bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of the Impact of Wire Resistance on Nano-scale Memristor Crossbar Array Implementing Perceptron Neural Network
Authors: Truong Son Ngoc
Published: July 2020

In this work, the impact of wire resistance in pure memristor crossbar array is mathematically analysed and verified by the circuit simulation. The memristor crossbar without CMOS device is utilized for application of character image recognition, in which wire resistance is presented. Memristor crossbar circuit is analysed separately with respect to wire resistance on vertical line and wire resistance on horizontal line. The result shows that wire resistance on vertical line can be eliminated because they can be self-compensated. The simulation result agrees with the analysis. The variation of output voltage caused by wire resistance less affect the recognition rate of memristor circuit. On the other hand, when wire resistance on horizontal line is assumed to be 2.5Ω. The output voltages are varied remarkably. Such variation of output voltage degrades the recognition rate of memristor crossbar circuit. The interesting phenomenon is also investigated. The column that is close to the first column has less variation of output voltage, whereas the one that is far from the first column has much variation of output voltage. The result can be used in improving the memristor crossbar architecture, which can tolerate the impact of wire resistance. For example, if we want to increase the size of crossbar, we should increase the number of rows, rather than the number of columns.
Study of Forming Efficiency by Real-time Correction of Head Nozzle Height in Directed Energy Deposition
Authors: Aizawa Kengo , Ueda Masahiro , Aoyama Hideki , Yamazaki Kazuo
Published: July 2020

Laser metal deposition is of two types: powder bed and metal deposition. Either method is expected to be a breakthrough in innovative design and manufacturing technology development because both methods can form shapes that cannot be formed by conventional removal processing. One metal deposition method is directed energy deposition (DED), in which a laser irradiates the target position on the metal layer to melt it, and metal powder is supplied to the target position to perform molding. DED is expected to produce large parts and repair molds. However, as the lamination mechanism is not sufficiently clarified, relationships between process parameters, material properties, molding accuracy, and molding efficiency are not clear, making stable molding difficult [1]One obstacle to stable molding is that the distance between the head nozzle that supplies the metal powder and the molten pool cannot currently be kept constant. In this study, we measure the distance between the head nozzle and the molten pool using a triangulation method, propose a method to control the position of the head nozzle to keep the distance constant, and experimentally verify the method’s usefulness.
Effect of Segment Thickness on Internal Force of Shield Tunnel under Abnormal Loading Conditions
Authors: Zhang Bolin , Zheng Jun
Published: July 2020

Segment thickness is one of the important parameters of shield tunnel structure design. Segment thickness determines the section stiffness and mechanical performance of shield tunnel structure. Considering the load type of overload and unload, a three-dimensional fine shield tunnel numerical model was established. The full-scale test was used to verify the correctness of the numerical model. In the end, the effect of segment thickness on the internal force of shield tunnel structure under abnormal loading conditions was analyzed. The results show that the internal force of each section of the tunnel structure increases with the increase of the thickness of the segment, and the difference of the internal force between the different segment thickness increases with the increase of the overload and the degree of unloading. Increasing the thickness of segment will delay the breakpoint of the bending moment and axial force (critical instability state). The excessive increase of the segment thickness can lead to a large increase in the internal force of the tunnel structure, resulting in a decrease in the crack resistance of the tunnel structure.
Effects of Friction Stir Welding Parameters of Dissimilar Aluminum Alloys on Residual Stress and Microhardness
Authors: Baisukhan Adirek , Nakkiew Wasawat
Published: July 2020

The aim of this research is to use a full factorial design to determine the significant factors of friction stir welding (FSW) process of dissimilar AA6061-T6 and AA7075-T651 aluminum alloys, on the surface residual stress and microhardness. There are a total of three factors studied: rotation speed, welding speed and workpiece layout. The results showed that the factors that have a statistically significant effect on residual stress occurring are welding speed, workpiece layout and interaction between rotation speed and welding speed. The appropriate parameters for FSW process of dissimilar aluminum alloys are rotation speed of 1400 rpm, welding speed of 50 mm/min and the layout of the workpiece by advancing side (AS) uses AA6061-T6 sheet, while retreating side (RS) uses AA7075-T651 sheet, which will result in the surface residual stress of −34.33 MPa. This compressive residual stress will be beneficial to the welded joint for retard the occurrence of cracks caused by fatigue. The hardness of all workpieces have similar tendency, thermo-mechanically affected zone (TMAZ) area in both AS and RS gave the least hardness, which found that the AA6061-T6 and AA7075-T651 sheets had a hardness of approximately 55HV and 110HV respectively.
Deformation behavior study in a model dual phase system of copper–martensitic steel using in-situ synchrotron X-ray diffraction
Authors: Teimouri M , Godfrey A , Yu B , Tsuji N
Published: July 2020

In this study, the deformation behavior of two phases in a model dual phase system of copper and a martensitic stainless steel was investigated using in situ synchrotron X-ray diffraction. Due to the different crystallographic structures of copper and martensite, their diffraction patterns are well separated such that the strain distribution and the load partitioning between the phases could be investigated under loading using standard methods. The copper matrix started to yield at low stress levels after a short stage of elastic deformation and the different lattice strain of the copper and martensite indicated that load partitioning took place after yielding of the copper.
Remaining Useful Life Prediction of Lithium-ion Battery based on Attention Mechanism with Positional Encoding
Authors: Zhou Beitong , Cheng Cheng , Ma Guijun , Zhang Yong
Published: July 2020

The rising demands of more reliable and stable electrical systems attach importance to accurate Remaining Useful Life (RUL) prediction of the lithium-ion batteries. As artificial intelligence and machine learning techniques advance, data-driven methods especially deep learning algorithms have become the rising star in RUL prediction. Recurrent Neural Networks (RNNs) and their variants such as Long Short Term Memory have proven effectiveness in various sequential tasks. However, due to its iterative nature along the time axis, RNNs take much time for information to flow through the network for prediction. Inspired by recent advance brought by Transformer in sequence transduction tasks, we proposed the attention mechanism based Convolutional Neural Network (CNN) with positional encoding to tackle this problem. The attention mechanism enables the network to focus on specific parts of sequences and positional encoding injects position information while utilizing the parallelization merits of CNN on GPUs. Empirical experiments show that the proposed approach is both time effective and accurate in battery RUL prediction.
Static characteristics of a simple rotor-bearing system: modelling and experiment
Authors: Dang Phuoc Vinh , Minh Nhat Le Dinh , Vo Nhu Thanh , Ngo Thanh Nghi , Le Hoai Nam , Nguyen Huu Nhan
Published: July 2020

The dynamics of rotating machinery have been extensively investigated during the past century. To date, longer rotating shafts, higher rotating velocity, higher fluid pressure, and generally high performances are required. For this purpose, a deep understanding and a more accurate modelling of the rotating machinery dynamical behaviour is needed, especially in terms of the resultant vibrations and stability issues. In this paper, a mathematical model was developed for a simple rigid rotor-bearing system using finite element method. Several natural frequencies and corresponding mode shapes of the systems were presented. In order to validate the model, some experimental tests were performed using a small test rig. The response of the system in the frequency domain and the direct orbit of the shaft were plotted as well.
Empirical study on influences of electromagnetic field on Hall Effect sensor for analysing oil lubricant deterioration
Authors: Satthamsakul S , Sriratana W , Sriratana L
Published: July 2020

This study aims to present the procedure developed for detecting deterioration of oil lubricant under variation of electromagnetic field which was generated by a ferrite-core solenoid coil. The overall diameter of coil was 18.5 mm and the inductance was 22.421 mH from direct current stimulation. The results were then compared to those from frequency stimulation. The optimal efficiency of measurement systems was then assessed by real-time analyzing the metal particle contamination of 3 oil lubricants categorized by grade namely ISO 32, ISO 46 and ISO 68 as well as the viscosity under specific conditions which were flow rate and temperature ranging from 25 °C to 100 °C. The analysis was performed to compare the results from experiments of unused and used (approximately 6 months) oil lubricants. From experiments, the viscosity of oil lubricant was reduced when the temperature exceeded 50 °C. However, the stimulation of coil using 0.9 A direct current could clearly distinguish the difference between the unused and used oil lubricants with metal particle contamination comparing to other values of direct currents applied with 0.42 % of error. Also, the 0.5 kHz of frequency would be the most appropriate value for frequency stimulation with 0.38 % of error.
Preparation and photochromic properties of phosphomolybdic acid/rare earth strontium aluminate luminous fiber
Authors: Li Jing , Tang Sisi , Ge Mingqiao , Zhu Yanan , Yu Yuan
Published: July 2020

In this study, we intend to obtain a novel luminous fiber with colour-tuned luminescence via the photoelectron transfer of a phosphomolybdic acid pigment (PAP). The luminous fiber include the SrAl2O4: Eu2+, Dy3+ materials as the luminescence sources, a solid solution of PAP and polyvinyl alcohol as the photoinitiator, amino silicone resin (ASR) as the surface-modified film-forming material and polypropylene (PP) as the matrix, which are prepared by the melt spinning method. The surface morphology was characterized using scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, ultraviolet-visible (UV–vis) spectroscopy, photoluminescence emission spectroscopy, and CIE-1931 chromaticity coordinates. Thus, promising results were obtained, which denoted that the luminescence colour of the luminous fibers could transform from yellow–green to blue by adjusting the PAP concentration. The PL emission spectra of these luminous fibers consisted of two emission peak regions in the range of 430–530 nm. The intensity of the two emission peaks in the fiber reaches the maximum when the concentration of the PAP was 50%. Further, the fibers gradually turned blue with luminescence decay when the fiber was placed in a dark place. The existence of photosensitive discoloration was found to be directly related to the amino groups embedded in the silicone resin coated with the luminous surface material, which reacted with PAP to develop phosphorous molybdenum blue via the photo-reduction process. These findings provide valuable insights toward developing next-generation luminescent materials and multicolor luminous fibers.
Surface defects incorporated diamond machining of silicon
Authors: Khatri Neha , Barkachary Borad M , Muneeswaran B , Al-Sayegh Rajab , Luo Xichun , Goel Saurav
Published: July 2020

This paper reports the performance enhancement benefits in diamond turning of the silicon wafer by incorporation of the surface defect machining (SDM) method. The hybrid micromachining methods usually require additional hardware to leverage the added advantage of hybrid technologies such as laser heating, cryogenic cooling, electric pulse or ultrasonic elliptical vibration. The SDM method tested in this paper does not require any such additional baggage and is easy to implement in a sequential micro-machining mode. This paper made use of Raman spectroscopy data, average surface roughness data and imaging data of the cutting chips of silicon for drawing a comparison between conventional single-point diamond turning (SPDT) and SDM while incorporating surface defects in the (i) circumferential and (ii) radial directions. Complementary 3D finite element analysis (FEA) was performed to analyse the cutting forces and the evolution of residual stress on the machined wafer. It was found that the surface defects generated in the circumferential direction with an interspacing of 1 mm revealed the lowest average surface roughness (Ra) of 3.2 nm as opposed to 8 nm Ra obtained through conventional SPDT using the same cutting parameters. The observation of the Raman spectroscopy performed on the cutting chips showed remnants of phase transformation during the micromachining process in all cases. FEA was used to extract quantifiable information about the residual stress as well as the sub-surface integrity and it was discovered that the grooves made in the circumferential direction gave the best machining performance. The information being reported here is expected to provide an avalanche of opportunities in the SPDT area for low-cost machining solution for a range of other nominal hard, brittle materials such as SiC, ZnSe and GaAs as well as hard steels.
Microstructure-based three-dimensional characterization of chip formation and surface generation in the machining of particulate-reinforced metal matrix composites
Authors: Wu Qi , Zhang Liangchi
Published: July 2020

Particulate-reinforced metal matrix composites (PRMMCs) are difficult to machine due to the inclusion of hard, brittle reinforcing particles. Existing experimental investigations rarely reveal the complex material removal mechanisms (MRMs) involved in the machining of PRMMCs. This paper develops a three-dimensional (3D) microstructure-based model for investigating the MRM and surface integrity of machined PRMMCs. To accurately mimic the actual microstructure of a PRMMC, polyhedrons were randomly distributed inside the matrix to represent irregular SiC particles. Particle fracture and matrix deformation and failure were taken into account. For the model’s capability comparison, a two-dimensional (2D) analysis was also conducted. Relevant cutting experiments showed that the established 3D model accurately predicted the material removal, chip morphology, machined surface finish, and cutting forces. It was found that the matrix-particle-tool interactions led to particle fractures, mainly in the primary shear and secondary deformation zones along the cutting path and beneath the machined surface. Particle fracture and dilodegment greatly influences the quality of a machined surface. It was also found that although a 2D model can reflect certain material removal features, its ability to predict microstructural variation is limited.
Uncovering interpretable relationships in high-dimensional scientific data through function preserving projections
Authors: Liu Shusen , Anirudh Rushil , Thiagarajan Jayaraman J , Bremer Peer-Timo
Published: July 2020

In many fields of science and engineering, we frequently encounter experiments or simulations datasets that describe the behavior of complex systems and uncovering human interpretable patterns between their inputs and outputs via exploratory data analysis is essential for building intuition and facilitating discovery. Often, we resort to 2D embeddings for examining these high-dimensional relationships (e.g. dimensionality reduction). However, most existing embedding methods treat the dimensions as coordinates for samples in a high-dimensional space, which fail to capture the potential functional relationships, and the few methods that do take function into consideration either only focus on linear patterns or produce non-linear embeddings that are hard to interpret. To address these challenges, we proposed function preserving projections (FPP), which construct 2D linear embeddings optimized to reveal interpretable yet potentially non-linear patterns between the domain and the range of a high-dimensional function. The intuition here is that humans are good at understanding potentially non-linear patterns in 2D but unable to interpret non-linear mapping from high-dimensional space to 2D. Therefore, we should restrict the projection to linear but not the pattern we are seeking. Using FPP on real-world datasets, one can obtain fundamentally new insights about high-dimensional relationships in extremely large datasets that could not be processed with existing dimension reduction methods.
Surface functionalization of multi-walled carbon nanotubes by ozone and the enhancement of their environmental applications
Authors: Elsehly Emad M , Chechenin N G , Makunin A V , Shemukhin A A , Motaweh H A
Published: July 2020

Selective functionalization of multiwalled carbon nanotubes (MWNTs) is essential for many prospective applications of such materials. In the present study, MWNTs grown by chemical vapor deposition are functionalized by ozone treatment at room temperature. Through this environmental and effective functionalization method, the chemical reactivity of MWNTs can be altered and tuned. Ozone functionalized MWNTs (F-MWNTs) were characterized by Raman spectroscopy, SEM, EDS, BET surface area, XPS, and FTIR. The results obtained confirm the formation of oxygen groups attached to the surface of ozone-treated nanotubes (e.g. carboxyl), which modify their physicochemical properties and boost the surface reactivity. The F-MWNT filters showed 99.5% manganese removal efficiency at 20 ppm concentration in the solution, which is higher than the efficiency reported earlier. The optimal parameters for Mn adsorption by F-MWNTs were studied. Possible mechanisms of F-MWNT adsorption processes are also discussed.
Engagement in Cognitively Stimulating Activities Mediates the Relationship between Openness and Attention/Executive Functions, but Not Memory in Older Adults
Authors: Mercuri Giulia , Holtzer Roee
Published: July 2020

Objective

Openness has a positive association with cognitive functioning and engagement in cognitively stimulating activities (CSA). Older adults who engage in more CSA tend to show greater preservation of their cognitive skills; thus, we examined whether: higher Openness would be associated with higher attention/executive functions (AEF) and verbal memory; and CSA would mediate the relationship between Openness and AEF, as well as verbal memory.

Method

477 community-dwelling older adults (65+ years) were included in the current cross-sectional study. Composite variables of AEF (TMT-A&B, COWAT, and DSST) and verbal memory (RBANS immediate and delayed verbal memory subtasks) were included. Openness was assessed via the Big-5 Inventory and CSA with the Leisure Activity Questionnaire.

Method

477 community-dwelling older adults (65+ years) were included in the current cross-sectional study. Composite variables of AEF (TMT-A&B, COWAT, and DSST) and verbal memory (RBANS verbal memory subtasks) were included. Openness was assessed via the Big-5 Inventory and CSA with the Leisure Activity Questionnaire.

Results

Linear regressions indicated a significant positive association between Openness and AEF (β = .09, p < .01), but not verbal memory (β = .06, p = .06). A significant partial mediation was demonstrated between Openness, CSA, and AEF (c: β = .08, p < .05, 95%CI = .02−.14; c′: β = .02, 95%CI = .01−.03). The mediation of Openness, CSA, and verbal memory was not significant (c: β = .06, p > .05, 95%CI = .01−.11; c′: β = .00, 95%CI = −.01−.01).

Conclusions

The association between Openness and AEF, but not verbal memory, was partially mediated by CSA in healthy older adults. The findings suggest that those who are more open to and highly engaged in CSA may have a later in life advantage in preserving their AEF abilities.
PDR: a new genome assembly evaluation metric based on genetics concerns
Authors: Xie Luyu , Wong Limsoon
Published: July 2020

Motivation

Existing genome assembly evaluation metrics provide only limited insight on specific aspects of genome assembly quality, and sometimes even disagree with each other. For better integrative comparison between assemblies, we propose, here, a new genome assembly evaluation metric, Pairwise Distance Reconstruction (PDR). It derives from a common concern in genetic studies, and takes completeness, contiguity, and correctness into consideration. We also propose an approximation implementation to accelerate PDR computation.

Results

Our results on publicly available datasets affirm PDR’s ability to integratively assess the quality of a genome assembly. In fact, this is guaranteed by its definition. The results also indicated the error introduced by approximation is extremely small and thus negligible.

Availabilityand implementation

https://github.com/XLuyu/PDR.

Supplementary information

Supplementary data are available at Bioinformatics online.
Experimental Criminology and the Free-Rider Dilemma
Authors: Koehler Johann , Smith Tobias
Published: July 2020

Experimental criminology promises a public good: when experiments generate findings about criminal justice interventions, everyone benefits from that knowledge. However, experimental criminology also produces a free-rider problem: when experiments test interventions on the units where problems concentrate, only the sample assumes the risk of backfire. This mismatch between who pays for criminological knowledge and who rides on it persists even after traditional critiques of experimental social science are addressed. We draw from medicine and economics to define experimental criminology’s free-rider problem and expose a dilemma. Either we distribute the costs of producing policy-actionable knowledge to the entire beneficiary population or we justify isolating the risk of experimental harm on that class of the population where ethical concerns are most acute.
Discharge, But No Exit: An Existential Qualitative Interpretive Meta-Synthesis of Veteran Reintegration
Authors: Tarbet Zachary , Moore Steven , Alanazi Ahmed
Published: July 2020

Ongoing campaigns in support of the Global War on Terrorism have created an influx of veterans attempting to reintegrate into civilian society. While some veterans reintegrate easily, others continue to struggle. An increasing number of studies have begun to take a more holistic approach to understanding the root causes of the distress observed in reintegrating veterans. The objective of this study was to utilise the existential framework as conceptualised by Irvin Yalom to generate a deeper understanding of the underlying factors contributing to the struggles that veterans experience in their return to society. A qualitative interpretive meta-synthesis (QIMS) approach was used to hear the combined voices of a selection of veterans from the USA and UK. A directed content analysis was used in conjunction with the QIMS methodology to categorise novel constructs in the context of existential ultimate concerns resulting in nine new themes: loss of identity, fear of death, loss of control, reliance on authority, feelings of alienation, self-isolation, resentment towards civilians, loss of collective sense of duty and loss of purpose. Findings enhance the understanding of conflicting values and beliefs underlying reintegration problems, informing future social work practice and research.
CD8 T cell nigral infiltration precedes synucleinopathy in early stages of Parkinson’s disease
Authors: Galiano-Landeira Jordi , Torra Albert , Vila Miquel , Bové Jordi
Published: July 2020

There is no consensus on the exact role of the adaptive immune system in Parkinson’s disease pathogenesis, although there is increasing evidence that it is somehow involved. Moreover, T cell infiltration in the brain has not been thoroughly studied in Parkinson’s disease and no study has assessed the infiltration in incidental Lewy body diseases cases that are considered to be early presymptomatic stages of the disease. In this study, we performed an immunohistochemistry/immunofluorescence quantitative and phenotypic assessment of T cell infiltration in human substantia nigra pars compacta and analysed the correlations with neuronal death and synucleinopathy throughout different stages of the disease. We included two groups of incidental Lewy disease in the study. One of the groups, which is believed to be the earliest stage of the disease, showed α-synuclein aggregates only in the olfactory bulb. The second group also presented α-synuclein aggregates in the substantia nigra. We also assessed the formation of different α-synuclein aggregates throughout the different stages of the unified staging system for Lewy body disorders (I to IV). We found that CD8 T cells were increased in diagnosed Parkinson’s disease cases compared to the control group and their density positively correlated with neuronal death. Some of the infiltrating CD8 T cells were indeed contacting dopaminergic neurons. No differences were found regarding CD4 T cells. In the earliest stage of the disease, when substantia nigra α-synuclein aggregation is absent, we found a robust CD8 T cell infiltration and no dopaminergic neuronal death yet. Conversely, in the next stage we found neuronal loss and a milder CD8 T cell infiltration. CD8 T cell infiltration paralleled that of α-synuclein accumulation and neuronal death throughout stages II to IV. We also confirmed that CD8 T cells in charge of immune surveillance and involved in the aetiopathogenesis of the disease are equipped with cytolytic enzymes (granzyme A, B and K) and/or proinflammatory cytokines (interferon gamma), and that phenotypic differences were observed between early and late stages of the disease. We also demonstrate that a high proportion of nigral CD8 T cells are tissue resident memory T cells. Our results show that nigral cytotoxic CD8 T cell infiltration is an earlier pathogenic event than α-synuclein aggregation and neuronal death and that it parallels the progression of neuronal death and synucleinopathy in Parkinson’s disease. Overall, our study suggests that CD8 T cell cytotoxic attack may initiate and propagate neuronal death and synucleinopathy in Parkinson’s disease.
Urethral Microbiota in Men: Association of Haemophilus influenzae and Mycoplasma penetrans With Nongonococcal Urethritis
Authors: Srinivasan Sujatha , Chambers Laura C , Tapia Kenneth A , Hoffman Noah G , Munch Matthew M , Morgan Jennifer L , Domogala Daniel , Sylvan Lowens M , Proll Sean , Huang Meei-Li , Soge Olusegun O , Jerome Keith R , Golden Matthew R , Hughes James P , Fredricks David N , Manhart Lisa E
Published: July 2020

Background

Nongonococcal urethritis (NGU) is a common syndrome with no known etiology in ≤50% of cases. We estimated associations between urethral bacteria and NGU in men who have sex with men (MSM) and men who have sex with women (MSW).

Methods

Urine was collected from NGU cases (129 MSM, 121 MSW) and controls (70 MSM, 114 MSW) attending a Seattle STD clinic. Cases had ≥5 polymorphonuclear leukocytes on Gram stain plus symptoms or discharge; controls had <5 PMNs, no symptoms, no discharge. NGU was considered idiopathic when Neisseria gonorrhoeae, Chlamydia trachomatis, Mycoplasma genitalium, Trichomonas vaginalis, adenovirus, and herpes simplex virus were absent. The urethral microbiota was characterized using 16S rRNA gene sequencing. Compositional lasso analysis was conducted to identify associations between bacterial taxa and NGU and to select bacteria for targeted qPCR.

Results

Among NGU cases, 45.2% were idiopathic. Based on compositional lasso analysis, we selected Haemophilus influenzae (HI) and Mycoplasma penetrans (MP) for targeted qPCR. Compared with 182 men without NGU, the 249 men with NGU were more likely to have HI (14% vs 2%) and MP (21% vs 1%) (both P ≤ .001). In stratified analyses, detection of HI was associated with NGU among MSM (12% vs 3%, P = .036) and MSW (17% vs 1%, P < .001), but MP was associated with NGU only among MSM (13% vs 1%, P = .004). Associations were stronger in men with idiopathic NGU.

Conclusions

HI and MP are potential causes of male urethritis. MP was more often detected among MSM than MSW with urethritis.
Human Immunodeficiency Virus (HIV) Drug Resistance, Phylogenetic Analysis, and Superinfection Among Men Who Have Sex with Men and Transgender Women in Sub-Saharan Africa: HIV Prevention Trials Network (HPTN) 075 Study
Authors: Sivay Mariya V , Palumbo Philip J , Zhang Yinfeng , Cummings Vanessa , Guo Xu , Hamilton Erica L , McKinstry Laura , Ogendo Arthur , Kayange Noel , Panchia Ravindre , Dominguez Karen , Chen Ying Q , Sandfort Theodorus G M , Eshleman Susan H
Published: July 2020

Background

The HIV Prevention Trials Network (HPTN) 075 study evaluated the feasibility of enrolling and retaining men who have sex with men (MSM) and transgender women (TGW) from Kenya, Malawi, and South Africa. During the study follow-up, 21 participants acquired human immunodeficiency virus (HIV) (seroconverters). We analyzed HIV subtype diversity, drug resistance, transmission dynamics, and HIV superinfection data among MSM and TGW enrolled in HPTN 075.

Methods

HIV genotyping and drug resistance testing were performed for participants living with HIV who had viral loads >400 copies/mL at screening (prevalent cases, n = 124) and seroconverters (n = 21). HIV pol clusters were identified using Cluster Picker. Superinfection was assessed by a longitudinal analysis of env and pol sequences generated by next-generation sequencing.

Results

HIV genotyping was successful for 123/124 prevalent cases and all 21 seroconverters. The major HIV subtypes were A1 (Kenya) and C (Malawi and South Africa). Major drug resistance mutations were detected in samples from 21 (14.6%) of 144 participants; the most frequent mutations were K103N and M184V/I. Phylogenetic analyses identified 11 clusters (2–6 individuals). Clusters included seroconverters only (n = 1), prevalent cases and seroconverters (n = 4), and prevalent cases only (n = 6). Superinfections were identified in 1 prevalent case and 2 seroconverters. The annual incidence of superinfection was higher among seroconverters than among prevalent cases, and was higher than the rate of primary HIV infection in the cohort.

Conclusions

This report provides important insights into HIV genetic diversity, drug resistance, and superinfection among MSM and TGW in sub-Saharan Africa. These findings may help to inform future HIV prevention interventions in these high-risk groups.
Proadrenomedullin Predicts Severe Disease in Children With Suspected Community-acquired Pneumonia
Authors: Florin Todd A , Ambroggio Lilliam , Brokamp Cole , Zhang Yin , Nylen Eric S , Rattan Mantosh , Crotty Eric , Belsky Michael A , Krueger Sara , Epperson Thomas N , Kachelmeyer Andrea , Ruddy Richard M , Shah Samir S
Published: July 2020

Background

Proadrenomedullin (proADM), a vasodilatory peptide with antimicrobial and anti-inflammatory properties, predicts severe outcomes in adults with community-acquired pneumonia (CAP) to a greater degree than C-reactive protein and procalcitonin. We evaluated the ability of proADM to predict disease severity across a range of clinical outcomes in children with suspected CAP.

Methods

We performed a prospective cohort study of children 3 months to 18 years with CAP in the emergency department. Disease severity was defined as mild (discharged home), mild–moderate (hospitalized but not moderate–severe or severe), moderate–severe (eg, hospitalized with supplemental oxygen, broadening of antibiotics, complicated pneumonia), and severe (eg, vasoactive infusions, chest drainage, severe sepsis). Outcomes were examined using proportional odds logistic regression within the cohort with suspected CAP and in a subset with radiographic CAP.

Results

Among 369 children, median proADM increased with disease severity (mild: median [IQR], 0.53 [0.43–0.73]; mild–moderate: 0.56 [0.45–0.71]; moderate–severe: 0.61 [0.47–0.77]; severe: 0.70 [0.55–1.04] nmol/L) (P = .002). ProADM was significantly associated with increased odds of developing severe outcomes (suspected CAP: OR, 1.68; 95% CI, 1.2–2.36; radiographic CAP: OR, 2.11; 95% CI, 1.36–3.38) adjusted for age, fever duration, antibiotic use, and pathogen. ProADM had an AUC of 0.64 (95% CI, .56–.72) in those with suspected CAP and an AUC of 0.77 (95% CI, .68–.87) in radiographic CAP.

Conclusions

ProADM was associated with severe disease and discriminated moderately well children who developed severe disease from those who did not, particularly in radiographic CAP.
Longitudinal Dynamics of the Neutralizing Antibody Response to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Infection
Authors: Wang Kai , Long Quan-Xin , Deng Hai-Jun , Hu Jie , Gao Qing-Zhu , Zhang Gui-Ji , He Chang-Long , Huang Lu-Yi , Hu Jie-Li , Chen Juan , Tang Ni , Huang Ai-Long
Published: July 2020

Background

Coronavirus disease 2019 (COVID-19) is a global pandemic with no licensed vaccine or specific antiviral agents for therapy. Little is known about the longitudinal dynamics of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)–specific neutralizing antibodies (NAbs) in patients with COVID-19.

Methods

Blood samples (n = 173) were collected from 30 patients with COVID-19 over a 3-month period after symptom onset and analyzed for SARS-CoV-2–specific NAbs using the lentiviral pseudotype assay, coincident with the levels of IgG and proinflammatory cytokines.

Results

SARS-CoV-2–specific NAb titers were low for the first 7–10 days after symptom onset and increased after 2–3 weeks. The median peak time for NAbs was 33 days (interquartile range [IQR], 24–59 days) after symptom onset. NAb titers in 93.3% (28/30) of the patients declined gradually over the 3-month study period, with a median decrease of 34.8% (IQR, 19.6–42.4%). NAb titers increased over time in parallel with the rise in immunoglobulin G (IgG) antibody levels, correlating well at week 3 (r = 0.41, P < .05). The NAb titers also demonstrated a significant positive correlation with levels of plasma proinflammatory cytokines, including stem cell factor (SCF), TNF-related apoptosis-inducing ligand (TRAIL), and macrophage colony-stimulating factor (M-CSF).

Conclusions

These data provide useful information regarding dynamic changes in NAbs in patients with COVID-19 during the acute and convalescent phases.
Transmission Dynamics in Tuberculosis Patients With Human Immunodeficiency Virus: A Systematic Review and Meta-analysis of 32 Observational Studies
Authors: Martinez Leonardo , Woldu Henok , Chen Cheng , Hallowell Benjamin D , Castellanos Maria Eugenia , Lu Peng , Liu Qiao , Whalen Christopher C , Zhu Limei
Published: July 2020

Background

There are large knowledge gaps on the transmission dynamics of Mycobacterium tuberculosis in settings where both tuberculosis and human immunodeficiency virus (HIV) are endemic. We aimed to assess the infectiousness of tuberculosis patients coinfected with HIV.

Methods

We systematically searched for studies of contacts of both HIV-positive and HIV-negative tuberculosis index cases. Our primary outcome was Mycobacterium tuberculosis infection in contacts. Data on sputum smear and lung cavitation status of index cases were extracted from each study to assess effect modification. Secondary outcomes included prevalent tuberculosis and HIV in contacts of HIV-positive and HIV-negative index cases.

Results

Of 5255 original citations identified, 32 studies met inclusion criteria, including 25 studies investigating M. tuberculosis infection (Nparticipants = 36 893), 13 on tuberculosis (Nparticipants = 18 853), and 12 on HIV positivity (Nparticipants = 18 424). Risk of M. tuberculosis infection was lower in contacts of HIV-positive index cases (odds ratio [OR], 0.67, 95% confidence interval [CI], .58–.77) but was heterogeneous (I2 = 75.1%). Two factors modified this relationship: the lung cavitary status of the index case and immunosuppression (measured through CD4 counts or HIV or acquired immunodeficiency syndrome diagnoses) among index people living with HIV. Rates of HIV were consistently higher in contacts of coinfected index cases (OR, 4.9; 95% CI, 3.0–8.0). This was modified by whether the study was in sub-Saharan Africa (OR, 2.8; 95% CI, 1.6–4.9) or in another global region (OR, 9.8; 95% CI, 5.9–16.3).

Conclusions

Tuberculosis patients coinfected with HIV are less infectious than HIV-uninfected cases when they have severe immunosuppression or paucibacillary disease. Contacts of coinfected index cases are almost 5 times more likely to also have HIV.
Role of Human Bocavirus Respiratory Tract Infection in Hematopoietic Cell Transplant Recipients
Authors: Ogimi Chikara , Martin Emily T , Xie Hu , Campbell Angela P , Waghmare Alpana , Jerome Keith R , Leisenring Wendy M , Milano Filippo , Englund Janet A , Boeckh Michael
Published: July 2020

Background

Limited data exist regarding the impact of human bocavirus (BoV) in hematopoietic cell transplant (HCT) recipients.

Methods

In a longitudinal surveillance study among allogeneic HCT recipients, pre-HCT and weekly post-HCT nasal washes and symptom surveys were collected through day 100, then at least every 3 months through 1 year post-HCT at the Fred Hutchinson Cancer Research Center (2005–2010). Samples were tested by multiplex semiquantitative polymerase chain reaction (PCR) for 12 viruses. Plasma samples from BoV + subjects were analyzed by PCR. Separately, we conducted a retrospective review of HCT recipients with BoV detected in lower respiratory tract specimens.

Results

Among 51 children and 420 adults in the prospective cohort, 21 distinct BoV respiratory tract infections (RTIs) were observed by 1 year post-HCT in 19 patients. Younger age and exposure to children were risk factors for BoV acquisition. Univariable models among patients with BoV RTI showed higher peak viral load in nasal samples (P = .04) and presence of respiratory copathogens (P = .03) were associated with presence of respiratory symptoms, but BoV plasma detection was not. Only watery eyes and rhinorrhea were associated with BoV RTI in adjusted models. With additional chart review, we identified 6 HCT recipients with BoV detected in lower respiratory tract specimens (incidence rate of 0.4% [9/2509] per sample tested). Although all cases presented with hypoxemia, 4 had respiratory copathogens or concomitant conditions that contributed to respiratory compromise.

Conclusions

BoV RTI is infrequent in transplant recipients and associated with mild symptoms. Our studies did not demonstrate convincing evidence that BoV is a serious respiratory pathogen.
Central Station-Based Demand Prediction for Determining Target Inventory in a Bike-Sharing System
Authors: Huang Jianbin , Sun Heli , Li He , Huang Longji , Li Ao , Wang Xiangyu
Published: July 2020

Predicting the bike demand can help rebalance the bikes and improve the service quality of a bike-sharing system. A lot of works focus on predicting the bike demand for all the stations, which is unnecessary as the travel cost of rebalance operations increases sharply as the number of stations increases. In this paper, we propose a framework for predicting the hourly bike demand based on the central stations we define. Firstly, we propose Two-Stage Station Clustering Algorithm to assign central stations and common stations into each cluster. Secondly, we propose a hierarchical prediction model to predict the hourly bike demand for every cluster and each central station progressively. Thirdly, we use a well-studied queuing model to determine the target initial inventory for each central station. The most innovative contribution of this paper is proposing the concept of central station, the use of a novel algorithm to cluster the central stations and present a hierarchical model, containing the Time and Weather Similarity Weighted K-Nearest Neighbor Algorithm and a linear model to predict the bike demand for central stations. The experimental results on the New York citi bike system demonstrate that our proposed method is more accurate than other methods in solving existing problems.
Maintenance Golimumab Treatment in Pediatric UC Patients With Moderately to Severely Active UC: PURSUIT PEDS PK Long-Term Study Results
Authors: Hyams Jeffrey S , O’Brien Christopher D , Padgett Lakshmi , Rosh Joel R , Turner Dan , Veereman Genevieve , Griffiths Anne M , Heyman Melvin B , Wahbeh Ghassan , Adedokun Omoniyi J , Strauss Richard S , Lynch John P , Chan Daphne
Published: July 2020

Background

Long-term safety, pharmacokinetics, and efficacy of open-label golimumab therapy in children with moderate–severe ulcerative colitis were evaluated.

Methods

Week-6 golimumab responders (Mayo score decrease of ≥30% and ≥3 points from baseline, rectal bleeding subscore of 0/1 or ≥1 decrease from baseline) entered the long-term extension at week 14 and received maintenance therapy (subcutaneous, q4w). Patients ≥45 kg could receive at-home treatments at week 18. Pharmacokinetic, safety, and efficacy results were summarized through week 126 (2 years).

Results

Among 35 enrolled children, 21 (60%) responded at week 6 and 20 entered the long-term extension (median age of 14.5 years and median weight of 46.1 kg). Eleven of 20 patients (55%) completed 2 years of treatment. No anaphylactic or serum sickness-like reactions, opportunistic infections, malignancies, tuberculosis, or deaths occurred. The safety profile of golimumab from weeks 14 through 126 and that observed through week 14 was generally consistent. Median trough golimumab concentrations in evaluable patients were consistent from weeks 14 (1.39, interquartile range 0.67–3.60) through 102 (1.18, 0.78–2.16), but higher at week 110 (4.10, 1.30–4.81). The incidence of antigolimumab antibodies increased from 10% (2/20) at week 30 to 25.0% (5/20) at week 126; 1 patient had neutralizing antibodies. At week 110, 50% (10/20) of patients were in remission (ie, Pediatric Ulcerative Colitis Activity Index <10). Among all enrolled patients, 28.6% (10/35) achieved remission at week 110.

Conclusions

Among children with ulcerative colitis who initially responded to golimumab induction and received q4w maintenance treatment in the long-term extension, 50% showed continued clinical benefit through 2 years. No new safety signals were observed.
School Crisis Management Planning
Authors: Elbedour Salman , Alsubie Futiem , Al’Uqdah Shareefah N , Bawalsah Joseph A
Published: July 2020

The fundamental need for safety in schools requires research-based and trauma-informed strategies for implementing crisis management plans (CMPs). Beyond the immediate harm, longer-term potential outcomes of crises are psychological trauma and damage to the reputation for safety of the school, leading to staff attrition. An effective CMP involves (a) planning, (b) communication, (c) protocols for immediate action, and (d) protocols specific to different types of school crises. School crises can occur on the organizational level, such as natural disasters or shootings; community level, such as bullying or community violence; or individual level, such as suicide, pregnancy, or family changes. This article incorporates research from the business sector as well as education, social work, and psychology to describe the vital components of a school CMP and the role of the school mental health staff. School mental health staff must be central to development and implementation of a trauma-informed school CMP that incorporates prevention, communication, and different protocols for the various types of crises.
Practitioners’ Self-Assessment of Family-Centered Practice in Telepractice Versus In-Person Early Intervention
Authors: McCarthy Melissa , Leigh Greg , Arthur-Kelly Michael
Published: July 2020

For infants and young children who are identified as deaf or hard of hearing (DHH), best practice principles indicate the provision of family-centered early intervention (FCEI). However, factors such as geographical inaccessibility and workforce shortages can limit families’ access to FCEI in their local area. One strategy for overcoming these barriers is telepractice—a method of connecting families and practitioners using synchronous, two-way audiovisual technologies. This study compared the self-assessed use of family-centered practices by a group of practitioners delivering FCEI through telepractice with that of a similar group delivering FCEI in-person. A sample of 38 practitioners (15 telepractice and 23 in-person) from two early intervention programs for children who are DHH completed a self-assessment tool: the Measures of Processes of Care for Service Providers. Results indicated that there were no significant differences between telepractice and in-person sessions with regard to practitioners’ self-assessment of their use of family-centered practices.
Case report: Synergetic effect of ischaemia and increased vagal tone inducing ventricular fibrillation in a patient with Brugada syndrome
Authors: Van Malderen Sophie C H , Schultz Carl J , Jordaens Luc
Published: July 2020

Background

Brugada syndrome (BS) is a hereditary channelopathy associated with syncope, malignant ventricular arrhythmia, and sudden cardiac death. Right ventricular ischaemia and BS have similar underlying substrates precipitating ventricular tachycardia or fibrillation (VF).

Case summary

A 72-year-old woman with BS and a stenosis on the proximal right coronary artery received several subsequent implantable cardioverter-defibrillator shocks due to VF during an episode of extreme nausea with vomiting.

Discussion

This case report emphasizes on the synergetic effect of mild ischaemia and increased vagal tone on the substrate responsible for BS to create pathophysiological changes precipitating VF.
Age Differences in Risk and Resilience Factors in COVID-19-Related Stress
Authors: Pearman Ann , Hughes MacKenzie L , Smith Emily L , Neupert Shevaun D
Published: July 2020

Objectives

Older adults are at higher risk for death and infirmity from COVID-19 than younger and middle-aged adults. The current study examines COVID-19-specific anxiety and proactive coping as potential risk and resilience factors that may be differentially important for younger and older adults in understanding stress experienced due to the COVID-19 pandemic.

Methods

Five hundred and fifteen adults aged 20–79 years in the United States reported on their anxiety about developing COVID-19, proactive coping, and stress related to COVID-19 in an online survey.

Results

Although there were no age differences in stress levels, anxiety about developing COVID-19 was associated with more COVID-19 stress for older adults relative to younger adults, but proactive coping was associated with less COVID-19 stress for older adults relative to younger adults.

Discussion

Our results suggest that anxiety might function as a risk factor, whereas proactive coping may function as a resilience factor for older adults’ COVID-19 stress. We encourage future context-dependent investigations into mental health among older adults during this pandemic and beyond.