Multilevel Hierarchical Model Research Articles

Effective and inclusive schools? Attention to diversity in highly effective schools in the Autonomous Region of the Basque Country

ABSTRACTThis paper forms part of a research project that aims to characterise best practices in highly effective schools in the Autonomous Region of the Basque Country (ARBC). The aim is for the best practices identified to serve as points of reference when designing improvement plans to be implemented in all schools in the ARBC, with the advice and support of the education inspectorate. Highly effective schools are identified through the results of the Diagnostic Assessments carried out by the Basque Institute for Research and Evaluation in Education (ISEI-IVEI) of all primary and secondary schools in the ARBC. Multilevel statistical modelling and Hierarchical Linear Models were used to select 32 highly effective schools, with highly effective being taken to mean any school with higher-than-expected student results after adjusting for the effect of contextual factors. Eighty-three interviews were conducted with management teams, educational advisors and inspectors at each of the selected schools. This paper presents the results obtained in relation to how attention to diversity is organised. The practices identified included, among others, inclusive actions such as support teaching in ordinary classrooms, the splitting up of classroom groups, the formation of heterogeneous groups and the conceptualisation of the support provided as a shared teaching responsibility.

The Effect of Hospital Characteristics on Racial/Ethnic Variation in Cirrhosis Mortality.

Racial/ethnic disparities in liver disease and cirrhosis are well established. Cirrhosis mortality is improving overall despite vast differences between hospitals. We sought to understand the hospital characteristics where minorities seek care, whether disparities in cirrhosis mortality persist, and determine how hospital differences contribute to these differences. We used data from the Nationwide Inpatient Sample and the American Hospital Association to identify inpatient episodes of care for cirrhosis and structural characteristics at the parent hospital. We used multi-level hierarchical regression models to understand the effect of hospital structural characteristics on racial/ethnic variation in cirrhosis mortality. From 2007 to 2011, 51,260 patients were admitted to the hospital with cirrhosis (White 66.5%, Black 7.6%, Hispanic 19.7%, Asian 2.0%, other 4.2%). The overall adjusted mortality rate was 7.8%, which significantly differed by race/ethnicity. Hospitals varied significantly in resource intensity. Higher mortality hospitals had a lower proportion of White patients and a higher proportion of Black and Hispanic patients compared to average and low mortality hospitals (p<0.0001). Compared to White patients, there was significant racial/ethnic variation in unadjusted odds of mortality (Black OR 1.17; Hispanic OR 0.90; Asian 0.77; other 0.96; all p<0.01). After accounting for hospital and patient differences, there were no racial/ethnic differences in mortality. The increased risk of cirrhosis mortality in Black patients appears to be mediated by facility differences and clinical co-morbidities, suggesting that access to higher quality health services at several points in both the early and late management of liver disease may improve disparate population outcomes.

Developing and validating a new national remote health advice syndromic surveillance system in England.

Public Health England (PHE) coordinates a suite of real-time national syndromic surveillance systems monitoring general practice, emergency department and remote health advice data. We describe the development and informal evaluation of a new syndromic surveillance system using NHS 111 remote health advice data. NHS 111 syndromic indicators were monitored daily at national and local level. Statistical models were applied to daily data to identify significant exceedances; statistical baselines were developed for each syndrome and area using a multi-level hierarchical mixed effects model. Between November 2013 and October 2014, there were on average 19 095 NHS 111 calls each weekday and 43 084 each weekend day in the PHE dataset. There was a predominance of females using the service (57%); highest percentage of calls received was in the age group 1-4 years (14%). This system was used to monitor respiratory and gastrointestinal infections over the winter of 2013-14, the potential public health impact of severe flooding across parts of southern England and poor air quality episodes across England in April 2014. This new system complements and supplements the existing PHE syndromic surveillance systems and is now integrated into the routine daily processes that form this national syndromic surveillance service.

The clinical and cost effectiveness of cognitive behavioural therapy plus treatment as usual for the treatment of depression in advanced cancer (CanTalk): study protocol for a randomised controlled trial

BackgroundThe prevalence of depressive disorder in adults with advanced cancer is around 20 %. Although cognitive behavioural therapy (CBT) is recommended for depression and may be beneficial in depressed people with cancer, its use for depression in those with advanced disease for whom cure is not likely has not been explored.MethodsPeople aged 18 years and above with advanced cancer attending General Practitioner (GP), oncology or hospice outpatients from centres across England will be screened to establish a DSM-IV diagnosis of depression. Self-referral is also accepted. Eligible consenters will be randomised to a single blind, multicentre, randomised controlled trial of the addition to treatment as usual (TAU) of up to 12 one-hour weekly sessions of manualised CBT versus TAU alone. Sessions are delivered in primary care through Increasing Access to Psychological Care (IAPT) service, and the manual includes a focus on issues for people approaching the end of life. The main outcome is the Beck Depression Inventory-II (BDI-II). Subsidiary measures include the Patient Health Questionnaire, quality of life measure EQ-5D, Satisfaction with care, Eastern Cooperative Oncology Group-Performance Status and a modified Client Service Receipt Inventory. At 90 % power, we require 240 participants to enter the trial. Data will be analysed using multi-level (hierarchical) models for data collected at baseline, 6, 12, 18 and 24 weeks. Cost effectiveness analysis will incorporate costs related to the intervention to compare overall healthcare costs and QALYs between the treatment arms. We will conduct qualitative interviews after final follow-up on patient and therapist perspectives of the therapy.DiscussionThis trial will provide data on the clinical and cost effectiveness of CBT for people with advanced cancer and depression. We shall gain an understanding of the feasibility of delivering care to this group through IAPT. Our findings will provide evidence for policy-makers, commissioners and clinicians in cancer and palliative care, and in the community.Trial registrationControlled Trials ISRCTN07622709, registered 15 July 2011.

Multi-pollutant exposure profiles associated with term low birth weight in Los Angeles County

Research indicates that multiple outdoor air pollutants and adverse neighborhood conditions are spatially correlated. Yet health risks associated with concurrent exposure to air pollution mixtures and clustered neighborhood factors remain underexplored. Statistical models to assess the health effects from pollutant mixtures remain limited, due to problems of collinearity between pollutants and area-level covariates, and increases in covariate dimensionality. Here we identify pollutant exposure profiles and neighborhood contextual profiles within Los Angeles (LA) County. We then relate these profiles with term low birth weight (TLBW). We used land use regression to estimate NO2, NO, and PM2.5 concentrations averaged over census block groups to generate pollutant exposure profile clusters and census block group-level contextual profile clusters, using a Bayesian profile regression method. Pollutant profile cluster risk estimation was implemented using a multilevel hierarchical model, adjusting for individual-level covariates, contextual profile cluster random effects, and modeling of spatially structured and unstructured residual error. Our analysis found 13 clusters of pollutant exposure profiles. Correlations between study pollutants varied widely across the 13 pollutant clusters. Pollutant clusters with elevated NO2, NO, and PM2.5 concentrations exhibited increased log odds of TLBW, and those with low PM2.5, NO2, and NO concentrations showed lower log odds of TLBW. The spatial patterning of pollutant cluster effects on TLBW, combined with between-pollutant correlations within pollutant clusters, imply that traffic-related primary pollutants influence pollutant cluster TLBW risks. Furthermore, contextual clusters with the greatest log odds of TLBW had more adverse neighborhood socioeconomic, demographic, and housing conditions. Our data indicate that, while the spatial patterning of high-risk multiple pollutant clusters largely overlaps with adverse contextual neighborhood cluster, both contribute to TLBW while controlling for the other.

Variation in prostate cancer treatment associated with population density of the county of residence.

We sought to assess variation in the primary treatment of prostate cancer by examining the effect of population density of the county of residence on treatment for clinically localized prostate cancer and quantify variation in primary treatment attributable to the county and state level. A total 138 226 men with clinically localized prostate cancer in the Surveillance, Epidemiology and End Result (SEER) database in 2005 through 2008 were analyzed. The main association of interest was between prostate cancer treatment and population density using multilevel hierarchical logit models while accounting for the random effects of counties nested within SEER regions. To quantify the effect of county and SEER region on individual treatment, the percent of total variance in treatment attributable to county of residence and SEER site was estimated with residual intraclass correlation coefficients. Men with localized prostate cancer in metropolitan counties had 23% higher odds of being treated with surgery or radiation compared with men in rural counties, controlling for number of urologists per county as well as clinical and sociodemographic characteristics. Three percent (95% confidence interval (CI): 1.2-6.2%) of the total variation in treatment was attributable to SEER site, while 6% (95% CI: 4.3-9.0%) of variation was attributable to county of residence, adjusting for clinical and sociodemographic characteristics. Variation in treatment for localized prostate cancer exists for men living in different population-dense counties of the country. These findings highlight the importance of comparative effectiveness research to improve understanding of this variation and lead to a reduction in unwarranted variation.

Genomic predictors of biochemical failure following radical prostatectomy.

114 Background: Although clinical correlates can help predict biochemical failure (BF), genomic correlates have yet to be identified. We hypothesized there would exist genomic profiles in patients who experience BF after radical prostatectomy (RP), for whom aggressive regional therapy may be more appropriate. Methods: Genes of interest were identified using the 25 most commonly mutated genes from the COSMIC dataset. The Cancer Genome Atlas (TCGA) was used to study normalized microarray gene expression data for patients who underwent RP for treatment of Gleason 7-10, T1/T2 N0 prostate adenocarcinoma. BF was considered PSA &gt; 0.1 following prostatectomy. Clinical data of interest included age, pre-treatment PSA, Gleason score, pathologic T stage, and country of origin. A multi-level hierarchical logistic regression model clustered with random effects by pathologic T stage and country of origin was built to identify predictors of BF. Variances were used to estimate how genomic differences explained differences in BF. Results: We identified 296 patients with T1/T2 N0 prostate adenocarcinoma who underwent RP. Median age was 60 with a median follow up of 2.3 years. 59% (n = 177) had Gleason 7 disease and 54% (n = 154) had T1 disease. 40.8% (n = 121) of patients had BF following RP. After adjusting for clinical covariates, 4 genes were associated with differences in BF. Specifically, increased RNA expression of E2F3 (OR 1.11 p &lt; .001), CTNNB1 (OR 1.49, p = .002), and AR (OR 1.21, p &lt; .001) were seen in patients who experienced BF. Expression of TP53 (OR 0.75, p &lt; .001) and Gleason 7 disease (OR 0.62 vs. Gleason 8-10, p &lt; .001) were associated with decreased likelihood of BF. Clustering by pathologic T stage accounted for 10% of variance in BF indicating that the 4 genes augment clinical patient characteristics. Conclusions: Genomic data augments pre-treatment clinical data in the stratification of patients undergoing RP. RNA expression of E2F3, CTNNB1, AR and TP53 is associated with differences in BF following RP. Clinically, these genes could aid in identifying patients who may benefit from more aggressive therapy. Further studies of the relationship between these genes and the development of prostate cancer could aid in future targeted therapies.

Can it be good to set the bar high? The role of motivational regulation in moderating the link from high standards to academic well-being

This study explored a motivational approach to examining individuals' perfectionistic strivings, using Self-Determination Theory as the theoretical foundation. Data were collected from 384 undergraduate students. Hierarchical multilevel models were performed to examine whether the association between the tendency to set high personal standards and learning outcomes would be moderated by people's type of motivational regulation. The results indicated that the striving for high standards was associated with less adaptive learning experiences when students experienced controlled regulation around their behaviors. We measured controlled regulation both as a personality orientation, and as students' reasons for participating in each of their classes. We found convergent evidence at both the between-person and the within-person, between-class levels that when students reported low controlled regulation, those who tended to set high standards for themselves reported less anxiety and difficulty in their learning, and more learning progress in their classes than the students who set low standards.

Temporomandibular Disorder Diagnostic Groups Affect Outcomes Independently of Treatment in Patients at Risk for Developing Chronicity: A 2-Year Follow-Up Study.

To evaluate whether a biobehavioral intervention would be more effective than a self-care intervention or no intervention in reducing psychosocial distress, reducing pain, and improving functioning in patients with an acute myofascial temporomandibular disorder (m-TMD). Participants (n = 435) were from community dental clinics in the Dallas-Fort Worth Metroplex who were seeking treatment for their acute TMD symptoms and were recruited between 2008 and 2013. The participants were diagnosed using the Research Diagnostic Criteria for TMD (RDC/TMD) and assigned to a biobehavioral intervention, self-care intervention, or no intervention. Three outcomes were assessed: psychosocial distress, pain, and functioning; and treatment effectiveness was assessed according to TMD diagnosis. Outcome evaluations were conducted immediately postintervention as well as at 1 and 2 years postintervention. Analyses were conducted using two-level hierarchical multilevel linear models (MLMs). Contrary to expectations, patients did not respond differently to the intervention based on their TMD diagnosis. Acute m-TMD patients, especially those with other comorbid TMD diagnoses, reported the highest levels of pain and pain-related symptoms and disability. They also exhibited poorer jaw functioning, especially if they were at high risk for chronic TMD. This study indicates that acute m-TMD tends to result in more severe symptom presentations, particularly if diagnosed in combination with other TMD comorbidities. Additionally, patients do not appear to respond better to biobehavioral or self-care intervention on the basis of their TMD diagnosis.

Cultural values and random breath tests as moderators of the social influence on drunk driving in 15 countries

IntroductionThe social influence on drunk driving has been previously observed in several countries. It is noteworthy, however, that the prevalence of alcohol in road fatalities is not the same in all countries. The present study aimed to explore whether cultural values and the number of roadside breath tests moderate the link between the perceived drunk driving of one's peers and self-reported behavior. MethodsBased on the European survey SARTRE 4, the responses of 10,023 car drivers from 15 countries were analyzed. Two cultural values, “tradition” and “conformism,” were identified as possibly being linked to social influence. Country scores for these values were taken from the European Social Survey. The number of random roadside breath tests per inhabitant was used as an indicator of drunk-driving enforcement in each country. ResultsA hierarchical multilevel modeling analysis confirmed the link between friends' drunk driving and one's own drunk driving in all countries, but the strength of the link was much stronger in some countries (e.g., Italy, Cyprus, and Israel) than in others (e.g., Finland, Estonia, and Sweden). Both the measured value of “tradition” and the number of alcohol breath tests were found to moderate the link between friends' and one's own drunk driving. Practical ApplicationsEuropean stakeholders should take into account cultural specificities of target countries when designing campaigns against drunk driving.

Do Physical Proximity and Availability of Adequate Infrastructure at Public Health Facility Increase Institutional Delivery? A Three Level Hierarchical Model Approach.

This study aims to examine the inter-district and inter-village variation of utilization of health services for institutional births in EAG states in presence of rural health program and availability of infrastructures. District Level Household Survey-III (2007–08) data on delivery care and facility information was used for the purpose. Bivariate results examined the utilization pattern by states in presence of correlates of women related while a three-level hierarchical multilevel model illustrates the effect of accessibility, availability of health facility and community health program variables on the utilization of health services for institutional births. The study found a satisfactory improvement in state Rajasthan, Madhya Pradesh and Orissa, importantly, in Bihar and Uttaranchal. The study showed that increasing distance from health facility discouraged institutional births and there was a rapid decline of more than 50% for institutional delivery as the distance to public health facility exceeded 10 km. Additionally, skilled female health worker (ANM) and observed improved public health facility led to significantly increase the probability of utilization as compared to non-skilled ANM and not-improved health centers. Adequacy of essential equipment/laboratory services required for maternal care significantly encouraged deliveries at public health facility. District/village variables neighborhood poverty was negatively related to institutional delivery while higher education levels in the village and women’s residing in more urbanized districts increased the utilization. “Inter-district” variation was 14 percent whereas “between-villages” variation for the utilization was 11 percent variation once controlled for all the three-level variables in the model. This study suggests that the mere availability of health facilities is necessary but not sufficient condition to promote utilization until the quality of service is inadequate and inaccessible considering the inter-districts variation for the program implementation.

Evaluation of the Family Integrated Care model of neonatal intensive care: a cluster randomized controlled trial in Canada and Australia.

BackgroundAdmission to the neonatal intensive care unit (NICU) may disrupt parent-infant interaction with adverse consequences for infants and their families. Several family-centered care programs promote parent-infant interaction in the NICU; however, all of these retain the premise that health-care professionals should provide most of the infant’s care. Parents play a mainly supportive role in the NICU and continue to feel anxious and unprepared to care for their infant after discharge. In the Family Integrated Care (FICare) model, parents provide all except the most advanced medical care for their infants with support from the medical team. Our hypothesis is that infants whose families complete the FICare program will have greater weight gain and better clinical and parental outcomes compared with infants provided with standard NICU care.Methods/DesignFICare is being evaluated in a cluster randomized controlled trial among infants born at ≤ 33 weeks’ gestation admitted to 19 Canadian, 6 Australian, and 1 New Zealand tertiary-level NICU. Trial enrollment began in April, 2013, with a target sample size of 675 infants in each arm, to be completed by August, 2015. Participating sites were stratified by country, and by NICU size within Canada, for randomization to either the FICare intervention or control arm. In intervention sites, parents are taught how to provide most of their infant’s care and supported by nursing staff, veteran parents, a program coordinator, and education sessions. In control sites standard NICU care is provided. The primary outcome is infants’ weight gain at 21 days after enrollment, which will be compared between the FICare and control groups using Student’s t-test adjusted for site-level clustering, and multi-level hierarchical models accounting for both clustering and potential confounders. Similar analyses will examine secondary outcomes including breastfeeding, clinical outcomes, safety, parental stress and anxiety, and resource use. The trial was designed, is being conducted, and will be reported according to the CONSORT 2010 guidelines for cluster randomized controlled trials.DiscussionBy evaluating the impact of integrating parents into the care of their infant in the NICU, this trial may transform the delivery of neonatal care.Trial registrationNCT01852695, registered December 19, 2012

Energy consumption hierarchical analysis based on interpretative structural model for ethylene production

Interpretative structural model (ISM) can transform a multivariate problem into several sub-variable problems to analyze a complex industrial structure in a more efficient way by building a multi-level hierarchical structure model. To build an ISM of a production system, the partial correlation coefficient method is proposed to obtain the adjacency matrix, which can be transformed to ISM. According to estimation of correlation coefficient, the result can give actual variable correlations and eliminate effects of intermediate variables. Furthermore, this paper proposes an effective approach using ISM to analyze the main factors and basic mechanisms that affect the energy consumption in an ethylene production system. The case study shows that the proposed energy consumption analysis method is valid and efficient in improvement of energy efficiency in ethylene production.

The Association between Life Satisfaction and Self–Reported Health Status in Europe

Previous research has shown that life satisfaction (LS) and self–reported health status are strongly related to each other. However, it is not clear whether this association holds across different nations or whether certain country–level indicators significantly affect this association. The study was based on nationally representative samples of 32 countries from the first six rounds of the European Social Survey (N = 291 686). Results from hierarchical multilevel modelling indicated that there was a positive association between LS and self–reported health status across countries, but this association was slightly stronger in countries where governments spent less on the health care of their residents. Self–reported health ratings were also more strongly tied to LS judgements in countries where variability in LS ratings was larger. These results suggest that, especially in less wealthy European countries, policies should target reducing overall social inequality and the negative impact of governments’ underinvestment in health care on LS. Copyright © 2015 European Association of Personality Psychology

Optimal surrogates selection for embedded, hierarchical multilevel aircraft models

This study proposes a methodology that reduces the memory size of hierarchical multilevel embedded models while keeping its structure and satisfying constraints on accuracy and computation time. Based on a choice among surrogates (high dimensional model representation, neural networks, etc.) associated with each submodel, an overall hierarchical multilevel model that fulfills avionics systems requirements is provided via the resolution of an integer programming problem. This methodology is illustrated on a fuel model used for aircraft performance estimations.

Code Status Documentation and Its Impact on In-Hospital Mortality in Colorectal Cancer Patients: A National Perspective

Introduction: Colorectal cancer is a major contributor of morbidity and mortality in the U.S. accounting for 8% of all cancer deaths. The impact of code status on mortality in colorectal cancer patients has never been documented. We aim to determine the impact of code status on mortality in patients with colorectal cancer. Methods: We reviewed the Healthcare Cost and Utilization Project's Nationwide Inpatient Sample (NIS) database of 2010 - 2011 for colorectal cancer as a principal diagnosis using ICD 9-CM codes (153 and 154). NIS represents 20% of all US hospital patients and weighted numbers represent national estimates. We defined patients' DNR status with ICD-9 code V49.86. Our primary outcome of interest was in-hospital mortality. We utilized chi-square test for univariate analysis of categorical variables and generated hierarchical multilevel regression models to determine independent predictors of mortality. Results: We analyzed a total of 56972 patients (weighted n= 278866) with principal diagnosis of colorectal cancer out of which 1114 (weighted n= 5360) patients had DNR status. The proportion of in-hospital mortality (13.94% vs. 1.49%, p < 0.001) was higher in patients with DNR orders. Even after adjusting for confounders (demographics, co-morbidities, admission type, hospital region, and hospital teaching status), DNR status was associated with higher in-hospital mortality (OR 7.12, 95% CI, 6.57 to 7.72, p < 0.001) and adverse outcomes (OR 1.06, 95% CI, 1.04 to 1.08, p < 0.001). Conclusion: DNR status in patients admitted with colorectal cancer appears to be an independent and significant predictor of substantially increased hospital mortality. The reasons for such an outcome are multi-factorial and can be attributed to advanced disease stage, other co morbidities not accounted in NIS and hospital & physician factors. Further studies, involving both quantitative/qualitative aspects, are warranted to investigate these factors in detail.Figure 1

Nursing consultations and control of diabetes in general practice: a retrospective observational study.

BackgroundDiabetes affects around 3.6 million people in the UK. Previous research found that general practices employing more nurses delivered better diabetes care, but did not include data on individual patient characteristics or consultations received.AimTo examine whether the proportion of consultations with patients with diabetes provided by nurses in GP practices is associated with control of diabetes measured by levels of glycated haemoglobin (HbA1c).Design and settingA retrospective observational study using consultation records from 319 649 patients with diabetes from 471 UK general practices from 2002 to 2011.MethodHierarchical multilevel models to examine associations between proportion of consultations undertaken by nurses and attaining HbA1c targets over time, controlling for case-mix and practice level factors.ResultsThe proportion of consultations with nurses has increased by 20% since 2002 but patients with diabetes made fewer consultations per year in 2011 compared with 2002 (11.6 versus 16.0). Glycaemic control has improved and was more uniformly achieved in 2011 than 2002. Practices in which nurses provide a higher proportion of consultations perform no differently to those where nurse input is lower (lowest versus highest nurse contact tertile odds ratio [OR] [confidence interval {95% CI}]: HbA1c ≤53 mmol/mol (7%) 2002, 1.04 [95% CI = 0.87 to 1.25] and 2011, 0.95 [95% CI = 0.87 to 1.03]; HbA1c ≤86 mmol/mol (10%) 2002, 0.97 [95% CI = 0.73 to 1.29] and 2011, 0.95 [95% CI = 0.86 to 1.04]).ConclusionPractices that primarily use GPs to deliver diabetes care could release significant resources with no adverse effect by switching their services towards nurse-led care.

Sex Differences in Academic Rank in US Medical Schools in 2014.

The proportion of women at the rank of full professor in US medical schools has not increased since 1980 and remains below that of men. Whether differences in age, experience, specialty, and research productivity between sexes explain persistent disparities in faculty rank has not been studied. To analyze sex differences in faculty rank among US academic physicians. We analyzed sex differences in faculty rank using a cross-sectional comprehensive database of US physicians with medical school faculty appointments in 2014 (91,073 physicians; 9.1% of all US physicians), linked to information on physician sex, age, years since residency, specialty, authored publications, National Institutes of Health (NIH) funding, and clinical trial investigation. We estimated sex differences in full professorship, as well as a combined outcome of associate or full professorship, adjusting for these factors in a multilevel (hierarchical) model. We also analyzed how sex differences varied with specialty and whether differences were more prevalent at schools ranked highly in research. Physician sex. Academic faculty rank. In all, there were 30,464 women who were medical faculty vs 60,609 men. Of those, 3623 women (11.9%) vs 17,354 men (28.6%) had full-professor appointments, for an absolute difference of -16.7% (95% CI, -17.3% to -16.2%). Women faculty were younger and disproportionately represented in internal medicine and pediatrics. The mean total number of publications for women was 11.6 vs 24.8 for men, for a difference of -13.2 (95% CI, -13.6 to -12.7); the mean first- or last-author publications for women was 5.9 vs 13.7 for men, for a difference of -7.8 (95% CI, -8.1 to -7.5). Among 9.1% of medical faculty with an NIH grant, 6.8% (2059 of 30,464) were women and 10.3% (6237 of 60,609) were men, for a difference of -3.5% (95% CI, -3.9% to -3.1%). In all, 6.4% of women vs 8.8% of men had a trial registered on ClinicalTrials.gov, for a difference of -2.4% (95% CI, -2.8% to -2.0%). After multivariable adjustment, women were less likely than men to have achieved full-professor status (absolute adjusted difference in proportion, -3.8%; 95% CI, -4.4% to -3.3%). Sex-differences in full professorship were present across all specialties and did not vary according to whether a physician's medical school was ranked highly in terms of research funding. Among physicians with faculty appointments at US medical schools, there were sex differences in academic faculty rank, with women substantially less likely than men to be full professors, after accounting for age, experience, specialty, and measures of research productivity.

Implementing a Simulation Study Using Multiple Software Packages for Structural Equation Modeling

A Monte Carlo simulation study is an essential tool for evaluating the behavior of various quantitative methods including structural equation modeling (SEM) under various conditions. Typically, a large number of replications are recommended for a Monte Carlo simulation study, and therefore automating a Monte Carlo simulation study is important to get the desired number of replications for a simulation study. This article is intended to provide concrete examples for automating a Monte Carlo simulation study using some standard software packages for SEM: Mplus, LISREL, SAS PROC CALIS, and R package lavaan. Also, the equivalence between the multilevel SEM and hierarchical linear modeling (HLM) is discussed, and relevant examples are provided. It is hoped that the codes in this article can provide some building blocks for researchers to write their own code to automate simulation procedures.

Mechanical analyses on the digital behaviour of the Tokay gecko (Gekko gecko) based on a multi-level directional adhesion model.

This paper proposes a multi-level hierarchical model for the Tokay gecko (Gekko gecko) adhesive system and analyses the digital behaviour of the G. gecko under macro/meso-level scale. The model describes the structures of G. gecko's adhesive system from the nano-level spatulae to the sub-millimetre-level lamella. The G. gecko's seta is modelled using inextensible fibril based on Euler's elastica theorem. Considering the side contact of the spatular pads of the seta on the flat and rigid substrate, the directional adhesion behaviour of the seta has been investigated. The lamella-induced attachment and detachment have been modelled to simulate the active digital hyperextension (DH) and the digital gripping (DG) phenomena. The results suggest that a tiny angular displacement within 0.25° of the lamellar proximal end is necessary in which a fast transition from attachment to detachment or vice versa is induced. The active DH helps release the torque to induce setal non-sliding detachment, while the DG helps apply torque to make the setal adhesion stable. The lamella plays a key role in saving energy during detachment to adapt to its habitat and provides another adhesive function which differs from the friction-dependent setal adhesion system controlled by the dynamic of G. gecko's body.