bluuebunny/crossref_metadata_2025 huggingface dataset:
Three-Dimensional Computational Loss Analysis of a Compressor for Heavy Duty Truck Engine Turbochargers
Authors: Abel Matthias , Martinez-Botas Ricardo F. , Wöhr Michael , Müller Markus , Leweux Johannes
Published: October 2019

This paper presents a detailed loss analysis of a centrifugal compressor stage with a vaned diffuser for application in a heavy-duty engine turbocharger. The analysis is carried out in order to investigate the loss distribution in the stage. To quantify the impact of different loss types and locations, a detailed validated steady-state three-dimensional (3D) computational fluid dynamics (CFD) solution is employed. The local entropy production rate is calculated for two operating points (full load and part load), which are most relevant to the real-world operation of the compressor in a truck application. Two methods are suggested as the procedure for the division of the whole fluid volume into subvolumes because this is key for the resulting loss distribution. The primary loss-generating mechanisms are shown at main operating conditions to reveal the regions of improvement. A detailed grid study was conducted to enable the calculation of the entropy ratio. It was possible to capture around 78% (partial load) and 70% (full load) of the entropy production with a mesh with circa 100 × 106 elements. Around half of the losses were due to the boundary layer friction, followed by losses associated with a boundary layer separation resulting from the back-flow at the shroud contour close to the impeller exit and back disk friction accounted for with 6–7% of the stage's losses.
A Novel Bulk-Flow Model for Pocket Damper Seals
Authors: Cangioli Filippo , Vannini Giuseppe , Chirathadam Thomas
Published: October 2019

In this paper, a novel bulk-flow model for pocket damper seals (PDS) is introduced. The model is based on two control volumes (CVs) for each circumferential pocket of the seal. The continuity, circumferential momentum, and energy equations are considered for each control volume. The circumferential recirculating flow within the pocket is modeled for the first time. The boundary layer theory is used to estimate the recirculating flow area, and the Swamee–Jain friction factor correlation allows for defining the dissipation of the circumferential velocity. The perturbation method is used to solve the partial derivative governing equations in the zeroth- and first-order system of equations. The rotordynamic coefficients are evaluated by integrating the dynamic pressure and rotor shear stresses along the circumferential direction. The predictions are compared to the experimental data, which refer to test conditions representative of high-pressure centrifugal compressors. Numerical predictions are accurate for both high positive–negative inlet preswirl ratios. Leakage predictions are also aligned with measurements. Finally, sealing selection approach is introduced in the paper for comparing the dynamic behavior of two different sealing technologies and identifying stable regions as a function of the rotor natural frequency and preswirl ratio.
Signal Processing for Enhancing Impulsiveness Toward Estimating Location of Multiple Roller Defects in a Taper Roller Bearing
Authors: Kumar Anil , Kumar Rajesh
Published: October 2019

Rolling element defect identification is a difficult task. The reason being that defect on the rolling element has both rotational as well as revolutionary motion. To identify rolling element defect in a taper roller bearing, a novel signal processing scheme is proposed which results in a substantial increase in kurtosis and impulse factor of the vibration signal. The scheme constitutes a series of operations. In the beginning, the raw signal is decomposed by ensemble empirical mode decomposition (EEMD) and inverse filtering (INF). The above two stages of signal processing extract hidden impulses which are suppressed in the noise present in the experimental data. In the third stage of processing, continuous wavelet transform (CWT) using adaptive wavelet is applied to the preprocessed signal to produce a 2D map of the CWT scalogram. This transformation results in a higher coefficient in the region of impulse produced due to the defect. Finally, time marginal integration (TMI) of the CWT scalogram is carried out for defect localization. The defect frequency was evaluated with an accuracy of 97.81% and defect location was identified with an accuracy of 92%.
Collapse Experiments and Reliability Analyses of Corroded Pipes for Offshore Applications
Authors: Oliveira N. , Netto T. A.
Published: October 2019

The collapse pressure of subsea pipelines containing corrosion defects is usually predicted by deterministic methods, either numerically or through empirical formulations. A simple deterministic procedure for estimating the collapse pressure of pipes with narrow and long defects has been recently proposed by Netto, T. A. (2009, “On the Effect of Narrow and Long Corrosion Defects on the Collapse Pressure of Pipelines,” Appl. Ocean Res., 31(2), pp. 75–81) and Netto, T. A. (2010, “A Simple Procedure for the Prediction of the Collapse Pressure of Pipelines With Narrow and Long Corrosion Defects—Correlation With New Experimental Data,” Appl. Ocean Res., 32(1), pp. 132–134). The formulation was based on a combined small-scale experimental program and nonlinear numerical analyses accounting for different materials and defect geometries. This paper presents additional experimental tests on corroded pipes under external pressure. The collapse pressure calculated using the equation proposed by Netto is compared with this new set of experiments and also with test results available in open literature. These results are used to estimate the equation uncertainty. A sensitivity analysis is also performed to identify how geometric parameters of the defects influence the reduction of collapse pressure. However, loads and resistance parameters have uncertainties. These uncertainties are related to the geometric and material parameters of the pipe and the operational conditions. To account for these uncertainties, a method to predict the probability of collapse of a corroded pipeline along its operational life is proposed. The methodology is illustrated through a case study in which concepts of structural reliability are used to evaluate the detrimental effect of corrosion damages in a pipeline, providing the basis to develop a risk-based maintenance strategy.
Hydrodynamic Performance Characteristics of a Fluid Film Journal Bearing With a Rectangular Jacking Pocket
Authors: Branagan Michael , Morgan Neal , Goyne Christopher , Fittro Roger , Rockwell Robert , He Minhui
Published: October 2019

To compensate for an extremely heavy journal, jacking pockets can be added to the surface of pads in fluid film bearings. Jacking pockets can range in size and shape and will have an influence on the hydrodynamic performance of the bearing. Computational fluid dynamics (CFD) was used to better understand the influence of the geometry of a rectangular/stadium-shaped, jacking pocket on the performance of bearings. First, the influence of the pocket depth on the pressure profile of the bearing was investigated. A varying profile occurred with jacking pocket depths less than 6.6 × Cb. After this threshold, the pocket depth ceased to have an influence on the pressure profile. A second study examined the circumferential length of the pocket, and the pressure profile was found to approach the smooth case as the pocket circumferential length decreased. Response surface models were created to map the influence of the jacking pocket geometry on the journal location in the bearing, power loss, and stiffness characteristics of the bearing. This is the first study on influence of the geometry of a jacking pocket on the operation and linear stiffnesses of the bearing in fluid film journal bearings.
Energy Harvesting Using a Torsional Mode L-Shaped Unimorph Structure: Modeling and Experimental Investigations
Authors: Li Haisheng , Liu Donghuan , Wang Jianjun , Shang Xinchun
Published: October 2019

Previous studies have proved that the piezoelectric L-shaped beam-mass structure is a good candidate to harvest energy from ambient mechanical vibration. However, most researches merely focused on bending mode of the structure, which only can capture energy from in-plane base excitation. To fully exert the advantages of L-shaped harvesters, this paper will explore their energy harvesting performance on torsional mode with out-of-plane base excitation. The electromechanical coupling governing equation of the L-shaped harvester in torsional mode is derived by applying Gauss's law and the Euler–Bernoulli beam theory with linear assumption, and the analytical results are also validated with experimental results. In addition, the influences of key geometric parameters on the resonance frequency and output voltage of the harvester are also presented. This work demonstrates the feasibility of utilizing torsional mode of the L-shaped unimorph structure to harvest energy from out-of-plane mechanical vibration, which shows the potential of designing multi-directional and multi-frequency L-shaped harvesters.
A Statistical Characterization of the Effects and Interactions of Small and Large Mistuning on Multistage Bladed Disks
Authors: Kurstak Eric , D'Souza Kiran
Published: October 2019

As turbomachinery systems continue to push the limits of modern technology, the modeling techniques being developed also continue to push modern computational limits. While modeling the pristine system during the design process is important, it is equally important to model behavior of mistuned systems, due to wear or manufacturing processes. This work carries out a statistical analysis on a two-stage system consisting of integrally bladed rotors. Various forms of large geometric mistuning, such as missing mass, bends, and dents, are considered. These forms of large mistuning are based on previously reported damage seen in actual engines that have ingested volcanic ash. This work also aims to investigate the interaction of these large mistuned systems with various levels of small mistuning to further understand this complex interaction. For every case studied, a reduced-order model (ROM) will be constructed that includes the effects of small and large mistuning. Large mistuning will only be applied to a single sector of a single stage. Random patterns of small mistuning will be applied to each case of large mistuning after which a modal analysis and a forced response analysis are run. By observing the energy distribution of each mode for the mistuned system, a qualitative trend can be created between various types and levels of large mistuning and the impact they have on changing the dynamics of the multistage system. The amplification factors from the forced response analyses help in understanding the impact small mistuning has when coupled with large mistuning and when the effects of small mistuning dominate over the large mistuning effects.
A Framework for Simulation-Based Internal Flooding Risk Assessment
Authors: Dubey Ankit R. , Gupta Abhinav , Coleman Justin
Published: October 2019

Internal flooding due to pipe breaks can interfere with a plant's ability to safely shut down or maintain the decay heat removal. Flooding simulation tools require information on location of pipe breaks and the degree of damage at each location as input for assessing the flooding risk. This can be especially challenging as the number of potential leakage locations are quite large and the state-of-the-art simulation tools cannot determine the degree of damage at a location. This paper presents a novel simulation-based framework that can be used to determine seismically induced flooding scenarios including the potential locations of leakage and the degree of leakage at each location. The proposed framework builds upon a few recent experimental and simulation-based studies on piping fragilities. This research identifies that a direct use of piping fragility information by flooding simulation tools is not appropriate. This paper presents a new approach that creates mutually exclusive and collectively exhaustive events to characterize the complete sample space at each location and employs the total probability theorem to characterize the probabilities for each event in this space. This paper also identifies the importance of including the temporal effects in the piping fragilities in order to allow a more realistic simulation of internal flooding scenarios.
Analysis and Validation of a Flexible Planar Two Degrees-of-Freedom Parallel Manipulator With Structural Passive Compliance
Authors: Chen Genliang , Zhang Zhuang , Kong Lingyu , Wang Hao
Published: October 2019

Passive compliance plays an important role in robot pick-and-place manipulation where large interaction force will be produced in response to small misalignments. In this paper, the authors report on compliance analysis and validation of a novel planar pick-and-place parallel manipulator consisting of a flexible limb. In the proposed manipulator, a planar flexible parallelogram linkage, which is coupled with a rigid one, is introduced to connect the moving and the base platforms. Since the flexible parallelogram linkage is capable of producing large deformation in both the horizontal and the vertical directions, the end effector of the manipulator can generate wide-range motions because of the flexible links. An efficient approach to the large deflection problem of flexible links is used to precisely predict the kinetostatics of the manipulator. Then, a compensation algorithm to the structural deflection of the links can be developed to actively control the position of the parallel manipulator’s end effector. The merit of the proposed flexible manipulator is its intrinsic passive compliance while performing pick-and-place tasks. A prototype is fabricated to conduct experiments for the validation of the proposed idea. The results show that the prototype has acceptable positioning accuracy, even when a large external load is exerted on its end effector. The compliance properties of the proposed flexible manipulator have also been verified in both the horizontal and the vertical directions.
Convolutional Neural Network Surrogate Models for the Mechanical Properties of Periodic Structures
Authors: Messner Mark C.
Published: October 2019

This work describes neural network surrogate models for calculating the effective mechanical properties of a periodic composites. The models achieve good accuracy even when only provided with training data sampling a small portion of the design space. As an example, the surrogate models are applied to solving the inverse design problem of finding structures with optimal mechanical properties. The surrogate models are sufficiently accurate to recover optimal solutions in general agreement with established topology optimization methods. However, improvements will be required to develop robust, efficient neural network-based surrogate models and several directions for future research are highlighted here.
A Deep Reinforcement Learning Approach for Global Routing
Authors: Liao Haiguang , Zhang Wentai , Dong Xuliang , Poczos Barnabas , Shimada Kenji , Burak Kara Levent
Published: October 2019

Global routing has been a historically challenging problem in the electronic circuit design, where the challenge is to connect a large and arbitrary number of circuit components with wires without violating the design rules for the printed circuit boards or integrated circuits. Similar routing problems also exist in the design of complex hydraulic systems, pipe systems, and logistic networks. Existing solutions typically consist of greedy algorithms and hard-coded heuristics. As such, existing approaches suffer from a lack of model flexibility and usually fail to solve sub-problems conjointly. As an alternative approach, this work presents a deep reinforcement learning method for solving the global routing problem in a simulated environment. At the heart of the proposed method is deep reinforcement learning that enables an agent to produce a policy for routing based on the variety of problems, and it is presented with leveraging the conjoint optimization mechanism of deep reinforcement learning. Conjoint optimization mechanism is explained and demonstrated in detail; the best network structure and the parameters of the learned model are explored. Based on the fine-tuned model, routing solutions and rewards are presented and analyzed. The results indicate that the approach can outperform the benchmark method of a sequential A* method, suggesting a promising potential for deep reinforcement learning for global routing and other routing or path planning problems in general. Another major contribution of this work is the development of a global routing problem sets generator with the ability to generate parameterized global routing problem sets with different size and constraints, enabling evaluation of different routing algorithms and the generation of training datasets for future data-driven routing approaches.
Wave Manipulation of Two-Dimensional Periodic Lattice by Parametric Excitation
Authors: Yang Xiao-Dong , Cui Qing-Dian , Zhang Wei
Published: October 2019

Phononic crystals composed of delicately designed periodic units are used to control spatial and spectral properties of acoustic or elastic waves. The ability to manipulate transmitting waves in a real-time dynamic manner provides a new concept in programable phononic crystals and metamaterials. In this study, the mechanical waves and bandgaps in a two-dimensional spring-mass array loaded by high-frequency parametric excitation have been investigated by both analytical and numerical methods. It is found that the high-frequency parametric excitation provides an equivalent additional stiffness which leads to low-frequency bandgaps. By tuning the parametric excitation, the versatility of such a dynamic modulating technique has been presented. The waveguide structure has also been designed and studied by non-uniformly distributed parametric excitations.
Fracture Strength Behaviors of Ultra-High-Temperature Materials
Authors: Cheng Tianbao , Qu Zhaoliang , Li Weiguo , Fang Daining
Published: October 2019

Ultra-high-temperature materials have been widely used as key components in high-end equipment. However, the existing studies are mainly conducted at room and moderate temperatures. Besides, they are mainly carried out by experiments. Theories on the temperature dependence of fracture strength are rarely reported. In this work, experimental methods for the ultra-high-temperature tensile properties of advanced materials and the elastic–plastic properties of coatings are developed, respectively, based on induction heating and radiation furnace heating technologies. A temperature-dependent fracture strength model for ceramics is proposed in the view of energy. The experimental methods and theoretical model are verified on the 2D plain-weave carbon fiber reinforced silicon carbide thermal structure composite, yttria-stabilized zirconia thermal barrier coating, and Si3N4 ceramics. The study shows that the mechanical properties of materials decrease significantly at ultra-high temperatures. The results are useful for the applications of ultra-high-temperature materials in thermal structure engineering.
Survey of Immersed Boundary Approaches for Finite Element Analysis
Authors: Kumar Ashok V.
Published: October 2019

Mesh generation for traditional finite element analysis has proven to be very difficult to fully automate especially using hexahedral elements for complex 3D geometry. Several modifications to the finite element method (FEM), such as the meshless methods, have been proposed for avoiding mesh generation. An alternative approach has recently gained popularity where the geometry, created as a solid model in cad software, is embedded or immersed in a nonconforming background mesh for analysis. In this approach, referred to here as the immersed boundary approach, a background mesh that is independent of the geometry is used for piecewise interpolation or approximation of the solution. Therefore, a uniform mesh with regular-shaped or undistorted elements can be used, and such a mesh is easy to generate automatically. When the geometry is immersed in the background mesh, the boundary elements are often only partly inside the geometry and the nodes of the mesh may not be on the boundaries. Many new methods have been developed to integrate over partial elements and to apply boundary and interface conditions when the boundaries of the geometries do not conform to the background mesh. These methods are reviewed in this article with particular emphasis on the implicit boundary method and step boundary method for applying boundary conditions. In addition, B-spline elements and several applications of the immersed boundary approach are surveyed including composite microstructures and structural elements for plates and shells.
Prediction and Experimental Validation of Part Thermal History in the Fused Filament Fabrication Additive Manufacturing Process
Authors: Roy Mriganka , Yavari Reza , Zhou Chi , Wodo Olga , Rao Prahalada
Published: October 2019

Part design and process parameters directly influence the instantaneous spatiotemporal distribution of temperature in parts made using additive manufacturing (AM) processes. The temporal evolution of temperature in AM parts is termed herein as the thermal profile or thermal history. The thermal profile of the part, in turn, governs the formation of defects, such as porosity and shape distortion. Accordingly, the goal of this work is to understand the effect of the process parameters and the geometry on the thermal profile in AM parts. As a step toward this goal, the objectives of this work are two-fold. First, to develop and apply a finite element-based framework that captures the transient thermal phenomena in the fused filament fabrication (FFF) additive manufacturing of acrylonitrile butadiene styrene (ABS) parts. Second, validate the model-derived thermal profiles with experimental in-process measurements of the temperature trends obtained under different material deposition speeds. In the specific context of FFF, this foray is the critical first-step toward understanding how and why the thermal profile directly affects the degree of bonding between adjacent roads (linear track of deposited material), which in turn determines the strength of the part, as well as, propensity to form defects, such as delamination. From the experimental validation perspective, we instrumented a Hyrel Hydra FFF machine with three non-contact infrared temperature sensors (thermocouples) located near the nozzle (extruder) of the machine. These sensors measure the surface temperature of a road as it is deposited. Test parts are printed under three different settings of feed rate, and subsequently, the temperature profiles acquired from the infrared thermocouples are juxtaposed against the model-derived temperature profiles. Comparison of the experimental and model-derived thermal profiles confirms a high degree of correlation therein, with a mean absolute percentage error less than 6% (root mean squared error <6 °C). This work thus presents one of the first efforts in validating thermal profiles in FFF via direct in situ measurement of the temperature. In our future work, we will focus on predicting defects, such as delamination and inter-road porosity based on the thermal profile.
Analytical Characterization and Experimental Validation of the Material Extrusion Wave Infill for Thin-Walled Structures
Authors: Chisena Robert S. , Shih Albert J.
Published: October 2019

The wave infill for material extrusion (MEX) of the thin-walled structure (TWS) is presented. The wave infill, a lightweight truss-like porous core structure sandwiched between two outer walls, is an efficient toolpath pattern for the MEX of TWS. Analytical models for predicting the stiffness, load capacity, fabrication time, and mass were established for two orthogonal in-plane and layer-to-layer variations inherent in MEX wave infill parts. Rectangular prism, four-point flexural bending specimens representing the in-plane and layer-to-layer orientations with wave infill were fabricated by MEX of polyamide-12 (Nylon-12) material. From these specimens, fabrication time and mass were measured, and four-point flexural tests were conducted to measure the stiffness and load capacity of the beam. Analytical models were compared with the experimental measurements to identify their predictive capabilities. Stiffness for in-plane and layer-to-layer orientations was predicted well with the relative root-mean-square error (RRMSE) of 7% and 6%, respectively. Load capacity in in-plane and layer-to-layer orientations had the RRMSE of 23% and 22%, respectively. Fabrication time and mass were predicted well with a RRMSE of 7% and 6%, respectively. The methods established in this study are the foundation for optimal design and MEX of wave infill TWSs with generalized loads.
In situ Auger electron spectroscopy of complex oxide surfaces grown by pulsed laser deposition
Authors: Orvis Thomas , Surendran Mythili , Liu Yang , Cunniff Austin , Ravichandran Jayakanth
Published: October 2019

The authors report in situ Auger electron spectroscopy (AES) of the surfaces of complex oxide thin films grown by pulsed laser deposition (PLD). The authors demonstrate the utility of the technique in studying elemental composition by collecting characteristic Auger spectra of elements from samples such as complex oxide thin films and single crystals. In the case of thin films, AES studies can be performed with single unit cell precision by monitoring thickness during deposition with reflection high energy electron diffraction. The authors address some of the challenges in achieving in situ and real-time AES studies on complex oxide thin films grown by PLD. Sustained layer-by-layer PLD growth of a CaTiO3/LaMnO3 superlattice allows depth-resolved elemental composition analysis during the growth process. The evolution of the Auger spectra of elements from individual layers was used to perform compositional analysis with monolayer-depth resolution.
HIF-independent synthetic lethality between CDK4/6 inhibition and VHL loss across species
Authors: Nicholson Hilary E. , Tariq Zeshan , Housden Benjamin E. , Jennings Rebecca B. , Stransky Laura A. , Perrimon Norbert , Signoretti Sabina , Harris Isaac S. , Endress Jennifer E. , Kaelin William G.
Published: October 2019

Blocking the kinases CDK4 and CDK6 may be a more broadly applicable therapy for patients with ccRCC.
Repurposing Salicylamide for Combating Multidrug-Resistant Neisseria gonorrhoeae
Authors: Alhashimi Marwa , Mayhoub Abdelrahman , Seleem Mohamed N.
Published: October 2019

The U.S. Centers for Disease Control and Prevention (CDC) lists
Neisseria gonorrhoeae
as one of the most urgent antibiotic-resistant threats in the United States. This is due to the emergence of clinical isolates that have developed resistance to nearly every antibiotic used to treat gonorrhea and highlights the critical need to find new therapeutics.
Derepression of the
smvA
Efflux System Arises in Clinical Isolates of Proteus mirabilis and Reduces Susceptibility to Chlorhexidine and Other Biocides
Authors: Pelling H. , Bock L. J. , Nzakizwanayo J. , Wand M. E. , Denham E. L. , MacFarlane W. M. , Sutton J. M. , Jones B. V.
Published: October 2019

Proteus mirabilis
is a common pathogen of the catheterized urinary tract and often described as intrinsically resistant to the biocide chlorhexidine (CHD). Here, we demonstrate that derepression of the
smvA
efflux system has occurred in clinical isolates of
P. mirabilis
and reduces susceptibility to CHD and other cationic biocides.
l-Serine Lowers the Inflammatory Responses during Pasteurella multocida Infection
Authors: He Fang , Yin Zheng , Wu Chenlu , Xia Yaoyao , Wu Miaomiao , Li Pan , Zhang Huihui , Yin Yuanyuan , Li Nengzhang , Zhu Guoqiang , Ren Wenkai , Peng Yuanyi
Published: October 2019

Pasteurella multocidacauses a variety of infectious diseases in various species of mammals and birds, resulting in enormous economic loss to the modern livestock and poultry industry. However, the mechanism of host-pathogen interaction is unclear. Here, we found thatl-serine levels were significantly decreased in murine lungs infected withP. multocida.
Taurine Alleviates Schistosoma-Induced Liver Injury by Inhibiting the TXNIP/NLRP3 Inflammasome Signal Pathway and Pyroptosis
Authors: Liu Xin , Zhang Ya-Rong , Cai Chen , Ni Xian-Qiang , Zhu Qing , Ren Jin-Ling , Chen Yao , Zhang Lin-Shuang , Xue Chang-Ding , Zhao Jie , Qi Yong-Fen , Yu Yan-Rong
Published: October 2019

Schistosomiasis is a parasitic helminth disease that can cause severe inflammatory pathology, leading to organ damage, in humans. During a schistosomal infection, the eggs are trapped in the host liver, and products derived from eggs induce a polarized Th2 cell response, resulting in granuloma formation and eventually fibrosis.
Is the local seismicity in western Hispaniola (Haiti) capable of imaging northern Caribbean subduction?
Authors: Corbeau J. , Gonzalez O.L. , Clouard V. , Rolandone F. , Leroy S. , Keir D. , Stuart G. , Momplaisir R. , Boisson D. , Prépetit C.
Published: October 2019

The boundary between the Caribbean and North American plates in the Hispaniola region is the northwestern termination of the North American plate subduction evolving from westward subduction in the Lesser Antilles to southward subduction in the Greater Antilles and oblique collision against the Bahamas platform in Cuba. We analyze P waveforms recorded by 27 broadband seismic temporary stations deployed during the Trans-Haiti project. Seismicity recorded by the temporary network from June 2013 to June 2014 is used to locate the earthquakes. A total of 514 events were identified with magnitudes ranging from 1 to 4.5. Twenty-six moment tensors were calculated by full waveform inversion using the ISOLA software. The analysis of the new moment tensors for the Haiti upper lithosphere indicates that normal, thrust and strike-slip faulting are present but with a majority of thrust faulting. The mean P and T axes for the moment tensors indicated that the current compressional deformation is mainly N-S to NNE-SSW. Moreover, a dozen intermediate-depth earthquakes (>70 km) are located under Haiti, with one event in the south of the island reaching 260 km depth. The seismic data of the Haiti network, over a one-year time period, tend to confirm the existence of a lithospheric slab inherited from southward subduction under the Greater Antilles. The scarcity of the intermediate-depth seismic events in this area may be the effect of the lack of a dense seismic network or may indicate that we image the western slab edge.
Primary care physicians’ access to in-house ultrasound examinations across Europe: a questionnaire study
Authors: Aakjær Andersen Camilla , Jensen Martin Bach B , Toftegaard Berit Skjødeberg , Vedsted Peter , Harris Michael , Research group Örenäs
Published: October 2019

Objective

The overall objective of this study was to examine the differences in ultrasound availability in primary care across Europe.

Design

Cross-sectional study.

Setting

Primary care.

Participants

Primary care physicians (PCPs).

Primary and secondary outcomes measures

The primary aim was to describe the variation in in-house primary care ultrasonography availability across Europe using descriptive statistics. The secondary aim was to explore associations between in-house ultrasonography availability and the characteristics of PCPs and their clinics using a mixed-effects logistic regression model.

Results

We collected data from 20 European countries. A total of 2086 PCPs participated, varying from 59 to 446 PCPs per country. The median response rate per country was 24.8%. The median (minimum–maximum) percentage of PCPs across Europe with access to in-house abdominal ultrasonography was 15.3% (0.0%–98.1%) and 12.1% (0.0%–30.8%) had access to in-house pelvic ultrasonography with large variations between countries. We found associations between in-house abdominal ultrasonography availability and larger clinics (OR 2.5, 95% CI 1.2 to 4.9) and clinics with medical doctors specialised in areas, which traditionally use ultrasonography (OR 2.1, 95% CI 1.1 to 3.8). Corresponding associations were found between in-house pelvic ultrasonography availability and larger clinics (OR 1.9, 95% CI 1.3 to 2.7) and clinics with medical doctors specialised in areas, which traditionally use ultrasonography (OR 3.0, 95% CI 1.8 to 5.1). Additionally, we found a negative association between urban clinics and in-house pelvic ultrasound availability (OR 0.5, 95% CI 0.2 to 0.9).

Conclusions

Across Europe, there is a large variation in PCPs’ access to in-house ultrasonography and organisational aspects of primary care seem to determine this variation. If evidence continues to support ultrasonography as a front-line point-of-care test, implementation strategies for increasing its availability in primary care are needed. Future research should focus on facilitators and barriers that may affect the implementation process.
Time from diagnosis to treatment of colorectal cancer in a South Australian clinical registry cohort: how it varies and relates to survival
Authors: Roder David , Karapetis Christos Stelios , Olver Ian , Keefe Dorothy , Padbury Robert , Moore James , Joshi Rohit , Wattchow David , Worthley Dan L , Miller Caroline Louise , Holden Carol , Buckley Elizabeth , Powell Kate , Buranyi-Trevarton Dianne , Fusco Kellie , Price Timothy
Published: October 2019

Objectives

Some early studies indicated lower survival with longer time from diagnosis to cancer treatment, but others showed the reverse. We investigated time to treatment of colorectal cancer and associations with survival.

Setting and participants

Clinical registry data for colorectal cancer cases diagnosed in 2000–2010 at four major public hospitals in South Australia and treated by surgery (n=1675), radiotherapy (n=616) and/or systemic therapy (n=1556).

Design

A historic cohort design, with rank-order tests for ordinal clinical and sociodemographic predictors and multiple logistic regression for comparing time from diagnosis to treatment. Unadjusted Kaplan-Meier estimates and adjusted Cox proportional hazards regression were used to investigate disease-specific survival by time to treatment.

Outcome measures

Time to treatment and survival from diagnosis to death from colorectal cancer.

Results

Treatment (any type) commenced for 87% of surgical cases<60 days of diagnosis, with 80% having surgery within this period. Of those receiving radiotherapy, 59% began this treatment<60 days, and of those receiving systemic therapy, the corresponding proportion was 56%. Adjusted analyses showed treatment delay >60 days was more likely for rectal cancers, 2006–2010 diagnoses, residents of northern than other metropolitan regions and for surgery, younger ages <50 years and unexpectedly, those residing closer to metropolitan services. Adjusting for clinical and sociodemographic factors, and diagnostic year, better survival occurred in<2 years from diagnosis for time to treatment >30 days. Survival in the 3–10 years postdiagnosis generally did not differ by time to treatment, except for lower survival for any treatment >90 days for surgical cases.

Conclusions

The lower survival<2 years from diagnosis for treatment<30 days of diagnosis is consistent with other studies attributed to preferencing more complicated cases for earlier care. Lower 3–10 years survival for surgical cases first treated >90 days from diagnosis is consistent with previously reported U-shaped relationships.
What is the best way to keep walking and moving around for individuals with Machado-Joseph disease? A scoping review through the lens of Aboriginal families with Machado-Joseph disease in the Top End of Australia
Authors: Carr Jennifer J , Lalara Joyce , Lalara Gayangwa , Smith Moira , Quaill Jennifer , Clough Alan R , Lowell Anne , Barker Ruth N
Published: October 2019

Objectives

Machado-Joseph disease (MJD) is the most common spinocerebellar ataxia worldwide. Prevalence is highest in affected remote Aboriginal communities of the Top End of Australia. Aboriginal families with MJD from Groote Eylandt believe ‘staying strong on the inside and outside’ works best to keep them walking and moving around, in accordance with six key domains that form the ‘Staying Strong’ Framework. The aim of this current study was to review the literature to: (1) map the range of interventions/strategies that have been explored to promote walking and moving around (functional mobility) for individuals with MJD and; (2) align these interventions to the ‘Staying Strong’ Framework described by Aboriginal families with MJD.

Design

Scoping review.

Data sources

Searches were conducted in July 2018 in MEDLINE, EMBASE, CINAHL, PsychINFO and Cochrane Databases.

Eligibility criteria for selecting studies

Peer-reviewed studies that (1) included adolescents/adults with MJD, (2) explored the effects of any intervention on mobility and (3) included a measure of mobility, function and/or ataxia were included in the review.

Results

Thirty studies were included. Few studies involved participants with MJD alone (12/30). Most studies explored interventions that aligned with two ‘Staying Strong’ Framework domains, ‘exercising your body’ (n=13) and ‘searching for good medicine’ (n=17). Few studies aligned with the domains having ‘something important to do’ (n=2) or ‘keeping yourself happy’ (n=2). No studies aligned with the domains ‘going country’ or ‘families helping each other’.

Conclusions

Evidence for interventions to promote mobility that align with the ‘Staying Strong’ Framework were focused on staying strong on the outside (physically) with little reflection on staying strong on the inside (emotionally, mentally and spiritually). Findings suggest future research is required to investigate the benefits of lifestyle activity programmes that address both physical and psychosocial well-being for families with MJD.
Treatment of essential tremor: current status
Authors: Sharma Soumya , Pandey Sanjay
Published: October 2019

Essential tremor is the most common cause of tremor involving upper limbs, head and voice. The first line of treatment for limb tremor is pharmacotherapy with propranolol or primidone. However, these two drugs reduce the tremor severity by only half. In medication refractory and functionally disabling tremor, alternative forms of therapy need to be considered. Botulinum toxin injections are likely efficacious for limb, voice and head tremor but are associated with side effects. Surgical interventions include deep brain stimulation; magnetic resonance-guided focused ultrasound and thalamotomy for unilateral and deep brain stimulation for bilateral procedures. Recent consensus classification for essential tremor has included a new subgroup, ‘Essential tremor plus’, who have associated subtle neurological ‘soft signs’, such as dystonic posturing of limbs and may require a different treatment approach. In this review, we have addressed the current management of essential tremor with regard to different anatomical locations of tremor as well as different modalities of treatment.
Life‐threatening hyperkalaemia in a five‐year‐old rottweiler undergoing bilateral elbow arthroscopy
Authors: Boustead Keagan John , Zeiler Gareth
Published: October 2019

A five‐year‐old aggressive female spayed rottweiler presenting for bilateral elbow arthroscopy developed an acute life‐threatening hyperkalaemia intraoperatively under general anaesthesia. The dog was premedicated with a combination of ketamine (9.5 mg/kg), medetomidine (0.033 mg/kg) and morphine (0.3 mg/kg) intramuscularly. The effect of the premedication was considered moderate. Anaesthesia was induced 30 minutes later with intravenous propofol and maintained with isoflurane in oxygen and air. Profound bradycardia (heart rate falling from 95 to 33 beats per minute) occurred at 140 minutes after administering the premedication. Initially, high vagal tone was suspected and anticholinergic drugs (atropine and glycopyrrolate) were administered with minimal effect. The bradycardia was permanently corrected with epinephrine and atipamezole treatment. A definitive diagnosis of hyperkalaemia was made postoperatively on analysis of serum samples collected intraoperatively. This case report discusses the potential causes of hyperkalaemia in this case and other veterinary reports using similar drug combinations.
Gluon GPDs and exclusive photoproduction of quarkonium in forward region
Authors: Cui Z. L. , Hu M. C. , Ma J. P.
Published: October 2019

Forward photoproduction of $$J/\psi $$J/ψ can be used to extract generalized parton distributions (GPDs) of gluons. We analyze the process at twist-3 level and study relevant classifications of twist-3 gluon GPDs. At leading power or twist-2 level the produced $$J/\psi $$J/ψ is transversely polarized. We find that at twist-3 the produced $$J/\psi $$J/ψ is longitudinally polarized. Our study shows that in the high-energy limit the twist-3 amplitude is only suppressed by the inverse power of the heavy quark mass relatively to the twist-2 amplitude. This indicates that the power correction to the cross-section of unpolarized $$J/\psi $$J/ψ can have a sizable effect.The poles in the hard factor convoluted with twist-3 gluon GPDs may concern the GPDs discontinuities, which will be briefly discussed in this work. We have also derived the amplitude of the production of $$h_c$$hc at twist-3, but the result contains end-point singularities. The production of other quarkonia has been briefly discussed.
The Restricted Edge-Connectivity of Kronecker Product Graphs
Authors: Ma Tianlong , Wang Jinling , Zhang Mingzu
Published: October 2019

The restricted edge-connectivity of a connected graph [Formula: see text], denoted by [Formula: see text], if exists, is the minimum number of edges whose deletion disconnects the graph such that each connected component has at least two vertices. The Kronecker product of graphs [Formula: see text] and [Formula: see text], denoted by [Formula: see text], is the graph with vertex set [Formula: see text], where two vertices [Formula: see text] and [Formula: see text] are adjacent in [Formula: see text] if and only if [Formula: see text] and [Formula: see text]. In this paper, it is proved that [Formula: see text] for any graph [Formula: see text] and a complete graph [Formula: see text] with [Formula: see text] vertices, where [Formula: see text] is minimum edge-degree of [Formula: see text], and a sufficient condition such that [Formula: see text] is [Formula: see text]-optimal is acquired.
Thermodynamics of the Bardeen black hole in anti-de Sitter space
Authors: Li Cong , Fang Chao , He Miao , Ding Jiacheng , Deng Jianbo
Published: October 2019

In this paper, we study thermodynamics of the regular black holes with Bardeen–AdS black hole. The cut-off radius which is the minimal radius of the stable Bardeen–AdS black hole has been obtained from temperature and heat capacity analysis, respectively. Moreover, the thermodynamical stability of the Bardeen–AdS black hole is learned by the Gibbs free energy and the heat capacity. In this work, we find similar properties to the van der Waals liquid-gas system.
The Influence of Hubness on NN-Descent
Authors: Bratić Brankica , Houle Michael E. , Kurbalija Vladimir , Oria Vincent , Radovanović Miloš
Published: October 2019

The K-nearest neighbor graph (K-NNG) is a data structure used by many machine-learning algorithms. Naive computation of the K-NNG has quadratic time complexity, which in many cases is not efficient enough, producing the need for fast and accurate approximation algorithms. NN-Descent is one such algorithm that is highly efficient, but has a major drawback in that K-NNG approximations are accurate only on data of low intrinsic dimensionality. This paper represents an experimental analysis of this behavior, and investigates possible solutions. Experimental results show that there is a link between the performance of NN-Descent and the phenomenon of hubness, defined as the tendency of intrinsically high-dimensional data to contain hubs – points with large in-degrees in the K-NNG. First, we explain how the presence of the hubness phenomenon causes bad NN-Descent performance. In light of that, we propose four NN-Descent variants to alleviate the observed negative inuence of hubs. By evaluating the proposed approaches on several real and synthetic data sets, we conclude that our approaches are more accurate, but often at the cost of higher scan rates.
Improving Time-Aware Recommendations in Open Source Packages
Authors: Symeonidis Panagiotis , Coba Ludovik , Zanker Markus
Published: October 2019

Collaborative filtering techniques have been studied extensively during the last decade. Many open source packages (Apache Mahout, LensKit, MyMediaLite, rrecsys etc.) have implemented them, but typically the top-N recommendation lists are only based on a highest predicted ratings approach. However, exploiting frequencies in the user/item neighborhood for the formation of the top-N recommendation lists has been shown to provide superior accuracy results in offline simulations. In addition, most open source packages use a time-independent evaluation protocol to test the quality of recommendations, which may result to misleading conclusions since it cannot simulate well the real-life systems, which are strongly related to the time dimension. In this paper, we have therefore implemented the time-aware evaluation protocol to the open source recommendation package for the R language — denoted rrecsys — and compare its performance across open source packages for reasons of replicability. Our experimental results clearly demonstrate that using the most frequent items in neighborhood approach significantly outperforms the highest predicted rating approach on three public datasets. Moreover, the time-aware evaluation protocol has been shown to be more adequate for capturing the life-time effectiveness of recommender systems.
Microscopic spin-orbit potential for p +6He elastic scattering
Authors: Mahmoud Zakaria M. M. , Ibraheem Awad A. , Hassanain M. A.
Published: October 2019

In this work, we simultaneously reanalyzed the differential elastic scattering cross-sections ([Formula: see text]) and the vector analyzing power ([Formula: see text]) of [Formula: see text]He elastic scattering. This analysis was performed using the folded optical model for both real central and spin-orbit (SO) potentials, respectively. For the imaginary central, we used the usual Woods-Saxon (WS) form. Three different model density distributions are used to calculate the potential. We aimed to examine the applicability of the microscopically derived SO potential and the structure effect of 6He nucleus. The presence of the [Formula: see text] experimental data of [Formula: see text]He makes it interesting for this study. Our calculations showed that the three densities gave similar predictions for the cross-sections data. The three microscopic SO potentials calculations of [Formula: see text] are not in a good agreement with the experimental data. We concluded that the SO formalism in its current form needs more investigations for exotic halo nuclei.