bluuebunny/crossref_metadata_2025_split huggingface dataset:
State of the Art of Lead-Free Solder Joint Reliability
Authors: Lau John H. 
Published: August 2020

AbstractThe state of the art of lead-free solder joint reliability is investigated in this study. Emphasis is placed on the design for reliability (DFR) and reliability testing and data analysis. For DFR: (a) the Norton power creep constitutive equations and examples for Au20Sn, Sn58Bi, Sn3.8Ag0.7Cu, and Sn3.8Ag0.7Cu0.03Ce, (b) the Wises two power creep constitutive equations and examples for Sn3.5Ag and Sn4Ag0.5Cu, (c) the Garofalo hyperbolic sine creep constitutive equations and examples for Sn3.5Ag, Sn3Ag0.5Cu, Sn3.9Ag0.6Cu, Sn3.8Ag0.7Cu, Sn3.5Ag0.5Cu, and Sn3.5Ag0.75Cu, Sn4Ag0.5Cu, Sn(3.5-3.9)Ag(0.5-0.8)Cu, 100In, Sn52In, Sn3.8Ag0.7Cu0.03Ce, and Au20Sn, and (d) the Anand viscoplasticity constitutive equations and examples for Sn3.5Ag, Sn3Ag0.5Cu, Sn3.8Ag0.7Cu, Sn3.8Ag0.7CuCe, Sn3.8Ag0.7CuAl, Au20Sn, Sn3.5Ag with temperature and strain rate-dependent parameters, and Sn1Ag0.5Cu, Sn2Ag0.5Cu, Sn3Ag0.5Cu, and Sn4Ag0.5Cu after extreme aging will be discussed. For reliability testing and data analysis: (a) the Weibull and lognormal life distributions for lead-free solder joints under thermal-cycling and drop tests, (b) the true Weibull slope, true characteristic life, and true mean life, and (c) the linear acceleration factors for various lead-free solder alloys based on: (i) frequency and maximum temperature, (ii) dwell time and maximum temperature, and (iii) frequency and mean temperature will be presented. Some recommendations will also be provided.
Review of Methodologies for Structural Integrity Evaluation of Power Modules
Authors: Miyazaki Noriyuki , Shishido Nobuyuki , Hayama Yutaka 
Published: August 2020

AbstractThis paper reviews the previous research on the methodologies for evaluating structural integrity of wire bonds and die-attachments in power modules. Under power module operation, these parts are subjected to repeated temperature variations which induce repeated thermal stress due to the mismatch in coefficients of thermal expansion (CTE) of the constituent materials. Thus, thermal fatigue phenomena are critical issues for the structural integrity of power modules. In the present paper, we also deal with the evaluation methodologies for thermal fatigue in the temperatures over 200 °C, which are expected operational temperatures for wide bandgap semiconductor power modules. The failure models based on the temperature range ΔT widely used in the power electronics community are critically reviewed from a mechanical engineering viewpoint. Detailed discussion is given concerning the superiority of failure models based on the physical quantities such as the inelastic strain range Δεin, the inelastic strain energy density range ΔWin, and the nonlinear fracture mechanics parameter range ΔT* over the conventional ΔT-based failure models. It is also pointed out that the distributed state concept (DSC) approaches based on the unified constitutive modeling and the unified mechanics theory are promising for evaluating the structural integrity of power modules. Two kinds of test methods, a power cycling test (PCT) and a thermal cycling test (TCT), are discussed in the relation to evaluating the lifetimes of wire-liftoff and die attach cracking.
The Non-Stationary Dynamic Analytical Solution of a Spherical/Cylindrical Cavity Expansion
Authors: Feldgun V. R. , Yankelevsky D. Z. 
Published: August 2020

Abstract
A review of the pertinent literature related to the dynamic expansion of a spherical/cylindrical cavity shows that all the solutions with kinematic boundary conditions deal with a constant velocity at the cavity boundary. This paper develops a new general solution of the nonstationary dynamic problem of cavity expansion, which allows the application of time-dependent motion conditions at the cavity boundary. This solution can be used, for example, in the development of approximate approaches for projectiles penetrating with a non-constant velocity into different targets. Due to the complexity of the nonlinear nonstationary problem, an analytical solution of the problem may be developed if simplified constitutive relationships are used. In the present model, a simplified material model with a locked equation of state and a linear shear failure relationship is implemented. This solution may be applied to different materials such as concrete, soil, and rock. Special cases of the newly developed nonstationary solution are compared with different spherical and cylindrical cavity expansions solutions reported in the literature, and a good agreement is obtained. The capability of the present model is demonstrated in a following investigation of representative cases of cavity expansion with zero, constant, and variable acceleration of the cavity boundary. A significant difference in the stress variation for the different cases is shown. Along with the general solution which deals with an elastic–plastic region, a simplified solution which disregards the contribution of the elastic region is presented and the evaluation of the elastic region effect may be assessed.
Time trends and determinants of breastfeeding practices among adolescents and young women in Nigeria, 2003–2018
Authors: Benova Lenka , Siddiqi Manahil , Abejirinde Ibukun-Oluwa Omolade , Badejo Okikiolu 
Published: August 2020

IntroductionOptimal breastfeeding practices have far-reaching health and economic benefits. Evidence suggests disparities in breastfeeding practices by maternal age-groups, with younger mothers often having lower rates of breastfeeding initiation, continuation and exclusivity compared with older mothers. There is limited knowledge of trends and factors associated with breastfeeding practices, particularly among adolescent and younger mothers in Nigeria. We examine key breastfeeding practices in Nigeria over a 15-year period, comparing adolescent mothers to young women.MethodsWe used four Nigeria Demographic and Health Surveys collected between 2003 and 2018. We constructed six key breastfeeding indicators to cover the time period of breastfeeding from initiation to child age 24 months in women of three maternal age groups at the time of birth: young adolescents (<18 years), older adolescents (18–19.9 years) and young women (20–24.9 years). We used logistic regression to examine the association between maternal age group and select breastfeeding behaviours on the 2018 survey.ResultsAnalysis showed an increase in optimal breastfeeding practices across the four surveys and among all maternal age groups examined. Adolescent mothers had consistently lower prevalence for three of the six key breastfeeding indicators: early initiation of breastfeeding, exclusive breastfeeding <6 months and no prelacteal feed. Compared with young women, adolescent mothers had a higher prevalence of continued breastfeeding at 1 and 2 years. In multivariate analysis, we found that maternal age group was not associated with early breastfeeding initiation or with exclusive breastfeeding <6 months. However, several sociodemographic (ethnicity, region of residence) and healthcare-related (mode of delivery, antenatal care, postnatal breastfeeding counselling) factors were strongly associated with these two practices.ConclusionsIn Nigeria, there is need to better support breastfeeding and nutritional practices in adolescents and young women focusing on ethnic groups (Hausa, Fulani, Kanuri/Beriberi) and geographic regions (South East) that are lagging behind.
Toxoplasma gondiiinfection in pregnant women: a cross-sectional study in Matehuala City, Mexico
Authors: Sandoval-Carrillo Ada-Agustina , Vértiz-Hernández Angel Antonio , Salas-Pacheco Jose-Manuel , González-Lugo Olga Edith , Antuna-Salcido Elizabeth-Irasema , Salas-Pacheco Sergio Manuel , Sánchez-Anguiano Luis Francisco , Méndez-Hernández Edna Madai , Hernández-Tinoco Jesús , Castellanos-Juárez Francisco Xavier , La-Llave-León Osmel , Alvarado-Esquivel Cosme 
Published: August 2020

ObjectivesThis study aimed to determine the seroprevalence ofToxoplasma gondii(T. gondii) infection in pregnant women in Matehuala City, Mexico; and the associated risk factors.DesignA cross-sectional study.SettingMatehuala City, Mexico.Participants311 pregnant women.Primary and secondary outcome measuresSera of women were analysed for anti-T. gondiiIgG and IgM antibodies by commercially available immunoassays. Bivariate and multivariate analyses were used to assess the association betweenT. gondiiseroprevalence and the characteristics of the pregnant women.ResultsThirteen (4.2%) of the 311 pregnant women studied were positive for anti-T. gondiiIgG antibodies. No anti-T. gondiiIgM antibodies were found in anti-T. gondiiIgG seropositive women. No association between seropositivity and history of blood transfusion, transplantation, caesarean sections, deliveries, miscarriages or number of pregnancies was found. Logistic regression analysis of sociodemographic, behavioural and housing variables showed that availability of potable water at street represented a risk factor forT. gondiiinfection (age-adjusted OR=2.18; 95% CI: 1.05 to 4.53; p=0.03), whereas being born in Mexico was a protective factor for infection (age-adjusted OR=0.01; 95% CI: 0.001 to 0.35; p=0.008).ConclusionsIn this first study on the seroepidemiology ofT. gondiiinfection in pregnant women in Matehuala, we conclude that the seroprevalence ofT. gondiiinfection is low and similar to those reported in pregnant women in other Mexican cities. However, the seroprevalence found is lower than those reported in pregnant women in other countries in the Americas and Europe. Two risk factors associated withT. gondiiinfection were identified. Results of the present study may help for the optimal planning of preventive measures against toxoplasmosis in pregnant women.
Mortality in gastro-oesophageal reflux disease in a population-based nationwide cohort study of Swedish twins
Authors: Ness-Jensen Eivind , Santoni Giola , Gottlieb-Vedi Eivind , Lindam Anna , Pedersen Nancy , Lagergren Jesper 
Published: August 2020

ObjectivesThe public health disorder gastro-oesophageal reflux disease (GORD) is linked with several comorbidities, including oesophageal adenocarcinoma (OAC), but whether life expectancy is reduced by GORD is uncertain. This study assessed all-cause and cancer-specific mortality in GORD after controlling for confounding by heredity and other factors.DesignPopulation-based cohort study from 1998 to 2015.SettingSwedish nationwide study.ParticipantsTwins (n=40 961) born in 1958 or earlier in Sweden.ExposureGORD symptoms reported in structured computer-assisted telephone interviews.OutcomesThe primary outcome was all-cause mortality and the secondary outcome was cancer-specific mortality among twins with GORD and twins without GORD. HRs and 95% CIs were analysed using parametric survival models, both in individual twin analyses and co-twin pair analyses, with adjustment for body mass index, smoking, education and comorbidity.ResultsAmong 40 961 individual twins, 5812 (14.2%) had GORD at baseline and 8062 (19.7%) died during follow-up of up to 16 years. The risks of all-cause mortality (HR=1.00, 95% CI: 0.94–1.07) and cancer-specific mortality (HR=0.99, 95% CI: 0.89–1.10) were not increased in individual twins with GORD compared with individual twins without GORD. Similarly, there were no differences in mortality outcomes in within-pair analyses. The OAC-specific mortality rate was 0.45 (95% CI: 0.32–0.66) per 1000 person-years in individual twins with GORD and 0.22 (95% CI: 0.18–0.27) per 1000 person-years without GORD, rendering an adjusted HR of 2.01 (95% CI: 1.35–2.98).ConclusionsGORD did not increase all-cause or cancer-specific mortality when taking heredity and other confounders into account. The increased relative risk of mortality in OAC was low in absolute numbers.
Psychological distress among mountainous farmers in Vietnam: a cross-sectional study of prevalence and associated factors
Authors: Hoang Men Thi , Do Khanh Nam , Pham Hai Quang , Nguyen Cuong Tat , Ha Giang Hai , Vu Giang Thu , Tran Bach Xuan , Latkin Carl , Ho Roger C M , Ho Cyrus SH 
Published: August 2020

BackgroundPsychological distress has been known as a major health problem among farmers across the world. In Vietnam, approximately 50% of farmers have lived in rural and mountainous areas. Yet, little has been known about how psychological distress impacts mountainous farmers’ health.ObjectivesThis study aimed to examine the prevalence and risk factors related to psychological distress among mountainous farmers in Vietnam.Design and settingA cross-sectional study was performed from August to September 2018 in Moc Chau district, Vietnam. A structured questionnaire and face-to-face interviews were used for data collection.ParticipantsA random sample of 197 farmers aged at least 18 years, spoke Vietnamese, was not suffering from severe diseases and residing in Moc Chau at the time of the survey were recruited.Primary and secondary outcome measuresThe Kessler Psychological Distress Scale (K6) was employed to measure psychological distress. The tobit and logistic regressions were applied to indicate associated factors.ResultsThe prevalence of psychological distress was 38.2% (95% CI 31.3% to 45.5%). Having a greater comorbidities (OR=6.17; 95% CI 1.44 to 26.43), drinking alcohol (OR=3.86; 95% CI 1.02 to 14.59) and obtaining health information from health workers (OR=3.77; 95% CI 1.22 to 11.66) were positively associated with the prevalence of psychological distress. By contrast, being overweight (OR=0.29; 95% CI 0.09 to 0.93), adopting books as the primary source of health information (OR=0.11; 95% CI 0.01 to 0.8), and receiving a higher number of home visits by community health workers (CHWs) (OR=0.38; 95% CI 0.14 to 0.99) were negatively associated with the prevalence of psychological distress.ConclusionThis study highlighted a high prevalence of psychological distress among mountainous farmers. Providing routine psychological and physical health screening, developing CHWs to provide clinical support and raising health awareness are critical implications for reducing psychological distress in this population.
Study protocol for a cluster randomised controlled trial testing the effectiveness of the ‘High schools High on life’ intervention on reducing excessive drinking in Danish high schools
Authors: Pisinger Veronica Sofie Clara , Hoffmann Sofie , Rosing Johanne Aviaja , Grønbæk Morten , Tolstrup Janne Schurmann , Thygesen Lau , Krølner Rikke 
Published: August 2020

IntroductionThis paper describes the evaluation design of the ‘High schools High on life’ intervention; a school-based intervention to reduce excessive drinking among high school students in Denmark. The intervention includes a school environmental component to limit access to alcohol at school, a school-educational component to change social norms around alcohol among first year students and a parental component addressing parents’ knowledge and attitudes towards alcohol.Methods and designThe study will employ a cluster randomised controlled study design and will include a random sample of 16 high schools randomly allocated 1:1 to either intervention or control group. Target group: first year high school students. Timeline: baseline survey: January to March 2019, collected as part of the Danish National Youth Study 2019. Delivery of intervention: April 2019 to March 2020. Follow-up survey: April to May 2020. Primary outcome measure: 30% reduction in mean number of binge-drinking episodes (five or more alcoholic drinks on one occasion) within the last 30 days. Secondary outcome measures: proportion of students who drink alcohol, mean weekly alcohol consumption, alcohol intake at last school party, alcohol intake at the school during last school party, proportion of students who agree to be able to have fun at a party without drinking and the proportion of students who think alcohol plays a too dominant part at the school. Implementation will be monitored through process evaluation.Ethics and disseminationThe Scientific Ethics Committees for the Capital Region of Denmark has declared that the trial is not subject to notification (jnr. 19021957). The study is registered at the Research an Innovation Office at University of Southern Denmark (ref: 10.314) allowing collection of personal data. Results will be published in peer-reviewed journals.Trial registration numberNCT03906500.
Associations between double-checking and medication administration errors: a direct observational study of paediatric inpatients
Authors: Westbrook Johanna I , Li Ling , Raban Magdalena Z , Woods Amanda , Koyama Alain K , Baysari Melissa Therese , Day Richard O , McCullagh Cheryl , Prgomet Mirela , Mumford Virginia , Dalla-Pozza Luciano , Gazarian Madlen , Gates Peter J , Lichtner Valentina , Barclay Peter , Gardo Alan , Wiggins Mark , White Leslie 
Published: August 2020

BackgroundDouble-checking the administration of medications has been standard practice in paediatric hospitals around the world for decades. While the practice is widespread, evidence of its effectiveness in reducing errors or harm is scarce.ObjectivesTo measure the association between double-checking, and the occurrence and potential severity of medication administration errors (MAEs); check duration; and factors associated with double-checking adherence.MethodsDirect observational study of 298 nurses, administering 5140 medication doses to 1523 patients, across nine wards, in a paediatric hospital. Independent observers recorded details of administrations and double-checking (independent; primed—one nurse shares information which may influence the checking nurse; incomplete; or none) in real time during weekdays and weekends between 07:00 and 22:00. Observational medication data were compared with patients’ medical records by a reviewer (blinded to checking-status), to identify MAEs. MAEs were rated for potential severity. Observations included administrations where double-checking was mandated, or optional. Multivariable regression examined the association between double-checking, MAEs and potential severity; and factors associated with policy adherence.ResultsFor 3563 administrations double-checking was mandated. Of these, 36 (1·0%) received independent double-checks, 3296 (92·5%) primed and 231 (6·5%) no/incomplete double-checks. For 1577 administrations double-checking was not mandatory, but in 26·3% (n=416) nurses chose to double-check. Where double-checking was mandated there was no significant association between double-checking and MAEs (OR 0·89 (0·65–1·21); p=0·44), or potential MAE severity (OR 0·86 (0·65–1·15); p=0·31). Where double-checking was not mandated, but performed, MAEs were less likely to occur (OR 0·71 (0·54–0·95); p=0·02) and had lower potential severity (OR 0·75 (0·57–0·99); p=0·04). Each double-check took an average of 6·4 min (107 hours/1000 administrations).ConclusionsCompliance with mandated double-checking was very high, but rarely independent. Primed double-checking was highly prevalent but compared with single-checking conferred no benefit in terms of reduced errors or severity. Our findings raise questions about if, when and how double-checking policies deliver safety benefits and warrant the considerable resource investments required in modern clinical settings.
Dynamics and the emergence of geometry in an information mesh
Authors: Tee Philip 
Published: August 2020

AbstractThe idea of a graph theoretical approach to modeling the emergence of a quantized geometry and consequently spacetime, has been proposed previously, but not well studied. In most approaches the focus has been upon how to generate a spacetime that possesses properties that would be desirable at the continuum limit, and the question of how to model matter and its dynamics has not been directly addressed. Recent advances in network science have yielded new approaches to the mechanism by which spacetime can emerge as the ground state of a simple Hamiltonian, based upon a multi-dimensional Ising model with one dimensionless coupling constant. Extensions to this model have been proposed that improve the ground state geometry, but they require additional coupling constants. In this paper we conduct an extensive exploration of the graph properties of the ground states of these models, and a simplification requiring only one coupling constant. We demonstrate that the simplification is effective at producing an acceptable ground state. Moreover we propose a scheme for the inclusion of matter and dynamics as excitations above the ground state of the simplified Hamiltonian. Intriguingly, enforcing locality has the consequence of reproducing the free non-relativistic dynamics of a quantum particle.
Functional renormalization group study of the critical region of the quark-meson model with vector interactions
Authors: Pereira Renan Câmara , Stiele Rainer , Costa Pedro 
Published: August 2020

AbstractThe critical region of the two flavour quark-meson model with vector interactions is explored using the Functional Renormalization Group, a non-perturbative method that takes into account quantum and thermal fluctuations. Special attention is given to the low temperature and high density region of the phase diagram, which is very important to construct the equation of state of compact stars. As in previous studies, without repulsive vector interaction, an unphysical region of negative entropy density is found near the first order chiral phase transition. We explore the connection between this unphysical region and the chiral critical region, especially the first order line and spinodal lines, using also different values for vector interactions. We find that the unphysical negative entropy density region appears because the $$s=0$$s=0 isentropic line, near the critical region, is displaced from its $$T=0$$T=0 location. For certain values of vector interactions this region is pushed to lower temperatures and high chemical potentials in such way that the negative entropy density region on the phase diagram can even disappear. In the case of finite vector interactions, the location of the critical end point has a non-trivial behaviour in the $$T-\mu _B$$T-μB plane, which differs from that in mean field calculations.
Stress Alters the Neural Context for Building New Memories
Authors: Meier Jacqueline Katharina , Weymar Mathias , Schwabe Lars 
Published: August 2020

Abstract
Stressful events affect mnemonic processing, in particular for emotionally arousing events. Previous research on the mechanisms underlying stress effects on human memory focused on stress-induced changes in the neural activity elicited by a stimulus. We tested an alternative mechanism and hypothesized that stress may already alter the neural context for successful memory formation, reflected in the neural activity preceding a stimulus. Therefore, 69 participants underwent a stress or control procedure before encoding neutral and negative pictures. During encoding, we recorded high-density EEG and analyzed—based on multivariate searchlight analyses—oscillatory activity and cross-frequency coupling patterns before stimulus onset that were predictive of memory tested 24 hr later. Prestimulus theta predicted subsequent memory in controls but not in stressed participants. Instead, prestimulus gamma predicted successful memory formation after stress, specifically for emotional material. Likewise, stress altered the patterns of prestimulus theta–beta and theta–gamma phase–amplitude coupling predictive of subsequent memory, again depending on the emotionality of the presented material. Our data suggest that stress changes the neural context for building new memories, tuning this neural context specifically to the encoding of emotionally salient events. These findings point to a yet unknown mechanism through which stressful events may change (emotional) memory formation.