Discontinuous Growth Research Articles

Psychosis Spectrum Symptoms Before and After Adolescent Cannabis Use Initiation

Adolescent cannabis use has been consistently posited to contribute to the onset and progression of psychosis. However, alternative causal models may account for observed associations between cannabis use and psychosis risk, including shared vulnerability for both cannabis use and psychosis or efforts to self-medicate distress from psychosis spectrum symptomology. To test 3 hypotheses that may explain cannabis-psychosis risk associations by modeling psychosis spectrum symptom trajectories prior to and after cannabis initiation across adolescent development (approximately 10-15 years of age). This cohort study used data from 5 waves across 4 years of follow-up from the Adolescent Brain Cognitive Development (ABCD) Study. The ABCD study is an ongoing large-scale, longitudinal study of brain development and mental and physical health of children in the US launched in June 2016. Data are collected from 21 research sites. The study included data from 11 868 adolescents aged 9 to 10 years at baseline. Three participants were excluded from the present analysis owing to missing data. Data analysis was performed from September 2023 to July 2024. Discontinuous growth curve modeling was used to assess trajectories of psychosis spectrum symptoms before and after cannabis initiation. Control variables considered for this investigation were age, sex, internalizing and externalizing symptoms, socioeconomic status, parental mental health, and other substance use. Among the 11 858 participants at wave 1, the mean (SD) age was 9.5 (0.5) years; 6182 (52%) participants were male. Consistent with a shared vulnerability hypothesis, adolescents who used cannabis at any point during the study period reported a greater number of psychosis spectrum symptoms (B, 0.86; 95% CI, 0.68-1.04) and more distress (B, 1.17; 95% CI, 0.96-1.39) from psychosis spectrum symptoms relative to those who never used cannabis. Additionally, consistent with a self-medication hypothesis, the number of psychosis spectrum symptoms (B, 0.16; 95% CI, 0.12-0.20) and distress (B, 0.23; 95% CI, 0.21-0.26) from psychosis spectrum symptoms increased in the time leading up to cannabis initiation. We observed mixed evidence for an increase in psychosis symptoms after cannabis initiation (ie, contributing risk hypothesis). The findings underscore the importance of accounting for shared vulnerability and self-medication effects when modeling cannabis-psychosis risk associations.

Does War Make States? Military Spending and the Italian State‐Building, 1861–1945

ABSTRACTWe present empirical evidence on the relationship between military spending and the expansion of other government budget items and tax revenues from the unification of Italy (1861) up to the end of World War II. Until 1922, investments in education and social transfers to families mainly moved in step with defence spending. This means that increases in defence spending imply an increase in both education spending and transfers. Moreover, transfers also play a compensatory role during recessions. Increases in defence spending do not crowd out investment in capital expenditure, while disinvestment in defence is associated with an increase in investment in capital. The pro‐cyclical behaviour of tax revenues is compatible with the debt‐financing dynamic of much government expenditure. Although our analytical narrative is not universally valid, it does support the persistent centrality of external wars in the discontinuous growth and expansion of central government in the Italian state, with some exceptions explained by historical events.

A convection-diffusion-reaction system with discontinuous flux modelling biofilm growth in slow sand filters

A Slow Sand Filter (SSF) consists of biofilm attached to saturated packed sand with supernatant water on top, through which water flows by gravity. SSFs are used in the production of drinking water to improve water quality and remove pathogens, and, as they use biological filtration via the microbes present in the biofilm, they are simple and cheap to construct. A drawback of SSFs is that the difficult sampling and the complex dynamics associated with biofilm growth of microbes pose an obstacle for analysis and predictions. In order to overcome this issue, a mathematical model consisting of a non-linear convection-diffusion-reaction system with discontinuous flux is developed from first principles as a unified framework for the dynamics in time and depth of the biofilm and microbial community, where a variety of ecological models can be included in the reaction terms, which also contain attachment, detachment and transfer processes. The multi-phase approach considers three main physical volumes: a biofilm matrix, the water volume enclosed by it and the flowing suspension through the SSF surrounding the biofilm. The only input data needed are the inflow concentrations and rate, light irradiation and temperature. The model includes a Cahn–Hilliard-type equation for the biofilm velocity in the supernatant water. A numerical scheme that preserves physical properties of the solution is also presented. This is achieved with a time-splitting scheme using an upwind scheme with an adaptive time-step size that ensures positivity of the solution under a CFL condition and a reasonable assumption on the separate numerical solution of the Cahn–Hilliard-type equation. The latter is solved numerically with a semi-implicit finite-difference scheme using a mixed form of the equation. The flexible model framework with its numerical scheme allows for including a variety of ecological models, making the investigation and development of increasingly complex simulations possible. Simulations with different model parameters are shown to be qualitatively consistent with the literature.

“Find Your Y”: histological differences in early stage (pT) and post-treatment (ypT) oesophageal adenocarcinoma with implications for salvage endoscopic resection

AimsCurrent guidelines offer limited strategies for managing recurrent/persistent oesophageal adenocarcinoma (EAC). Salvage endoscopic mucosal/submucosal resection (ER) shows promise in oesophageal squamous cell carcinoma, however its success in EAC is limited....

Goal Orientation and Discontinuous Growth in Psychological Capital

Goal Orientation and Discontinuous Growth in Psychological Capital

From disruption to recovery: a multi-country analysis of tourism and hospitality firms’ performance post-COVID-19

ABSTRACT This study employs a discontinuous growth model, a method that captures shifts in trends over time, to explore how the performance of tourism and hospitality firms has evolved from the pre-COVID to the post-COVID period. It uncovers two key insights. Firstly, a substantial decrease in tourism and hospitality firms’ financial and market performance was evident in 2020. For instance, their return on assets in 2020 was 348% lower than in 2019. Secondly, while there was no improvement in their financial performance in 2021, a noteworthy improvement in market performance was observed. In 2022, both financial and market performance exhibited significant recovery. Remarkably, the degree of recovery in market performance in 2021 and financial performance in 2022 mirrored their respective declines in 2020, indicating a restoration of tourism and hospitality firms’ performance to the pre-crisis level. However, this restoration was not observable among firms with low liquidity, little retained earnings, and high financial constraints, suggesting that such firms may take actions (such as cost-cutting) that can lead to a decline in their quality of services and customer experiences. Therefore, this study underscores the importance of government support to some tourism and hospitality firms even in the aftermath of the COVID-19 crisis.

A Longitudinal Investigation of the Association Between Stroke and Loneliness.

The present research examined associations between stroke and long-term trajectories of loneliness. We conducted secondary analyses in 3 large representative panel studies of adults 50 years and older in the United States, Europe, and Israel: the English Longitudinal Study of Aging (ELSA; analytic N = 14,992); the Survey of Health, Aging, and Retirement in Europe (SHARE; analytic N = 103,782); and the Health and Retirement Study (HRS; analytic N = 22,179). Within each sample, we used discontinuous growth curve modeling to estimate loneliness trajectories across adulthood and the impact of stroke on loneliness trajectories. Across all 3samples, participants who experienced stroke reported higher levels of loneliness relative to participants who did not experience stroke. In ELSA and HRS (but not SHARE), loneliness levels were higher after stroke onset relative to before stroke onset. This research adds to a growing body of evidence demonstrating elevated loneliness among stroke survivors and highlights the need for interventions to increase social connectedness after stroke.

From Intent to Impact: A Proactive Event Approach for Amplifying Sustainability Across Time

We extend event system theory (EST) to conceptualize proactive events and examine how event duration, timing, criticality, and disruption are related to two phases of change associated with an organizationally initiated event. Specifically, we explore the impact of a new sustainability monitoring system on energy consumption using longitudinal archival data from 87 manufacturing units of a Fortune 200 multinational firm. We use a variant of mixed-effects discontinuous growth modeling (DGM) to test EST propositions related to initial and longer-term changes associated with implementing the monitoring system. Results indicate that while the new sustainability monitoring system is effective in reducing within-unit energy consumption on average, there are significant differences in change magnitude between units. The magnitude of change during the pre-post phase was related to between-unit differences in event duration, timing, criticality, and disruption. Longer-term change patterns were related to between-unit differences in managerial criticality behaviors. The results empirically validate several of EST’s core propositions and provide an illustration of how DGM can be modified to study events that vary in onset and duration across entities.

A theory of stochastic fluvial landscape evolution

Geometries of eroding landscapes contain important information about geologic, climatic, biotic and geomorphic processes. They are also characterized by variability, which makes disentangling their origins challenging. Observations and physical models of fluvial processes, which set the pace of erosion on most continents, emphasize complexity and variability. By contrast, the spectral content of longitudinal river profiles and similarity of geometries at scales greater than approximately 100 km highlight relatively simple emergent properties. A general challenge then, addressed in this manuscript, is development of a theory of landscape evolution that embraces such scale-dependent insights. We do so by incorporating randomness and probability into a theory of fluvial erosion. First, we explore the use of stochastic differential equations of the Langevin type, and the Fokker–Planck equation, for predicting migration of erosional fronts. Second, analytical approaches incorporating distributions of driving forces, critical thresholds and associated proxies are developed. Finally, a linear programming approach is introduced, that, at its core, treats evolution of longitudinal profiles as a Markovian stochastic problem. The theory is developed essentially from first principles and incorporates physics governing fluvial erosion. We explore predictions of this theory, including the natural growth of discontinuities and scale-dependent evolution, including local complexity and emergent simplicity.

Moving on: Exploring the implications of leader departure and incoming temporary leaders for collective turnover and unit performance.

While leader departures from work units frequently occur within organizations and are assumed to negatively impact unit functioning, the collective reaction to a leader departure event can vary across time. While a common expectation of leader departure models is that the incoming leader is permanent, it is unclear how unit-level reactions, such as collective turnover and unit performance, might change over time in response to a departure event when the departing leader is replaced with a temporary leader. We draw on context emergent turnover (CET) theory and literature on leader departures to develop and empirically test specific hypotheses exploring relationships among leader departures, collective turnover, and unit performance over time. In addition, we examine the extent to which these relationships are influenced by the temporary status of the incoming leader. Using discontinuous growth models, we examine a longitudinal data set from 324 units within a large Latin American operation of a global direct sales company (N = 3,082 performance periods). Findings indicate that, after a leader departs, there is an immediate increase in collective turnover and that unit performance decreases over time. Further, when the incoming leader is temporary, unit performance increases briefly, but the rate of performance drops over time. Overall, our research offers insights with regard to how leader departures impact unit outcomes, as well as how long such effects last. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

청소년의 공동체의식 변화 유형 분류와 주요 예측변인 영향력 검증

This study was conducted to explore the key predictors of change in sense of community during adolescence, to classify latent classes of sense of community changes, and to test the impact of key predictors on classification of latent classes. To this end, SEMforest was applied to KELS 2013 data from 3rd to 8th wave to derive the key predictors of changes in sense of community during middle school and high school, and discontinuous piecewise latent class growth analysis was utilized using a three-step approach. The results were as follows. First, as a result of SEMforest, five student-related variables were found to be common to both the middle and high school years, and two student-related variables were selected differentially for each of the middle and high school years. Additionally, one parental-related variable was derived to be common to both middle and high school years, and two parental-related variables were selected discriminatively for each of the middle and high school years. Second, three latent classes in sense of community during adolescence were identified: low-level decline (22.2%), middle-level gain-decline (52.0%), and high-level gain-decline (25.8%). Third, self-concept (academic and social), rule observance, multicultural acceptance (relationship with multicultural neighbors/friends), and volunteerism awareness were found to have a significant effect on classifying latent classes in both the middle and high school years. Finally, based on the main results, educational implications for fostering a sense of community among adolescents were discussed.

Job Satisfaction Across the Workweek

Abstract: The present study tested different perspectives on the time course of job satisfaction over the workweek: the “rested and recharged” perspective, the “Monday blues” perspective, and the “Thank God it’s Friday” perspective. A sample of 330 employees reported on an affect scale of job satisfaction during the workweek and on explicit and implicit affect at the start of the study. The results from discontinuous growth model analyses found evidence for a positive peak at the end of the week, from Thursday to Friday. Explicit negative affect at the beginning of the week was associated with lower affective job satisfaction at the beginning of the week, but with a higher rate of growth in affective job satisfaction over the course of the week. The results provide new insights into the time course of job satisfaction during the workweek and indicate a distinction between affective and cognitive components of job satisfaction.

Continuous vs. discontinuous garnet growth in mylonitic micaschists from northeastern Sardinia, Italy: Evidence from LA-ICPMS trace element mapping

Garnet with complex, discontinuous zoning is a common occurrence in metamorphic terrains, and the relationship between major and trace element zoning can provide insight into the metamorphic evolution of the host rock. Mylonitic micaschists along the Posada-Asinara Shear Zone in the Axial Zone of the Sardinia Variscan chain contain garnet porphyroblasts, enveloped by the S2 schistosity, with distinct core and rim domains. A large garnet porphyroblasts was investigated by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICPMS) mapping. The major element compositional variation follows a bell-shaped zoning, with Ca and Mn contents progressively decreasing, and Fe and Mg increasing, from the core to the outer rim. LA-ICPMS mapping revealed a thin and sharp annular enrichment zone in Y, Sc, Dy, Ho, Er, Tm at the mantle-rim boundary. The trace element (TE) compositional profiles show a central enrichment area for HREE (Tm, Yb, Lu). This enrichment decreases progressively, as a function of atomic number, for Er, Ho and Dy. Elements with even lower atomic number (Tb, Gd, Eu and Sm), are depleted in this central domain, but their content increases in broad shoulders towards the garnet rim. The position of these lateral shoulders migrates progressively rimwards with decreasing atomic number. The REE distribution, trend and behavior in the growth zones of the garnet is an example of TE control during a continuous growth ruled by diffusion-limited REE uptake. The Y + HREE annular enrichment zone, interpreted as resulting from a decrease in the garnet growth rate, reflects a short-lived episode in the garnet growth history.

Discontinuous Urban Growth: A Discussion from the Perspective of Sustainability

Objective: The study analyzes the phenomenon of discontinuity in the growth of the urban fabric directly related to planning, urbanization and the sustainability of municipal management. The analyzes presented are directed to the case study of Vitória da Conquista, in the State of Bahia, Brazil. Theoretical framework: The study brings theoretical reflections on the issue of discontinuity in the city's urban fabric, correlating it to spatial segregation; public policy; optimization of installed infrastructure; the urban voids generated by real estate speculation, the actions of space transforming agents. Method: The Geographic Information System was used as a methodological instrument, with geoprocessing resources, using orbital data in raster format (satellite images) obtained from the National Institute for Space Research (INPE), and vector cartographic bases available at IBGE. Results and conclusion: The growth of the city of Vitória da Conquista over the years resulted in a morphology with the creation of urban voids, with speculative purposes, where residual spaces were created with discontinuous growth, in a logic that restructures spaces in the urban area. Implications of the research: Access to urban rights or the right to the city of an indivisible nature, guaranteed by the 1988 constitution to all inhabitants of the city, of present and future generations. The equity of living, enjoying and participating in the production of fair, inclusive and sustainable cities. Originality/value: This research has academic value, as it supports public policies and urban planning, with the originality of the discussions presented.

Pseudo‐single crystal growth of the entropy‐stabilized compound CoTi2O5: Microstructural evolution and kinetics

AbstractThe solid‐state transformation behavior of cobalt dititanate (CoTi2O5) has been studied at different temperatures. The starting structure consisted of a duplex (1:1 molar) mixture of CoTiO3 and TiO2 grains. A seed layer of CoTi2O5 grains was incorporated at the upper surface of the green, precursor powder samples. Cobalt dititanate is a member of the pseudobrookite family (Cmcm, orthorhombic); it is an entropy‐stabilized compound, hence is stable only at elevated temperatures (T > 1140°C). It was observed that transformation initiated adjacent to the seed layer. First, a narrow layer of CoTi2O5 forms at the diphase boundaries, creating a 3‐D network that propagates at a constant velocity through the structure. The velocity of the reaction front follows an Arrhenius dependence on temperature. Both the rates of nucleation and growth increase with increasing temperature. At 1300°C, the velocity was estimated to be in excess of 10 mm/h. The progression of the reaction front was modelled based on a discontinuous template growth mechanism, with enhanced diffusion along the boundary between the product and reactant phases. The activation energy derived for boundary diffusion was 475 ± 69 kJ/mol. Behind the reaction front, the microstructure consists of a continuous matrix of CoTi2O5, with isolated remnant grains of CoTiO3 and TiO2. Further transformation occurs more slowly by solid‐state diffusion through the CoTi2O5 phase. Studies of the crystallographic orientation of the CoTi2O5 phase showed that it was pseudo‐ single crystal, with a preferred growth direction of [100]. The system exhibits novel features, which have not been reported previously for ceramic systems.

Novices’ professional identification awakened: Uncovering the impact of positive profession‐spotlighting events

AbstractMany professions experience unique events that highlight their relevance and value. These positive profession‐spotlighting events may significantly influence employees’ professional identification, especially for novices in the highlighted professions. In this paper, we aim to gain a comprehensive understanding of this phenomenon. Drawing on the identity construction process model, we investigate how and why positive profession‐spotlighting events influence novices’ professional identification. In Study 1, using 10‐wave longitudinal data (five waves before and five after the outbreak of COVID‐19) collected from 322 new graduate nurses, we use discontinuous growth modeling to investigate the impact of the pandemic as a positive profession‐spotlighting event on their increase in professional identification. We found that new graduate nurses’ professional identification gradually fell during their initial months in professional practice but rose dramatically after the onset of COVID‐19. We also found that sensegiving and moral elevation during the event led to an increase in professional identification. We further theorize an increase in work meaningfulness as the core mechanism for the hypothesized relationships and obtain supporting evidence from one experiment (Study 2) and two quasi‐experiments (Studies 3a and 3b). Our research reveals the significant influence of positive profession‐spotlighting events on both the identity construction and socialization processes and offers practical implications for how to manage such events.

A Dynamic Perspective on Job Knowledge Characteristics during the COVID-19 Pandemic

AbstractJob knowledge characteristics have long been regarded as relatively fixed. However, this may no longer be the case given the dynamic and complex situations faced by employees during the COVID-19 pandemic. On the basis of event system theory and the work design literature, we argue that the onset of COVID-19 created an immediate decrease in job knowledge characteristics, which gradually increased over time in the post-onset period because of employees’ coping with the pandemic. The rate of increase in job knowledge characteristics is higher for those with higher individual task adaptivity than for others. We further argue that changes in job knowledge characteristics produced changes in job stress, and that this effect is weakened by job security. We conducted a 6-month, 6-wave longitudinal survey to gather data from 235 employees in Macau, China covering the pre-onset, onset, and post-onset periods of the COVID-19 outbreak. The results, based on discontinuous growth modeling and latent change score modeling, support our arguments. Our study advances the dynamic view of work design by identifying how a macro event may shape job knowledge characteristics and the implications of a time-to-time change in job knowledge characteristics. Overall, we suggest that there are psychological costs when employees cope at work with the business interruptions caused by COVID-19.

The Relation Between Decadal Droughts and Eruptions of Steamboat Geyser in Yellowstone National Park, USA

AbstractIn the past century, most eruptions of Steamboat Geyser in Yellowstone National Park's Norris Geyser Basin were mainly clustered in three episodes: 1961–1969, 1982–1984, and ongoing since 2018. These eruptive episodes resulted in extensive disturbance to surrounding trees. To characterize tree response over time as an indicator of geyser activity adjustments to climate variability, aerial and ground images were analyzed to document changes in tree coverage around the geyser since 1954. Radiocarbon dating of silicified tree remnants from within 14 m of the geyser vent was used to examine geyser response to possible variations in decadal to centennial precipitation patterns. We searched for atypical or absent growth rings in cores from live trees in years associated with large geyser eruptions. Photographs indicate that active eruptive phases have adversely affected trees up to 30 m from the vent, primarily in the dominant downwind direction. Radiocarbon dates indicate that the geyser formed before 1878, in contrast to the birthdate reported in historical documents. Further, the ages of the silicified trees cluster within three episodes that are temporally correlated with periods of relative drought in the Yellowstone region during the 15th–17th centuries. The discontinuous growth of trees around the geyser suggests that changes in eruptive patterns occur in response to decadal to multidecadal droughts. This inference is supported by the lack of silicified specimens with more than 20 annual rings and by the existence of atypical or missing rings in live trees during periods of extended geyser activity.

Generalized Backward Doubly Stochastic Differential Equations Driven by Lévy Processes with Discontinuous and Linear Growth Coefficients

Generalized Backward Doubly Stochastic Differential Equations Driven by Lévy Processes with Discontinuous and Linear Growth Coefficients

Precipitation Behavior of the Second Phase in High-Nitrogen Austenitic Stainless Steel Alloyed with V and Nb

The retaining ring is one of the components with the highest stress on the rotor of the turbine generator. Due to the high content of alloying elements in this type of steel, it is extremely easy to precipitate a large amount of the second phase during the forming process of a material, which deteriorates the processability, Therefore, it is very important to study the second phase precipitation of high-nitrogen steel. This work addresses the precipitation behavior of the second phase in a high-nitrogen austenitic stainless steel alloyed with V and Nb. The optical microscopy, scanning electron microscopy, transmission electron microscopy and X-ray diffractometry were applied to investigate the influence of heat treatment parameters on the morphology and composition of the precipitated particles. The addition of V and Nb results in the formation of NbVN and VN particles, of which the amount is slightly decreased after a subsequent solution treatment at 1200 °C for 1 h. The results demonstrate that an additional aging treatment at 800~1000 °C for three leads to the participation of lamellar Cr2N and the undissolved MX phase. The content of the precipitates increases with increasing both the aging temperature and the aging time. The addition of V/Nb elements effectively improves the stability of MX phase, and the existence of high energy zones (the MX phase interface and grain boundary) promotes the early formation of Cr2N. Cr2N is shown to nucleate in the high energy zones, which thereafter grows into austenite grains, demonstrating a normal discontinuous cellular growth.