bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechano-Chemical Surface Modification of High-Speed Steel Cutting Tools
Authors: Qi Ye , Nguyen Vinh , Melkote Shreyes , Varenberg Michael
Published: February 2019

In this work, a mechano-chemical surface modification to improve cutting tool performance is proposed. We applied this surface modification via shot peening the rake faces of high-speed steel tools with a blend of Al2O3 and Cu2S particles that serve as a plastic deformation medium and a chemical precursor, respectively. Orthogonal cutting experiments under base oil lubrication demonstrated that the proposed treatment results in a reduction of cutting and thrust forces, as well as in a reduction of built-up edge formation. These effects are explained by favorable changes in the lubricity and roughness of the rake face, and they suggest that this method has the potential to increase cutting tool life, lower energy consumption, and improve the dimensional accuracy and surface quality of a machined workpiece.
Wisdom of Microcrowds in Evaluating Solutions to Esoteric Engineering Problems
Authors: Gecer Ulu Nurcan , Messersmith Michael , Goucher-Lambert Kosa , Cagan Jonathan , Kara Levent Burak
Published: February 2019

A multitude of studies in economics, psychology, political and social sciences have demonstrated the wisdom of crowds (WoC) phenomenon, where the collective estimate of a group can be more accurate than estimates of individuals. While WoC is observable in such domains where the participating individuals have experience or familiarity with the question at hand, it remains unclear how effective WoC is for domains that traditionally require deep expertise or sophisticated computational models to estimate objective answers. This work explores how effective WoC is for engineering design problems that are esoteric in nature, that is, problems (1) whose solutions traditionally require expertise and specialized knowledge, (2) where access to experts can be costly or infeasible, and (3) in which previous WoC studies with the general population have been shown to be highly ineffective. The main hypothesis in this work is that in the absence of experts, WoC can be observed in groups that consist of practitioners who are defined to have a base familiarity with the problems in question but not necessarily domain experts. As a way to emulate commonly encountered engineering problem-solving scenarios, this work studies WoC with practitioners that form microcrowds consisting of 5–15 individuals, thereby giving rise to the term the wisdom of microcrowds (WoMC). Our studies on design evaluations show that WoMC produces results whose mean is in the 80th percentile or better across varying crowd sizes, even for problems that are highly nonintuitive in nature.
Singularity Avoidance for a Deployable Mechanism Using Elastic Joints
Authors: Zhang Tieshan , Huang Hailin , Guo Hongwei , Li Bing
Published: February 2019

This paper aims at dealing with the deployment vibration problem of the rigid-links deployable mechanism caused by mobility bifurcation. A triangular prismoid deployable mechanism with mobility bifurcation is employed as an example to demonstrate the design and analysis process. First, the mobility of the triangular prismoid deployable mechanism is analyzed, which shows that there exists mobility bifurcation and the possibility of deployment vibration. Second, the revolute joints that introduce mobility bifurcation are analyzed, which shows that they can be replaced by the elastic joints without changing its mobility. Third, a detailed design procedure for this type of elastic joints is discussed; the main parameters of the elastic joints can then be determined based on the mobility and motion range of the deployable mechanism. Physical prototypes of both the rigid-links prismoid deployable mechanism and the corresponding improved mechanism with elastic joints are fabricated, and the deployment experiments of both mechanisms are conducted to show improvement in the latter mechanism.
Free-Form Design of Electrical Machine Rotor Cores for Production Using Additive Manufacturing
Authors: Garibaldi Michele , Gerada Christopher , Ashcroft Ian , Hague Richard
Published: February 2019

This work presents a finite element analysis-based, topology optimization (TO) methodology for the combined magnetostatic and structural design of electrical machine cores. Our methodology uses the Bi-directional Evolutionary Structural Optimization (BESO) heuristics to remove inefficient elements from a meshed model based on elemental energies. The algorithm improves the average torque density while maintaining structural integrity. To the best of our knowledge, this work represents the first effort to address the structural-magnetostatic problem of electrical machine design using a free-form approach. Using a surface-mounted permanent magnet motor (PMM) as a case study, the methodology is first tested on linear and nonlinear two-dimensional problems whereby it is shown that the rapid convergence achieved makes the algorithm suitable for real-world applications. The proposed optimization scheme can be easily extended to three dimensions, and we propose that the resulting designs are suitable for manufacturing using selective laser melting, a 3D printing technology capable of producing fully dense high-silicon steel components with good soft magnetic properties. Three-dimensional TO results show that the weight of a PMM rotor can be slashed by 50% without affecting its rated torque profile when the actual magnetic permeability of the 3D-printed material is considered.
Control of Process Settings for Large-Scale Additive Manufacturing With Sustainable Natural Composites
Authors: Vijay Yadunund , Sanandiya Naresh D. , Dritsas Stylianos , Fernandez Javier G.
Published: February 2019

We present a system for 3D printing large-scale objects using natural biocomposite materials, which comprises a precision extruder mounted on an industrial six-axis robot. This paper highlights work on controlling process settings to print filaments of desired dimensions while constraining the operating point to a region of maximum tensile strength and minimum shrinkage. Response surface models relating the process settings to the geometric and physical properties of extruded filaments are obtained through face-centered central composite designed experiments. Unlike traditional applications of this technique that identify a fixed operating point, the models are used to uncover dimensions of filaments obtainable within the operating boundaries of our system. Process-setting predictions are then made through multi-objective optimization of the models. An interesting outcome of this study is the ability to produce filaments of different shrinkage and tensile strength properties by solely changing process settings. As a follow-up, we identify optimal lateral overlap and interlayer spacing parameters to define toolpaths to print structures. If unoptimized, the material’s anisotropic shrinkage and nonlinear compression characteristics cause severe delamination, cross-sectional tapering, and warpage. Finally, we show the linear scalability of the shrinkage model in 3D space, which allows for suitable toolpath compensation to improve the dimensional accuracy of printed artifacts. We believe this first-ever study on the parametrization of the large-scale additive manufacture technique with biocomposites will serve as reference for future sustainable developments in manufacturing.
Characterization and Impact of Secondary Flows in a Discrete Passage Centrifugal Compressor Diffuser
Authors: Erickson David W. , Tan Choon S. , Macrorie Michael
Published: February 2019

Truncating the exit of a discrete passage centrifugal compressor diffuser is observed to enhance a research compressor's stall line. By interrogating the experimental data along with a set of well-designed Reynolds-Averaged Navier–Stokes computations, this improvement is traced to the reduced impact of secondary flows on the truncated diffuser's boundary layer growth. The secondary flow system is characterized by counter-rotating streamwise vortex pairs that persist throughout the diffuser passage. The vortices originate from two sources: flow nonuniformity at the impeller exit and separation off the leading edge cusps unique to a discrete passage diffuser. The latter detrimentally impacts the diffuser pressure rise capability by accumulating high loss flow along the diffuser wall near the plane of symmetry between the vortices. This contributes to a large passage separation in the baseline diffuser. Using reduced-order modeling, the impact of the vortices on the boundary layer growth is shown to scale inversely with the diffuser aspect ratio, and thus, the separation extent is reduced for the truncated diffuser. Because the diffuser incidence angle influences the strength and location of the vortices, this mechanism can affect the slope of the compressor's pressure rise characteristic and impact its stall line. Stall onset for the baseline diffuser configuration is initiated when the vortex location and the corresponding passage separation transition from pressure to suction side with increased cusp incidence. Conversely, because the extent of the passage separation in the truncated diffuser is diminished, the switch in separation side does not immediately initiate instability.
An Innovative Approach of Using Continuous Impedance-Graded Metallic Composite System for Attenuation of Stress Waves
Authors: Fernando P. L. N. , Mohotti Damith , Remennikov Alex
Published: February 2019

This paper presents an innovative approach of stress attenuation through a continuous impedance-graded material system for high strain-rate events. High energetic dynamic events such as blasts and impact could cause stress waves—in the form of elastic, plastic, and shock—to propagate in a solid material. An impedance-graded composite is created by arranging different metallic alloys in the reducing order of their impedance through the system. Impedance, which is the product of volumetric mass density and wave velocity, is chosen as the function as it plays a governing role in elastic, plastic, and shock waves. An analytical framework to quantify the stress wave propagation through an impedance-graded multimaterial system is developed based on the principles of shock and elastic wave theories. The numerical simulations carried out using nonlinear finite element code, LS-DYNA, were able to capture and quantify the elastic, plastic, and shock waves and their reflections at different interfaces. It was identified that the final transmitted stress wave, which could comprise elastic, plastic, and shock waves, as well as the reflected tensile elastic wave at each material interface, needs to be controlled in order to develop a robust multimaterial system.
Coulomb Friction Crawling Model Yields Linear Force–Velocity Profile
Authors: Wu Ziyou , Zhao Dan , Revzen Shai
Published: February 2019

Conventional wisdom would have it that moving mechanical systems that dissipate energy by Coulomb friction have no relationship between force and average speed. One could argue that the work done by friction is constant per unit of distance travelled, and if propulsion forces exceed friction, the net work is positive, and the system accumulates kinetic energy without bound. We present a minimalistic model for legged propulsion with slipping under Coulomb friction, scaled to parameters representative of single kilogram robots and animals. Our model, amenable to exact solutions, exhibits nearly linear (R2 > 0.96) relationships between actuator force and average speed over its entire range of parameters, and in both motion regimes, it supports. This suggests that the interactions inherent in multilegged locomotion may lead to governing equations more reminiscent of viscous friction than would be immediately obvious.
Wave-Packet Models for Jet Dynamics and Sound Radiation
Authors: Cavalieri André V. G. , Jordan Peter , Lesshafft Lutz
Published: February 2019

Organized structures in turbulent jets can be modeled as wavepackets. These are characterized by spatial amplification and decay, both of which are related to stability mechanisms, and they are coherent over several jet diameters, thereby constituting a noncompact acoustic source that produces a distinctive directivity in the acoustic field. In this review, we use simplified model problems to discuss the salient features of turbulent-jet wavepackets and their modeling frameworks. Two classes of model are considered. The first, that we refer to as kinematic, is based on Lighthill's acoustic analogy, and allows an evaluation of the radiation properties of sound-source functions postulated following observation of jets. The second, referred to as dynamic, is based on the linearized, inhomogeneous Ginzburg–Landau equation, which we use as a surrogate for the linearized, inhomogeneous Navier–Stokes system. Both models are elaborated in the framework of resolvent analysis, which allows the dynamics to be viewed in terms of an input–ouput system, the input being either sound-source or nonlinear forcing term, and the output, correspondingly, either farfield acoustic pressure fluctuations or nearfield flow fluctuations. Emphasis is placed on the extension of resolvent analysis to stochastic systems, which allows for the treatment of wavepacket jitter, a feature known to be relevant for subsonic jet noise. Despite the simplicity of the models, they are found to qualitatively reproduce many of the features of turbulent jets observed in experiment and simulation. Sample scripts are provided and allow calculation of most of the presented results.
Robust Attitude Control for Quadrotors Based on Parameter Optimization of a Nonlinear Disturbance Observer
Authors: Mishra Shatadal , Rakstad Todd , Zhang Wenlong
Published: February 2019

This paper presents a nonlinear disturbance observer (NDOB) for active disturbance rejection in the attitude control loop for quadrotors. An optimization framework is developed for tuning the parameter in the NDOB structure, which includes the infinity-norm minimization of the weighted sum of noise-to-output transfer function and load disturbance sensitivity function. Subsequently, the minimization generates an optimal value of the parameter based on the tradeoff between disturbance rejection and noise propagation in the system. The proposed structure is implemented on PIXHAWK, a real-time embedded flight control unit. Simulation tests are carried out on a custom built, high-fidelity simulator providing physically accurate simulations. Furthermore, experimental flight tests are conducted to demonstrate the performance of the proposed approach. The system is injected with step, sinusoidal, and square wave disturbances, and the corresponding system tracking performance is recorded. Experimental results show that the proposed algorithm attenuates the disturbances better compared to just a baseline controller implementation. The proposed algorithm is computationally cheap, an active disturbance rejection technique and robust to exogenous disturbances.
Surface oxidation model in plasma enhanced atomic layer deposition for silicon oxide films including various aminosilane precursors
Authors: Yamamoto Kosuke , Suzuki Ayuta , Kagaya Munehito , Matsukuma Masaaki , Moriya Tsuyoshi
Published: February 2019

In this study, a surface oxidation model for the plasma enhanced atomic layer deposition process for silicon oxide films formed by the combination of aminosilane with Ar/O2 plasma is proposed. After the discussion of the dominant oxidation pathways involving both reactive species generation and reaction energy barriers, the authors develop a surface oxidation model and compare it with experimental deposition results. From plasma simulation results, they confirmed two dominant species generated by Ar/O2 plasma; triplet oxygen atom (3O) and singlet oxygen molecule (1O2). The authors then compared the reaction energy barrier along the oxidation pathways for these oxidation species and the corresponding surface terminations by using density functional theory calculations. The calculated activation barriers were negligible in the oxidation paths with 3O, but not in the ones with 1O2. These results support that oxidation by 3O was dominant, especially at low substrate temperatures. The authors suggest a surface oxidation model having two kinds of surface terminations; hydrogen terminations (Si–H) and amino ligand terminations (Si–R). This model can explain the experimental saturation curve for surface oxidation against plasma irradiation time as a function of substrate temperature. The authors confirmed that saturation trends observed with various aminosilane precursors can successfully be explained by their differing ratios of Si–H and Si–R bonds present prior to oxidation.
Empirical corrections for predicting the sound insulation of double leaf cavity stud building elements with stiffer studs
Authors: Davy John L. , Fard Mohammad , Dong Wayland , Loverde John
Published: February 2019

The experimentally determined normal incident mass-air-mass resonance frequency for a double leaf cavity stud building element is significantly greater than the theoretically predicted frequency for wood studs and steel studs manufactured from thicker sheet steel. This paper gives a method for calculating the effective mass-air-mass resonance frequency as the root mean square sum of the mass-air-mass resonance frequency and the resonance frequency of the first bending wave mode of the leaves between the studs. This calculation should use the isothermal mass-air-mass resonance frequency if the building element cavity contains porous sound absorbing material. If the cavity does not contain porous sound absorbing material, the usual adiabatic mass-air-mass resonance frequency should be used in the calculation. Because the exact boundary conditions of the building element leaves at the studs and the effective in situ damping are unknown, the paper gives empirical correction factors to determine the actual resonance frequency and the depth of the dip in the predicted sound insulation. This paper also gives empirically derived formulae for the line and point equivalent translational compliances of steel studs manufactured from different sheet steel gauges and compares them with formulae derived by other authors for the case of 25 gauge steel studs.
Abrogation of Triazole Resistance upon Deletion of
CDR1
in a Clinical Isolate of
Candida auris
Authors: Rybak Jeffrey M. , Doorley Laura A. , Nishimoto Andrew T. , Barker Katherine S. , Palmer Glen E. , Rogers P. David
Published: February 2019

Candida auris
has rapidly emerged as a health care-associated and multidrug-resistant pathogen of global concern. In this work, we examined the relative expression of the four
C. auris
genes with the highest degree of homology to
Candida albicans
CDR1
and
MDR1
among three triazole-resistant clinical isolates as compared to the triazole-susceptible genome reference clinical isolate.
Cefepime Pharmacokinetics in Critically Ill Pediatric Patients Receiving Continuous Renal Replacement Therapy
Authors: Stitt Gideon , Morris Jennifer , Schmees Lindsay , Angelo Joseph , Akcan Arikan Ayse
Published: February 2019

This retrospective study included pediatric intensive care unit patients receiving continuous veno-venous hemodiafiltration (CVVHDF) being treated with cefepime. The free drug concentration above one time the MIC (
fT
>1×MIC) and four times a presumed MIC (
fT
>4×MIC) of 8 μg/ml were calculated.
Negative Impact of Carbapenem Methylation on the Reactivity of β-Lactams for Cysteine Acylation as Revealed by Quantum Calculations and Kinetic Analyses
Authors: Bhattacharjee Nicholus , Triboulet Sébastien , Dubée Vincent , Fonvielle Matthieu , Edoo Zainab , Hugonnet Jean-Emmanuel , Ethève-Quelquejeu Mélanie , Simorre Jean-Pierre , Field Martin J. , Arthur Michel , Bougault Catherine M.
Published: February 2019

The
Enterococcus faecium
l
,
d
-transpeptidase (Ldt
fm
) mediates resistance to most β-lactam antibiotics in this bacterium by replacing classical peptidoglycan polymerases. The catalytic Cys of Ldt
fm
is rapidly acylated by β-lactams belonging to the carbapenem class but not by penams or cephems.
A FASII Inhibitor Prevents Staphylococcal Evasion of Daptomycin by Inhibiting Phospholipid Decoy Production
Authors: Pee Carmen J. E. , Pader Vera , Ledger Elizabeth V. K. , Edwards Andrew M.
Published: February 2019

Daptomycin is a treatment of last resort for serious infections caused by drug-resistant Gram-positive pathogens, such as methicillin-resistant
Staphylococcus aureus
. We have shown recently that
S. aureus
can evade daptomycin by releasing phospholipid decoys that sequester and inactivate the antibiotic, leading to treatment failure.
Clinical and Molecular Characteristics of
qacA
- and
qacB
-Positive Methicillin-Resistant
Staphylococcus aureus
Causing Bloodstream Infections
Authors: Hong Sun In , Lee Yu-Mi , Park Ki-Ho , Ryu Byung-Han , Hong Kyung-Wook , Kim Sunjoo , Bae In-Gyu , Cho Oh-Hyun
Published: February 2019

The increasing use of chlorhexidine for methicillin-resistant
Staphylococcus aureus
(MRSA) decolonization has raised concerns about the emergence of resistance to these agents. However, the clinical significance of MRSA positive for the
qacA
and
qacB
chlorhexidine tolerance genes has not been established.
Whole-Genome Sequencing for Drug Resistance Profile Prediction in
Mycobacterium tuberculosis
Authors: Gygli Sebastian M. , Keller Peter M. , Ballif Marie , Blöchliger Nicolas , Hömke Rico , Reinhard Miriam , Loiseau Chloé , Ritter Claudia , Sander Peter , Borrell Sonia , Collantes Loo Jimena , Avihingsanon Anchalee , Gnokoro Joachim , Yotebieng Marcel , Egger Matthias , Gagneux Sebastien , Böttger Erik C.
Published: February 2019

Whole-genome sequencing allows rapid detection of drug-resistant
Mycobacterium tuberculosis
isolates. However, the availability of high-quality data linking quantitative phenotypic drug susceptibility testing (DST) and genomic data have thus far been limited.
Comparison of Loop-Mediated Isothermal Amplification and Real-Time PCR Assays for Detection of Strongyloides Larvae in Different Specimen Matrices
Authors: Watts Matthew R. , Kim Rady , Ahuja Vishal , Robertson Gemma J. , Sultana Yasmin , Wehrhahn Michael C. , Bradbury Richard S. , Gilbert Gwendolyn L. , Lee Rogan
Published: February 2019

Strongyloides stercoralis
can cause disease that ranges from asymptomatic chronic infection to fatal hyperinfection. Diagnosis from stool can be challenging because the most sensitive conventional tests require live larvae to be effective and there can be low larval output in chronic infection.
Zika Virus Infection in Tupaia belangeri Causes Dermatological Manifestations and Confers Protection against Secondary Infection
Authors: Zhang Na-Na , Zhang Li , Deng Yong-Qiang , Feng Yue , Ma Feng , Wang Qi , Ye Qing , Han Yuanyuan , Sun Xiaomei , Zhang Fu-Chun , Qi Xiaopeng , Wang Guoqing , Dai Jiejie , Xia Xueshan , Qin Cheng-Feng
Published: February 2019

The reemergence of Zika virus (ZIKV) has caused a global public health crisis since 2016, and there are currently no vaccines or antiviral drugs to prevent or treat ZIKV infection. However, considerable advances have been made in understanding the biology and pathogenesis of ZIKV infection. In particular, various animal models have been successfully established to mimic ZIKV infection and its associated neurological diseases and to evaluate potential countermeasures. However, the clinical symptoms in these mouse and nonhuman primate models are different from the common clinical manifestations seen in human ZIKV patients; in particular, dermatological manifestations are rarely recapitulated in these animal models. Here, we developed a new animal model of ZIKV infection in tree shrews, a rat-sized, primate-related mammal.
In vitro
and
in vivo
characterization of ZIKV infection in tree shrews established a direct link between ZIKV infection and the immune responses and dermatological manifestations. The tree shrew model described here, as well as other available animal models, provides a valuable platform to study ZIKV pathogenesis and to evaluate vaccines and therapeutics.
Hepatitis Delta Antigen Regulates mRNA and Antigenome RNA Levels during Hepatitis Delta Virus Replication
Authors: Harichandran Kaneemozhe , Shen Yiran , Stephenson Tsoris Susannah , Lee See-Chi , Casey John L.
Published: February 2019

Hepatitis delta virus (HDV) is a satellite of hepatitis B virus that increases the severity of liver disease; approximately 15 million people are chronically infected worldwide. There are no licensed therapies available. HDV is not related to any known virus, and few details regarding its replication cycle are known. One key question is whether and how HDV regulates the relative amounts of viral RNA and protein in infected cells. Such regulation might be important because the HDV RNA and protein form complexes that are essential for HDV replication, and the proper stoichiometry of these complexes could be critical for their function. Our results show that the relative amounts of HDV RNA and protein in cells are indeed important for HDV replication and that the virus does control them. These observations indicate that further study of these regulatory mechanisms is required to better understand replication of this serious human pathogen.
Comparison of Subtyping Approaches and the Underlying Drivers of Microbial Signatures for Chronic Rhinosinusitis
Authors: Biswas Kristi , Cavubati Raewyn , Gunaratna Shan , Hoggard Michael , Waldvogel-Thurlow Sharon , Hong Jiwon , Chang Kevin , Wagner Mackenzie Brett , Taylor Michael W. , Douglas Richard G.
Published: February 2019

Chronic rhinosinusitis (CRS) is a major human health problem that significantly reduces quality of life. While various microbes have been implicated, there is no clear understanding of the role they play in CRS pathogenesis. Another equally important observation made for CRS patients is that the epithelial barrier in the sinonasal cavity is defective. Finding a robust approach to subtype CRS patients would be the first step toward unravelling the pathogenesis of this heterogeneous condition. Previous work has explored stratification based on the clinical presentation of the disease (with or without polyps), inflammatory markers, pathology, or microbial composition. Comparisons between the different stratification approaches used in these studies have not been possible due to the different cohorts, analytical methods, or sample sites used. In this study, two approaches for subtyping CRS patients were compared, and the underlying drivers of the heterogeneity in CRS were also explored.
The Vacuolar Ca
2+
ATPase Pump Pmc1p Is Required for Candida albicans Pathogenesis
Authors: Luna-Tapia Arturo , DeJarnette Christian , Sansevere Emily , Reitler Parker , Butts Arielle , Hevener Kirk E. , Palmer Glen E.
Published: February 2019

Maintenance of Ca
2+
homeostasis is important for fungal cells to respond to a multitude of stresses, as well as antifungal treatment, and for virulence in animal models. Here, we demonstrate that a P-type ATPase, Pmc1p, is required for
Candida
albicans
to respond to a variety of stresses, affects azole susceptibility, and is required to sustain tissue invasive hyphal growth and to cause disease in a mouse model of disseminated infection. Defining the mechanisms responsible for maintaining proper Ca
2+
homeostasis in this important human pathogen can ultimately provide opportunities to devise new chemotherapeutic interventions that dysregulate intracellular signaling and induce Ca
2+
toxicity.
Displacement, deprivation and hard work among Syrian refugee children in Lebanon
Authors: Habib Rima R , Ziadee Micheline , Abi Younes Elio , Harastani Houda , Hamdar Layal , Jawad Mohammed , El Asmar Khalil
Published: February 2019

Background

The protracted Syrian war resulted in the largest refugee crisis of our time. The most vulnerable are children who face separation from parents, interruption of schooling and child labour. This study explores the living and working conditions of Syrian children in Lebanon.

Methods

In this cross-sectional study, we randomly selected 153 informal tented settlements and conducted interviewer-administered surveys among Syrian refugee working children in the Bekaa Valley in Lebanon. Those aged 8–18 completed a questionnaire on sociodemographic and occupational characteristics; those aged 4–8 years were surveyed through a household questionnaire.

Results

We surveyed 1902 households, including 12 708 individuals and 4377 working children. Female-headed households were poorer and more food-insecure than male-headed households. Among working children (4–18 years), the average age of starting work was 10.9 years and 74.8% worked in agriculture. Compared with boys, girls earned less and were less likely to be enrolled in school. For 96.3% of working children aged 8–18 years, forced exodus to Lebanon was associated with a first child labour experience. Working conditions were harsh and worse for girls who compared to boys were less likely to receive their salary on time and take time off work. Girls worked longer in the sun and cold and were more likely to report having a health symptom at work, working under pressure and using sharp or heavy objects at work. Seventy-nine children reported knowing another child who died following a work accident.

Conclusion

Children, as young as 4, are forced to work, and many are compelled to forgo educational opportunities in favour of harsh and harmful labour due to difficult economic conditions. State policies facilitating access to work for adult refugees will help families meet basic needs and decrease their dependence on child labour as a coping strategy.
TGR5-dependent hepatoprotection through the regulation of biliary epithelium barrier function
Authors: Merlen Grégory , Kahale Nicolas , Ursic-Bedoya Jose , Bidault-Jourdainne Valeska , Simerabet Hayat , Doignon Isabelle , Tanfin Zahra , Garcin Isabelle , Péan Noémie , Gautherot Julien , Davit-Spraul Anne , Guettier Catherine , Humbert Lydie , Rainteau Dominique , Ebnet Klaus , Ullmer Christoph , Cassio Doris , Tordjmann Thierry
Published: February 2019

Objective

We explored the hypothesis that TGR5, the bile acid (BA) G-protein-coupled receptor highly expressed in biliary epithelial cells, protects the liver against BA overload through the regulation of biliary epithelium permeability.

Design

Experiments were performed under basal and TGR5 agonist treatment. In vitro transepithelial electric resistance (TER) and FITC-dextran diffusion were measured in different cell lines. In vivo FITC-dextran was injected in the gallbladder (GB) lumen and traced in plasma. Tight junction proteins and TGR5-induced signalling were investigated in vitro and in vivo (wild-type [WT] and TGR5-KO livers and GB). WT and TGR5-KO mice were submitted to bile duct ligation or alpha-naphtylisothiocyanate intoxication under vehicle or TGR5 agonist treatment, and liver injury was studied.

Results

In vitro TGR5 stimulation increased TER and reduced paracellular permeability for dextran. In vivo dextran diffusion after GB injection was increased in TGR5-knock-out (KO) as compared with WT mice and decreased on TGR5 stimulation. In TGR5-KO bile ducts and GB, junctional adhesion molecule A (JAM-A) was hypophosphorylated and selectively downregulated among TJP analysed. TGR5 stimulation induced JAM-A phosphorylation and stabilisation both in vitro and in vivo, associated with protein kinase C-ζ activation. TGR5 agonist-induced TER increase as well as JAM-A protein stabilisation was dependent on JAM-A Ser285 phosphorylation. TGR5 agonist-treated mice were protected from cholestasis-induced liver injury, and this protection was significantly impaired in JAM-A-KO mice.

Conclusion

The BA receptor TGR5 regulates biliary epithelial barrier function in vitro and in vivo through an impact on JAM-A expression and phosphorylation, thereby protecting liver parenchyma against bile leakage.
Histopathological evaluation of scleritis
Authors: Hankins Mark , Margo Curtis Edward
Published: February 2019

The sclera is an uncommon site of primary inflammation. Biopsy is infrequently employed in the evaluation of scleritis, but familiarity with its differential diagnosis is instrumental in ensuring efficient histological evaluation. This review provides a clinical overview of scleritis and describes the context in which scleral biopsy might arise. Most cases are associated with systemic autoimmune disease, but a sizeable proportion occur as an isolated disorder. Conditions mimicking autoimmune scleritis include infection and neoplasm. Histological patterns of inflammation in eyes removed surgically or at autopsy have been placed into three groups: (1) autoimmune scleritis characterised by varying mixtures of palisading granulomas, necrosis and vasculitis; (2) infectious scleritis, characterised by acute inflammation and necrosis; and (3) idiopathic scleritis, characterised by chronic non-specific inflammation with follicles and varying amounts of fibrosis. This traditional system of classification may be oversimplified. Aetiological or categorical classification is not always possible on small biopsies given the histopathological overlap of infectious and non-infectious scleritis.
Additional loss of MSH2 and MSH6 expression in sporadic deficient mismatch repair colorectal cancer due to MLH1 promoter hypermethylation
Authors: Westwood Alice , Glover Amy , Hutchins Gordon , Young Caroline , Brockmoeller Scarlet , Robinson Rachel , Worrilow Lisa , Wallace Dave , Rankeillor Kate , Adlard Julian , Quirke Philip , West Nicholas
Published: February 2019

Colorectal cancer (CRC) is common with 3% of cases associated with germline mutations in the mismatch repair pathway characteristic of Lynch syndrome (LS). The UK National Institute for Health and Care Excellence recommends screening for LS in all patients newly diagnosed with CRC, irrespective of age. The Yorkshire Cancer Research Bowel Cancer Improvement Programme includes a regional LS screening service for all new diagnoses of CRC. In the first 829 cases screened, 80 cases showed deficient mismatch repair (dMMR) including four cases showing areas with loss of expression of all four mismatch repair proteins by immunohistochemistry. The cases demonstrated diffuse MLH1 loss associated with BRAF mutations and MLH1 promoter hypermethylation in keeping with sporadic dMMR, with presumed additional double hit mutations in MSH2+/−MSH6 rather than underlying LS. Recognition and accurate interpretation of this unusual phenotype is important to prevent unnecessary referrals to clinical genetics and associated patient anxiety.
Interstitial lung abnormalities: erecting fences in the path towards advanced pulmonary fibrosis
Authors: Hunninghake Gary M
Published: February 2019

Interstitial lung abnormalities, when present in members of undiagnosed family members recruited on the basis of familial interstitial pneumonia, or in undiagnosed research participants, have been associated with a syndrome that includes distinct sets of imaging abnormalities, restrictive physiological and exercise impairments, and an increased prevalence of histopathological findings, and genetic predictors, that have been noted in patients with idiopathic pulmonary fibrosis. Recent longitudinal studies have demonstrated that qualitative and quantitative assessments of interstitial abnormalities are associated with accelerated lung function decline, an increased rate of clinical diagnoses of interstitial lung disease and an increased rate of mortality. In this perspective, in addition to reviewing the prior information, four major efforts that could help the field of early pulmonary fibrosis detection move forward are discussed. These efforts include: (1) developing standards for characterising and reporting imaging findings from patients with existing CTs; (2) developing consensus statements on when undiagnosed and asymptomatic imaging abnormalities should be considered a disease; (3) identifying populations for which screening efforts might be beneficial; and (4) considering approaches to developing effective secondary prevention trials.
Thermoelectric and electronic properties of B-doped graphene nanoribbon
Authors: Jafari A. , Ramezani A.H. , Fayaz V. , Hossienkhani H.
Published: February 2019

The effect of concentration and position of boron atoms as impurities in graphene nanoribbons have been studied through density functional theory (DFT) and the Landauer approach. For this purpose, we designed a graphene nanoribbon doped with three different concentrations of boron atoms and calculated the density of states (DOS), electronic current, and thermopower. The comparison between the DOS curve of the pure graphene and that of the boron-doped graphene shows that the presence of boron atoms as impurities in graphene has caused an energy gap near the Fermi energy. Moreover, the study of the I–V characteristics shows that not only the current quantization is established, but also the reduction in conductivity caused by doping with boron atoms can be observed; however, this reduction is not sensitive to the concentration of boron atoms. In addition, the changes of the Seebeck coefficient shows that in both pure and boron-doped graphene, the curve has a minimum value at the temperature of 10 K, which decreases to a lower value by increasing the concentration of boron atoms. Generally, the result of calculations shows that by increasing the boron concentration, not only the energy gap of graphene is changed, but also several changes appear in its thermoelectric properties that can be attributed to the impurity potential distribution. The results of this study can be effectively used for designing semiconductor electronic devices based on the graphene nanoribbon.
Theoretical investigation of high-efficiency GaN–Si heterojunction betavoltaic battery
Authors: Yürük Reyyan Kavak , Tütüncüler Hayriye
Published: February 2019

The wide-bandgap semiconductors, which have the advantages of radiation resistance and high carrier mobility, have gained increased research attention in recent years for the conversion nuclear battery. Nevertheless, when a wide-bandgap semiconductor is used, the collection efficiency and current are reduced, even though the open circuit voltage is increased. In this research, a heterojunction photovoltaic cell is used to increase collection efficiency and power in the betavoltaic battery. A theoretical investigation of the electrical performance has been carried out on Ni63/GaN and Ni63/GaN–Si betavoltaic cells. The effects of doping concentration and junction depth on the maximum power are examined. By optimizing the doping concentration and junction depth, a high-efficiency heterojunction betavoltaic microbattery can be achieved. The maximum power is calculated as 22.90 nW/cm2 using 1 mCi Ni63 beta source and GaN–Si heterojunction with junction depth of 0.1 μm and doping concentrations of Na = 4 × 1017 cm−3 and Nd = 4 × 1016 cm−3 in the emitter and the base region, respectively.
A cyclic universe with varying cosmological constant in f(R, T) gravity
Authors: Ahmed Nasr , Alamri Sultan Z.
Published: February 2019

A new kind of evolution for cyclic models in which the Hubble parameter oscillates and remains positive has been explored in a specific f(R, T) gravity reconstruction. A singularity-free cyclic universe with negative varying cosmological constant has been obtained, which supports the role suggested for negative Λ in stopping the eternal acceleration. The cosmological solutions have been obtained for the case of a flat universe, supported by observations. The cosmic pressure grows without singular values; it is positive during the early-time decelerated expansion and negative during the late-time accelerating epoch. The time-varying equation of state parameter ω(t) shows quintom behavior and is restricted to the range –2.25 ≤ ω(t) ≲ 1/3. The validity of the classical linear energy conditions and the sound speed causality condition has been studied. The non-conventional mechanism of negative cosmological constant that are expected to address the late-time acceleration has been discussed.
Crustal architecture and Moho topography beneath the eastern Indian and Bangladesh margins – new insights on rift evolution and the continent–ocean boundary
Authors: Ismaiel Mohammad , Krishna Kolluru S. , Srinivas Karlapati , Mishra Jitendriya , Saha Dipendu
Published: February 2019

The thick sedimentary cover (≤18 km) along the Eastern Continental Margin of India (ECMI) and over the Bay of Bengal has hindered understanding of the mechanisms of rifting that operated on the eastern Indian and Bangladesh margins. Analysis of multichannel seismic reflection data, together with 3D gravity inversion and 2D gravity forward modelling, illuminates basement configuration, crustal thickness and Moho topography, thereby revealing the modes of rift evolution and the location of the continent–ocean boundary (COB) along these margins. The basement, particularly in the shelf and slope regions of eastern peninsular India, is traversed by nearly coast-perpendicular graben, and their seaward continuity is delineated up to 125 km from the coastline. Three different types of continental margin are present along the ECMI: (1) sheared rift on the southern segment of the ECMI, up to 14° N latitude (offshore the Southern Granulite Terrain); (2) hyper-extended rift in the central segment between 14° N and 17° N (offshore the Dharwar Craton); and (3) hypo-extended rift on the northern segment between 17° N and 20° N (offshore the Eastern Ghats Mobile Belt). The graben terminations, crustal thickness and Moho topography of both the ECMI and offshore Bengal Basin clearly suggest that the COB runs nearly parallel to the coastline of peninsular India, but takes an orthogonal turn offshore in the Bengal Basin and connects the palaeo-continental shelf and the Rajmahal–Sylhet Line onshore in the Bengal Basin. Crustal thickness (8–10 km) and depth to the Moho discontinuity (≤28 km) beneath the Bangladesh margin are unusual because the crustal thickness increased through interaction of the Kerguelen plume with the existing oceanic lithosphere. The Moho deepened largely due to the load of the Bengal Fan sediments. The absence of rifted crustal blocks on the Bangladesh margin and the continuity of the COB into the onshore Bengal Basin together imply that the present Bangladesh region was under marine conditions at least until the beginning of Bengal Fan sedimentation (i.e. no less than 23 Ma).
Age, origin and palaeogeography of the Southern Irumide Belt, Zambia
Authors: Alessio Brandon L. , Collins Alan S. , Clark Chris , Glorie Stijn , Siegfried Pete R. , Taylor Richard
Published: February 2019

The Southern Irumide Belt (SIB) records over one and a half billion years (
c
. 2000–500 Ma) of tectonic evolution along the southern Congo Craton margin. To understand this evolution we present U–Pb, Lu–Hf, REE zircon and structural data for the SIB of Zambia, which are used to investigate its formation, evolution and relationship to the Irumide Belt of the southern Congo Craton. Orthogneiss in the Chewore–Rufunsa and Chipata terranes yields ages between
c
. 2040 and 2000 Ma. This implies the presence of Paleoproterozoic basement throughout the SIB, similar to basement rocks within the Irumide Belt. Detrital zircon data from the Chipata Terrane yield age populations and
ε
Hf
(
t
) values that are equivalent to those for samples from other SIB terranes and the Irumide Belt. The similarities between basement units and overlying sedimentary sequences in the SIB and Irumide Belt indicate that the SIB formed an integral part of the southern Congo margin since the Paleoproterozoic, rather than accreting to this margin during the late Mesoproterozoic. Subsequent structural deformation in this region occurred as two phases, a north–south-directed compression during the late Neoproterozoic to Cambrian, and a weaker east–west-directed compression during the Phanerozoic.

Supplementary material:
Sample locations and descriptions, including descriptions of zircon morphologies and cathodoluminescence characteristics (accompanied by images), U–Pb, Lu–Hf and REE zircon data (including diagrams) for all unknowns and reference materials, as well as whole-rock geochemical data (including diagram) for granites of the Nyimba–Sinda Terrane are available at:
https://doi.org/10.6084/m9.figshare.c.4386344
Himalayan earthquakes: a review of historical seismicity and early 21st century slip potential
Authors: Bilham Roger
Published: February 2019

This article summarizes recent advances in our knowledge of the past 1000 years of earthquakes in the Himalaya using geodetic, historical and seismological data, and identifies segments of the Himalaya that remain unruptured. The width of the Main Himalayan Thrust is quantified along the arc, together with estimates for the bounding coordinates of historical rupture zones, convergence rates, rupture propagation directions as constrained by felt intensities. The 2018 slip potential for fifteen segments of the Himalaya are evaluated and potential magnitudes assessed for future earthquakes should these segments fail in isolation or as contiguous ruptures. Ten of these fifteen segments are sufficiently mature currently to host a great earthquake (M
w
≥ 8). Fatal Himalayan earthquakes have in the past occurred mostly in the daylight hours. The death toll from a future nocturnal earthquake in the Himalaya could possibly exceed 100 000 due to increased populations and the vulnerability of present-day construction methods.
Climate change, water-related disasters, flood control and rainfall forecasting: a case study of the São Francisco River, Brazil
Authors: Kuwajima Julio Issao , Fan Fernando Mainardi , Schwanenberg Dirk , Assis Dos Reis Alberto , Niemann André , Mauad Frederico Fábio
Published: February 2019

Because of climate change, the frequency, intensity and/or duration of extreme weather events such as floods, droughts, storms and extreme temperatures is increasing. These events are often related to loss of property, money and life, especially in poor and developing countries where there is no or poor disaster management due to social and financial difficulties or due to a lack of synergy between the mitigation actions taken. Negative impacts can be reduced and losses can be better handled with proper water management techniques. However, these should not be handled solely with traditional management. The actual problem cannot be over simplified as merely a question of coping with resources availability and demand. Therefore, the present paper aims to summarize advances in weather forecasting and reservoir operation in the Upper São Francisco River, strategic to Brazil because it provides water to the semi-arid region and energy for economically thriving Brazilian regions. Moreover, it discusses challenges, opportunities and improvements needed to implement these advances in the current national integrated water resources management. This is mainly focused on water-related disaster mitigation.
Issues and Challenges of Load Balancing Techniques in Cloud Computing
Authors: Kumar Pawan , Kumar Rakesh
Published: February 2019

With the growth in computing technologies, cloud computing has added a new paradigm to user services that allows accessing Information Technology services on the basis of pay-per-use at any time and any location. Owing to flexibility in cloud services, numerous organizations are shifting their business to the cloud and service providers are establishing more data centers to provide services to users. However, it is essential to provide cost-effective execution of tasks and proper utilization of resources. Several techniques have been reported in the literature to improve performance and resource use based on load balancing, task scheduling, resource management, quality of service, and workload management. Load balancing in the cloud allows data centers to avoid overloading/underloading in virtual machines, which itself is a challenge in the field of cloud computing. Therefore, it becomes a necessity for developers and researchers to design and implement a suitable load balancer for parallel and distributed cloud environments. This survey presents a state-of-the-art review of issues and challenges associated with existing load-balancing techniques for researchers to develop more effective algorithms.