Selecting the Number and Labels of Topics in Topic Modeling: A Tutorial

13 pagesTopic modeling is a type of text analysis that identifies clusters of co-occurring words, or latent topics. A challenging step of topic modeling is determining the number of topics to extract. This tutorial describes tools researchers can use to identify the number and labels of topics in topic modeling. First, we outline the procedure for narrowing down a large range of models to a select number of candidate models. This procedure involves comparing the large set on fit metrics, including exclusivity, residuals, variational lower bound, and semantic coherence. Next, we describe the comparison of a small number of models using project goals as a guide and information about topic representative and solution congruence. Finally, we describe tools for labeling topics, including frequent and exclusive words, key examples, and correlations among topics

The Impact of Advocacy Organizations on Low-Income Housing Policy in U.S. Cities

Financial support for affordable housing competes with many other municipal priorities. This work seeks to explain the variation in support for affordable housing among U.S. cities with populations of 100,000 or more. Using multivariate statistical analysis, this research investigates political explanations for the level of city expenditures on housing and community with a particular interest in the influence of housing advocacy organizations (AOs). Data for the model were gathered from secondary sources, including the U.S. Census and the National Center for Charitable Statistics. Among other results, the analysis indicates that, on average, the political maturity of AOs has a statistically significant, positive effect on local housing and community development expenditures

Multiorgan MRI findings after hospitalisation with COVID-19 in the UK (C-MORE): a prospective, multicentre, observational cohort study

Introduction: The multiorgan impact of moderate to severe coronavirus infections in the post-acute phase is still poorly understood. We aimed to evaluate the excess burden of multiorgan abnormalities after hospitalisation with COVID-19, evaluate their determinants, and explore associations with patient-related outcome measures. Methods: In a prospective, UK-wide, multicentre MRI follow-up study (C-MORE), adults (aged ≥18 years) discharged from hospital following COVID-19 who were included in Tier 2 of the Post-hospitalisation COVID-19 study (PHOSP-COVID) and contemporary controls with no evidence of previous COVID-19 (SARS-CoV-2 nucleocapsid antibody negative) underwent multiorgan MRI (lungs, heart, brain, liver, and kidneys) with quantitative and qualitative assessment of images and clinical adjudication when relevant. Individuals with end-stage renal failure or contraindications to MRI were excluded. Participants also underwent detailed recording of symptoms, and physiological and biochemical tests. The primary outcome was the excess burden of multiorgan abnormalities (two or more organs) relative to controls, with further adjustments for potential confounders. The C-MORE study is ongoing and is registered with ClinicalTrials.gov, NCT04510025. Findings: Of 2710 participants in Tier 2 of PHOSP-COVID, 531 were recruited across 13 UK-wide C-MORE sites. After exclusions, 259 C-MORE patients (mean age 57 years [SD 12]; 158 [61%] male and 101 [39%] female) who were discharged from hospital with PCR-confirmed or clinically diagnosed COVID-19 between March 1, 2020, and Nov 1, 2021, and 52 non-COVID-19 controls from the community (mean age 49 years [SD 14]; 30 [58%] male and 22 [42%] female) were included in the analysis. Patients were assessed at a median of 5·0 months (IQR 4·2–6·3) after hospital discharge. Compared with non-COVID-19 controls, patients were older, living with more obesity, and had more comorbidities. Multiorgan abnormalities on MRI were more frequent in patients than in controls (157 [61%] of 259 vs 14 [27%] of 52; p<0·0001) and independently associated with COVID-19 status (odds ratio [OR] 2·9 [95% CI 1·5–5·8]; padjusted=0·0023) after adjusting for relevant confounders. Compared with controls, patients were more likely to have MRI evidence of lung abnormalities (p=0·0001; parenchymal abnormalities), brain abnormalities (p<0·0001; more white matter hyperintensities and regional brain volume reduction), and kidney abnormalities (p=0·014; lower medullary T1 and loss of corticomedullary differentiation), whereas cardiac and liver MRI abnormalities were similar between patients and controls. Patients with multiorgan abnormalities were older (difference in mean age 7 years [95% CI 4–10]; mean age of 59·8 years [SD 11·7] with multiorgan abnormalities vs mean age of 52·8 years [11·9] without multiorgan abnormalities; p<0·0001), more likely to have three or more comorbidities (OR 2·47 [1·32–4·82]; padjusted=0·0059), and more likely to have a more severe acute infection (acute CRP >5mg/L, OR 3·55 [1·23–11·88]; padjusted=0·025) than those without multiorgan abnormalities. Presence of lung MRI abnormalities was associated with a two-fold higher risk of chest tightness, and multiorgan MRI abnormalities were associated with severe and very severe persistent physical and mental health impairment (PHOSP-COVID symptom clusters) after hospitalisation. Interpretation: After hospitalisation for COVID-19, people are at risk of multiorgan abnormalities in the medium term. Our findings emphasise the need for proactive multidisciplinary care pathways, with the potential for imaging to guide surveillance frequency and therapeutic stratification

The early life history of coral trout (Plectropomus leopardus) at Green and Arlington reefs, Australia

The relative contributions of pre- and post-settlement processes to the early life history of coral trout were examined, with the aim of understanding how events occurring during the first year of life influence adult demographic parameters. Juvenile coral trout showed distinctive patterns of distribution and abundance at sites around Green Reef, which were consistent in both space (among sites) and time (between years). These patterns were influenced by substratum characteristics, with habitat associations changing as juveniles grew. Newly settled fish initially showed strong associations with low-relief, rubble-covered sand bottoms, but switched to high-relief features such as coral heads and consolidated rubble mounds after approximately two months of benthic life. Post-settlement processes (mortality and movement) for new recruits appeared to be influenced by the amount of sand-rubble habitat available; individuals occupying areas containing relatively high amounts of this substratum suffered less mortality and were more inclined to be site-attached than those from alternate habitats. Temporal patterns of recruitment were variable, but a strong settlement event coincided with the November new moon in all years of the study. Following settlement, juveniles were site-attached, and occupied home ranges that increased in area as they grew. Home ranges of the smallest recruits (25 - 60 mm SL) showed little overlap, and this pattern appeared to be facilitated by intra-specific aggression. Agonistic behaviour was rarely observed in larger recruits (61 - 102 mm), and home ranges broadly overlapped. Recruits displayed an ability to return to former locations when displaced short distances (20 m), and the distance from which juveniles could home increased with age. Recruits displayed higher site-fidelity than 1+ fish; 88% of marked 0+ individuals were resighted within 20 metres of their capture point, while only 20% of one year old fish were resighted within these areas. A change in diet occurred during early growth: diets of newly settled fish consisted mostly of epibenthic crustaceans, whereas larger juveniles (60-100 mm) were mainly piscivorous. Coral trout of all sizes consumed fish, and most piscine prey were recent recruits to the reef. Foraging modes and diurnal feeding patterns differed between size classes: larger juveniles typically fed by ambushing prey (usually small fish), whereas small recruits concentrated feeding activities around morning hours, and typically foraged by striking at invertebrates associated with rubble substrata. Diets varied spatially for large juveniles, but not for small individuals: large juveniles inhabiting structurally complex habitats (coral heads, rubble mounds) shifted to a primarily piscivorous diet sooner than those from less complex habitats. Estimates of growth rates of juvenile coral trout were influenced by larval growth histories, size-selective mortality, and variations in water temperature. Significant inter- and intra-annual differences were detected in planktonic growth rate, which were positively correlated with subsequent benthic growth. These initial patterns were accentuated by higher mortality of slow-growing juveniles, which resulted in relatively faster mean growth rates for juveniles collected later in the year. Temperature also had a strong influence on growth, and accounted for 55% of the variability in somatic growth following settlement

The early life history of coral trout (Plectropomus leopardus) at Green and Arlington reefs, Australia\ud

The relative contributions of pre- and post-settlement processes to the early life history of coral trout were examined, with the aim of understanding how events occurring during the first year of life influence adult demographic parameters. Juvenile coral trout showed distinctive patterns of distribution and abundance at sites around Green Reef, which were consistent in both space (among sites) and time (between years). These patterns were influenced by substratum characteristics, with habitat associations changing as juveniles grew. Newly settled fish initially showed strong associations with low-relief, rubble-covered sand bottoms, but switched to high-relief features such as coral heads and consolidated rubble mounds after approximately two months of benthic life. Post-settlement processes (mortality and movement) for new recruits appeared to be influenced by the amount of sand-rubble habitat available; individuals occupying areas containing relatively high amounts of this substratum suffered less mortality and were more inclined to be site-attached than those from alternate habitats. Temporal patterns of recruitment were variable, but a strong settlement event coincided with the November new moon in all years of the study. Following settlement, juveniles were site-attached, and occupied home ranges that increased in area as they grew. Home ranges of the smallest recruits (25 - 60 mm SL) showed little overlap, and this pattern appeared to be facilitated by intra-specific aggression. Agonistic behaviour was rarely observed in larger recruits (61 - 102 mm), and home ranges broadly overlapped. Recruits displayed an ability to return to former locations when displaced short distances (20 m), and the distance from which juveniles could home increased with age. Recruits displayed higher site-fidelity than 1+ fish; 88% of marked 0+ individuals were resighted within 20 metres of their capture point, while only 20% of one year old fish were resighted within these areas. A change in diet occurred during early growth: diets of newly settled fish consisted mostly of epibenthic crustaceans, whereas larger juveniles (60-100 mm) were mainly piscivorous. Coral trout of all sizes consumed fish, and most piscine prey were recent recruits to the reef. Foraging modes and diurnal feeding patterns differed between size classes: larger juveniles typically fed by ambushing prey (usually small fish), whereas small recruits concentrated feeding activities around morning hours, and typically foraged by striking at invertebrates associated with rubble substrata. Diets varied spatially for large juveniles, but not for small individuals: large juveniles inhabiting structurally complex habitats (coral heads, rubble mounds) shifted to a primarily piscivorous diet sooner than those from less complex habitats. Estimates of growth rates of juvenile coral trout were influenced by larval growth histories, size-selective mortality, and variations in water temperature. Significant inter- and intra-annual differences were detected in planktonic growth rate, which were positively correlated with subsequent benthic growth. These initial patterns were accentuated by higher mortality of slow-growing juveniles, which resulted in relatively faster mean growth rates for juveniles collected later in the year. Temperature also had a strong influence on growth, and accounted for 55% of the variability in somatic growth following settlement

Anion complexation properties of thiophene-2,4-and-2,5-biscarboxamides

Thiophene-2,4- and -2,5-biscarboxamides have been synthesised and shown to act as anion receptors in DMSO-d(6)/water solution. The crystal structure of the fluoride complex of a N,N'-diphenylthiophene-2,5-biscarboxamide derivative has been solved and reveals the involvement of the thiophene CH protons in anion complexation in the solid state

Anion complexation properties of 2,2'-bisamidodipyrrolylmethanes

Two new bis-amido dipyrrolylmethanes (bis-N-butylamide-5,5'-methylenebis(4-ethyl-3-methyl-2-pyrrolecarboxylat e) 1 and bis-N-phenylamide-5,5'-methylenebis( 4-ethyl-3-methyl-2-pyrrolecarboxylate) 2 have been synthesised and shown to exhibit selectivity for oxo-anions from among a variety of putative anionic guest species in DMSO/water solution