This study aimed to examine the impact of years of experience and field of expertise on the development of chemistry knowledge structures from STEM experts comprising 103 professors, 10 postdocs, and 146 doctoral students. Of these participants, 127 were specialized in chemistry and the rest were from various science and engineering disciplines. Although most participants were part of a research university located in Northern California, the pool included a small group of experts from different universities and countries. The main source of the data was a Word Association Test generated with 17 keywords that refer to major topics or concepts commonly introduced in the general chemistry curricula. The knowledge structures were examined to determine if the contents and the orientations of the clusters varied between the expert groups. In addition, their analysis was enriched with the consideration of chemistry triplet designations and central terms identified by eccentricity values on each structure. The overall expert knowledge structure generated in this study was also compared to undergraduate structures determined by using the same instrument and methodology. The investigation of the structures revealed several differences between expert groups and provided insight into the transformation of novices into experts. The paper also presents practical suggestions for educators on how to utilize structures while teaching, informing their instructional practices, and reforming teaching materials.
Despite the increasing demographic diversity of the United States’ aging population, there remain significant gaps in post-mortem research investigating the ethnoracial heterogeneity in the neuropathological landscape of Alzheimer Disease (AD). Most autopsy-based studies have focused on cohorts of non-Hispanic White decedents (NHWD), with few studies including Hispanic decedents (HD). We aimed to characterize the neuropathologic landscape of AD in NHWD (n = 185) and HD (n = 92) evaluated in research programs across three institutions: University of California San Diego, University of California Davis, and Columbia University. Only persons with a neuropathologic diagnosis of intermediate/high AD determined by NIA Reagan and/or NIA-AA criteria were included. A frequency-balanced random sample without replacement was drawn from the NHWD group using a 2:1 age and sex matching scheme with HD. Four brain areas were evaluated: posterior hippocampus, frontal, temporal, and parietal cortices. Sections were stained with antibodies against Aβ (4G8) and phosphorylated tau (AT8). We compared the distribution and semi-quantitative densities for neurofibrillary tangles (NFTs), neuropil threads, core, diffuse, and neuritic plaques. All evaluations were conducted by an expert blinded to demographics and group status. Wilcoxon’s two-sample test revealed higher levels of neuritic plaques in the frontal cortex (p = 0.02) and neuropil threads (p = 0.02) in HD, and higher levels of cored plaques in the temporal cortex in NHWD (p = 0.02). Results from ordinal logistic regression controlling for age, sex, and site of origin were similar. In other evaluated brain regions, semi-quantitative scores of plaques, tangles, and threads did not differ statistically between groups. Our results demonstrate HD may be disproportionately burdened by AD-related pathologies in select anatomic regions, particularly tau deposits. Further research is warranted to understand the contributions of demographic, genetic, and environmental factors to heterogeneous pathological presentations.
Background: Transactive Response DNA Binding Protein 43 kDa (TDP-43) pathology is frequently found in cases with Alzheimer’s disease (AD). TDP-43 pathology is associated with hippocampal atrophy and greater AD severity denoted by cognition and clinical representation. Current TDP-43 pathology studies are predominantly based on non-Hispanic White cohorts. Objective: We sought to evaluate the presence of TDP-43 pathology across ethnoracial groups utilizing the National Alzheimer’s Coordinating Center; a database containing data from over 29 institutions across the United States. Cases (N = 1,135: Hispanics/Latinos = 29, African Americans/Black Americans = 51, Asians/Asian Americans = 10, American Indians/Alaskan Natives = 2, non-Hispanic White = 1,043) with intermediate/high AD having data on TDP-43 pathology in the amygdala, hippocampus, entorhinal cortex, and neocortex. Methods: TDP-43 pathology frequency in each neuroanatomic region among ethnoracial groups were compared using generalized linear mixed effects models with center as a random effect adjusting for age at death, education, and gender. Results: Although groups were imbalanced, there was no significant difference across ethnoracial groups based on TDP-43 pathology (p = 0.84). With respect to neuroanatomical regions evaluated, there were no significant differences across ethnoracial groups (p-values > 0.06). There were also no significant differences for age at death and gender ratios across ethnoracial groups based on TDP-43 pathology. Although not statistically significant, TDP-43 pathology was present less often in Hispanic/Latinos (34%) when compared to non-Hispanic Whites (46%). Conclusion: While this is a preliminary evaluation, it highlights the need for diverse cohorts and on TDP-43 pathology research across ethnoracial groups. This is the first study to our knowledge having a focus on the neuroanatomical distribution of TDP-43 deposits in Hispanic/Latino decedents with AD.
Concept maps are powerful tools used to reveal challenges in students' learning. However, their use introduces complexities when a large group of students' conceptualizations need to be examined. In this study, concept maps of 344 general chemistry students were analyzed after grouping them based on achievement in chemistry, math proficiency, and gender. The analysis was also expanded with the consideration of eccentricity values and the extended chemistry triplet. Although some similarities exist between the map of high-achieving students in chemistry and that of high-performing students in the Mathematics Placement Test (MPT), the calculated eccentricity values show interesting variations. On the other hand, the analysis of the map of the low-performing students in MPT and that of low-achieving students in chemistry revealed no clear patterns of symbolic, macroscopic, and submicroscopic terms. Practical suggestions were included to increase the use of representative maps in different assessment and teaching scenarios.
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