bluuebunny/crossref_metadata_2025 huggingface dataset:
Prediction of Turbulent Flow Over a Flat Plate With a Step Change From a Smooth to a Rough Surface Using a Near-Wall RANS Model
Authors: Chu Minghan , Bergstrom Donald J.
Published: September 2019

The present paper reports a numerical study of fully developed turbulent flow over a flat plate with a step change from a smooth to a rough surface. The Reynolds number based on momentum thickness for the smooth flow was Reθ=5950. The focus of the study was to investigate the capability of the Reynolds-averaged Navier–Stokes (RANS) equations to predict the internal boundary layer (IBL) created by the flow configuration. The numerical solution used a two-layer k−ε model to implement the effects of surface roughness on the turbulence and mean flow fields via the use of a hydrodynamic roughness length y0. The prediction for the mean velocity field revealed a development zone immediately downstream of the step in which the mean velocity profile included a lower region affected by the surface roughness below and an upper region with the characteristics of the smooth-wall boundary layer above. In this zone, both the turbulence kinetic energy and Reynolds shear stress profiles were characterized by a significant reduction in magnitude in the outer region of the flow that is unaffected by the rough surface. The turbulence kinetic energy profile was used to estimate the thickness of the IBL, and the resulting growth rate closely matched the experimental results. As such, the IBL is a promising test case for assessing the ability of RANS models to predict the discrete roughness configurations often encountered in industrial and environmental applications.
Temperature Fields Generated by a Circular Heat Source: Solution of a Composite Solid of Two Different Isotropic Semi-Infinite Media
Authors: Emanuel Michael , Emanuel Avi
Published: September 2019

The problem of a three-dimensional (3D) heat flow from a circular heat source (CHS) embedded inside a composite solid of two isotropic but different semi-infinite media is solved for the first time in this paper. This CHS asymmetrical measurement setup is useful when two identical samples are not available for measurement. Two different time-dependent temperature fields are derived for the composite semi-infinite media, as well as their corresponding heat fluxes. The derivation of the 3D solution uses first principles with basic assumptions and employs the Hankel and Laplace transforms. The Laplace inversion theorem is used to find the inverse Laplace transform of the temperature functions, since no tabulated inverse transform functions are available for this case. The solution is exact with no approximations and is given in an integral form, which can easily be evaluated numerically. This solution is a generic one and can be applied to more complex asymmetrical setups, such as the case involving thermal contact resistances.
Effects of Streamlining a Bluff Body in the Laminar Vortex Shedding Regime
Authors: Dobriyal Ritvik , Mishra Maneesh , Bölander Markus , Skote Martin
Published: September 2019

Two-dimensional flow over bluff bodies is studied in the unsteady laminar flow regime using numerical simulations. In previous investigations, lift and drag forces have been studied over different cross-sectional shapes like circles, squares, and ellipses. We aim to extend the previous research by studying the variation of hydrodynamic forces as the shape of the body changes from a circular cylinder to a more streamlined or a bluffer body. The different body shapes are created by modifying the downstream circular arc of a circular cylinder into an ellipse, hence elongating or compressing the rear part of the body. The precise geometry of the body is quantified by defining a shape factor. Two distinct ranges of shape factors with fundamentally different behavior of lift and drag are identified. The geometry constituting the limit is where the rear part ellipse has a semi-minor axis of half the radius of the original circle, independent of the Reynolds number. On the other hand, the vortex shedding frequency decreases linearly over the whole range of shape factors. Furthermore, the variation of the forces and frequency with Reynolds number, and how the relations vary with the shape factor are reported.
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

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

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

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

This 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

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

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.
Prophylaxis of Mycobacterium tuberculosis H37Rv Infection in a Preclinical Mouse Model via Inhalation of Nebulized Bacteriophage D29
Authors: Carrigy Nicholas B. , Larsen Sasha E. , Reese Valerie , Pecor Tiffany , Harrison Melissa , Kuehl Philip J. , Hatfull Graham F. , Sauvageau Dominic , Baldwin Susan L. , Finlay Warren H. , Coler Rhea N. , Vehring Reinhard
Published: September 2019

Globally, more people die annually from tuberculosis than from any other single infectious agent. Unfortunately, there is no commercially available vaccine that is sufficiently effective at preventing the acquisition of pulmonary tuberculosis in adults. In this study, preexposure prophylactic pulmonary delivery of active aerosolized antituberculosis bacteriophage D29 was evaluated as an option for protection against
Mycobacterium tuberculosis
infection.
Phenotypic, Biochemical, and Genetic Analysis of KPC-41, a KPC-3 Variant Conferring Resistance to Ceftazidime-Avibactam and Exhibiting Reduced Carbapenemase Activity
Authors: Mueller Linda , Masseron Amandine , Prod’Hom Guy , Galperine Tatiana , Greub Gilbert , Poirel Laurent , Nordmann Patrice
Published: September 2019

A novel KPC variant, KPC-41, was identified in a
Klebsiella pneumoniae
clinical isolate from Switzerland. This β-lactamase possessed a 3-amino-acid insertion (Pro-Asn-Lys) located between amino acids 269 and 270 compared to the KPC-3 amino acid sequence.
Entamoeba histolytica Interaction with Enteropathogenic Escherichia coli Increases Parasite Virulence and Inflammation in Amebiasis
Authors: Fernández-López Luz A. , Gil-Becerril Karla , Galindo-Gómez Silvia , Estrada-García Teresa , Ximénez Cecilia , Leon-Coria Aralia , Moreau France , Chadee Kris , Tsutsumi Víctor
Published: September 2019

Epidemiological studies suggest frequent association of enteropathogenic bacteria withEntamoeba histolyticaduring symptomatic infection. In this study, we sought to determine if the interaction with enteropathogenic (EPEC) or nonpathogenicEscherichia coli(strain DH5α) could modify the virulence ofE. histolyticato cause disease in animal models of amebiasis.In vitrostudies showed a 2-fold increase in CaCo2 monolayer destruction whenE. histolyticainteracted with EPEC but not withE. coliDH5α for 2.5 h.
Effect of Clinically Meaningful Antibiotic Concentrations on Recovery of Escherichia coli and Klebsiella pneumoniae Isolates from Anaerobic Blood Culture Bottles with and without Antibiotic Binding Resins
Authors: Chen Iris H. , Nicolau David P. , Kuti Joseph L.
Published: September 2019

Blood cultures are routinely collected in pairs of aerobic and anaerobic bottles. Artificial sterilization of Gram-negative bacteria in aerobic bottles containing clinically meaningful antibiotic concentrations has previously been observed. This study assessed recovery from anaerobic bottles with and without antibiotic binding resins.
Transcriptional Regulation and Mechanism of SigN (ZpdN), a pBS32-Encoded Sigma Factor in Bacillus subtilis
Authors: Burton Aisha T. , DeLoughery Aaron , Li Gene-Wei , Kearns Daniel B.
Published: September 2019

Sigma factors are utilized by bacteria to control and regulate gene expression. Some sigma factors are activated during times of stress to ensure the survival of the bacterium. Here, we report the presence of a sigma factor that is encoded on a plasmid that leads to cellular death after DNA damage.
Explaining Order among Those Who Share Positions in the Author Byline
Authors: Casadevall Arturo , Schloss Patrick
Published: September 2019

In an effort to reduce gender biases in authorship positions,
mBio
will now require an explanation for how order was determined among those who share positions in the author byline. We hope that by requiring explanations, the explanation will help those in second and third positions get their full share of credit, even when not listed first.
Control of Type III Secretion System Effector/Chaperone Ratio Fosters Pathogen Adaptation to Host-Adherent Lifestyle
Authors: Elbaz Netanel , Socol Yaakov , Katsowich Naama , Rosenshine Ilan
Published: September 2019

Host colonization by extracellular pathogens often entails the transition from a planktonic lifestyle to a host-attached state. Enteropathogenic
E. coli
(EPEC), a Gram-negative pathogen, attaches to the intestinal epithelium of the host and employs a type III secretion system (T3SS) to inject effector proteins into the cytoplasm of infected cells. The most abundant effector protein injected is Tir, whose translocation is dependent on the Tir-bound chaperon CesT. Upon Tir injection, the liberated CesT binds to and inhibits the posttranscriptional regulator CsrA, resulting in reprogramming of gene expression in the host-attached bacteria. Thus, adaptation to the host-attached state involves dynamic remodeling of EPEC gene expression, which is mediated by the relative levels of Tir and CesT. Fluctuating from the optimal Tir/CesT ratio results in a decrease in EPEC virulence. Here we elucidate a posttranscriptional circuit that prevents sharp variations from this ratio, thus improving host colonization.
Theoretical and Simulation-Based Investigation of the Relationship between Sequencing Effort, Microbial Community Richness, and Diversity in Binning Metagenome-Assembled Genomes
Authors: Royalty Taylor M. , Steen Andrew D.
Published: September 2019

Short-read sequencing with Illumina sequencing technology provides an accurate, high-throughput method for characterizing the metabolic potential of microbial communities. Short-read sequences can be assembled and binned into metagenome-assembled genomes, thus shedding light on the function of microbial ecosystems that are important for health, agriculture, and Earth system processes. The work presented here provides an analytical framework for selecting sequencing effort as a function of genome relative abundance. As such, experimental goals in metagenome-assembled genome creation projects can select sequencing effort based on the rarest target genome as a constrained threshold. We hope that the results presented here, as well as GRASE, will be valuable to researchers planning sequencing experiments.
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

Objectives

To 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.

Design

Prospective cohort study.

Methods

Sixty-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.

Results

Seventeen 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.

Conclusion

Injuries 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

Objectives

To 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).

Methods

Seventy-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.

Results

Current 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.

Conclusions

Further 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 evidence

This study provides class III evidence that available MRI midbrain-based assessments do not have diagnostic value in differentiating the Movement Disorder Society PSP subtypes.
When does an advantage become unfair? Empirical and normative concerns in Semenya’s case
Authors: Camporesi Silvia
Published: September 2019

There is a fundamental tension in many sports: human sex is not binary, but there are only two categories in which people can compete: male and female. Over the past 10 years, the International Association of Athletics Federations (IAAF) regulations have been at the centre of two notable legal disputes. The Court of Arbitration for Sport (CAS) reached two contradictory rulings: in the first case (Dutee Chand vs Athletics Federation India and IAAF), the IAAF regulations for the eligibility of athletes to compete in the female category were suspended (24 July 2015) on grounds of "discrimination against the female category"; in the latter (Caster Semenya and Athletics South Africa vs IAAF), the regulations were reaffirmed (1 May 2019) on grounds that although discriminatory, they are necessary to maintain a "level playing field" and to “protect” the female category. Although Semenya’s case has paved the way for questioning existing gender norms in sport, a new stable norm has yet to emerge from her case. The pharmacological solution put forward by IAAF to the tension between fairness and inclusivity of bodies non-conforming to two sexes is not, however, the only possible solution/resolution to the case, as I aim to show in this paper. Here I present some reflections on this topic and suggest how CAS should approach the case if it hopes to resolve it.
Should pregnant women be charged for non-invasive prenatal screening? Implications for reproductive autonomy and equal access
Authors: Bunnik Eline M , Kater-Kuipers Adriana , Galjaard Robert-Jan H , de Beaufort Inez D
Published: September 2019

The introduction of non-invasive prenatal testing (NIPT) in healthcare systems around the world offers an opportunity to reconsider funding policies for prenatal screening. In some countries with universal access healthcare systems, pregnant women and their partners are asked to (co)pay for NIPT. In this paper, we discuss two important rationales for charging women for NIPT: (1) to prevent increased uptake of NIPT and (2) to promote informed choice. First, given the aim of prenatal screening (reproductive autonomy), high or low uptake rates are not intrinsically desirable or undesirable. Using funding policies to negatively affect uptake, however, is at odds with the aim of screening. Furthermore, copayment disproportionally affects those of lower socioeconomic status, which conflicts with justice requirements and impedes equal access to prenatal screening. Second, we argue that although payment models may influence pregnant women’s choice behaviours and perceptions of the relevance of NIPT, the copayment requirement does not necessarily lead to better-informed choices. On the contrary, external (ie, financial) influences on women’s personal choices for or against prenatal screening should ideally be avoided. To improve informed decision-making, healthcare systems should instead invest in adequate non-directive, value-focused pretest counselling. This paper concludes that requiring (substantial) copayments for NIPT in universal access healthcare systems fails to promote reproductive autonomy and is unfair.
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

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.
DOES FOREIGN AID HELP OR HINDER THE INSTITUTIONAL QUALITY OF THE RECIPIENT COUNTRY? NEW EVIDENCE FROM THE OIC COUNTRIES
Authors: CHOWDHURY MOHAMMAD ASHRAFUL FERDOUS , ARIFF MOHAMED , MASIH MANSUR , ISMAIL IZLIN
Published: September 2019

This study examines the impact of foreign aid on the institutional quality (IQ) of the OIC countries. Using the data of OIC countries for the three-year average period from 1991 to 2016, the system GMM finds that aid in general deteriorates the IQ for the aid recipient countries. However, quantile regression suggests that the negative impact of foreign aid on institutional quality (IQ) is relatively greater in the countries where the existing quality of institution is poor. The findings of the study suggest that improving the existing capacity is essential for reaping the optimum benefit of foreign aid on institutional development.
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.
A 50-Year Journey from Phosphate to Autonomous Underwater Vehicles
Authors: Perry Mary Jane
Published: September 2019

This narrative is a personal account of my evolution as a student of phytoplankton and the ocean. Initially I focused on phytoplankton nutrient physiology and uptake, later switching to photosynthetic physiology. Better models of photosynthesis naturally require a better understanding of spectral underwater light fields and absorption coefficients, which precipitated my involvement in the nascent field of bio-optical oceanography. Establishment of the now 34-year-old summer graduate course in ocean optics, which continues to attract students from around the globe, is a legacy of my jumping into optics. The importance of social interactions in advancing science cannot be underestimated; a prime example is how a TGIF gathering led to my immersion in the world of autonomous underwater vehicles for the past two decades of my career. Working with people who you like and respect is also critical; I believe collegial friendship played a major role in the great success of the 2008 North Atlantic Bloom Experiment.
Origins of Refractive Errors: Environmental and Genetic Factors
Authors: Harb Elise N. , Wildsoet Christine F.
Published: September 2019

Refractive errors are the product of a mismatch between the axial length of the eye and its optical power, creating blurred vision. Uncorrected refractive errors are the second leading cause of worldwide blindness. One refractive error currently attracting significant scientific interest is myopia, mostly owing to the recent rise in its prevalence worldwide and associated ocular disease burden. This increase in myopia prevalence has also been rapid, suggesting environmental influences in addition to any genetic influences on eye growth. This review defines refractive errors, describes their prevalence, and presents evidence for the influence of genetic and environmental factors related to refractive error development.
Innovative Approximate Analytical Solution for Standard Model of Viral Dynamics: Hepatitis C with Direct‐Acting Agents as an Implemented Case
Authors: Elkaranshawy Hesham A. , Ezzat Hossam M. , Abouelseoud Yasmine , Ibrahim Nermeen N.
Published: September 2019

In this article, a novel approximate analytical solution is presented for solving the standard viral dynamic model. Basically, the standard model is used to study viral dynamics in patients for a wide range of viruses like HIV, HPV, HBV, and HCV. In this research work, the standard model for hepatitis C virus (HCV) is considered in detail; however, the analysis and results can be applicable for all other viruses. This standard model is used to study viral dynamics in patients treated with direct‐acting antiviral agents (DAAs). Power series solution combined with Laplace–Padé resummation method (PSLP) is used to obtain the approximate analytical solutions for the model. To test the capability as well as the validity of the proposed method, results are compared with available viral load data published in the literature and with published simulation results. Good fits are obtained in the comparison for all cases considered. Given that medical specialists and physicians are more interested in solutions that yield direct and simple predictions, it is expected that the proposed approximate analytical solution would be attractive to them and help them to obtain a straightforward and a proper estimation regarding the viral load due to variations in treatment and/or patient’s parameters.
A Questionnaire Study on the Attitude towards Death of the Nursing Interns in Eight Teaching Hospitals in Jiangsu, China
Authors: Xu Fengqin , Huang Kun , Wang Yinhe , Xu Yuzi , Ma Liang , Cao Yang
Published: September 2019

Introduction. Nurses play an important role in caring for dying patients. However, little is known about the attitude towards death of the registered nurses in China. Materials and Methods. A knowledge, attitude, and the practice (KAP) survey using standardized questionnaires was conducted at eight teaching hospitals in Jiangsu Province, China. In total, 366 nursing interns were recruited and 357 turned in valid response. Data about the interns’ demographic characteristics and their attitudes to death in five domains, including fear of death, death avoidance, natural acceptance, approach acceptance, and escape acceptance, were collected. Results. Compared to the norms, the nursing interns had statistically significantly higher scores in the domains death avoidance, approach acceptance, and fear of death (14.9 vs. 11.1, 26.2 vs. 24.2, and 20.3 vs. 19.0, respectively); however, statistically significantly lower scores were in the domains natural acceptance and escape acceptance (18.4 vs. 22.0, and 13.6 vs. 15.1, respectively). Religious belief, experience of a deceased relative in family, death education, and family atmosphere of discussing death are positively associated with one or more domains of attitude towards death. Conclusion. The positive attitude towards death and death education before clinical practice are helpful for nursing interns when they care for dying patients. In general, the scores of attitude towards death are at a moderate level in the surveyed Chinese nursing interns. The death education for nursing students needs to be reinforced in China.
Laser Irradiation of Mung Bean (Vigna radiata L.) at Two Wavelengths for Enhanced Seedling Development
Authors: Janayon Rayno Vic B. , Guerrero Raphael A.
Published: September 2019

Two laser sources operating at wavelengths of 632.8 nm (He-Ne) and 488 nm (Ar+) are used in examining the effects of coherent, low-power, continuous wave exposure on the development of Vigna radiata L. Presowing laser irradiation of seeds leads to an improvement of mung bean seedling characteristics, with increased values of hypocotyl length (an increase of up to 22.5%), root length (an increase of up to 28.8%), and seedling mass (a maximum increase of 29.2%). Measured parameters between seedlings from laser-irradiated seeds and from control samples are statistically different at a level of significance equal to 0.05. For both laser wavelengths, an optimal exposure time of 2 minutes is determined for enhanced growth of mung bean seedlings.
A First Case Report of Subependymoma in PTPN11 Mutation-Associated Noonan Syndrome
Authors: Boonyawat Boonchai , Charoenpitakchai Mongkon , Suwanpakdee Piradee
Published: September 2019

Noonan syndrome (NS) is an autosomal dominant disorder in some cases caused by PTPN11 mutations. Since somatic mutations in PTPN11 are seen in several tumor types, NS which causes germline PTPN11 mutations are also increase the risk of hematologic malignancies and brain solid tumors. However, the report of brain tumors in Noonan syndrome remains rather rare. Here, we report the first case of an 11-year-old Thai boy with Noonan syndrome who presented with symptoms related to hydrocephalus secondary to subependymoma in the fourth ventricle, and PTPN11 mutation was identified in this patient.
Cure Kinetics of an Optical Polythiourethane with Amine Catalyst by IR Analysis
Authors: Du Weiping , Zhang Guiming , Wang Song , Tan Lianjiang , Chen Huifang
Published: September 2019

An optical polythiourethane based on m-xylylene diisocyanate (XDI) and 4-mercaptomethyl-3,6-dithia-1,8-octanedithiol (BES) has been studied. Triethylamine was adopted as a catalyst, and the solid-state isothermal cure reaction was carried out using FTIR spectroscopy, in the temperature range of 75°C-105°C. The -NCO absorption band of XDI was used to monitor the conversion of diisocyanate into polythiourethane. The reaction rate enhanced with an increase in the content of the catalyst, and the gel time determined by swelling test was shorter for the system with higher catalyst content. Kinetic parameters were calculated from the infrared spectrum data, and the results showed that the curing reaction of polythiourethane accords with first-order kinetic characteristics. The activation parameters obtained from the evaluation of kinetic data were △H∗=97.22 kJ mol−1, △S∗=−6.77 J K−1 mol−1, and Ea=100.23 kJ mol−1. The observed negative entropy of activation value supported the formation of a transition state in the cure reaction.
DOA Estimation Performance Analysis and Verification of Dual Crossed-Loop/Monopole Antenna Array
Authors: Wang Sijie , Wen Biyang , Tian Yingwei
Published: September 2019

The compact high-frequency surface wave radar using a crossed-loop/monopole (CLM) antenna as the receiving sensor has been widely used in ocean remote sensing and target monitoring. However, the direction of arrival (DOA) estimation accuracy of a single CLM antenna is the dominant factor that restricts the target monitoring performance of the compact HF radar. Besides, the single CLM antenna can estimate two signals simultaneously at most, but its effectiveness is challenged by the pattern distortion and the existence of coherent sources, which limits the application range of the compact HF radar. In this study, a compact array combining two CLM antennas is proposed to improve the DOA estimation accuracy and solve the multisource DOA estimation problem. The estimation error and multisource DOA estimation performance of a dual CLM antenna array are analyzed by formula derivation and simulation. Furthermore, the field experiment results are given to demonstrate the performance improvement of the dual CLM antenna array.
Ushering in Liquid Biopsy for the Microsatellite Status: Advantages and Caveats
Authors: Wang Linghua , Ajani Jaffer A.
Published: September 2019

Microsatellite 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

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

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.