting response a priori remains a significant challenge. Here, we utilized the Novartis collection of patient-derived xenografts to characterize transcriptional alterations elicited by BRAF and MEK inhibitors in vivo, in an effort to identify mechanisms governing differential response to MAPK inhibition. We show that the expression of an MITF-high, “epithelial-like” transcriptional program is associated with reduced sensitivity and adaptive response to BRAF and MEK inhibitor treatment. On the other hand, xenograft models that express an MAPK-driven “mesenchymal-like” transcriptional program are preferentially sensitive to MAPK inhibition. These gene-expression programs are somewhat similar to the MITF-high and -low phenotypes described in cancer cell lines, but demonstrate an inverse relationship with drug response. This suggests a discrepancy between in vitro and in vivo experimental systems that warrants future investigations. Finally, BRAFV600-mutant melanoma relies on either MAPK or alternative pathways for survival under BRAF and MEK inhibition in vivo, which in turn predicts their response to further pathway suppression using a combination of BRAF, MEK, and ERK inhibitors. Our findings highlight the intertumor heterogeneity in BRAFV600-mutant melanoma, and the need for precision medicine strategies to target this aggressive cancer.
Ketotifen Modulates Mast Cell Chemotaxis to Kit-Ligand, but Does Not Impact Mast Cell Numbers, Degranulation, or Tumor Behavior in Neurofibromas of Nf1-Deficient Mice
Authors: Burks Ciersten A. , Rhodes Steven D. , Bessler Waylan K. , Chen Shi , Smith Abbi , Gehlhausen Jeffrey R. , Hawley Eric T. , Jiang Li , Li Xiaohong , Yuan Jin , Lu Qingbo , Jacobsen Max , Sandusky George E. , Jones David R. , Clapp D. Wade , Blakeley Jaishri O. 
Published: September 2019

Abstract
Neurofibromatosis Type 1 (NF1) is one of the most common genetic tumor predisposition syndromes in humans. Mutant NF1 results in dysregulated RAS allowing neoplasms throughout the neuroaxis. Plexiform neurofibromas (pNF) afflict up to 50% of patients with NF1. They are complex tumors of the peripheral nerve that cause major morbidity via nerve dysregulation and mortality via conversion to malignant sarcoma. Genetically engineered mouse models (GEMM) of NF1 provide valuable insights for the identification of therapies that have utility in people with pNF. Preclinical studies in GEMMs implicate mast cells and the c-Kit/Kit ligand pathway in pNF tumorigenesis. Kit ligand is a potent chemokine secreted by tumorigenic, Nf1-deficient Schwann cells. Ketotifen is an FDA-approved drug for the treatment of allergic conjunctivitis and asthma that promotes mast cell stabilization and has been used in prior case studies to treat or prevent pNFs. This study investigated the effect of ketotifen on mast cell infiltration and degranulation in the presence and absence of Kit ligand provocation and the effect of ketotifen on shrinking or preventing pNF formation in the Nf1flox/flox;PostnCre+ GEMM. Ketotifen decreased mast cell infiltration in response to exogenous Kit ligand administration, but did not affect mast cell degranulation. Importantly, ketotifen did not reduce mast cells numbers or activity in pNF and did not prevent pNF formation or decrease the volume of established pNF despite administration of pharmacologically active doses. These findings suggest that ketotifen has limited use as monotherapy to prevent or reduce pNF burden in the setting of Nf1 mutations.