Experimental Design for Unbalanced Data Involving a Two level Logistic Model

The multilevel logistic model is used to analyze hierarchical data with binary outcomes, to detect variation both between and within clusters. I extended explicit variance formulae for a fixed effect in two level model for balanced binary data to account for imbalance both between and within clusters. The derivation of the variance is based on a linearization of the two level logistic model using first order marginal quasilikelihood (MQL1) estimation. In a simulation study, I used second order propensity quasilikelihood (PQL2) estimation to collaborate the accuracy of the analytic variance formula based on the observed racial distribution in a multi-center study of racial disparities. Using the site specific racial distributions, I simulated the log odds ratio for black race that could be detected with 80% power. These methods are illustrated in the context of a multi-center study of racial disparities in 30-day mortality in the Veterans Affairs (VA) Healthcare System, where the racial distributions are dramatically unbalanced across the 149 sites. We also consider a subset of 42 sites that include a majority of the black hospitalizations. The same analytic variance is obtained when one has either equal numbers of observations per site and/or a constant proportion of black veterans across sites. The observed racial imbalance both within and across sites increases the variance of the race coefficient more in the Random Coefficient (RC) model than in the random intercept (RI) model. Compared to PQL2, the analytic variances using MQL1 are, severely downwardly biased with smaller variance components. The simulation variances are virtually identical to the analytic variances for these data. For a given power, somewhat smaller log odds ratios can be detected in the RI model than in the RC model. The derived formulas provide a basis for planning multi-center studies when a predictor of primary importance is highly imbalanced both between and within sites. In studies of racial disparities in health care, the site-specific population distributions are often known from administrative data. The public health relevance of this work is that these methods for unbalanced data may facilitate more effective planning of multi-center studies of racial disparities

Fast Methods for Millimeter-wave Dielectric Resonator and Antenna Analysis and Design

Ever-increasing interest in millimeter-wave and terahertz spectrum has prompted research and development of novel passive components working at these frequencies. Compared with the conventional planar components, non-planar dielectric devices become more attractive as frequencies increase due to their higher quality factors and dimensional tolerances. In this thesis, we present fast methods to analyze the millimeter-wave dielectric resonator and rod antenna. First, an analytical method has been developed to evaluate resonant frequencies, quality factors of the Whispering Gallery Mode (WGM) disk resonators and also the resonator-waveguide coupling. A numerical solver based on full-wave finite element method is implemented to verify the analytical result. This analytical model provides a solution for fast design and optimization of WGM resonators in filter and sensor applications. Secondly, a fast analytical approach based on local mode theory is introduced to calculate the radiation from tapered dielectric rod antenna. This efficient approximate model consumes much less computing resources and time, and demonstrates good agreements with full-wave numerical results. It supplies a quantitative way to understand the radiation mechanism and interaction between different parts of the antenna. Based on this, design criteria for the taper profile of rod antennas are given

Polypharmacy Among People Living with Dementia — Israel and 24 Countries in European Union, 2015–2019.

What is already known about this topic? With a growing number of people living with dementia (PLWD), the practice of taking multiple medications to manage symptoms or comorbidities, i.e., polypharmacy, among PLWD has become a global health challenge. What is added by this report? In 2015–2019, polypharmacy for PLWD varied substantially among 25 studied countries, with approximately 1 in 5 Estonian PLWD and 4 in 5 Cypriot PLWD having polypharmacy. In addition, Switzerland, Poland, Austria, and the Czech Republic have experienced a significantly increasing trend in polypharmacy for PLWD. What are the implications for public health practice? Countries should pay special attention to polypharmacy and make efforts to control polypharmacy among PLWD, especially in countries where the trend of polypharmacy among PLWD has been increasing

Breaking the amyotrophic lateral sclerosis early diagnostic barrier: the promise of general markers

Amyotrophic lateral sclerosis (ALS) is a severe neurodegenerative disease that is associated with selective and progressive loss of motor neurons. As a consequence, the symptoms of ALS are muscle cramps and weakness, and it eventually leads to death. The general markers for early diagnosis can assist ALS patients in receiving early intervention and prolonging their survival. Recently, some novel approaches or previously suggested methods have validated the potential for early diagnosis of ALS. The purpose of this review is to summarize the status of current general markers discovery and development for early diagnosis of ALS, including genes, proteins neuroimaging, neurophysiology, neuroultrasound, and machine learning models. The main genetic markers evaluated are superoxide dismutase 1 (SOD1), chromosome 9 open reading frame 72 (C9orf72), transactivation-responsive DNA binding protein 43 (TARDBP), and fused in sarcoma (FUS) genes. Among proteins, neurofilament light chain is still the most established disease-specific adaptive change in ALS. The expression of chitinases, glial fibrillary acidic protein (GFAP), and inflammatory factors are changed in the early stage of ALS. Besides, more patient-friendly and accessible feature assays are explored by the development of neuroimaging, neurophysiology, and neuroultrasound techniques. The novel disease-specific changes exhibited the promising potential for early diagnosis of ALS. All of these general markers still have limitations in the early diagnosis, therefore there is an urgent need for the validation and development of new disease-specific features for ALS

Trends in Gender and Racial/Ethnic Disparities in Physical Disability and Social Support Among U.S. Older Adults With Cognitive Impairment Living Alone, 2000-2018

BACKGROUND AND OBJECTIVES: Informal care is the primary source of support for older adults with cognitive impairment, yet is less available to those who live alone. We examined trends in the prevalence of physical disability and social support among older adults with cognitive impairment living alone in the United States. RESEARCH DESIGN AND METHODS: We analyzed 10 waves of data from the U.S. Health and Retirement Survey spanning 2000-2018. Eligible people were those aged ≥65, having cognitive impairment, and living alone. Physical disability and social support were measured via basic and instrumental activities of daily living (BADLs, IADLs). We estimated linear temporal trends for binary/integer outcomes via logistic/Poisson regression, respectively. RESULTS: A total of 20 070 participants were included. Among those reporting BADL/IADL disability, the proportion unsupported for BADLs decreased significantly over time (odds ratio [OR] 0.98, 95% confidence interval [CI] 0.97-0.99), and the proportion unsupported for IADLs increased (OR = 1.02, CI 1.01-1.04). Among those receiving IADL support, the number of unmet IADL support needs increased significantly over time (relative risk [RR] 1.04, CI 1.03-1.05). No gender disparities were found for these trends. Over time, Black respondents had a relatively increasing trend of being BADL-unsupported (OR = 1.03, CI 1.0-1.05) and Hispanic and Black respondents had a relatively increasing trend in the number of unmet BADL needs (RR = 1.02, CI 1.00-1.03; RR = 1.01, CI 1.00-1.02, respectively), compared to the corresponding trends in White respondents. DISCUSSION AND IMPLICATIONS: Among lone-dwelling U.S. older adults with cognitive impairment, fewer people received IADL support over time, and the extent of unmet IADL support needs increased. Racial/ethnic disparities were seen both in the prevalence of reported BADL/IADL disability and unmet BADL/IADL support needs; some but not all were compatible with a reduction in disparity over time. This evidence could prompt interventions to reduce disparities and unmet support needs

Related consistent lures increase the judgment of multiplication facts: Evidence using event-related potential technique

Simple multiplication errors are primarily shown in whether the lures are related to the operands (relatedness, such as 3 × 4 = 15 vs. 17) or whether the same decades are shared with the correct answers (consistency, such as 3 × 4 = 16 vs. 21). This study used a delayed verification paradigm and event-related potential technique to investigate the effects of relatedness and consistency in simple multiplication mental arithmetic for 30 college students in an experiment of presenting probes in auditory channels. We found that, compared to the related inconsistent lures, the related consistent lures showed significantly faster reaction time and induced significantly large amplitudes of N400 and late positive component. The findings suggest that related consistent lures are less affected by the activation diffusion of the arithmetic problem, and the credibility of being perceived as the correct answer is less; the lures related to operands and sharing the same decades with the accurate results can promote the judgment of multiplication mental arithmetic, and the results support the Interacting Neighbors Model

Quantitative assessment of renal functions using 68Ga-EDTA dynamic PET imaging in renal injury in mice of different origins

BackgroundEarly detection of kidney diseases can be challenging as conventional methods such as blood tests or imaging techniques (computed tomography (CT), magnetic resonance imaging (MRI), or ultrasonography) may be insufficient to assess renal function. A single-photon emission CT (SPECT) renal scan provides a means of measuring glomerular filtration rates (GFRs), but its diagnostic accuracy is limited due to its planar imaging modality and semi-quantification property. In this study, we aimed to improve the accuracy of GFR measurement by preparing a positron emission tonometry (PET) tracer 68Ga-Ethylenediaminetetraacetic acid (68Ga-EDTA) and comprehensively evaluating its performance in healthy mice and murine models of renal dysfunction.MethodsDynamic PET scans were performed in healthy C57BL/6 mice and in models of renal injury, including acute kidney injury (AKI) and unilateral ureter obstruction (UUO) using 68Ga-EDTA. In a 30-min dynamic scan, PET images and time-activity curves (TACs) were acquired. Renal function and GFR values were measured using renograms and validated through serum renal function parameters, biodistribution results, and pathological staining.Results68Ga-EDTA dynamic PET imaging quantitatively captured the tracer elimination process. The calculated GFR values were 0.25 ± 0.02 ml/min in healthy mice, 0.01 ± 0.00 ml/min in AKI mice, and 0.25 ± 0.04, 0.29 ± 0.03 and 0.24 ± 0.01 ml/min in UUO mice, respectively. Furthermore, 68Ga-EDTA dynamic PET imaging and GFRPET were able to differentiate mild renal impairment before serum parameters indicated any changes.ConclusionsOur findings demonstrate that 68Ga-EDTA dynamic PET provides a reliable and precise means of evaluating renal function in two murine models of renal injury. These results hold promise for the widespread clinical application of 68Ga-EDTA dynamic PET in the near future