Clustering Effect Research Articles

Treadmill Exercise Mitigates Alzheimer’s Pathology by Modulating Glial Polarization and Reducing Oligodendrocyte Precursor Cell Perivascular Clustering

ABSTRACT Purpose This study aimed to investigate the pathological responses of glial cells at different distances from amyloid plaques and the characteristics of oligodendrocyte precursor cells (OPCs) in perivascular clustering. Additionally, it sought to explore the impact of exercise training on AD pathology, specifically focusing on the modulation of glial responses and the effects of OPC perivascular clustering. Methods Three-month-old C57BL/6 and APP/PS1 mice were divided into four groups: wild-type sedentary, wild-type exercise, sedentary AD, and exercise AD groups. The Barnes maze test was conducted to analyze spatial learning and memory. Enzyme-linked immunosorbent assay (ELISA) analysis, Immunofluorescence staining, Fluro-Jade C staining, TUNEL staining, Sholl analysis, and 3D rendering analysis were employed to detect Aβ 1-42, tau hyperphosphorylation, typical amyloid plaques, abnormal tau phosphorylation, neuronal damage, apoptosis, neurodegeneration, microglial and astrocytic activation and phenotypic polarization, and OPC perivascular clustering. Results Behavioral results revealed that long-term exercise training ameliorated cognitive deficits in APP/PS1 mice. Histopathological analysis showed a reduction in amyloid deposition and decreased tau hyperphosphorylation. Immunofluorescence and Fluro-Jade C staining indicated that exercise attenuated neuronal damage, degeneration, and apoptosis. Sholl and 3D rendering analysis demonstrated that exercise mitigated spatially dependent glial phenotypic changes surrounding amyloid plaques in the AD cortex and hippocampus. Further, immunofluorescence staining revealed that exercise alleviated plaque-associated glial changes in these regions. Exercise also alleviated the reduction of microglial SIRPα and reduced synaptic loss mediated by microglial and astrocyte phagocytosis. Lastly, exercise mitigated OPC senescence and cellular senescence-induced OPC perivascular clustering in AD mice. Conclusions Exercise can counteract AD pathological features by modulating glial responses and reducing OPC senescence and perivascular clustering near amyloid plaques, highlighting its potential as a therapeutic strategy for AD.

Improved Honey Badger Algorithm and Its Application to K-Means Clustering

As big data continues to evolve, cluster analysis still has a place. Among them, the K-means algorithm is the most widely used method in the field of clustering, which can cause unstable clustering results due to the random selection of the initial clustering center of mass. In this paper, an improved honey badger optimization algorithm is proposed: (1) The population is initialized using sin chaos to make the population uniformly distributed. (2) The density factor is improved to enhance the optimization accuracy of the population. (3) A nonlinear inertia weight factor is introduced to prevent honey badger individuals from relying on the behavior of past individuals during position updating. (4) To improve the diversity of solutions, random opposition learning is performed on the optimal individuals. The improved algorithm outperforms the comparison algorithm in terms of performance through experiments on 23 benchmark test functions. Finally, in this paper, the improved algorithm is applied to K-means clustering and experiments are conducted on three data sets from the UCI data set. The results show that the improved honey badger optimized K-means algorithm improves the clustering effect over the traditional K-means algorithm.

Probing Cosmic Isotropy with the FAST All Sky H i Survey

Abstract This paper leverages the first released catalog from the FAST All Sky H i Survey (FASHI) to examine the hypothesis of cosmic isotropy in the local Universe. Given the design of the overall FAST survey, the inhomogeneous detection sensitivity of FASHI is likely to introduce significant biases in the statistical properties of the catalog. To mitigate the potential influence of spurious clustering effects due to these sensitivity variations, we focus on extragalactic H i sources within the sensitivity range of [0.65, 1.0]. This refined subsample is divided into 10 distinct sky regions, for which we compute the two-point angular correlation functions (2PACF) over angular scales of 0 . ° 5 < θ < 10°. We apply the Markov Chain Monte Carlo method to fit these 2PACFs with a power-law model and assess the statistical significance of the best-fit parameters for the 10 FASHI sky regions by comparing them against results from mock catalogs generated under the assumptions of homogeneity and isotropy. Our findings indicate that the local Universe, as traced by the H i sources in the FASHI survey, aligns with the cosmic isotropy hypothesis within a 2σ confidence level. We do not detect any statistically significant deviations from cosmic isotropy in the FASHI survey data.

Effects of the MyBFF@school obesity intervention program with nutrition education intervention on nutrition knowledge and attitude of secondary schoolchildren: a cluster randomized controlled trial

BackgroundThe increasing global and national prevalence of childhood obesity particularly among schoolchildren has warranted a more viable school-based obesity intervention. Apart from physical activity, nutrition is important in any obesity intervention package. This study examined the effects of the MyBFF@school program with nutrition education intervention (NEI) on nutrition knowledge and attitude of overweight and obese secondary schoolchildren.MethodsThis is a cluster randomized controlled trial which involved schoolchildren aged 13, 14 and 16 years old from 15 out of 415 government secondary schools in central Peninsular Malaysia which were randomly assigned into six intervention (N = 579 schoolchildren) and nine control (N = 462 schoolchildren). The intervention group was given NEI consisting of a nutrition education module carried out by trained personnel for 24 weeks on top of the existing curriculum while the control group only followed the existing school curriculum by the Ministry of Education. The primary outcomes were the nutrition knowledge and attitude score. The mixed effect model taking into consideration the cluster effect was used to assess the changes of nutrition knowledge and attitude scores from baseline until 6 months.ResultsOverall, there was no significant increase in the adjusted mean difference (AMD) of nutrition knowledge score (AMD = 0.33%, Confident Interval (95 CI): -4.35% to 5.01) between the intervention and control group after 6 months of intervention after controlling for nutrition knowledge score at baseline, gender, location and ethnicity. Similarly, after controlling for the nutrition attitude score at baseline, ethnicity, location and gender as well as taking into account the cluster effects, there was no significant increase on the AMD of nutrition attitude score in the overall (AMD = 0.194, (95 CI): -1.17 to 1.56) and also among girls, location (urban vs rural) and Malays. There was also no significant reduction of AMD in the nutrition attitude score among boys and non-Malays.ConclusionMyBFF@school with NEI resulted with no significant improvement for nutrition knowledge and attitude among older schoolchildren. Therefore, to effectively impart the nutrition knowledge and change their nutrition attitude requires an in-depth study and multi-pronged and customized approach.Trial registrationClinical trial number: NCT04155255, November 7, 2019 (Retrospective registered). National Medical Research Register: NMRR-13–439-16563. Registered July 23, 2013. The intervention program was approved by the Medical Research and Ethics Committee (MREC), Ministry of Health Malaysia and Educational Planning and Research Division (EPRD), Ministry of Education Malaysia. It was funded by the Ministry of Health Malaysia.

Improving Spike Sorting Efficiency with Separability Index and Spectral Clustering

This study explores the effectiveness of spectral clustering for spike sorting and proposes a Separability Index to measure the difficulty of spike sorting for a signal. The accuracy of spectral clustering is evaluated using different feature sets, including raw samples, first and second derivatives, and principal components analysis (PCA), and compared to two previously published methods. The results obtained over a dataset including 16 signals show that raw samples, with an average accuracy of 73.84%, are effective for spectral clustering-based spike sorting. The analysis demonstrates that the proposed Separability Index can be utilized to classify signals beforehand, reducing the cost and processing time of large datasets. Furthermore, the proposed index can reveal spike sorting difficulty, making it a valuable tool for comparing the performance of various spike sorting methods in depth. The proposed method has higher accuracy (up to 23%) compared to two previously published methods, and its accuracy is aligned with the Separability Index (correlation coefficient = 0.71). Overall, this study contributes to the field of spike sorting and offers insights into leveraging spectral clustering for this task.

Facile in situ synthesis of silver nanoclusters for promoting highly sensitive surface-enhanced Raman scattering detection of alkyne-tagged biomolecules.

We synthesized two novel silver-based nanocluster materials (TOS-Ag4 NCs and TNS-Ag8 NCs) that were used as SERS substrates, combining the powerful adsorption capability and aggregation effect of silver-sulfur clusters to achieve a highly sensitive identification and detection of alkyne-tagged molecules in the Raman-silent region. This work provides new insights for designing novel nanoclusters as SERS substrates displaying ultrahigh sensitive detection of alkyne-tagged molecules.

Chemical characterization of polymer and chloride content in waste plastic materials using pyrolysis - direct analysis in real time - high-resolution mass spectrometry.

The increasing global demand for plastic has raised the need for effective waste plastic management due to its long lifetime and resistance to environmental degradation. There is a need for rapid plastic identification to improve the mechanical waste plastic sorting process. This study presents a novel application of Temperature-Programmed Desorption-Direct Analysis in Real Time-High Resolution Mass Spectrometry (TPD-DART-HRMS) that enables rapid characterization of various plastics. This technique was applied on four commercially available reference polymers (polyethylene, polypropylene, polystyrene, polyvinyl chloride) as well as three "waste" plastic samples of mixed origin. These waste plastic samples were obtained as discards from various industrial processes with limited analytical characterization data. Through the application of CH2 Kendrick mass defect (KMD) grouping, characteristic trends in the mass spectra of each sample were identified, allowing for a simplified numerical comparison. This approach utilized a robust statistical approach using the Tanimoto coefficient, allowing for the quantitative measures of similarity between standards and unknown samples. The application of this mathematical evaluation methodology was used to identify plastic types and to distinguish structurally similar polymers. Additionally, we report that a chloride ion clustering effect with copper substrate can identify chlorinated polymer PVC (polyvinyl chloride) utilizing pyro-(-)DART-HRMS mode. PVC polymer is of particular interest in recycling due to its high chloride content, which can present technical challenges for some types of recycling. We found that chloride ion clusters are a good screening marker for the presence of chlorinated polymers in mixed waste plastic samples. This study can possibly help advance rapid and accurate analytical techniques for identifying the composition of waste plastics to advance the effectiveness of the waste plastic sorting process.

Prevalence of hepatitis C virus co-infection in adults living with HIV in Mexico: a cross-sectional, seroprevalence study in a nationally representative sample.

The proportion of people living with HIV (PLWHIV) co-infected with HCV in Mexico was unknown. Ouraim was to estimate the seroprevalence of HCV among adults with HIV in Mexico. Using a complex-survey design, we collected blood samples and applied structured questionnaires between May 2nd, 2019 and February 17th, 2020 in a nationally, representative sample of adults receiving care for HIV-infection in 24 randomly selected HIV-care centres in 8 socio-demographically regions in Mexico. We tested serum for anti-HCV IgG antibodies and collected data on risky exposures. We estimated the seroprevalence of HCV and associated exposures using regression models and the Taylor linearization method to account for the cluster effect by region and centre. We collected blood samples of 2545 participants. Most participants were men (75.8%) with a median age of 37 years. The estimated seroprevalence of HCV is 3.9% (95% CI 3.1%-4.7%). Only 39 of 99 participants (40%) withHCV antibodies had active replication determined by RNA quantification. Seroprevalence of HCV was significantly higher among people with life-time history of imprisonment (9%, 95% CI 4.4%-13.6%), tattoo use (5.9%, 95% CI 3.9%-8%), and lifetime (22.3%, 95% CI 12.1%-32.6%) and recent (49.3%, 95% CI 18.3%-80.3%) injecting-drug use. Seroprevalence of HCV infection among PLWHIV in Mexico is ten times as high as the seroprevalence for the general population. The national program for HCV elimination focused in PLWHIV should target people that use injecting drugs and living in prisons. Abbvie Farmacéuticos, S.A de C.V Mexico through Investigator Initiated Study (2018).

Moderate-to-vigorous physical activity modulates the association between serum 25-hydroxyvitamin D and bone stiffness in European children and adolescents

It remains unclear how serum 25-hydroxyvitamin D (25(OH)D) concentrations relate to childhood bone health. We hypothesized that 25(OH)D was inversely associated with bone turnover biomarkers and positively associated with bone stiffness. Cross-sectional analyses were performed using data from participants (2-15-year-old, 51% boys) from the IDEFICS/I.Family cohort, comprising 3,638 serum 25(OH)D measurements collected in 2007/2008 and 2012/2013 across eight European countries. A biomarker of bone formation (serum osteocalcin), a biomarker of bone resorption (serum C-terminal telopeptides of type I collagen [CTx]), and stiffness index measured using calcaneal quantitative ultrasound were considered outcomes. Linear mixed-effects models were used to adjust for confounders (i.e., age, sex, parental education, time spent in sports club, dairy products consumption, sedentary behavior, height and weight z-scores), the cluster effect of country and repeated measurements. Interactions of calcium intake, moderate-to-vigorous physical activity (MVPA) and weight status with 25(OH)D on outcomes were tested. Only 1 in 3 participants reached the sufficient 25(OH) D concentration of 20 ng/ml. Sufficient 25(OH)D was associated with higher stiffness index if participants had MVPA ≥ 60 min/day (β = 12.14, p < 0.05). Moreover, 25(OH)D was inversely associated with CTx (β = -7.09, p < 0.05); this association was positive but not statistically significant among primary school children living with overweight/obesity. No interaction was observed for calcium intake. In conclusion, serum 25(OH)D and CTx were inversely associated. MVPA interacted the positive association between 25(OH)D and bone stiffness, highlighting the importance of promoting MVPA guidelines in future vitamin D and bone health interventions.

Can the Opening of High-speed Rail (HSR) Stimulate Residents' Consumption? --An Interpretation Based on the Clustering Effect of Innovation Factors

Can the Opening of High-speed Rail (HSR) Stimulate Residents' Consumption? --An Interpretation Based on the Clustering Effect of Innovation Factors

Exploring the spatial clustering and spillover effects of COVID-19 vaccination uptake in Romania: an analysis at municipality level

AbstractThis study investigates the spatial clustering and spillover effects of COVID-19 vaccine uptake in Romania, focusing on the municipality-level distribution of vaccine acceptance and hesitancy while considering the factors that influence it. The research uses the Spatial Durbin Error Model (SDEM) and identifies spatial clusterization, as well as significant contagion and diffusion processes in the vaccination behaviour conditioned by socioeconomic factors, labour market characteristics, social and religious attitudes, urban, and health indicators. We find evidence in favour of spatial spillover effects of the poverty rate, opposition to same-sex marriage, COVID-19 infection rate, peri-urban towns, and denser cities. Our findings contribute to the literature of the spatial distribution and determinants of vaccine uptake and carry practical implications for policy makers offering evidence-based insights that can inform targeted strategies and interventions to enhance vaccine acceptance and address hesitancy in specific locations.

Possibilistic C-means with novel image representation for image segmentation

Image segmentation is the process of automatically dividing an image into several parts and extracting the relevant data and information. Compared to the traditional Fuzzy C-Means algorithm, the Possibilistic C-Means (PCM) algorithm has advantages in reducing the influence of noise on cluster center estimation. However, the PCM algorithm still shows poor clustering performance under high-intensity noise, which may lead to overlapping cluster centers. Considering the impact of neighborhood information of image pixels on the image segmentation results, this paper proposes a Vector-Based Possibilistic C-Means (VBPCM) algorithm. The algorithm incorporates neighborhood information and uses a vector representation method to describe image pixels. Additionally, an adjustable distance based on an exponential function is proposed to describe the similarity between vectors. The proposed VBPCM algorithm outperforms the conventional PCM, obtaining uplifiting gains of 4%, 2%, and 9% in Pixel Accuracy, Mean Pixel Accuracy, and Mean Intersection over Union, respectively. The experimental outputs illustrate that VBPCM algorithm can achieve more satisfactory cluster effect with high-intensity noise, further perform better in image segmentation task.

Towards 90-70-90 targets: Individual and community level factors associated with cervical cancer screening among women of reproductive age in Tanzania: A multi-level analysis based on 2022 Tanzania demographic and health survey.

Cervical cancer is a major public health problem worldwide, and is mainly caused by human papillomaviruses. More than 90% of cervical cancer cases can be prevented by using a human papilloma vaccine and screening. Despite the ongoing global cervical cancer screening target, uptake remains unacceptably low in sub-Saharan Africa such as Tanzania. Although cervical cancer is the leading cause of mortality in Tanzania, evidence on the individual- and community-level factors associated with cervical cancer screening among women of reproductive age is scarce. Therefore, this study aimed to determine the individual- and community-level factors associated with cervical cancer screening among women of reproductive age in Tanzania. This study used data from the 2022 Tanzania Demographic and Health Survey (TDHS). A weighted sample of 15,140 women of reproductive age was included in this study. Given the effect of clustering and binary nature of the outcome variable, we used a multilevel binary logistic regression model. The adjusted odds ratio (AOR) with 95% Confidence Interval (CI) was statistically significant. Moreover, the model with the lowest deviance best suited the data. The overall uptake of cervical cancer screening among Tanzanian women was 7.28% (95% confidence interval [CI]: 6.87%, 7.70%). Women's age (25-34, 35-49), women with primary, secondary, and higher educational levels, being employed, a high household wealth index, visiting health facilities in the last 12 months, owning mobile phones, urban residence, and southern highlands, Southern, and Zanzibar administrative zones, were significantly associated with cervical cancer screening. Cervical cancer screening among women in Tanzania was low. Low uptake underscores the need for increased focus on addressing the coverage of the 2030 Sustainable Development Goals (SDGs). The study would help policymakers create programs that consider education, employment, visiting health facilities, mobile phones, wealth, residence, and administrative zones, which would make women undergo cervical cancer screening. Pointing to women living with low cervical cancer screening could help increase their uptake and achieve the targets of the national and World Health Organization.

Comparison of temporal trends in suicidal behaviors among high school students in Mississippi and the United States

BackgroundMississippi youth are demographically unique compared to that of the nation. The purpose of this study is to determine the prevalence and trend of suicide ideation, suicide plans, suicidal attempts, and suicidal injury among high school students in Mississippi vs. in the United States (U.S.).MethodSummary statistics, prevalence ratio (PR), and trend analysis were generated and compared between Mississippi high school students and their U.S. counterparts.ResultsThe 2021 prevalences for suicide plans, suicide attempts, and suicide injury are all significantly higher for Mississippi high school students compared to their national counterparts. From 2001 to 2021, on the national level, none of the four suicide behaviors showed significant change, whereas, in Mississippi, suicide plans, suicide attempts, and suicide injury all had an increasing trend.ConclusionsOur study reveals alarming increasing trends and significantly greater severity of suicidal burdens among Mississippi high school students compared to the nation. Left unattended, these trends may continue quicker due to a clustering effect. There is an urgent need for Mississippi to implement more and better intervention and prevention measures to stop and reverse the increasing trend of suicidal behaviors among its 9–12 graders.

Individual, household, and community-level determinants of undernutrition among pregnant women in the northern zone of the Sidama region, Ethiopia: A multi-level modified Poisson regression analysis.

In Ethiopia, maternal undernutrition is a major public health concern. However, comprehensive evidence is lacking in the southern part of Ethiopia, specifically the household and community-level related determinants of undernutrition. Besides, the evidence about the prevalence and determinants of undernutrition is not yet documented in the current study setting. Thus, this study aimed to determine the prevalence of undernutrition and identify its determinants among pregnant women in Hawela Lida district of the Sidama region, Ethiopia. A community-based cross-sectional study was conducted on a sample of 515 pregnant women from June 1-25, 2024. A multi-stage sampling method was utilized to select eligible pregnant women. We collected data using a structured and pretested interviewer-administrated questionnaire and an anthropometric measurement. Data were collected using the Open Data Kit smart phone device and exported it to Stata version 17 for further processing and analysis. A multi-level mixed-effects modified Poisson regression analysis with robust variance was used to account for confounders and between and with cluster effects. The prevalence of undernutrition among pregnant women was 41.7% (95% CI: 37.3-45.6). The prevalence of undernutrition was associated with planned pregnancy (adjusted prevalence ratio [APR]: 0.80; 95% CI: 0.66-0.98), household food insecurity (APR: 1.64; 95% CI: 1.26-2.13), inadequate dietary diversity (APR: 1.79; 95% CI: 1.43-2.25), and women's poor knowledge of nutrition (APR: 1.68; 95% CI: 1.32-2.12) at individual levels. The identified determinants of undernutrition at the community level were low community literacy rates (APR: 4.62; 95% CI: 1.13-18.79) and low community wealth status (APR: 1.91; 95% CI: 1.10-3.31). Two in five pregnant women had an undernutrition problem in the study setting. Individual and community-level determinants contributed to the high prevalence of undernutrition. Thus, any prevention and control approaches to undernutrition should consider inter-sectorial collaboration to account for determinants at various levels. Besides, any program must emphasize the delivery of nutrition education about dietary diversity, particularly targeting pregnant mothers who have poor knowledge of nutrition and unplanned pregnancy at the individual level. Moreover, creating a small business reform for the community with low wealth status using agricultural extension workers must be considered.

Multinuclear Antimony-Bismuth-Lanthanide Cluster-Connected Polyoxometalate for the Detection of 5-Hydroxyindoleacetic Acid via Luminescence.

The judicious selection and combination of multicomponents provide great potential for the further exploration of new polyoxometalate (POM) materials. Here, a delicate control on tungstate, SbIII and BiIII sources, Eu3+ ions, and organic molecules led to the discovery of a novel multimetal cluster-embedded POM [H2N(CH3)2]9Na8H5{[Eu4(H2O)6Sb4Bi2W2O12](SbW9O33)2(SbW8O31)2}·78H2O (1). The polyoxoanion of 1 was constructed from four in situ-formed [SbW8O31]11- and [SbW9O33]9- building blocks connected by two hexa-metallic [Eu2(H2O)3Sb2BiWO6]9+ clusters, to be a rare member of Sb- and Bi-coexisting POM. The most impressive characteristic of 1 is the intricate [Eu2(H2O)3Sb2BiWO6]9+ cluster linker, which contains a SbIII-BiIII coinserted [Sb2BiWO6]3+ core grasping one [Eu1(H2O)2]3+ cation and one [Eu2(H2O)]3+ cation on both sides through Sb-O-Eu and Bi-O-Eu bonds. Functionalized by luminescence centers of Eu3+ ions, 1 can emit intense emission in water and be capable of detecting the biomarker of carcinoids, 5-hydroxyindoleacetic acid (5-HIAA) with a low limit of detection of 0.43 μM, high selectivity, and excellent anti-interference, as well as fast response (12 s). The high detectability of 1 for 5-HIAA is relevant to the underlying dynamic quenching and energy-transfer mechanism. In urine conditions, remarkable recognition of 1 for 5-HIAA and satisfactory recoveries were achieved, indicative of the possibility of 1 in detecting 5-HIAA in a real environment. This work reveals the special clustering effect of SbIII and BiIII atoms in the assembly of neoteric POM species and also promotes the application of POMs as potential diagnostic tool in the early detection of carcinoids.

Unsupervised clustering approach to assess heterogeneity of treatment effects across patient phenotypes in randomized clinical trials.

Primary results from randomized clinical trials (RCT) only inform on the average treatment effect in the studied population, and it is critical to understand how treatment effect varies across subpopulations. In this paper we describe a clustering-based approach for the assessment of Heterogeneity of Treatment Effect (HTE) over patient phenotypes, which maintains the unsupervised nature of classical subgroup analysis while jointly accounting for relevant patient characteristics. We applied phenotype-based stratification in the ENGAGE AF-TIMI 48 trial, a non-inferiority trial comparing the effects of higher-dose edoxaban regimen (direct anticoagulant) versus warfarin (vitamin K antagonist) on a composite endpoint of stroke and systemic embolism in 14,062 patients with atrial fibrillation. We identified three distinct phenotypes: non-white participants, mostly from Asia (A); white participants without previous use of vitamin-K antagonists (B); and white participants with previous use of vitamin-K antagonist (C). The effect of the higher-dose edoxaban regimen vs warfarin significantly varied over phenotypes (p for interaction=0.03) with the strongest benefit in cluster A (HR=0.72, 95% CI: 0.52-1.00), moderate effect in cluster B (HR=0.80, 95% CI: 0.61, 1.06) and no observed effect in cluster C (HR=1.01, 95% CI: 0.80, 1.27). Assessing HTE over patients' phenotypes might represent a relevant complement to other stratification approaches to elucidate results from subgroups analyses, especially in those settings where an overwhelming superiority overall effect was not observed. Cluster analysis allows a clear discrimination of patients with direct interpretability of who are the patients that would most benefit from the investigated strategy or treatment.

Bayesian hierarchical model for heterogeneity in the diagnosis and treatment of hepatocellular carcinoma (HCC) in the African continent

HCC prevalence and etiology differ between African regions. To better understand these differences, a survey was conducted to characterize the health care practices in HCC management in Africa. Due to limited number of respondents from certain countries in Africa and due to scarce availability of resources, the traditional method of adaptive quadrature produces unstable estimates in this complex setting with sparse multinomial outcomes and with sparse clustered random effects. We propose a Bayesian hierarchical model to address this challenge, apply it to the sparse real data captured in the survey, and validate the proposed method through simulations on synthetic data.

Associations supporting items gained and maintained across recall tests.

When performing successive recall tests without restudy, subjects' recalls exhibit intriguing variability across tests, including gaining or losing items across tests. To examine the cognitive mechanisms underlying this variability, research has focused primarily on hypermnesia, the finding that recall performance increases across tests (Erdelyi & Becker, 1974). Hypermnesia studies commonly consider conditions that impact recall levels of items gained across tests versus items maintained across tests. By contrast, analyses of recall clustering in hypermnesia studies typically collapse across maintained items and item gains. Here, I examine associative processes separately for item gains and maintained items. Experiment 1 examines these effects in final free recall, a paradigm also used to examine changes in recall across tests but less commonly linked with hypermnesia, whereas Experiment 2 uses a classic hypermnesia design. In both experiments, subjects exhibited significant temporal and semantic clustering for maintained items, but there was less evidence of these associations supporting item gains. In Experiment 1, transitions to maintained items boasted a greater proportion of same-list transitions than item gains, and in Experiment 2, there were no significant clustering effects to item gains on a test producing hypermnesia. Further, in Experiment 1, subjects exhibiting greater list-level temporal clustering of maintained items also maintained more items across tests. The results highlight the importance of episodic and semantic associations to changes in recall across tests and have implications for current theories of hypermnesia. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Cluster Effects of the Manufacturing Industry in Sichuan Province: Insights from County-Level Economic Development

Cluster Effects of the Manufacturing Industry in Sichuan Province: Insights from County-Level Economic Development