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Longitudinal studies predictably experience non-random attrition over time. Among older adults, risk factors for attrition may be similar to risk factors for outcomes such as cognitive decline and dementia, potentially biasing study results.
To characterize participants lost to follow-up which can be useful in the study design and interpretation of results.
In a longitudinal aging population study with 10 years of annual follow-up, we characterized the attrited participants (77%) compared to those who remained in the study. We used multivariable logistic regression models to identify attrition predictors. We then implemented four machine learning approaches to predict attrition status from one wave to the next and compared the results of all five approaches.
Multivariable logistic regression identified those more likely to drop out as older, male, not living with another study participant, having lower cognitive test scores and higher clinical dementia ratings, lower functional ability, fewer subjective memory complaints, no physical activity, reported hobbies, or engagement in social activities, worse self-rated health, and leaving the house less often. The four machine learning approaches using areas under the receiver operating characteristic curves produced similar discrimination results to the multivariable logistic regression model.
Attrition was most likely to occur in participants who were older, male, inactive, socially isolated, and cognitively impaired. Ignoring attrition would bias study results especially when the missing data might be related to the outcome (e.g. cognitive impairment or dementia). We discuss possible solutions including oversampling and other statistical modeling approaches.
Children with attention-deficit hyperactivity disorder (ADHD) may suffer marked impairment in early adulthood, increasing their risk for serious self-harmful behaviors. Deliberate self-poisoning (DSP) is the most common form of deliberate self-harm. An association may exist between ADHD diagnosis and subsequent DSP events. The purpose of study was to determine whether children and adolescents with ADHD are at a greater risk for DSP than are age-matched controls.
Claims data from the Taiwan National Health Insurance Database were used to conduct a retrospective cohort analysis of emergency department visits. The study cohort contained 3685 patients with ADHD (< 8 years old). Each ADHD patient was frequency matched based on sex, age, urbanization, parental occupation, and index year to 10 control patients without ADHD. A Cox proportional-hazards regression model was used to estimate the risk of DSP in the ADHD and comparison cohorts.
The risk of developing DSP was significantly higher in the ADHD cohort than in the comparison cohort (P < .0001 for log-rank test). After adjusting for potential confounders, the regression model showed that the ADHD patients were at a 4.65-fold greater risk of developing DSP than the control patients were (HR = 4.65, 95% CI: 2.41–8.94).
Children with ADHD are at greater risk of developing DSP. Identifying risk factors of DSP is crucial efforts to implement prevention strategies. The identification of the underlying cause of increased DSP among ADHD patients warrants further investigation.
For electronic packaging structure, there are many design parameters that will affect its reliability performance, using experimental way to obtain the reliability result will take a considerable amount of time. Therefore, how to shorten the design time becomes a critical issue for new electronic packaging structure development. This research will combine artificial intelligence (AI) and simulation technology to assess the long-term reliability of wafer level packaging (WLP). A simulation technology using finite element method (FEM) with appropriate mechanics theories has been validated by multiple experiments will replace the experiment to create reliability results for different WLP structures. After a big WLP structure-reliability database created, this study will apply artificial neural network (ANN) theory to analyze this database and obtains a regression model for structure-reliability relationship of WLP. Once the regression model is established and validated, the WLP geometry, such as pad size, die and buffer layer thickness, and solder volume, etc. can be simply entered, and then the WLP reliability results can be immediately obtained through the ANN regression model.
Retinoblastoma is the most common primary intraocular tumor of childhood with >95% survival rates in the US. Traditional therapy for retinoblastoma often included enucleation (removal of the eye). While much is known about the visual, physical, and cognitive ramifications of enucleation, data are lacking about survivors' perception of how this treatment impacts overall quality of life.
Qualitative analysis of an open-ended response describing how much the removal of an eye had affected retinoblastoma survivors' lives and in what ways in free text, narrative form.
Four hundred and four retinoblastoma survivors who had undergone enucleation (bilateral disease = 214; 52% female; mean age = 44, SD = 11) completed the survey. Survivors reported physical problems (n = 205, 50.7%), intrapersonal problems (n = 77, 19.1%), social and relational problems (n = 98, 24.3%), and affective problems (n = 34, 8.4%) at a mean of 42 years after diagnosis. Three key themes emerged from survivors' responses; specifically, they (1) continue to report physical and intrapersonal struggles with appearance and related self-consciousness due to appearance; (2) have multiple social and relational problems, with teasing and bullying being prominent problems; and (3) reported utilization of active coping strategies, including developing more acceptance and learning compensatory skills around activities of daily living.
Significance of results
This study suggests that adult retinoblastoma survivors treated with enucleation continue to struggle with a unique set of psychosocial problems. Future interventions can be designed to teach survivors more active coping skills (e.g., for appearance-related issues, vision-related issues, and teasing/bullying) to optimize survivors' long-term quality of life.
To assess independent and joint effects of pairs of vascular and cardiometabolic risk factors (VCMRFs) in relation to risk of all-cause dementia.
Population-based longitudinal cohort study of cognitive impairment. We used an algorithm to select pairs of VCMRFs and tested their joint effects in time-dependent Cox models. We used attributable proportions (AP) to measure the proportion of risk from interactions beyond any additive effect.
Economically depressed small-town population.
Adults age 65+ years with up to 10 yearly study visits (N=1701, median (Q1, Q3) age, 78 (71.0, 83.0), 62.3% female, 94.9% white).
Among 1701 participants free from prevalent dementia with at least one follow-up visit, 109 developed incident all-cause dementia. In pairings of APOE*4 with hypertension (HTN) and congestive heart failure (CHF), the variables contributed independently and additively to all-cause dementia risk. In pairings of APOE*4 with stroke and stroke with CHF, the variables demonstrated independent contributions to all-cause dementia risk; their joint effects showed excess detriment demonstrating synergistic interactions (joint HR [95% CI]: 28.33 [6.74, 119.01] and 50.30 [14.57, 173.57] respectively, fully adjusted models). Physical activity (PA) was independently associated with lower all-cause dementia risk when paired with APOE*4, stroke, and CHF in unadjusted models; these associations did not survive covariate adjustment. The joint effect of low PA and APOE*4 was associated with additively increased all-cause dementia risk (joint HR [95% CI]: 4.61 [2.07, 10.23], fully adjusted model).
Reduction of VCMRFs, including low PA, could be valuable for dementia prevention, especially among APOE*4 carriers.
Evidence suggests that semantic interference may be a sensitive indicator of early dementia. We examined the utility of the Semantic Interference Test (SIT), a cognitive stress memory paradigm which taps proactive and retroactive semantic interference, for predicting progression from mild cognitive impairment (MCI) to dementia in both a clinical and a population-based sample.
Participants with MCI in the clinical (n = 184) and population-based (n = 435) samples were followed for up to four years. We employed receiver operating characteristic (ROC) methods to establish optimal thresholds for four different SIT indices. Threshold performance was compared in the two samples using logistic and Cox proportional hazard regression models.
Within four years, 42 (22.8%) MCI individuals in the clinical sample and 45 (10.3%) individuals in the population-based sample progressed to dementia. Overall classification accuracy of SIT thresholds ranged from 61.4% to 84.8%. Different subtests of the SIT had slightly different performance characteristics in the two samples. However, regression models showed that thresholds established in the clinical sample performed similarly in the population sample before and after adjusting for demographics and other baseline neuropsychological test scores.
Despite differences in demographic composition and progression rates, baseline SIT scores predicted progression from MCI to dementia similarly in both samples. Thresholds that best predicted progression were slightly below thresholds established for distinguishing between amnestic MCI and cognitively normal subjects in clinical practice. This confirms the utility of the SIT in both clinical and population-based samples and establishes thresholds most predictive of progression of individuals with MCI.
Prior to integrated circuit (IC) packaging, die performance must be verified using probe cards to screen for defective products. With the decrease in IC line width, the dimensions of the pads used for performance verification and the spacing between adjacent pads have also decreased. However, when the pad pitch is reduced to less than 30 μm, commonly used probe cards will face manufacturing problems in miniaturization. To resolve probe card manufacturing problems caused by the miniaturization of IC components, the use of an anisotropic conductive film (ACF) in probe cards was proposed in this study. Theoretical calculations and experimental testing of this probe structure were conducted to demonstrate the feasibility of this concept.
In theoretical calculations, composite material and buckling theory were utilized to evaluate the buckling behavior of the ACF. In experimental testing, photolithography and electroplating techniques were used to control the line width and spacing intervals of the micron-scale metal wires in the ACF. After the ACF was fabricated, the mechanical properties of the ACF during wafer testing were assessed. Theoretical analyses and experimental testing verified that ACFs can potentially be applied to the performance verification of IC products. In the ACF structure, multiple probes came into contact with each pad. Therefore, ACFs can potentially be applied to the performance verification of IC components with pad diameters of less than 20 μm. The results of this study directly benefit the miniaturization of ICs.
A compact hybrid rocket motor design that incorporates a dual-vortical-flow (DVF) concept is proposed. The oxidizer (nitrous oxide, N2O) is injected circumferentially into various sections of the rocket motor, which are sectored by several solid fuel “rings” (made of hydroxyl-terminated polybutadiene, HTPB) that are installed along the central axis of the motor. The proposed configuration not only increases the residence time of the oxidizer flow, it also implies an inherent “roll control” capability of the motor. Based on a DVF motor geometry with a designed thrust level of 11.6 kN, the characteristics of the turbulent reacting flow within the motor and its rocket performance were analyzed with a comprehensive numerical model that implements both real-fluid properties and finite-rate chemistry. Data indicate that the vacuum specific impulse (Isp) of the DVF motor could reach 278 s. The result from a preliminary ground test of a lab-scale DVF hybrid rocket motor (with a designed thrust level of 3,000 N) also shows promising performance. The proposed DVF concept is expected to partly resolve the issue of scalability, which remains challenging for hybrid rocket motors development.
The propensity score (PS) weighting method is an analytic technique that has been applied in multiple fields for a number of purposes. Here, we discuss two common applications, which are (1) to correct for selection bias and (2) to adjust for confounding variables when estimating the effect of an exposure variable on the outcome of interest.
In many developed countries, cognitive functioning (as measured by neuropsychological tests) appears to be improving over time in the population at large, in parallel with the declining age-specific incidence of dementia. Here, we investigated cohort effects in the age-associated trajectories of verbal memory function in older adults. We sought to determine whether they varied by decade of birth and, if so, whether the change would be explained by increasing educational attainment.
Pooling data from two prospective US population-based studies between 1987 and 2015, we identified four birth cohorts born 1902–1911, 1912–1921, 1922–1931, and 1932–1943. Among these cohorts, we compared age-associated trajectories both of performance and of practice effects on immediate and delayed recall of a 10-item Word List. We used mixed effects models, first including birth cohorts and cohort X age interaction terms, and then controlling for education and education X age interaction.
We observed significant cohort effects in performance (baseline and age-associated trajectories) in both immediate recall and delayed recall, with function improving between the earliest- and latest-born cohorts. For both tests, we also observed cohort effects on practice effects with the highest levels in the latest-born cohorts. Including education in the models did not attenuate these effects.
In this longitudinal population study, across four decade-long birth cohorts, there were significant improvements in test performance and practice effects in verbal memory tests, not explained by education. Whether this reflects declining disease incidence or other secular trends awaits further investigation.
We recently demonstrated a sub-bandgap photoresponse with our wafer-scale
Au/TiO2 metallic-semiconductor photonic crystals (MSPhC). The
sub-bandgap energy with 590 nm peak could be absorbed in the form of hot
electron and injected to TiO2, which provides 5.28 times more energy
for photolysis than that of energy absorbed to flat TiO2. If the
solar energy already absorbed above 700 nm could be injected to the catalyst,
higher than 10 times improvement will be achieved, and above 20% solar to fuel
efficiency will be feasible with the robust but inefficient TiO2
catalyst. In order to achieve photocurrent near and above 700 nm spectrum, we
deposited gold nanorods on the surface of MSPhC to incur localized surface
plasmon (LSP) modes absorption and subsequent injection to the TiO2
catalyst. We used electrophoretic deposition (EPD) method to deposit nanorods on
the top, sidewall and bottom well surface of the photonic nanocavities. The
deposition of nanorods was achieved reasonably uniform and sparse not to block
the optical cavities of MSPhC. Flat gold surfaces were tested at 4 different
suspension densities to get the optimum gold nanorods density. Under 10V applied
electric field, positively charged gold nanorods at the concentration of
6.52×1013 #/mL could deposit MSPhC surface
with the density of 230 #/µm2, which was reasonably
uniform and sparse. Preliminary tests show an absorbance increase near 700 nm on
flat device coated with gold nanorods. Photocurrent measurement is under way to
demonstrate the enhanced hot electron transfer over full visible light and
near-infrared solar spectrum.
The relationship between subjective memory complaints (SM) and objective memory (OM) performance in aging has been variably characterized in a substantial literature, to date. In particular, cross-sectional studies often observe weak or no associations. We investigated whether subjective memory complaints and objectively measured cognition influence each other over time, and if so, which is the stronger pathway of change—objective to subjective, or subjective to objective—or whether they are both important. Using bivariate latent change score modeling in data from a population study (N=1980) over 5 annual assessment cycles, we tested four corresponding hypotheses: (1) no coupling between SM and OM over time; (2) SM as leading indicator of change in OM; (3) OM as leading indicator of change in SM; (4) dual coupling over time, with both SM and OM leading subsequent change in the other. We also extended objective cognition to two other domains, language and executive functions. The dual-coupling models best fit the data for all three objective cognitive domains. The SM–OM temporal dynamics differ qualitatively compared to other domains, potentially reflecting changes in insight and self-awareness specific to memory impairment. Subjective memory and objective cognition reciprocally influence each other over time. The temporal dynamics between subjective and objective cognition in aging are nuanced, and must be carefully disentangled to shed light on the underlying processes. (JINS, 2015, 21, 732–742)
The possibility of cooling enhancement of flat plate heat pipes (FPHPs) by tilting was examined experimentally in this study. All of the FPHPs were made of Al and were partially filled with acetone. They had the same size of 120 mm (length) by 36 mm (width) by 2.5 mm (thickness) and the same liquid filling ratio of 25.1%. The effects of six tilting angles of -30°, -15°, -10°, 0°, 45°, and 90° were explored. The results showed that the thermal resistance decreased and the effective thermal conductivity increased when the tilting angle was increased. By increasing the tilting angle from 0° to 45° and further to 90°, the maximum effective thermal conductivity increased by a factor of 1.205 from 4561 W/mK to 5497 W/mK and of 1.212 to 5530 W/mK, respectively. The corresponding maximum heat transport capability increased by a factor of 2.89 from 39.8 W to 115 W and of 3.27 to 130 W. Hence, by proper tilting into positve angles, cooling enhancement of the FPHPs can be greatly achieved.
Information on the risk factors for community-associated skin and soft-tissue infections (SSTIs) due to methicillin-resistant Staphylococcus aureus in Asian populations is scarce. To this end we performed a case-control study of patients treated at two hospital-affiliated outpatient clinics in Taiwan to determine potential risk factors for MRSA SSTIs. S. aureus was isolated from 39 of 100 eligible patients, and 74% were MRSA. Apart from resistance to clindamycin and erythromycin, most MRSA isolates were susceptible to appropriate antimicrobials. The significant risk factors identified by multivariate analysis for MRSA SSTIs were male gender (P = 0·09), nasal carriage of MRSA (P = 0·02), exposure to an individual who had surgery within a year before infection (P = 0·02), and antibiotic treatment for SSTI in the year before infection (P = 0·04). The identification of such factors may assist provision of appropriate treatment to patients with suspected S. aureus SSTIs particularly in Taiwan.
To describe covariates and patterns of late-life analgesic use in the rural, population-based MoVIES cohort from 1989 to 2002.
Secondary analysis of epidemiologic survey of elderly people conducted over six biennial assessment waves. Potential covariates of analgesic use included age, gender, depression, sleep, arthritis, smoking, alcohol, and general health status. Of the original cohort of 1,681, this sample comprised 1,109 individuals with complete data on all assessments. Using trajectory analysis, participants were characterized as chronic or non-chronic users of opioid and non-opioid analgesics. Multivariable regression was used to model predictors of chronic analgesic use.
The cohort was followed for mean (SD) 7.3 (2.7) years. Chronic use of opioid analgesics was reported by 7.2%, while non-opioid use was reported by 46.1%. In the multivariable model, predictors of chronic use of both opioid and non-opioid analgesics included female sex, taking ≥2 prescription medications, and “arthritis” diagnoses. Chronic opioid use was also associated with age 75–84 years; chronic non-opioid use was also associated with sleep continuity disturbance.
These epidemiological data confirm clinical observations and generate hypotheses for further testing. Future studies should investigate whether addressing sleep problems might lead to decreased use of non-opioid analgesics and possibly enhanced pain management.
Colloidal quantum dot photovoltaic devices have improved from initial, sub-1% solar power conversion efficiency to current record performance of over 7%. Rapid advances in materials processing and device physics have driven this impressive performance progress. The highest-efficiency approaches rely on a fabrication process that starts with nanocrystals in solution, initially capped with long organic molecules. This solution is deposited and the resultant film is treated using a solution containing a second, shorter capping ligand, leading to a cross-linked, non-redispersible, and dense layer. This procedure is repeated, leading to the widely employed layer-by-layer solid-state ligand exchange. We will review the properties and features of this process, and will also discuss innovative pathways to creating even higher-performing films and photovoltaic devices.
Pre-pregnancy obesity has been associated with adverse birth outcomes. Poor essential fatty acid (EFA) and micronutrient status during pregnancy may contribute to these associations. We assessed the associations between pre-pregnancy BMI and nutritional patterns of maternal micronutrient and EFA status during mid-pregnancy.
A cross-sectional analysis from a prospective cohort study. Women provided non-fasting blood samples at ≤20 weeks’ gestation that were assayed for red cell EFA; plasma folate, homocysteine and ascorbic acid; and serum retinol, 25-hydroxyvitamin D, α-tocopherol, soluble transferrin receptors and carotenoids. These nutritional biomarkers were employed in a factor analysis and three patterns were derived: EFA, Micronutrients and Carotenoids.
The Antidepressant Use During Pregnancy Study, Pittsburgh, PA, USA.
Pregnant women (n 129).
After adjustment for parity, race/ethnicity and age, obese pregnant women were 3·0 (95 % CI 1·1, 7·7) times more likely to be in the lowest tertile of the EFA pattern and 4·5 (95 % CI 1·7, 12·3) times more likely to be in the lowest tertile of the Carotenoid pattern compared with their lean counterparts. We found no association between pre-pregnancy obesity and the Micronutrient pattern after confounder adjustment.
Our results suggest that obese pregnant women have diminished EFA and carotenoid concentrations.
This nationwide population-based cohort study investigated the risk of tuberculosis (TB) in patients with end-stage renal disease (ESRD) and receiving dialysis. The evaluations included 4131 incident ESRD patients receiving dialysis and 16 524 age- and gender-matched controls, recruited between 1998 and 2009. We used Cox proportional hazards regression analysis to measure the association between TB and ESRD. Compared to the controls, the ESRD cohort had a significantly higher risk of TB within 1 year [incident rate ratio (IRR) 4·13], and 1–2 years (IRR 2·12), of occurrence of ESRD. The Cox proportional hazards model revealed that ESRD [hazard ratio (HR) 2·40], age >65 years (HR 2·41), male sex (HR 1·94), diabetes mellitus (HR 1·36), silicosis (HR 7·70) and chronic obstructive pulmonary disease (HR 1·61) are independent risk factors for TB. Patients with ESRD are associated with an increased risk of TB, and should thus be monitored more carefully for TB, especially within 2 years of onset of ESRD.