bluuebunny/crossref_metadata_2025 huggingface dataset:
Inhibition of mTOR in head and neck cancer cells alters endothelial cell morphology in a paracrine fashion
Authors: Duarte Andressa , André‐Grégoire Gwennan , Trillet Kilian , Thys An , Bidère Nicolas , Ribeiro‐Silva Alfredo , Gavard Julie
Published: September 2018

Head and neck squamous cell carcinoma (HNSCC) represent aggressive classes of tumors with a high mortality rate. The mammalian target of rapamycin (mTOR) pathway is instrumental in their initiation and expansion. Although results from pre‐clinical models promise mTOR targeting as a potent novel therapeutic approach, its impact on the tumor microenvironment, such as endothelial cells is only scarcely investigated. Here, we first confirmed the effects of mTOR pharmacological inhibition on cell viability, clonogenicity, and proliferation in HNSCC human cell lines, HN26, and HN30. While Everolimus and Torin1 potently blunted mTOR‐based proliferation of HN26 and HN30 lines, endothelial cells were left intact. To further explore the possibility of a paracrine bystander action of HNSCC‐treated cells on endothelial cells, conditioned medium from Everolimus‐ and Torin1‐challenged HN26 and HN30 cells were collected and applied to naive human endothelial cells. Although endothelial cell viability was again not modified, morphology and mobility were changed. Indeed, spreading of endothelial cells was altered upon challenge with mTOR‐pretreated tumor conditioned‐media, as measured via cell impedance and imagery. Interestingly, this was associated with an augmentation of focal adhesion kinase (FAK) active phosphorylation and enhanced migratory behavior. From a molecular standpoint, the production of vascular endothelial growth factor was elevated in treated HNSCC cells and might contribute to FAK phosphorylation. Although mTOR inhibition in tumor cells did hinder their growth, it also favors the release of factors that subsequently enable endothelial cell migration. Further studies will address how this paracrine action may affect tumor‐driven angiogenesis upon pharmacological treatments.
Informant‐ and Self‐Appraisals on the Psychosis and Hallucinations Questionnaire (PsycH‐Q) Enhances Detection of Visual Hallucinations in Parkinson's Disease
Authors: Muller Alana J. , Mills Joanna M. Z. , O'Callaghan Claire , Naismith Sharon L. , Clouston Paul D. , Lewis Simon J. G. , Shine James M.
Published: September 2018

Background

Clinicians vary in their ability to elicit and interpret hallucinatory symptoms in patients with Parkinson's disease (PD). There is limited evidence for informant‐report measures of PD hallucinations as adjuncts to clinician‐rated scales.

Objectives

To determine the utility of an informant version of the validated Psychosis and Hallucinations Questionnaire (PsycH‐Q) for assessing the presence and severity of hallucinations in PD; and, to evaluate accuracy of clinician judgements by comparison with informant report and self‐report.

Methods

One hundred sixty‐three PD patient‐informant dyads completed self‐ and informant‐report versions of PsycH‐Q and three common questionnaire measures: Neuropsychiatric Inventory Questionnaire; Parkinson's Psychosis Questionnaire; and Scales for Outcomes in Parkinson's disease–Psychiatric Complications. We compared self‐ratings and informant ratings across analogous subscales for the presence of hallucinations with clinician interview ratings on MDS‐UPDRS as a diagnostic standard.

Results

There was a low level of agreement between dyads (average κ = 0.39; κ range = 0.32–0.47; P < 0.001), and patients indicated the highest prevalence of hallucinations compared to informant or clinician estimates. Clinician interview missed 32% of PsycH‐Q hallucinators identified by dyads. Relative to the sample, 22 patients with exclusively clinician‐appraised hallucinations had poorer overall quality of life measured by the Parkinson's Disease Questionnaire.

Conclusions

The sole use of clinician‐rated scales may underestimate prevalence of PD hallucinations, and there is room for introducing self‐ and informant‐report tools. Nonetheless, clinician appraisals are critical in cases when informant and patient insight might be affected by the impact of illness on quality of life.
Analysis of trends in rainfall and dry/wet years over a century in the Eastern Ganga Canal command
Authors: Krishan Radha , Nikam Bhaskar R. , Pingale Santosh M. , Chandrakar Ayush , Khare Deepak
Published: September 2018

In the present study, an attempt has been made to analyse the variability and trends in annual and seasonal rainfall over the Eastern Ganga Canal command area, India. To determine the trend in annual/seasonal rainfall and rainy days, the non‐parametric Mann−Kendall test and Sen's slope method were used over daily gridded rainfall for the time period 1901–2012. The results of the trend analysis revealed a decreasing trend in annual and monsoon rainfall in the range 18.5−61.7 and 19.4−56.7 mm/decade, respectively. For annual and monsoon rainy days, the results demonstrated a decreasing trend which varied from 1.8 to 2.9 and 1.4 to 2.2 days/decade, respectively, and an increasing trend in the range 0.2−1.4 and 1.0 days/decade, respectively. A variability analysis was performed to highlight the need for selecting an appropriate confidence level in trend analysis. It was observed that the grids showing a statistically non‐significant trend at the 95% confidence level exhibit a statistically significant trend at lower confidence levels. An analysis of dry and wet years on an annual scale revealed that the chances of occurrence of a wet year are more in comparison with the chances of occurrence of a dry year in the command area by a ratio of 14:13. However, data from the last one and a half decades has a contradictory trend with higher chances of occurrence of a dry year to very minimal chances of occurrence of a wet year. Dependable rainfall at various probability levels was estimated using a gamma distribution function. It was observed that the 75% dependable weighted annual and seasonal rainfall over the command area (985.48 and 727.54 mm) was significantly different with respect to the climatic mean weighted annual and seasonal rainfall against the weighted mean annual and seasonal rainfall (1,165.93 and 901.95 mm).
A numerical approach for solving weakly singular partial integro‐differential equations via two‐dimensional‐orthonormal Bernstein polynomials with the convergence analysis
Authors: Mirzaee Farshid , Alipour Sahar , Samadyar Nasrin
Published: September 2018

In this paper, we develop an efficient matrix method based on two‐dimensional orthonormal Bernstein polynomials (2D‐OBPs) to provide approximate solution of linear and nonlinear weakly singular partial integro‐differential equations (PIDEs). First, we approximate all functions involved in the considerable problem via 2D‐OBPs. Then, by using the operational matrices of integration, differentiation, and product, the solution of Volterra singular PIDEs is transformed to the solution of a linear or nonlinear system of algebraic equations which can be solved via some suitable numerical methods. With a small number of bases, we can find a reasonable approximate solution. Moreover, we establish some useful theorems for discussing convergence analysis and obtaining an error estimate associated with the proposed method. Finally, we solve some illustrative examples by employing the presented method to show the validity, efficiency, high accuracy, and applicability of the proposed technique.
Revised antiemetics guidelines and the impact on nutritional status during induction chemotherapy in children with high‐risk neuroblastoma
Authors: Carroll Catherine , Clinton Frieda , Smith Aisling , Fox Aine , Capra Michael , Pears Jane , Owens Cormac
Published: September 2018

Background

High‐risk neuroblastoma (HR NBL) treatment requires intensive induction chemotherapy. The profoundly emetogenic agents used can compromise nutritional status. Our institution introduced a new antiemetic guideline in 2010 incorporating regular dexamethasone, in addition to ondansetron, for all highly emetogenic protocols.

Procedure

A retrospective comparative review of pediatric patients diagnosed with HR NBL who received rapid COJEC induction chemotherapy as per HR‐SIOPEN NBL trial. Prophylactic antiemetics were prescribed regardless of chemotherapy emetogenicity in group A (2004–2010) but for defined time periods considering chemotherapy emetogenicity in group B (2010–2017).

Results

Sixty‐three children were eligible for inclusion (median age, 31 months; range, 1–88 months). Group A had more episodes of emesis than group B (189 vs. 116, P < 0.0001). There was a significant difference in weight‐for‐age Z score change between the groups by induction end (P = 0.0027). Four children (13%) in group A lost >10% body weight versus none in group B. Nutrition support (NS) was utilized by 29 children (94%) in group A and 22 children (69%) in group B. Group A had a median of 3 (range, 1–7) admissions for febrile neutropenia (FN) versus a median of 1.5 (range, 0–4) for group B (P = 0.003) during induction.

Conclusion

The review of our guidelines led to reduced emesis frequency for group B. They also required less NS, followed expected growth trajectories more closely and had fewer FN admissions. We propose that this may have occurred due to better emesis control resulting in improved nutritional status and associated enhanced immune function.
Influence of functionalized molybdenum disulfide (MoS2) with triazine derivatives on the thermal stability and flame retardancy of intumescent Poly(lactic acid) system
Authors: Xu Lingfeng , Tan Xinwen , Xu Ruijie , Xie Jiayi , Lei Caihong
Published: September 2018

Molybdenum disulfide (MoS2) with two‐dimensional (2D) lamellar structure was functionalized with melamine‐cyanuric acid (MCA) hybrids via a facile way. A core‐shell composite particle (MoMA) was obtained. Acting as one kind of synergistic flame retardant, it was mixed with traditional intumescent flame retardant (IFR) to prepare the flame retardant poly(lactic acid) composites by melt blending. UL‐94 V‐0 rating and LOI value of 29.8% for PLA composites were achieved while the total amount of flame retardants was 12 wt%, with the optimal weight ratio of IFR to MoMA 3:1. The inclusion of MoMA can enhance the amount of char residue and suppress the pyrolysis rate. The thermal degradation kinetic studies indicated that more pyrolysis conversion energy was needed. Finally, the investigation of char residue further confirmed that the addition of MoMA can improve the continuity and thermal stability of intumescent char layer and promote its graphitization degree. The condensed phase mechanism was mainly responsible for the improved flame retardant performance. This work suggests a novel strategy for improving flame retardant performance of PLA by combination of MoMA with IFR. The mechanical properties were studied as well. POLYM. COMPOS., 40:2244–2257, 2019. © 2018 Society of Plastics Engineers
Helix‐sense‐selective copolymerization of triphenylmethyl methacrylate with chiral 2‐isopropenyl‐4‐phenyl‐2‐oxazoline
Authors: Shen Jun , Ikeda Naoto , Bi Wanying , Satoh Kotaro , Kamigaito Masami , Okamoto Yoshio
Published: September 2018

The asymmetric induction leading to a one‐handed helix was investigated in the anionic and radical copolymerization of triphenylmethyl methacrylate (TrMA) and (S)‐2‐isopropenyl‐4‐phenyl‐2‐oxazoline ((S)‐IPO), and highly isotactic copolymers with a reasonable optical activity were obtained. In the anionic copolymerization, the optical activity of the obtained copolymers depended on the polarity of solvents, and a highly optically active copolymer was produced in the copolymerization in toluene. The chiral oxazoline monomer functioned not only as a comonomer but also as a chiral ligand to endow the polymer with large negative optical rotation in the copolymerization with TrMA. The copolymers with small positive optical rotation were obtained in THF, indicating that IPO unit may work only as the chiral monomer that dictates the helical sense via copolymerization with TrMA. The isotacticity of the obtained copolymers depended on the contents of TrMA units in the copolymers, but was almost independent of the solvent for copolymerization. In the radical copolymerization, the obtained copolymers exhibited small optical activities. It seemed that the chiral monomer cannot induce one‐handed helical structure of TrMA sequences even if the sequences probably have a high isotacticity. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 441–447
Active site flexibility revealed in crystal structures of Parabacteroides merdae β‐glucuronidase from the human gut microbiome
Authors: Little Michael S. , Ervin Samantha M. , Walton William G. , Tripathy Ashutosh , Xu Yongmei , Liu Jian , Redinbo Matthew R.
Published: September 2018

β‐Glucuronidase (GUS) enzymes in the gastrointestinal tract are involved in maintaining mammalian‐microbial symbiosis and can play key roles in drug efficacy and toxicity. Parabacteroides merdae GUS was identified as an abundant mini‐Loop 2 (mL2) type GUS enzyme in the Human Microbiome Project gut metagenomic database. Here, we report the crystal structure of P. merdae GUS and highlight the differences between this enzyme and extant structures of gut microbial GUS proteins. We find that P. merdae GUS exhibits a distinct tetrameric quaternary structure and that the mL2 motif traces a unique path within the active site, which also includes two arginines distinctive to this GUS. We observe two states of the P. merdae GUS active site; a loop repositions itself by more than 50 Å to place a functionally‐relevant residue into the enzyme's catalytic site. Finally, we find that P. merdae GUS is able to bind to homo and heteropolymers of the polysaccharide alginic acid. Together, these data broaden our understanding of the structural and functional diversity in the GUS family of enzymes present in the human gut microbiome and point to specialization as an important feature of microbial GUS orthologs.
Recommended drug therapies for inflammatory bowel disease
Authors: White Christopher , Thakor Amit , Goel Rishi
Published: September 2018

The treatment of inflammatory bowel disease (ulcerative colitis and Crohn's disease) has been revolutionised in recent years with the advent of biological therapies. This article discusses the current role of both conventional and biological treatments in the management of these conditions.
Online consultations: the future of NHS GP appointments?
Authors: Ogden Joy
Published: September 2018

In 2016, the General Practice Forward View invested £45 million in a national programme to support uptake of online consultation systems in every GP practice. This article examines the progress that has been made so far, and whether this new way of working is proving popular with health professionals and patients.
Wave‐Packet Dynamics in Nonlinear Disordered Chains under the Effect of Acoustic Waves
Authors: de Oliveira Sales Messias , Ranciaro Neto Adhemar , de Moura Francisco Anacleto Barros Fidelis
Published: September 2018

In this work, the wave‐packet dynamics is considered under the effect of diagonal disorder distribution, electron–lattice interaction, and acoustic‐wave pumping. Electronic transport is taken into account quantum mechanically, whereas lattice vibrations are described through a classical nonlinear Morse Hamiltonian. The electronic hopping term takes the form of an exponential function of the effective distance between nearest‐neighbor lattice elements. The electron wave‐packet is initially localized at the first site of the chain alongside a Gaussian pulse generator. The results suggest that the disorder distribution breaks down the solitonic energy profile that exists within this kind of nonlinear Morse lattice. On the other hand, it is shown that the acoustic pumping sustains the wave packet dynamics within this disordered nonlinear model.
Enhanced Room‐Temperature Ferromagnetism in Composite CeO2/CeF3 Nanoparticles
Authors: Morozov Oleg A. , Pavlov Vitaly V. , Rakhmatullin Rafail M. , Semashko Vadim V. , Korableva Stella L.
Published: September 2018

A considerable enhancement of the room‐temperature ferromagnetism is observed in the composite CeO2/CeF3 nanoparticles. The saturation magnetization for the composite CeO2/CeF3 nanoparticles (the average particle size ≈100 nm) is more than a half order of magnitude higher compared to the initial CeO2 nanoparticles (the average particle size ≈30 nm). The composite CeO2/CeF3 nanoparticles are synthesized by fluorination of initial CeO2 nanoparticles. For this purpose, the initial ceria powder is annealed in the vacuum followed by an intake in the furnace of gaseous tetrafluoromethane (CF4). X‐ray diffraction (XRD) patterns show that resulting powder has both CeO2 and CeF3 structures with the ratio CeO2/CeF3 depending on the temperature and the duration of the annealing. It is supposed that the CeF3 structure forms on the surface of the CeO2 nanoparticles as a result of the chemical reactions on the surface of the CeO2. A considerable increase of the saturation magnetization in the CeO2/CeF3 nanoparticles compared to the initial, vacuum, and air annealed CeO2 nanoparticles is supposed due to the interface CeO2/CeF3 structure produced by the applied method of fluorination. The present study suggests that adjusting the interface in the composite nanoparticles containing ceria is a perspective way to enhance the room temperature ferromagnetism.
A characterization of constant‐sample testable properties
Authors: Blais Eric , Yoshida Yuichi
Published: September 2018

We characterize the set of properties of Boolean‐valued functions on a finite domain that are testable with a constant number of samples (x,f(x)) with x drawn uniformly at random from . Specifically, we show that a property is testable with a constant number of samples if and only if it is (essentially) a k‐part symmetric property for some constant k, where a property is k‐part symmetric if there is a partition of such that whether satisfies the property is determined solely by the densities of f on . We use this characterization to show that symmetric properties are essentially the only graph properties and affine‐invariant properties that are testable with a constant number of samples and that for every constant , monotonicity of functions on the d‐dimensional hypergrid is testable with a constant number of samples.
U.S. Top 50 Report
Authors: Bowers Diane
Published: September 2018

This report is excerpted from the AMA Gold Top 50 Report, produced by Diane Bowers which was published in the June‐July 2018 issue of Marketing News.
Video Analytics
Authors: Heeg Robert
Published: September 2018

Seeing the People Behind the Data
Research and technology
Authors: Macer Tim
Published: September 2018

The 2017/18 annual MR technology report reveals key opportunities for research companies and research company providers
Choice Factory: The Book That Zags
Authors: Miles Jack
Published: September 2018

How biases affect buying decisions
Advances in Digital Analytics
Authors: Munoz Gemma
Published: September 2018

From descriptive to prescriptive
Experiences in creating a software tool to analyze and postprocess simulated and measured data
Authors: Ceraolo Massimo
Published: September 2018

Today, there is a great availability of software to plot simulated or measured data either commercial or free, possibly open source. The author has created one of them, which has the specificity of being compact, compatible with several input formats, and freely distributed, available for Windows, Macintosh, and Unix. It has also the ability to postprocess simulated and measured data. This paper shows some of the choices that have been made to produce this tool, gives hints on their implementation, and shows which special characteristics were searched for, which not always are available on larger tools or tools built into simulation or measuring software.
Catalytic Enantioselective Flow Processes with Solid‐Supported Chiral Catalysts
Authors: Rodríguez‐Escrich Carles , Pericàs Miquel A.
Published: September 2018

Sustainability concerns are the wind in the sails for the development of novel, more selective catalytic processes. Hence, chiral catalysts play a crucial role in the green production of enantioenriched compounds. To further increase the green profile of this approach, the use of solid‐supported catalytic species is appealing due to the reduced generation of waste, as well as the possibility of reusing the precious catalyst. Even more attractive is the implementation of flow processes based on these immobilized catalysts, a flexible strategy that allows to generate from milli‐ to multi‐gram amounts of chiral product with a reduced footprint set‐up. Herein, we will present the efforts devoted in our laboratory towards the immobilization of chiral catalysts and their use in single‐pass, highly enantioselective, flow processes. Proline, diarylprolinols, other aminocatalysts, squaramides, thioureas, phosphoric acids and even chiral ligands and metal‐based catalysts constitute our current toolkit of supported species for enantioselective catalysis.
Reaching Out to Students From Title I Schools
Authors: Johnston Vickie , Martelli Cynthia Dawn
Published: September 2018

A university's literacy festival can promote reading and foster the idea that books make a difference, especially to undersupported students from Title I schools. A literacy festival featuring a variety of diverse authors presenting hands‐on workshops showcasing their literary craft can enable students from Title I schools to engage with the authors and can motivate students from diverse backgrounds to develop an excitement for reading. It can also motivate teachers and librarians to use literature that reflects their population to engage students in reading and can transform teacher candidates’ understanding of students from diverse backgrounds. The authors describe how a university College of Education's literacy festival was implemented and explore how it provided an opportunity for children in low‐socioeconomic‐status communities to be exposed to books and authors of quality children's literature.
Vinyl acetate ethylene copolymer and nanosilica reinforced epoxidized natural rubber: Effects of sulfur curing systems on cure characteristics, tensile properties, thermal stability, dynamic mechanical properties and oil resistance
Authors: Raksaksri Laksamon , Chuayjuljit Saowaroj , Chaiwutthinan Phasawat , Boonmahitthisud Anyaporn
Published: September 2018

This study aimed at preparing nanocomposite from epoxidized natural rubber with about 40 mol% epoxidation (ENR40), vinyl acetate ethylene copolymer (VAE) contained about 70 wt% acetate groups and nanosilica (nSiO2). Two parts by weight per hundred parts of rubber/resin of nSiO2 were assembled to 80/20 (w/w) ENR40/VAE blend via latex blending. The resulting nanocomposite latex was coagulated before compounding with curing agents in an internal mixer. Tetrabenzylthiuram disulphide was used as a non‐carcinogenic accelerator in three sulfur vulcanization/curing systems, namely conventional (CV), semi‐efficient (semi‐EV) and efficient (EV) systems. The rubber compounds were sheeted on a two‐roll mill and press‐cured using a compression molding machine. Influence of curing systems on cure characteristics, tensile properties, thermal stability, dynamic mechanical properties and oil resistance of the nanocomposites was investigated. The results revealed that the CV system exhibited the highest crosslink density, tensile properties and storage modulus, while the EV system exhibited the longest scorch and cure time and the highest thermal stability and oil resistance. Moreover, the percentage retention of the tensile properties after thermal aging for CV system was lower than that of semi‐EV and EV systems. However, the pristine ENR40 and 80/20 (w/w) ENR40/VAE blend were also prepared for comparison. J. VINYL ADDIT. TECHNOL., 25:E28–E38, 2019. © 2018 Society of Plastics Engineers
Evaluating airsoft electric guns for control of invasive brown treesnakes
Authors: Knox Adam J. , Lardner Björn , Yackel Adams Amy , Reed Robert N.
Published: September 2018

Firearms are often used in lethal control of invasive vertebrates, but safety and regulatory aspects limit the circumstances under which they can be used. During August 2016 at the Brown Treesnake Project laboratory on Guam, we evaluated hobby‐grade Airsoft Electric Guns (AEGs)—a lower powered, less‐hazardous, and less‐regulated alternative to firearms—for capture and control of small animals, with specific emphasis on invasive brown treesnakes (Boiga irregularis). Tests of AEGs differing in power with ammunition (plastic pellets) masses ranging from 0.20 to 0.39 g, fired at gelatin blocks from distances of 4, 8, and 12 m, showed that heavy ammunition is of overriding importance for maximizing lethality: 0.39‐g pellets penetrated more deeply at 12 m than did 0.20‐g pellets at 4 m. Inspection of tissue damage in brown treesnake carcasses subjected to fire with the 0.39‐g ammunition from the same distances suggested that injuries sustained by a direct hit from 12 m would often be lethal, and snakes would be unlikely to survive multiple hits from automatic fire discharged at approximately 17/s. Limited trials with live snakes helped us to understand behavioral responses in a snake hit by ≥1 pellets, including distance traveled over time. Based on these factors, we assessed the risk that a snake injured by pellet fire might evade subsequent capture by rapid responders in the proximity. We also discuss ethical considerations and regulatory advantages of using AEGs. Published 2018. This article is a U.S. Government work and is in the public domain in the USA.
A refined two‐dimensional theory for thermal bending of functionally graded plates with thickness normal strains
Authors: Fares M. E. , Elmarghany M. Kh. , Atta Doaa , Salem A. G.
Published: September 2018

A refined theory is presented for the thermal response of composite functionally graded plates under thermo‐mechanical loads. The theory includes shear deformation and normal strain effects by assuming through‐the‐thickness linear in‐plane displacements and parabolic transverse displacement. A mixed variational approach is used to introduce stresses satisfying the loading conditions on the plate surfaces without employing any shear correction factor used in other theories of the same order. A thermal bending problem is solved for metal/ceramic rectangle plates. Some numerical results are compared with numerical results of 3D exact solutions. The importance of the normal strain effect for such problems is studied.
Supersymmetric Galilean conformal blocks
Authors: Lodato Ivano , Merbis Wout , Zodinmawia
Published: September 2018

Abstract

We set up the bootstrap procedure for supersymmetric Galilean Conformal (SGC) field theories in two dimensions by constructing the SGC blocks in the$$ \mathcal{N}=1 $$N=1and two possible$$ \mathcal{N}=2 $$N=2extensions of the Galilean conformal algebra. In all analyzed cases, we present the bootstrap equations by crossing symmetry of the four point function. In addition, we compute the global SGC blocks analytically by solving the differential equations obtained by acting with the Casimirs of the global subalgebras inside the four point function. These global blocks agree with the general SGC blocks in the limit of large central charge. We comment on possible applications to supersymmetric BMS3invariant field theories and flat holography.
Neyman-type sample allocation for domains-efficient estimation in multistage sampling
Authors: Khan M. G. M. , Wesołowski Jacek
Published: September 2018

We consider a problem of allocation of a sample in two- and three-stage sampling. We seek allocation which is both multi-domain and population efficient. Choudhry et al. (Survey Methods 38(1):23–29, 2012) recently considered such problem for one-stage stratified simple random sampling without replacement in domains. Their approach was through minimization of the sample size under constraints on relative variances in all domains and on the overall relative variance. To attain this goal, they used nonlinear programming. Alternatively, we minimize here the relative variances in all domains (controlling them through given priority weights) as well as the overall relative variance under constraints imposed on total (expected) cost. We consider several two- and three-stage sampling schemes. Our aim is to shed some light on the analytic structure of solutions rather than in deriving a purely numerical tool for sample allocation. To this end, we develop the eigenproblem methodology introduced in optimal allocation problems in Niemiro and Wesołowski (Appl Math 28:73–82, 2001) and recently updated in Wesołowski and Wieczorkowski (Commun Stat Theory Methods 46(5):2212–2231, 2017) by taking under account several new sampling schemes and, more importantly, by the (single) total expected variable cost constraint. Such approach allows for solutions which are direct generalization of the Neyman-type allocation. The structure of the solution is deciphered from the explicit allocation formulas given in terms of an eigenvector

$${\underline{v}}^*$$

v
̲

∗

of a population-based matrix

$$\mathbf{D}$$

D

. The solution we provide can be viewed as a multi-domain version of the Neyman-type allocation in multistage stratified SRSWOR schemes.
Design optimisation of separate-jet exhausts for the next generation of civil aero-engines
Authors: Goulos I. , Otter J. , Stankowski T. , Macmanus D. , Grech N. , Sheaf C.
Published: September 2018

The next generation of civil large aero-engines will employ greater bypass ratios compared with contemporary architectures. This results in higher exchange rates between exhaust performance and specific fuel consumption (SFC). Concurrently, the aerodynamic design of the exhaust is expected to play a key role in the success of future turbofans. This paper presents the development of a computational framework for the aerodynamic design of separate-jet exhaust systems for civil aero-engines. A mathematical approach is synthesised based on class-shape transformation (CST) functions for the parametric geometry definition of gas-turbine exhaust components such as annular ducts and nozzles. This geometry formulation is coupled with an automated viscous and compressible flow solution method and a cost-effective design space exploration (DSE) approach. The framework is deployed to optimise the performance of a separate-jet exhaust for very-high-bypass ratio (VHBR) turbofan engine. The optimisations carried out suggest the potential to increase the engine’s net propulsive force compared with a baseline architecture, through optimum exhaust re-design. The proposed method is able to identify and alleviate adverse flow-features that may deteriorate the aerodynamic behaviour of the exhaust system.
Difference in snowmelt processes between an opening and three Japanese cedar stands
Authors: Murakami Shigeki , Takeuchi Yukari
Published: September 2018

Snowmelt was measured on a daily basis for 17 days at the open site and 18 days at three Japanese cedar sites with canopy closure of 17.8% (cedar stand A), 5.2% (B) and 2.4% (C) in April. Measured daily snowmelt at each site was reproduced by heat-balance calculation with an accuracy of <±1 mm w.e. From 1st April to the date of snow disappearance net radiation accounted for 88.4, 43.0, 32.7 and 34.2% of total snowmelt energy at the open site, the cedar stands A, B and C, respectively. The ratio of sensible and latent heat to total snowmelt was 33.1–37.9 and 25.9–29.4%, respectively, at three cedar stands. The ratios of sensible and latent heat increased over time in accordance with the rise in temperature at all cedar sites. They became large on a daily basis when air temperature and/or wind speed were high. Wind speed is dependent on morphology around each site that also dictated snowmelt.
Modal analysis of the wake past a marine propeller
Authors: Magionesi Francesca , Dubbioso Giulio , Muscari Roberto , Di Mascio Andrea
Published: September 2018

Modal decomposition techniques are used to analyse the wake field past a marine propeller achieved by previous numerical simulations (Muscariet al. Comput. Fluids, vol. 73, 2013, pp. 65–79). In particular, proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD) are used to identify the most energetic modes and those that play a dominant role in the inception of the destabilization mechanisms. Two different operating conditions, representative of light and high loading conditions, are considered. The analysis shows a strong dependence of temporal and spatial scales of the process on the propeller loading and correlates the spatial shape of the modes and the temporal scales with the evolution and destabilization mechanisms of the wake past the propeller. At light loading condition, due to the stable evolution of the wake, both POD and DMD describe the flow field by the non-interacting evolution of the tip and hub vortex. The flow is mainly associated with the ordered convection of the tip vortex and the corresponding dominant modes, identified by both decompositions, are characterized by spatial wavelengths and frequencies related to the blade passing frequency and its multiples, whereas the dynamic of the hub vortex has a negligible contribution. At high loading condition, POD and DMD identify a marked separation of the flow field close to the propeller and in the far field, as a consequence of wake breakdown. The tonal modes are prevalent only near to the propeller, where the flow is stable; on the contrary, in the transition region a number of spatial and temporal scales appear. In particular, the phenomenon of destabilization of the wake, originated by the coupling of consecutive tip vortices, and the mechanisms of hub–tip vortex interaction and wake meandering are identified by both POD and DMD.
Oblique waves in steady supersonic flows of Bethe–Zel’dovich–Thompson fluids
Authors: Vimercati Davide , Kluwick Alfred , Guardone Alberto
Published: September 2018

Steady self-similar solutions to the supersonic flow of Bethe–Zel’dovich–Thompson fluids past compressive and rarefactive ramps are derived. Inviscid, non-heat-conducting, non-reacting and single-phase vapour flow is assumed. For convex isentropes and shock adiabats in the pressure–specific volume plane (classical gas dynamic regime), the well-known oblique shock and centred Prandtl–Meyer fan occur at a compressive and rarefactive ramp, respectively. For non-convex isentropes and shock adiabats (non-classical gas dynamic regime), four additional wave configurations may possibly occur; these are composite waves in which a Prandtl–Meyer fan is adjacent up to two oblique shock waves. The steady two-dimensional counterparts of the wave curves defined for the one-dimensional Riemann problem are constructed. In the present context, such curves consist of all the possible states connected to a given initial state (namely, the uniform state upstream of the ramp/wedge) by means of a steady self-similar solution. In addition to the classical case, as many as six non-classical wave-curve configurations are singled out. Moreover, the necessary conditions leading to each type of wave curves are analysed and a map of the upstream states leading to each configuration is determined.
Large-eddy simulation of flow over a rotating cylinder: the lift crisis at
Authors: Cheng W. , Pullin D. I. , Samtaney R.
Published: September 2018

We present wall-resolved large-eddy simulation (LES) of flow with free-stream velocity

$\boldsymbol{U}_{\infty }$

over a cylinder of diameter

$D$

rotating at constant angular velocity

$\unicode[STIX]{x1D6FA}$

, with the focus on the lift crisis, which takes place at relatively high Reynolds number

$Re_{D}=U_{\infty }D/\unicode[STIX]{x1D708}$

, where

$\unicode[STIX]{x1D708}$

is the kinematic viscosity of the fluid. Two sets of LES are performed within the (

$Re_{D}$

,

$\unicode[STIX]{x1D6FC}$

)-plane with

$\unicode[STIX]{x1D6FC}=\unicode[STIX]{x1D6FA}D/(2U_{\infty })$

the dimensionless cylinder rotation speed. One set, at

$Re_{D}=5000$

, is used as a reference flow and does not exhibit a lift crisis. Our main LES varies

$\unicode[STIX]{x1D6FC}$

in

$0\leqslant \unicode[STIX]{x1D6FC}\leqslant 2.0$

at fixed

$Re_{D}=6\times 10^{4}$

. For

$\unicode[STIX]{x1D6FC}$

in the range

$\unicode[STIX]{x1D6FC}=0.48{-}0.6$

we find a lift crisis. This range is in agreement with experiment although the LES shows a deeper local minimum in the lift coefficient than the measured value. Diagnostics that include instantaneous surface portraits of the surface skin-friction vector field

$\boldsymbol{C}_{\boldsymbol{f}}$

, spanwise-averaged flow-streamline plots, and a statistical analysis of local, near-surface flow reversal show that, on the leeward-bottom cylinder surface, the flow experiences large-scale reorganization as

$\unicode[STIX]{x1D6FC}$

increases through the lift crisis. At

$\unicode[STIX]{x1D6FC}=0.48$

the primary-flow features comprise a shear layer separating from that side of the cylinder that moves with the free stream and a pattern of oscillatory but largely attached flow zones surrounded by scattered patches of local flow separation/reattachment on the lee and underside of the cylinder surface. Large-scale, unsteady vortex shedding is observed. At

$\unicode[STIX]{x1D6FC}=0.6$

the flow has transitioned to a more ordered state where the small-scale separation/reattachment cells concentrate into a relatively narrow zone with largely attached flow elsewhere. This induces a low-pressure region which produces a sudden decrease in lift and hence the lift crisis. Through this process, the boundary layer does not show classical turbulence behaviour. As

$\unicode[STIX]{x1D6FC}$

is further increased at constant

$Re_{D}$

, the localized separation zone dissipates with corresponding attached flow on most of the cylinder surface. The lift coefficient then resumes its increasing trend. A logarithmic region is found within the boundary layer at

$\unicode[STIX]{x1D6FC}=1.0$

.
Fluid deformation in random steady three-dimensional flow
Authors: Lester Daniel R. , Dentz Marco , Le Borgne Tanguy , de Barros Felipe P. J.
Published: September 2018

The deformation of elementary fluid volumes by velocity gradients is a key process for scalar mixing, chemical reactions and biological processes in flows. Whilst fluid deformation in unsteady, turbulent flow has gained much attention over the past half-century, deformation in steady random flows with complex structure – such as flow through heterogeneous porous media – has received significantly less attention. In contrast to turbulent flow, the steady nature of these flows constrains fluid deformation to be anisotropic with respect to the fluid velocity, with significant implications for e.g. longitudinal and transverse mixing and dispersion. In this study we derive an ab initio coupled continuous-time random walk (CTRW) model of fluid deformation in random steady three-dimensional flow that is based upon a streamline coordinate transform which renders the velocity gradient and fluid deformation tensors upper triangular. We apply this coupled CTRW model to several model flows and find that these exhibit a remarkably simple deformation structure in the streamline coordinate frame, facilitating solution of the stochastic deformation tensor components. These results show that the evolution of longitudinal and transverse fluid deformation for chaotic flows is governed by both the Lyapunov exponent and power-law exponent of the velocity probability distribution function at small velocities, whereas algebraic deformation in non-chaotic flows arises from the intermittency of shear events following similar dynamics as that for steady two-dimensional flow.
Numerical modelling of two-dimensional melt fracture instability in viscoelastic flow
Authors: Kwon Youngdon
Published: September 2018

Computationally modelling the two-dimensional (2-D) Poiseuille flow along and outside a straight channel with a differential viscoelastic constitutive equation, we demonstrate unstable dynamics involving bifurcations from steady flow to periodic melt fracture (sharkskin instability) and its further transition regime to a chaotic state. The numerical simulation first exposes transition from steady flow to a weak instability of periodic fluctuation, and in the middle of this periodic limit cycle (in the course of increasing flow intensity) a unique bifurcation into the second steady state is manifested. Then, a subcritical (Hopf) transition restoring this stable flow to stronger periodic instability follows, which results from the high stress along the streamlines of finite curvature with small vortices near the die lip. Its succeeding chaotic transition at higher levels of flow elasticity that induces gross melt fracture, seems to take a period doubling as well as quasiperiodic route. By simple geometrical modification of the die exit, we, as well, illustrate reduction or complete removal of sharkskin and melt fractures. The result as a matter of fact suggests convincing evidence of the possible cause of the sharkskin instability and it is thought that this fluid dynamic transition has to be taken into account for the complete description of melt fracture. The competition between nonlinear dynamic transition and other possible origins such as wall slip will ultimately determine the onset of the sharkskin and melt fractures. Therefore, the current study conceivably provides a robust methodology to portray every possible type of melt fracture if combined with an appropriate mechanism that also results in flow instability.
Propagation, proppant transport and the evolution of transport properties of hydraulic fractures
Authors: Wang Jiehao , Elsworth Derek , Denison Martin K.
Published: September 2018

Hydraulic fracturing is a widely used method for well stimulation to enhance hydrocarbon recovery. Permeability, or fluid conductivity, of the hydraulic fracture is a key parameter to determine the fluid production rate, and is principally conditioned by fracture geometry and the distribution of the encased proppant. A numerical model is developed to describe proppant transport within a propagating blade-shaped fracture towards defining the fracture conductivity and reservoir production after fracture closure. Fracture propagation is formulated based on the PKN-formalism coupled with advective transport of an equivalent slurry representing a proppant-laden fluid. Empirical constitutive relations are incorporated to define rheology of the slurry, proppant transport with bulk slurry flow, proppant gravitational settling, and finally the transition from Poiseuille (fracture) flow to Darcy (proppant pack) flow. At the maximum extent of the fluid-driven fracture, as driving pressure is released, a fracture closure model is employed to follow the evolution of fracture conductivity with the decreasing fluid pressure. This model is capable of accommodating the mechanical response of the proppant pack, fracture closure of potentially contacting rough surfaces, proppant embedment into fracture walls, and most importantly flexural displacement of the unsupported spans of the fracture. Results show that reduced fluid viscosity increases the length of the resulting fracture, while rapid leak-off decreases it, with both characteristics minimizing fracture width over converse conditions. Proppant density and size do not significantly influence fracture propagation. Proppant settling ensues throughout fracture advance, and is accelerated by a lower viscosity fluid or greater proppant density or size, resulting in accumulation of a proppant bed at the fracture base. ‘Screen-out’ of proppant at the fracture tip can occur where the fracture aperture is only several times the diameter of the individual proppant particles. After fracture closure, proppant packs comprising larger particles exhibit higher conductivity. More importantly, high-conductivity flow channels are necessarily formed around proppant banks due to the flexural displacement of the fracture walls, which offer preferential flow pathways and significantly influence the distribution of fluid transport. Higher compacting stresses are observed around the edge of proppant banks, resulting in greater depths of proppant embedment into the fracture walls and/or an increased potential for proppant crushing.
Squirming motion in a Brinkman medium
Authors: Nganguia Herve , Pak On Shun
Published: September 2018

Micro-organisms encounter heterogeneous viscous environments consisting of networks of obstacles embedded in a viscous fluid medium. In this paper we analyse the characteristics of swimming in a porous medium modelled by the Brinkman equation via a spherical squirmer model. The idealized geometry allows an analytical and exact solution of the flow surrounding a squirmer. The propulsion speed obtained agrees with previous results using the Lorentz reciprocal theorem. Our analysis extends these results to calculate the power dissipation and hence the swimming efficiency of the squirmer in a Brinkman medium. The analytical solution enables a systematic analysis of the structure of the flow surrounding the squirmer, which can be represented in terms of singularities in Brinkman flows. We also discuss the spatial decay of flows due to squirming motion in a Brinkman medium in comparison with the decay in a purely viscous fluid. The results lay the foundation for subsequent studies on hydrodynamic interactions, nutrient transport and uptake by micro-organisms in heterogeneous viscous environments.
Testing the Use of δ2H Values for Reservoir Corrections in Radiocarbon Dating Human Bone
Authors: van der Sluis L G , Ogle N , Reimer P J
Published: September 2018

Consumption of marine protein in humans and animals can result in an apparent older radiocarbon (14C) age due to reservoir offsets. In order to correct for this, an estimate of the marine protein intake should be used to correct the 14C age for reservoir offsets, which is ordinarily done using δ13C or δ15N values. However, these two isotopic proxies can be influenced by a number of factors which can hamper estimation of the correct marine protein intake. A small dataset of 12 samples from the Limfjord, Denmark, ranging in age from Mesolithic to Viking Age, was used to test the use of δ2H values to quantify marine protein intake and determine the reservoir corrections. Each of the three stable isotopic values (δ2H, δ13C, δ15N) was used to estimate the percent marine protein intake, which produced three different calibrated 14C ages. The calculated percent marine protein intake differed between the use of the stable isotopic ratios with a maximum difference of 42.1% between the use of δ15N and δ13C, 23.8% between δ2H and δ13C, and 46.2% between δ2H and δ15N. In some cases the calculated percent marine protein intake changed the sample’s archaeological period, although there was generally still overlap in the archaeological periods for samples used in this study.
Honour Among (Cyber)thieves?
Authors: Lusthaus Jonathan
Published: September 2018

It is well known that criminals, who operate outside the law and the protection of the state, face difficulties in cooperating due both to the requirement of secrecy and a deficit of trust. For cybercriminals the anonymity of the Internet creates further challenges, making it even more difficult to assess trustworthiness and enforce agreements. Yet, contrary to expectations, collaboration among cybercriminals is prevalent, and a sophisticated industry has emerged. The purpose of this paper is to address this puzzle in relation to profit-driven cybercrime. It draws on a collection of interviews with former cybercriminals that provide a valuable form of data on micro-level and often secretive interactions. It examines four key mechanisms that lead to improved cooperation: reputation, appearance, performance and enforcement. It also addresses the rarely discussed, and somewhat counterintuitive, role that offline interactions may play in enhancing collective action among cybercriminals.