bluuebunny/crossref_metadata_2025 huggingface dataset:
Injection-Related Risk Behavior and Engagement in Outreach, Intervention and Prevention Services Across 20 US Cities
Authors: Mackesy-Amiti Mary E. , Boodram Basmattee , Spiller Michael W. , Paz-Bailey Gabriela , Prachand Nikhil , Broz Dita ,   for the NHBS Study Group
Published: June 2017

Background:

Monitoring the effects of HIV prevention efforts on risk behaviors among persons who inject drugs is a key to inform prevention programs and policy.

Methods:

Using data from the 2012 National HIV Behavioral Surveillance interviews with persons who inject drugs across 20 US cities (n = 10,171), we conducted latent class analysis to identify injection risk classes and assess the relationship between engagement in prevention services and injection-related risk behavior. We conducted stratified analyses to examine the consistency of these associations across different geographical regions.

Results:

The latent class analysis identified 6 distinct classes of injection-related risk behavior. The class structure was consistent across regions of the United States, but the distribution of risk classes varied significantly across regions. With covariate adjustment, the South had the most high-risk behavior (21%) and the Midwest had the least (6%). Participation in syringe access services and other prevention services was the lowest in the South. Syringe access was associated with a significantly lower likelihood of membership in the highest risk class in all regions except the Midwest. Participation in individual or group intervention with a practical skills component was associated with less risky injection behavior in all regions except the Northeast. Interventions that featured only safer injection information and discussion had no relationship with risk class.

Conclusions:

Our findings support evidence of the effectiveness of syringe service programs and safer injection skills training in reducing high-risk injection behavior and underscore the need to improve access to these prevention interventions in the South of the United States.
Trends in HIV and HCV Risk Behaviors and Prevalent Infection Among People Who Inject Drugs in New York City, 2005–2012
Authors: Neaigus Alan , Reilly Kathleen H. , Jenness Samuel M. , Hagan Holly , Wendel Travis , Gelpi-Acosta Camila , Marshall David M.
Published: June 2017

Background:

We assess trends in HIV and hepatitis C virus (HCV) risk behaviors and prevalent infection among people who inject drugs (PWID) in New York City (NYC).

Methods:

PWID in NYC were sampled using respondent-driven sampling in 2005, 2009, and 2012 (serial cross sections) for the Centers for Disease Control and Prevention–sponsored National HIV Behavioral Surveillance study. Participants were interviewed about their current (≤12 months) risk behaviors and tested for HIV and HCV. The crude and adjusted risk ratio (RR) and 95% confidence interval (95% CI) for linear time trends were estimated using generalized estimating equations regression with a modified Poisson model.

Results:

The sample comprised 500, 514, and 525 participants in 2005, 2009, and 2012, respectively. Significant (P < 0.05) linear trends in risk behaviors included a decline in unsafe syringe sources (60.8%, 31.3%, 46.7%; RR = 0.86, 95% CI: 0.81 to 0.92), an increase in all syringes from syringe exchanges or pharmacies (35.4%, 67.5%, 50.3%; RR = 1.15, 95% CI: 1.09 to 1.22), and an increase in condomless vaginal or anal sex (53.6%, 71.2%, 70.3%; RR = 1.14, 95% CI: 1.09 to 1.19). Receptive syringe sharing (21.4%, 27.0%, 25.1%), sharing drug preparation equipment (45.4%, 43.4%, 46.7%), and having ≥2 sex partners (51.2%, 44.0%, 50.7%) were stable. Although HIV seroprevalence declined (18.1%, 12.5%, 12.2%), HCV seroprevalence was high (68.2%, 75.8%, 67.1%). In multivariate analysis, adjusting for sample characteristics significantly associated with time, linear time trends remained significant, and the decline in HIV seroprevalence gained significance (adjusted RR = 0.76, 95% CI: 0.64 to 0.91, P = 0.003).

Conclusions:

This trend analysis suggests declining HIV prevalence among NYC PWID. However, HCV seroprevalence was high and risk behaviors were considerable. Longitudinal surveillance of HIV and HCV risk behaviors and infections is needed to monitor trends and for ongoing data-informed prevention among PWID.
Exchange Sex and HIV Infection Among Women Who Inject Drugs—20 US Cities, 2009
Authors: Nerlander Lina M. , Hess Kristen L. , Rose Charles E. , Sionean Catlainn , Thorson Anna , Broz Dita , Paz-Bailey Gabriela ,   for the NHBS Study Group
Published: June 2017

Background:

Women who inject drugs and who also exchange sex are at increased risk for HIV infection, but data on this population in the United States remain sparse.

Methods:

This study assessed the prevalence of exchanging sex for money or drugs among women who inject drugs using data from the 2009 US National HIV Behavioral Surveillance (NHBS) system. Prevalence of being HIV-positive (testing positive in NHBS), HIV-positive–unaware (reporting being HIV-negative or unknown status but testing positive in NHBS), and risk behaviors and use of services were compared between women who did and did not exchange sex. The association between exchange sex and being HIV-positive–unaware of the infection was examined using multivariate Poisson models with robust standard errors.

Results:

Among 2305 women who inject drugs, 39% reported receiving things like money or drugs from ≥1 male partners in exchange for oral, vaginal, or anal sex in the previous 12 months. Women who exchanged sex were more likely to be unemployed, homeless, lack health insurance, have multiple condomless vaginal or anal sex partners, and receptively share syringes. In multivariate analysis, exchange sex was associated with being HIV-positive–unaware (adjusted prevalence ratio 1.97, 95% confidence intervals: 1.31 to 2.97).

Conclusions:

Prevalence of exchange sex was high in this population. Women who exchange sex were more likely to be socially disadvantaged, report sexual and injection risk, and be HIV-positive–unaware. They represent an important group to reach with HIV prevention, testing, and care services.
Preferences for Home-Based HIV Testing Among Heterosexuals at Increased Risk for HIV/AIDS: New Orleans, Louisiana, 2013
Authors: Robinson William T. , Zarwell Meagan , Gruber DeAnn
Published: June 2017

Participants in the New Orleans arm of the National HIV Behavioral Surveillance of Heterosexuals at Increased Risk for HIV were asked about potential utilization of self-administered home-based tests for HIV. The majority (86%) would use a free home-based test if provided by mail and 99% would seek treatment based on a positive result. In addition, more than half of respondents would return test results in some format to the test provider, whereas most of the remaining participants preferred to discuss results only with their doctor. These findings point toward a potential method for advancing the National HIV/AIDS Strategy.
What Factors Are Associated With Receiving a Recommendation to Get Tested for HIV by Health Care Providers Among Men Who Have Sex With Men?
Authors: Vincent Wilson , McFarland Willi , Raymond H. Fisher
Published: June 2017

Background:

The approach of treatment as prevention for reducing HIV incidence and prevalence hinges on early detection of HIV infection and treatment to achieve viral suppression and, thus, to reduce HIV transmissibility. However, men who have sex with men (MSM), who are at greater risk of HIV infection than the average adult in the United States, are often not tested because many providers do not provide routine opt-out testing or even recommend HIV testing.

Methods:

In a sample of 244 MSM in San Francisco, CA, this study examined whether (1) sociodemographic characteristics (ie, youth, education, employment status, being African American, being Latino), (2) health care access and utilization, and (3) participants disclosing their sexual orientation to their health care providers were associated with their odds of having received a recommendation from a health care provider for HIV testing.

Results:

Results showed that none of the sociodemographic or health care–related factors were associated with whether a health care provider recommended HIV testing, but MSM disclosing their sexual orientation to their health care providers was associated with an over 8 times greater odds of MSM receiving a recommendation for HIV testing.

Conclusion:

The study findings underscore the need for routine opt-out HIV testing to screen members of high-risk populations who may not enter the HIV continuum of care and for health care providers to be able to ask patients about HIV risk behavior and sexual orientation and behavior.
Syphilis Screening and Diagnosis Among Men Who Have Sex With Men, 2008–2014, 20 U.S. Cities
Authors: An Qian , Wejnert Cyprian , Bernstein Kyle , Paz-Bailey Gabriela ,   for the NHBS Study Group
Published: June 2017

Background:

Annual screening for syphilis is indicated for all sexually active men who have sex with men (MSM).

Methods:

Using National HIV Behavioral Surveillance data from 2008, 2011, and 2014, we assessed trends in self-reported syphilis testing and diagnoses in the past 12 months among MSM. We calculated percentages of syphilis screening and diagnosis by selected characteristics for each year. Trends were assessed using Poisson regression models with generalized estimation equations. Analysis of syphilis diagnosis was limited to participants who reported syphilis screening.

Results:

Analysis included data from 28,295 sexually active MSM. Overall, 49% of MSM interviewed in 2014 reported syphilis screening, a significant increase from 40% in 2011 and 38% in 2008. In 2014, syphilis screening was most commonly reported by MSM who were aged 25–29 years (56%), HIV positive (68%), and had >10 sexual partners in the past 12 months (65%). The largest increases in syphilis screening between 2008 and 2014 were among MSM aged 30–39 years (37%–52%) and MSM who reported >10 sex partners (48%–65%). Among MSM who reported syphilis screening, the diagnoses of syphilis increased from 9% in 2008 to 11% in 2014. Increases in syphilis diagnosis were observed among MSM who were aged 25–29 years (6%–10%), black (9%–14%), HIV positive (15%–21%), and reported >10 sexual partners (11%–17%).

Conclusions:

Although syphilis screening among MSM increased during 2008–2014, less than half of MSM reported recent syphilis screening in 2014. Given continued increases in syphilis among MSM, innovative interventions are needed to improve compliance with screening recommendations.
Development of an HIV Testing Dashboard to Complement the HIV Care Continuum Among MSM, PWID, and Heterosexuals in Washington, DC, 2007–2015
Authors: Patrick Rudy , Greenberg Alan , Magnus Manya , Opoku Jenevieve , Kharfen Michael , Kuo Irene
Published: June 2017

Background:

We developed an HIV testing dashboard to complement the HIV care continuum in selected high-risk populations. Using National HIV Behavioral Surveillance (NHBS) data, we examined trends in HIV testing and care for men who have sex with men (MSM), persons who inject drugs (PWID), and heterosexuals at elevated risk (HET).

Methods:

Between 2007 and 2015, 4792 participants ≥18 years old completed a behavioral survey and were offered HIV testing. For the testing dashboard, proportions ever tested, tested in the past year, testing HIV-positive, and newly testing positive were calculated. An abbreviated care continuum for self-reported positive (SRP) persons included ever engagement in care, past year care, and current antiretroviral (ARV) use. The testing dashboard and care continuum were calculated separately for each population. Chi-square test for trend was used to assess significant trends over time.

Results:

Among MSM, lifetime HIV testing and prevalence significantly increased from 96% to 98% (P = 0.01) and 14%–20% (P = 0.02) over time; prevalence was highest among black MSM at all time points. HIV prevalence among female persons who inject drugs was significantly higher in 2015 vs. 2009 (27% and 13%; P < 0.01). Among heterosexuals at elevated risk from 2010 to 2013, annual testing increased significantly (45%–73%; P < 0.001) and the proportion newly diagnosed decreased significantly (P < 0.01). Self-reported positive MSM had high levels of care engagement and antiretroviral use; among self-reported positive persons who inject drugs and heterosexuals at elevated risk, past year care engagement and antiretroviral use increased over time.

Conclusions:

The HIV testing dashboard can be used to complement the HIV care continuum to display improvements and disparities in HIV testing and care over time.
HIV Among MSM and Heterosexual Women in the United States: An Ecologic Analysis
Authors: Raymond H. Fisher , Al-Tayyib Alia , Neaigus Alan , Reilly Kathleen H. , Braunstein Sarah , Brady Kathleen A. , Sey Ekow , Risser Jan , Padget Paige , Lalota Marlene , Schacht John-Mark , Forrest David W. , Macomber Katie , Griffin Vivian , Higgins Emily , Robinson William T. , Zarwell Meagan C. , Opoku Jenevieve , Magnus Manya , Kuo Irene , Burt Richard , Thiede Hanne , Glick Sara , Flynn Colin , German Danielle
Published: June 2017

Background:

Phylogenetic studies show links between heterosexual women and men who have sex with men (MSM) that are more numerous than from heterosexual men to women suggesting that HIV infections among heterosexual women may stem from MSM. Poor communities have been associated with high rates of HIV among heterosexual women. Our analysis investigates potential transmission of HIV between MSM and female heterosexuals.

Methods:

National HIV Behavioral Surveillance data describe transmission risk behaviors of MSM, and HIV case reporting data describe the percentages of cases that are attributed to transmission risk categories. We examined correlations between the percentages of men who were MSM who also have sex with women and female heterosexual cases. We also examined census data to characterize each city in terms of poverty level and race/ethnicity makeup.

Results:

There was a high correlation (0.93) between the percentage of reported living HIV cases attributed to male heterosexual contact and female heterosexual contact and a moderate nonsignificant correlation (0.49) between the percentage of MSM who were men who have sex with men and women (MSMW) in National HIV Behavioral Surveillance and the percentage of reported cases that were attributed to female heterosexual contact suggesting some potential overlap. Cities with high levels of poverty and African American/Black residents had higher levels of MSMW and higher levels of heterosexual female cases.

Conclusions:

Addressing HIV in cities with high levels of MSMW may have the dual effect of improving the health of MSM populations that have a high burden of HIV and to improve the health of their larger communities.
Characteristics of Black Men Who Have Sex With Men in Baltimore, Philadelphia, and Washington, D.C.: Geographic Diversity in Socio-Demographics and HIV Transmission Risk
Authors: German Danielle , Brady Kathleen , Kuo Irene , Opoku Jenevieve , Flynn Colin , Patrick Rudy , Park Ju Nyeong , Adams Joella , Carroll Makeda , Simmons Ron , Smith Carlton R. , Davis Wendy W. ,   for the Mid-Atlantic CFAR Consortium
Published: June 2017

Background:

Baltimore, Philadelphia, and Washington, DC are geographically proximate cities with high HIV prevalence, including among black men who have sex with men (BMSM). Using data collected among BMSM in CDC's National HIV Behavioral Surveillance project, we compared socio-demographic characteristics, HIV risk behaviors, and service utilization to explore similarities and differences that could inform local and regional HIV intervention approaches.

Methods:

BMSM were recruited through venue time location sampling, June–December, 2011. Participants completed identical socio-behavioral surveys and voluntary HIV testing. Analyses were conducted among the full sample and those aged 18–24.

Findings:

Participants included 159 (DC), 364 (Baltimore), and 331 (Philadelphia) eligible BMSM. HIV prevalence was 23.1% (DC), 48.0% (Baltimore), 14.6% (Philadelphia) with 30.6%, 69.0%, 33.3% unrecognized HIV infection, respectively. Among BMSM 18–24, HIV prevalence was 11.1% (DC), 38.9% (Baltimore), 9.6% (Philadelphia) with unrecognized HIV infection 0.0%, 73.8%, 60.0% respectively. Compared with the other 2 cities, Baltimore participants were less likely to identify as gay/homosexual; more likely to report unemployment, incarceration, homelessness, sex exchange; and least likely to use the internet for partners. DC participants were more likely to have a college degree and employment. Philadelphia participants were more likely to report gay/homosexual identity, receptive condomless anal sex, having only main partners, and bars/clubs as partner meeting places. Sexually transmitted disease testing was universally low.

Conclusions:

Analyses showed especially high HIV prevalence among BMSM in Baltimore including among young BMSM. Socio-demographic characteristics and HIV infection correlates differed across cities but unrecognized HIV infection and unknown partner status were universally high.
Is Multiple Sclerosis Associated With a Lower Intraocular Pressure?
Authors: Lincoff Norah S. , Buccilli Andrea , Weinstock-Guttman Bianca , Sieminski Sandra , Gandhi Sirin
Published: June 2017

Objective:

To determine if multiple sclerosis (MS) is associated with lower intraocular pressure (IOP) compared with individuals without MS.

Methods:

Thirty patients with clinically definite MS were identified and a retrospective chart review was conducted. Each patient with MS underwent IOP recording by a single investigator using kinetic applanation tonometry. Measurement of central corneal thickness (CCT) also was obtained. Similarly, 30 study controls were identified and kinetic applanation tonometry and CCT were recorded. Univariate analysis of covariance was conducted to determine a statistically significant difference between IOP between MS and control groups, controlling for age.

Results:

Analyses were adjusted for age and 2 subjects were excluded because of steroid use. The average IOP in MS group was 12.3 mm Hg (right eye = 12.3 mm Hg, left eye = 12.2 mm Hg) and in the control group was 17 mm Hg (right eye = 16.9 mm Hg, left eye = 17 mm Hg). There was a significant effect of presence of MS on IOP accounting for 53% variability in mean IOP (F(1,55) = 60.7; P < 0.001) when compared with the control group.

Conclusions:

This study demonstrated that IOP was significantly lower in patients with MS compared with controls. A more in-depth prospective study design is required, along with further investigation of possible etiologies. Identifying the mechanism of decreased IOP in patients with MS might allow development of new-targeted therapies for the treatment of glaucoma.
Changing geographic patterns and risk factors for avian influenza A(H7N9) infection in China
Authors: Artois Jean , Wang Xiling , Jiang Hui , Qin Ying , Pearcy Morgan , Lai Shengjie , Shi Yujing , Zhang Juanjuan , Peng Zhibin , Zheng Jiandong , He Yangni , Dhingra Madhur S , Dobschuetz Sophie von , Guo Fusheng , Martin Vincent , Kalpravidh Wantanee , Claes Filip , Robinson Timothy , Hay Simon I. , Xiao Xiangming , Feng Luzhao , Gilbert Marius , Yu Hongjie
Published: June 2017

The 5thepidemic wave in 2016-2017 of avian influenza A(H7N9) virus in China caused more human cases than any previous waves but the factors that may explain the recent range expansion and surge in incidence remain unknown. We investigated the effect of anthropogenic, poultry and wetland information and of market closures on all epidemic waves (1-5). Poultry predictor variables recently became much more important than before, supporting the assumption of much wider H7N9 transmission in the chicken reservoir, that could be linked to increases in pathogenicity. We show that the future range expansion of H7N9 to northern China may translate into a higher risk of coinciding peaks with those of seasonal influenza, leading to a higher risk of reassortments. Live-poultry market closures are showed to be effective in reducing the local incidence rates of H7N9 human cases, but should be paired with other prevention and control measures to prevent transmission.
Performance Of Children With Autism In Parent-Administered Cognitive And Language Exercises
Authors: Dunn Rita , Elgart Jonah , Lokshina Lisa , Faisman Alexander , Khokhlovich Edward , Gankin Yuriy , Vyshedskiy Andrey
Published: June 2017

There is a broad scientific consensus that early and intensive therapy has the greatest chance of positive impact on an individual with autism spectrum disorder (ASD). However, the availability, quality, and general funding for early intervention programs is often lacking, leaving newly diagnosed children without adequate and sufficient therapy during the most critical early period of their development. Parent-administered iPad-assisted therapy has the potential to reduce the gap between the amount of therapy recommended for children with ASD and the amount they receive. However it is unclear how ASD severity and age influence a child’s ability to engage with and learn from computerized cognitive exercises. In this manuscript, we describe data from a tablet-based therapeutic application administered by parents to 1,514 young children with ASD over the course of four to twelve months. We report that older children and children with milder forms of ASD performed better and progressed faster in cognitive and language exercises. However, most children were able to engage with and learn from exercises independent of their age or ASD severity. This data confirm that tablet-based cognitive and language exercises can be successfully administered by parents to children as young as two years of age over the course of many months independent of ASD severity.
The integrated stress response pathway activates 4E-BP to bias mRNA translation and boost antimicrobial peptide synthesis in response to bacterial infection
Authors: Vasudevan Deepika , Clark Nicholas K. , Sam Jessica , Ueberheide Beatrix , Marr Michael T. , Ryoo Hyung Don
Published: June 2017

Pathogenic bacterial infection imposes considerable cellular stress on the host and often leads to attenuation of mRNA translation. In this translation-suppressive environment, it is unclear how the host synthesizes various antimicrobial peptides (AMPs) to mount innate immune response. Here, we useDrosophilaas a model to demonstrate that AMP production during infection relies on a translation bias mechanism mediated by the inhibitor of cap-dependent translation 4E-BP (DrosophilaThor), and the AMP 5’UTRs that can undergo cap-independent translation. We found that 4E-BP is induced upon infection with the pathogenic bacteriaEcc15by the stress-responsive transcription factor ATF4, and its upstream kinase GCN2. Moreover, loss ofgcn2, atf4or4e-bpcompromised immunity againstEcc15.In 4E-BP mutants, the transcriptional induction of AMPs after infection was unaffected, while the protein levels of AMPs were substantially reduced in their hemolymph. Analysis of the 5’UTRs of AMPs using cell-based bicistronic reporters andin vitrotranslation analysis indicated that AMPs are translated in a cap-independent mechanism. Analysis of bicistronic reporters in the presence of 4E-BP indicate that infection enhances cap-independent translational activity associated with AMP 5’UTRs, accounting for enhanced AMP translation during infection.

Highlights

4E-BP is transcriptionally induced by GCN2/ATF signaling in response to bacterial infection

4E-BP mutants show unaltered antimicrobial peptide (AMP) transcript levels, but have reduced AMP translation

AMP 5’UTRs are translated cap-independently

Translation bias by 4E-BP drives cap-independent AMP translation
Engagement rules that underpin DBL-DARC interactions for ingress ofPlasmodium knowlesiandPlasmodium vivaxinto human erythrocytes
Authors: Yogavel Manickam , Jamwal Abhishek , Gupta Swati , Sharma Amit
Published: June 2017

The molecular mechanisms by whichP. knowlesiandP. vivaxinvade human red blood cells have long been studied. Malaria parasite erythrocytic stages comprise of repeated bursts of parasites via cyclical invasion of host RBCs using dedicated receptor-ligand interactions. A family of erythrocyte-binding proteins (EBPs) fromP. knowlesiandP. vivaxattach to human Duffy antigen receptor for chemokines (DARC) via their Duffy binding-like domains (Pv-DBL andPk-DBL respectively) for invasion. Here, we provide a comprehensive overview that presents new insights on the atomic resolution interactions that underpin the binding of human DARC withPk/Pv-DBLs. Based on extensive structural and biochemical data, we provide a novel, testable and overarching interaction model that rationalizes even contradictory pieces of evidence that have so far existed in the literature onPk/Pv-DBL/DARC binding determinants. We address the conundrum of how parasite-encodedPk/Pv-DBLs recognize human DARC via its two sulfated tyrosine residues. We collate evidence for two distinct DARC integration sites onPk/Pv-DBLs that together likely engage the DARC’s sulfated extracellular domain. These analyses are important for both malaria vaccine and inhibitor development efforts that are targeted at abrogatingPk/Pv-DBL/DARC coupling as one avenue to prevent invasion ofP. vivaxinto human red blood cells.
Reduction of small-angle scattering profiles to finite sets of structural invariants
Authors: Houdayer Jérôme , Poitevin Frédéric
Published: June 2017

This paper shows how small-angle scattering (SAS) curves can be decomposed in a simple sum using a set of invariant parameters calledKnwhich are related to the shape of the object of study. TheseKn, together with a radiusR, give a complete theoretical description of the SAS curve. Adding an overall constant, these parameters are easily fitted against experimental data giving a concise comprehensive description of the data. The pair distance distribution function is also entirely described by this invariant set and theDmaxparameter can be measured. In addition to the understanding they bring, these invariants can be used to reliably estimate structural moments beyond the radius of gyration, thereby rigorously expanding the actual set of model-free quantities one can extract from experimental SAS data, and possibly paving the way to designing new shape reconstruction strategies.
Efficient numerical simulation of injection mold filling with the lattice Boltzmann method
Authors: Deng Lin , Liang Junjie , Zhang Yun , Zhou Huamin , Huang Zhigao
Published: June 2017

Purpose

Lattice Boltzmann method (LBM) has made great success in computational fluid dynamics, and this paper aims to establish an efficient simulation model for the polymer injection molding process using the LBM. The study aims to validate the capacity of the model for accurately predicting the injection molding process, to demonstrate the superior numerical efficiency in comparison with the current model based on the finite volume method (FVM).

Design/methodology/approach

The study adopts the stable multi-relaxation-time scheme of LBM to model the non-Newtonian polymer flow during the filling process. The volume of fluid method is naturally integrated to track the movement of the melt front. Additionally, a novel fractional-step thermal LBM is used to solve the convection-diffusion equation of the temperature field evolution, which is of high Peclet number. Through various simulation cases, the accuracy and stability of the present model are validated, and the higher numerical efficiency verified in comparison with the current FVM-based model.

Findings

The paper provides an efficient alternative to the current models in the simulation of polymer injection molding. Through the test cases, the model presented in this paper accurately predicts the filling process and successfully reproduces several characteristic phenomena of injection molding. Moreover, compared with the popular FVM-based models, the present model shows superior numerical efficiency, more fit for the future trend of parallel computing.

Research limitations/implications

Limited by the authors’ hardware resources, the programs of the present model and the FVM-based model are run on parallel up to 12 threads, which is adequate for most simulations of polymer injection molding. Through the tests, the present model has demonstrated the better numerical efficiency, and it is recommended for the researcher to investigate the parallel performance on even larger-scale parallel computing, with more threads.

Originality/value

To the authors’ knowledge, it is for the first time that the lattice Boltzmann method is applied in the simulation of injection molding, and the proposed model does obviously better in numerical efficiency than the current popular FVM-based models.
Analysis of repetitive and near-repetitive structures by transformation to equivalent circulant structures
Authors: Kaveh A. , Rahami H. , Jodaki A.
Published: June 2017

Purpose

There are many structures that have a repetitive pattern. If a relationship can be established between a repetitive structure and a circulant structure, then the repetitive structure can be analyzed by using the properties of the corresponding circulant structure. The purpose of this paper is to develop such a transformation.

Design/methodology/approach

A circulant matrix has certain properties that can be used to reduce the complexity of the analysis. In this paper, repetitive and near-repetitive structures are transformed to circulant structures by adding and/or eliminating some elements of the structure. Numerical examples are provided to show the efficiency of the present method.

Findings

A transformation is established between a repetitive structure and a circulant structure, and the analysis of the repetitive structure is performed by using the properties of the corresponding circulant structure.

Originality/value

Repetitive and near-repetitive structures are transformed to circulant structures, and the complexity of the analysis of the former structures is reduced by analyzing the latter structures.
Coupling of 2D discretized Peridynamics with a meshless method based on classical elasticity using switching of nodal behaviour
Authors: Shojaei Arman , Zaccariotto Mirco , Galvanetto Ugo
Published: June 2017

Purpose

The paper aims to use a switching technique which allows to couple a nonlocal bond-based Peridynamic approach to the Meshless Local Exponential Basis Functions (MLEBF) method, based on classical continuum mechanics, to solve planar problems.

Design/methodology/approach

The coupling has been achieved in a completely meshless scheme. The domain is divided in three zones: one in which only Peridynamics is applied, one in which only the meshless method is applied and a transition zone where a gradual transition between the two approaches takes place.

Findings

The new coupling technique generates overall grids that are not affected by ghost forces. Moreover, the use of the meshless approach can be limited to a narrow boundary region of the domain, and in this way, it can be used to remove the “surface effect” from the Peridynamic solution applied to all internal points.

Originality/value

The current study paves the road for future studies on dynamic and static crack propagation problems.
A numerical study of thermo-diffusion, diffusion-thermo and chemical reaction effects on flow of a micropolar fluid in an asymmetric channel with dilating and contracting permeable walls
Authors: Mohyud-din Syed Tauseef , Ahmed Naveed , Khan Umar , Rashidi Mohammad Mehdi
Published: June 2017

Purpose

The purpose of this study is to analyze thermo-diffusion and diffusion-thermo effects, combined with first-order chemical reaction, in the flow of a micropolar fluid through an asymmetric channel with porous boundaries. Suction/injection velocities of upper and lower walls are taken to be different from each other. The channel exhibits a parting or embracing motion and the fluid enters, or leaves, the channel because of suction/injection through the permeable walls.

Design/methodology/approach

The solution of the problem is obtained by using the fourth-order Runge-Kutta method combined with the shooting technique.

Findings

The asymmetric nature of the channel that is caused by the different permeabilities of the walls deeply influences the flow. The temperature of the fluid rises significantly by increasing the absolute value of A for both Case I and Case II. While, for the concentration profile, the concentration drops near the lower vicinity of the center in Case I, and, it falls near the lower wall of the channel in Case II. Stronger Dufour effects increase the temperature of the fluid except for Case 1 at the center of the channel and for Case II in lower quarter of the channel.

Originality/value

It is confirmed that the presented work is original and is not under consideration by any other journal.
Thermo-mechanical coupling particle simulation of three-dimensional large-scale non-isothermal problems
Authors: Xia Ming
Published: June 2017

Purpose

The main purpose of this paper is to present a comprehensive upscale theory of the thermo-mechanical coupling particle simulation for three-dimensional (3D) large-scale non-isothermal problems, so that a small 3D length-scale particle model can exactly reproduce the same mechanical and thermal results with that of a large 3D length-scale one.

Design/methodology/approach

The objective is achieved by following the scaling methodology proposed by Feng and Owen (2014).

Findings

After four basic physical quantities and their similarity-ratios are chosen, the derived quantities and its similarity-ratios can be derived from its dimensions. As the proposed comprehensive 3D upscale theory contains five similarity criteria, it reveals the intrinsic relationship between the particle-simulation solution obtained from a small 3D length-scale (e.g. a laboratory length-scale) model and that obtained from a large 3D length-scale (e.g. a geological length-scale) one. The scale invariance of the 3D interaction law in the thermo-mechanical coupled particle model is examined. The proposed 3D upscale theory is tested through two typical examples. Finally, a practical application example of 3D transient heat flow in a solid with constant heat flux is given to illustrate the performance of the proposed 3D upscale theory in the thermo-mechanical coupling particle simulation of 3D large-scale non-isothermal problems. Both the benchmark tests and application example are provided to demonstrate the correctness and usefulness of the proposed 3D upscale theory for simulating 3D non-isothermal problems using the particle simulation method.

Originality/value

The paper provides some important theoretical guidance to modeling 3D large-scale non-isothermal problems at both the engineering length-scale (i.e. the meter-scale) and the geological length-scale (i.e. the kilometer-scale) using the particle simulation method directly.
Distortion-resistant and locking-free eight-node elements effectively capturing the edge effects of Mindlin–Reissner plates
Authors: Bao Yi , Cen Song , Li Chenfeng
Published: June 2017

Purpose

A simple shape-free high-order hybrid displacement function element method is presented for precise bending analyses of Mindlin–Reissner plates. Three distortion-resistant and locking-free eight-node plate elements are proposed by utilizing this method.

Design/methodology/approach

This method is based on the principle of minimum complementary energy, in which the trial functions for resultant fields are derived from two displacement functions,Fandf, and satisfy all governing equations. Meanwhile, the element boundary displacements are determined by the locking-free arbitrary order Timoshenko’s beam functions. Then, three locking-free eight-node, 24-DOF quadrilateral plate-bending elements are formulated: HDF-P8-23β for general cases, HDF-P8-SS1 for edge effects along soft simply supported (SS1) boundary and HDF-P8-FREE for edge effects along free boundary.

Findings

The proposed elements can pass all patch tests, exhibit excellent convergence and possess superior precision when compared to all other existing eight-node models, and can still provide good and stable results even when extremely coarse and distorted meshes are used. They can also effectively solve the edge effect by accurately capturing the peak value and the dramatical variations of resultants near the SS1 and free boundaries. The proposed eight-node models possess potential in engineering applications and can be easily integrated into commercial software.

Originality/value

This work presents a new scheme, which can take the advantages of both analytical and discrete methods, to develop high-order mesh distortion-resistant Mindlin–Reissner plate-bending elements.
Free vibration of moderately thick functionally graded parabolic and circular panels and shells of revolution with general boundary conditions
Authors: Wang Qingshan , Shi Dongyan , Liang Qian , Pang Fuzhen
Published: June 2017

Purpose

The purpose of this work is to apply the Fourier–Ritz method to study the vibration behavior of the moderately thick functionally graded (FG) parabolic and circular panels and shells of revolution with general boundary conditions.

Design/methodology/approach

The modified Fourier series is chosen as the basis function of the admissible functions of the structure to eliminate all the relevant discontinuities of the displacements and their derivatives at the edges, and the vibration behavior is solved by means of the Ritz method. The complete shells of revolution can be achieved by using the coupling spring technique to imitate the kinematic compatibility and physical compatibility conditions of FG parabolic and circular panels at the common meridian of θ = 0 and 2π. The convergence and accuracy of the present method are verified by other contributors.

Findings

Some new results of FG panels and shells with elastic restraints, as well as different geometric and material parameters, are presented and the effects of the elastic restraint parameters, power-law exponent, circumference angle and power-law distributions on the free vibration characteristic of the panels are also presented, which can be served as benchmark data for the designers and engineers to avoid the unpleasant, inefficient and structurally damaging resonant.

Originality/value

The paper could provide the reference for the research about the moderately thick FG parabolic and circular panels and shells of revolution with general boundary conditions. In addition, the change of the boundary conditions can be easily achieved by just varying the stiffness of the boundary restraining springs along all the edges of panels without making any changes in the solution procedure.
A multiscale computational method with inheriting simulation of moving trans-scale boundary for damage-induced structural deterioration
Authors: Zheng Zheyuan , Li Zhaoxia
Published: June 2017

Purpose

This paper aims to introduce a multiscale computational method for structural failure analysis with inheriting simulation of moving trans-scale boundary (MTB). This method is motivated from the error in domain bridging caused by cross-scale damage evolution, which is common in structural failure induced by damage accumulation.

Design/methodology/approach

Within the method, vulnerable regions with high stress level are described by continuum damage mechanics, while elastic structural theory is sufficient for the rest, dividing the structural model into two scale domains. The two domains are bridged to generate mixed dimensional finite element equation of the whole system. Inheriting simulation is developed to make the computation of MTB sustainable.

Findings

Numerical tests of a notched three-point bending beam and a steel frame show that this MTB method can improve efficiency and ensure accuracy while capturing the effect of material damage on deterioration of components and structure.

Originality/value

The proposed MTB method with inheriting simulation is an extension of multiscale simulation to structural failure analysis. Most importantly, it can deal with cross-scale damage evolution and improve computation efficiency significantly.
Linear and non-linear free vibration of nano beams based on a new fractional non-local theory
Authors: Rahimi Zaher , Sumelka Wojciech , Yang Xiao-Jun
Published: June 2017

Purpose

Recently, a new formulation has been introduced for non-local mechanics in terms of fractional calculus. Fractional calculus is a branch of mathematical analysis that studies the differential operators of an arbitrary (real or complex) order and is used successfully in various fields such as mathematics, science and engineering. The purpose of this paper is to introduce a new fractional non-local theory which may be applicable in various simple or complex mechanical problems.

Design/methodology/approach

In this paper (by using fractional calculus), a fractional non-local theory based on the conformable fractional derivative (CFD) definition is presented, which is a generalized form of the Eringen non-local theory (ENT). The theory contains two free parameters: the fractional parameter which controls the stress gradient order in the constitutive relation and could be an integer and a non-integer and the non-local parameter to consider the small-scale effect in the micron and the sub-micron scales. The non-linear governing equation is solved by the Galerkin and the parameter expansion methods. The non-linearity of the governing equation is due to the presence of von-Kármán non-linearity and CFD definition.

Findings

The theory has been used to study linear and non-linear free vibration of the simply-supported (S-S) and the clamped-free (C-F) nano beams and then the influence of the fractional and the non-local parameters has been shown on the linear and non-linear frequency ratio.

Originality/value

A new parameter of the theory (the fractional parameter) makes the modeling more fixable – this model can conclude all of integer and non-integer operators and is not limited to special operators such as ENT. In other words, it allows us to use more sophisticated mathematics to model physical phenomena. On the other hand, in the comparison of classic fractional non-local theory, the theory applicable in various simple or complex mechanical problems may be used because of simpler forms of the governing equation owing to the use of CFD definition.
Efficient force method for tetrahedron finite element analysis using mathematical optimization technique
Authors: Daei Maryam , Mirmohammadi S. Hamid
Published: June 2017

Purpose

The efficiency of the finite element analysis via force method depends on the overall flexibility matrix of the structure, while this matrix is directly affected from null bases vectors. As the null bases for an indeterminate structure are not unique, for an optimal analysis, the selected null bases should be sparse and banded corresponding to sparse, banded and well-conditioned flexibility matrix. This paper aims to present an efficient method for the formation of optimal flexibility matrix of finite element models comprising tetrahedron elements via mathematical optimization technique.

Design/methodology/approach

For this purpose, a linear mixed integer programming model is presented for finding sparse solution of underdetermined linear system, which is correspond to sparse null vector. The charged system search algorithm is improved and used to find the best generator for formation of null bases.

Findings

The efficiency of the present method is illustrated through some examples. The proposed method leads to highly sparse, banded and accurate null basis matrices. It makes an efficient force method feasible for the analysis of finite element model comprising tetrahedron elements.

Originality/value

The force method, in which the member forces are used as unknowns, can be appealing to engineers. The main problem in the application of the force method is the formation of a self-stress matrix corresponding to a sparse flexibility matrix. In this paper, the highly sparse, banded and accurate null basis matrices gains by using mathematical optimization technique.
Automatic tunable deployment for real-time strategy games
Authors: Yang Cheng-Ta , Yeh Her-Tyan , Chen Bing-Chang , Jian Guo-Xiang
Published: June 2017

Purpose

Extensive efforts have been conducted on the real-time strategy (RTS) games. The purpose of this paper is the specific artificial intelligence (AI) challenges posed by RTS games; non-player character (NPC) is started out by collecting game-map resources to build up defenses and attack forces, to upgrade combat deployment.

Design/methodology/approach

The authors used weak AI fuzzy theory as the foundation for tunable development. With the fuzzy theory, the AI was more humanistic in its judgment process.

Findings

Well-developed AIs have been used brilliantly in various aspects in RTS games, especially in those developed by large production teams. For small production teams, how to develop an AI system in less time and at a lower cost is extremely important.

Research limitations/implication

This study aimed to develop a system using player unit threat levels for NPC deployment and arrangement so that the further strategy would be adopted for NPCs in response to player actions.

Originality/value

The RTS games would become more challenging for players to play.
Compressive strength analysis of soil reinforced with fiber extracted from water hyacinth
Authors: Vardhan Harsha , Bordoloi Sanandam , Garg Akhil , Garg Ankit , S. Sreedeep
Published: June 2017

Purpose

The purpose of this study is to measure the effects of density, moisture, fiber content on unconfined compressive strength (UCS) of soil by formulating the models based on evolutionary approach and artificial neural networks (ANN).

Design/methodology/approach

The present work proposes evolutionary approach of multi-gene genetic programming (MGGP) to formulate the functional relationships between UCS of reinforced soil and four inputs (soil moisture, soil density, fiber content and unreinforced soil strength) of the silty sand. The hidden non-linear relationships between UCS of reinforced soil and the four inputs are determined by sensitivity and parametric analysis of the MGGP model.

Findings

The performance of MGGP is compared to those of ANN and the statistical analysis indicates that the MGGP model is the best and is able to generalize the UCS of reinforced soil satisfactorily beyond the given input range.

Research limitations/implications

The explicit MGGP model will be useful to provide optimum input values for design and analysis of various geotechnical infrastructures. In addition, utilization of Water hyacinth reinforced fiber reinforced soil will minimize negative impact of this species on environment and may generate rural employment.

Originality/value

This work is first of its kind in application and development of explicit holistic model for evaluating the compressive strength of heterogeneous soil blinded with fiber content. This includes the experimental and cross-validation for testing robustness of the model.