Transition Rates Research Articles

Changing patterns of treatment and prescribers of stimulants for children, adolescents and young adults with attention deficit hyperactivity disorder in New South Wales, Australia: evidence for a treatment bottleneck? - A database study.

Investigate the treatment patterns and prescribers of stimulants for attention deficit hyperactivity disorder (ADHD) in young people in New South Wales (NSW). Longitudinal cohort study of persons born after 1983 and prescribed stimulants for ADHD as per the NSW Ministry of Health Controlled Drugs Data Collection. Results were analyzed descriptively: a) treatment prevalence by year; age; sex; b) speciality of prescribers over time; c) rate of transition from paediatrics to adult psychiatry. The main analysis covered 2003-2015, with data on general practitioner prescribing to 2023. Treatment prevalence rates were highest at age 10 (22.8 per 1000 person years), declining among teenagers and stabilizing in adulthood at 2.5 per 1000. The childhood male treatment predominance (4:1) resolved to 1.6:1 in adulthood. Paediatricians were the main prescribers until age 20. The average annual percent increase in prescribers was: adult psychiatry - 13%, general practice - 20%, paediatrics - 2.6%. Only 6.3% of treated children had transitioned to adult psychiatrists by age 25; 50% starting treatment with adult psychiatrists had no previous treatment records. The proportion on treatment and the male predominance declined substantially with age. Future studies may determine whether increased prescribing by general practitioners and psychiatrists reduces treatment attrition during adolescence.

Compartmental Models Driven by Renewal Processes: Survival Analysis and Applications to SVIS Epidemic Models

Compartmental models with exponentially distributed lifetime stages assume a constant hazard rate, limiting their scope. This study develops a theoretical framework for systems with general lifetime distributions, modeled as transition rates in a renewal process. Applications are provided for the SVIS (Susceptible-Vaccinated-Infected-Susceptible) disease epidemic model to investigate the impacts of hazard rate functions (HRFs) on disease control. The novel SVIS model is formulated as a non-autonomous nonlinear system (NANLS) of ordinary differential equations (ODEs), with coefficients defined by HRFs. Key statistical properties and the basic reproduction number () are derived, and conditions for the system’s asymptotic autonomy are established for specific lifetime distributions. Four HRF behaviors—monotonic, bathtub, reverse bathtub, and constant—are analyzed to determine conditions for disease eradication and the asymptotic population under these scenarios. Sensitivity analysis examines how HRF behaviors shape system trajectories. Numerical simulations illustrate the influence of diverse lifetime models on vaccine efficacy and immunity, offering insights for effective disease management.

Constraining theoretical corrections to Gamow-Teller transition rates

Constraining theoretical corrections to Gamow-Teller transition rates

Study of blood flow patterns in a stenosed artery through the combined effect of body acceleration and generalized womersley solution

Stenosis causes the narrowing of arteries due to plaque buildup, which impedes blood flow and affects flow dynamics. This work numerically analyzes flow fluctuations in stenosed arteries under realistic physiological conditions (resting and exercise) and external body acceleration. The artery is inclined at angle Θ, and blood rheology is modeled using a generalized power-law fluid. A modified two-dimensional SIMPLE pressure-correction-based numerical solver with orthogonal coordinate transformation simulates blood flow. A generalized Womersley solution is imposed at the inlet. We validate the solver and perform simulations to assess the influence of geometric and flow parameters, analyzing time-averaged and phase-averaged data. We investigate the correlation between hyperviscosity and physiological conditions, finding that exercise increases recirculation downstream of the stenosis. We also study the impact of transitioning between resting and exercise conditions, noting that the transition rate correlates with stenosis development, indicating potential complications.

Toward Grid-Based Models for Molecular Association.

This paper presents a grid-based approach to model molecular association processes as an alternative to sampling-based Markov models. Our method discretizes the six-dimensional space of relative translation and orientation into grid cells. By discretizing the Fokker-Planck operator governing the system dynamics via the square-root approximation, we derive analytical expressions for the transition rate constants between grid cells. These expressions depend on geometric properties of the grid, such as the cell surface area and volume, which we provide. In addition, one needs only the molecular energy at the grid cell center, circumventing the need for extensive MD simulations and reducing the number of energy evaluations to the number of grid cells. The resulting rate matrix is closely related to the Markov state model transition matrix, offering insights into metastable states and association kinetics. We validate the accuracy of the model in identifying metastable states and binding mechanisms, though improvements are necessary to address limitations like ignoring bulk transitions and anisotropic rotational diffusion. The flexibility of this grid-based method makes it applicable to a variety of molecular systems and energy functions, including those derived from quantum mechanical calculations. The software package MolGri, which implements this approach, offers a systematic and computationally efficient tool for studying molecular association processes.

Adaptive sampling-based structural prediction reveals opening of a GABAA receptor through the αβ interface.

γ-Aminobutyric acid type A (GABAA) receptors are ligand-gated ion channels in the central nervous system with largely inhibitory function. Despite being a target for drugs including general anesthetics and benzodiazepines, experimental structures have yet to capture an open state of classical synaptic α1β2γ2 GABAA receptors. Here, we use a goal-oriented adaptive sampling strategy in molecular dynamics simulations followed by Markov state modeling to capture an energetically stable putative open state of the receptor. The model conducts chloride ions with comparable conductance as in electrophysiology measurements. Relative to experimental structures, our open model is relatively expanded at both the cytoplasmic (-2') and central (9') gates, coordinated with distinctive rearrangements at the transmembrane αβ subunit interface. Consistent with previous experiments, targeted substitutions disrupting interactions at this interface slowed the open-to-desensitized transition rate. This work demonstrates the capacity of advanced simulation techniques to investigate a computationally and experimentally plausible functionally critical of a complex membrane protein yet to be resolved by experimental methods.

Tailored Metal‐Oxygen Bonding in Amorphous Perovskite CoSnO3 for Broadband Ultrafast Laser State Active Manipulation

AbstractAmorphous perovskite CoSnO3 has attracted significant attention due to its unique properties and various modification methods. However, modifying metal‐oxygen bonds on the nonlinear optical (NLO) characteristics remains uncharted. In this study, a dehydration method is employed to convert the metal‐hydroxyl bonds (M─OH) of hydroxide CoSn(OH)6 into metal‐oxygen bonds (M─O), successfully preparing amorphous CoSnO3 with oxygen vacancies. Subsequently, effective regulation of the metal‐oxygen bonds in amorphous CoSnO3 is achieved through an ion exchange strategy, yielding Fe‐doped CoSnO3 (Fe‐CoSnO3). Comprehensive characterization and analysis revealed that the regulation of metal‐oxygen bonds accelerated the electron transition rate, resulting in a fast recovery time of ≈245.1 fs for Fe‐CoSnO3, accompanied by a significant boost in broadband NLO properties. Notably, when Fe‐CoSnO3 is utilized as a saturable absorber (SA), it exhibited superior mode‐locking characteristics compared to CoSnO3 in the range of 1–2 µm. Specifically at the communication band of 1.5 µm, the dynamic switching between single‐wavelength and dual‐wavelength mode‐locking operations is achieved. With the ultrafast laser state manipulation, a digital encoding is also demonstrated. This work confirmed that the tailoring of metal‐oxygen bonds makes Fe‐CoSnO3 an excellent NLO material for ultrafast optical applications, and this tailoring strategy provides new insights for designing advanced NLO materials.

Theoretical understanding of the in-plane tensile strain effects on enhancing the ferroelectric performance of Hf0.5Zr0.5O2 and ZrO2 thin films.

In-plane tensile strain was reported to enhance the ferroelectricity of Hf1-xZrxO2 thin films by promoting the formation of a polar orthorhombic (PO-) phase. However, its origin remains yet to be identified unambiguously, although a strain-related thermodynamic stability variation was reported. This work explores the kinetic effects that have been overlooked to provide a precise answer to the problem, supplementing the thermodynamic calculations. The in-plane strain-dependent phase fractions were identified by calculating the relative influences of the thermodynamic factor (Boltzmann distribution of free energies of polymorphs) and the kinetic factor (transition rate between polymorphs using the Johnson-Mehl-Avrami equation). The monoclinic (M-) phase constitutes the ground state under almost all conditions. However, its formation is kinetically suppressed by the high activation barrier for the transition from the tetragonal (T-) phase. In contrast, PO-phase formation is dominated by thermodynamic effects and is promoted under in-plane tensile strain due to the energetic stabilization of the PO-phase, while the T- to PO-phase transition is kinetically probable due to a low activation barrier. The in-plane tensile strain also lowers the activation barrier of T → M. Hence, the optimal tensile strain for PO-phase formation varies depending on the thermal conditions. The remanent polarization was calculated using spontaneous polarization and the PO-phase fraction. The in-plane tensile strain of 2-2.5% and moderate annealing at approximately 700 K were optimum for increasing ferroelectricity by 34% in Hf0.5Zr0.5O2 and 106% in ZrO2 along the 〈111〉 orientation.

Long-chain crosslinker-induced patterning on an elastic polymer film for robust and reversible information encryption/decryption.

While reversible information encryption and decryption are readily achievable with hydrogels, this process presents a significant challenge when applied to elastic polymer films. This is due to the inherent chemical stability of anhydrous polymer films which significantly increases the difficulty of information writing. In this study, we propose a solvent-free radical polymerization method for chemical patterning on the elastic film of poly(styrene-butadiene-styrene) (SBS). Unlike short chain crosslinkers-induced patterning, which increases the brittleness of the film, the long-chain crosslinkers are chemically bonded with the chains of SBS. This not only enhances the mechanical stability of film, but also improves its softness and robustness (the strength increases 1.8 times and the toughness increases 2.3 times), thereby greatly extending its durability for information encryption and decryption. When patterned with a photomask, the crosslinked regions maintain transparency upon acetone absorption, while the non-crosslinked regions become opaque due to an acetone-induced phase change. Upon removal of acetone, these opaque regions can be restored to transparency. Compared with hydrogels liable to water loss and deformation, the patterned films show greater stability, retaining pattern encryption/decryption functions after 30 days in a natural environment without special storage. The rate of this phase transition is directly related to the degree of crosslinking. Therefore, by adjusting the degree of crosslinking, the patterned films can undergo multistage encryption/decryption in response to acetone, providing a promising method for information security and storage.

Differential Mg2+ deposition on DNA Holliday Junctions dictates the rate and stability of conformational exchange.

DNA Holliday junctions (HJs) are crucial intermediates in genetic recombination and genome repair processes, characterized by a dynamic nature and transitioning among multiple conformations on the timescale ranging from sub-milliseconds to seconds. Although the influence of ions on HJ dynamics has been extensively studied, precise quantification of the thermodynamic feasibility of transitions and detailed kinetic cooperativity remain unexplored. Understanding the heterogeneity of stochastic gene recombination using ensemble-averaged experimental techniques is extremely difficult because of its lack of ability to differentiate dynamics and function in a high spatiotemporal resolution. Herein, we developed a new technique that combines single-molecule fluorescence resonance energy transfer (smFRET) experiments and molecular simulation to investigate the kinetic choreography and preferential stability of HJ conformations under ionic conditions that closely mimic the physiological environment relevant to cellular biology. Our findings predict the prevalence of three distinct conformational macrostates in HJ dynamics. At low ion concentrations, HJs transition rapidly among three thermodynamically stable conformational macrostates. However, in a physiological ionic environment, the open conformation becomes predominant. Using a kinetic network model based on the multi-order time correlation function (TCF), we delineated thermodynamic parameters that govern heterogeneous dynamics as a function of divalent ion concentration. Stabilization of conformations due to an ionic environment and activation barriers concertedly affect transition rates between open and closed conformations. Furthermore, we observed a significant enhancement of Mg2+ condensation in the central region of HJs rather than branch ends, leading to a plausible conclusion that the differential stability of conformational states may be governed by the junction region of HJs rather than duplex branches. This study gives a new insight into the complex interplay between the ionic environment and HJ dynamics, offering a comprehensive understanding of their behavior under conditions relevant to cellular biology and roles in key biological processes for creating a heterogeneous nature of life.

The Role of Polar Optical Modes in Wide Bandgap Semiconductor Quantum Structures

: In this paper, the interface polariton (IP), the confined (CF) modes in nanostructures made with wide bandgap semiconductors, as well as their contributions to the carrier scattering mechanism have been investigated. An asymmetric quantum well (AQW) made with ZnSe/CdSe/ZnS has been studied. More specifically, the dielectric continuum (DC) model has been employed to describe both the IP and the CF modes. Additionally, the Fermi golden rule has been used to estimate the electron transition rate within the asymmetric structure. Our numerical results show that the scattering rate for an electron which is localized at the bottom of the first subband above the well and drops within the quantum well, is characterized by regular peaks with an almost linear increase as the size of the QW increases. The emerge peaks are related to two different physical characteristics of the AQW system. These peaks are related to electron resonances and the threshold phonon emission (both CF and IP) called phonon resonances. The scattering rate of an electron which is localized at the bottom of the second subband above the well and makes transitions to all possible states within the quantum well gives only rise to phonon resonances. The research highlights the importance of the CF and IP modes on transition rates and their dependence on both the size of the quantum well and the asymmetry of the barrier materials. : PACS: 68.65.Fg, 74.25.Kc, 63.22.−m, 63.22.+m

Quantized repetitive tracking control for Markovian jump nonlinear systems with disturbances and incomplete knowledge of transition rates

Quantized repetitive tracking control for Markovian jump nonlinear systems with disturbances and incomplete knowledge of transition rates

Estimating Phase Transition Rates in Shallow Cumulus Clouds from Mass Flux. Part II: Vertically Dependent Formulation

Abstract This work continued the investigation of the relationship between phase transition rates and mass flux in trade wind cumulus clouds. The latter was simulated by an LES model initialized with soundings from the Rain in Cumulus over the Ocean (RICO) field project. In Part I, we demonstrated that a very high correlation exists between integral phase transition rates and upward mass flux. In this study, we focused on the vertically dependent variables and showed that a similar high correlation exists between the condensation rate and the upward mass flux . Based on condensation theory, we showed that under quasi-steady approximation condensation rates can be calculated by a linear function of with the slope coefficient dependent only on temperature and pressure. The model data showed that the error of such approximation is less than a few tenths of a percent. The parameterization of the evaporation process is more complex, mostly because of the slow evaporation of raindrops as they fall through the cloud’s unsaturated areas. Nevertheless, it was possible to define the fraction of the evaporation to condensation rate as a function of vertical coordinate z and cloud thickness H. This function can be quite accurately approximated by the third-order polynomials of z and H. It is suggested that the proposed formulation of evaporation together with the quasi-steady formulation of condensation can serve as a parameterization of water phase transition rates in shallow cumulus clouds. Significance Statement This study investigated condensation/evaporation processes in tropical cumulus clouds. The energy exchanged during these processes is an important driving force behind a wide range of atmospheric phenomena. It was found that the vertical distribution of this energy source can be expressed as a linear function of cloud updrafts. This finding suggests a new approach to calculate cloud energy transformations in numerical weather prediction models.

CHURN: TRANSITIONS OUT OF HEALTH SECTOR EMPLOYMENT FOR LOW-PREPARATION WORKERS, 2017–2022

Abstract Shortages and turnover for front-line paid caregivers and support staff in long-term services and supports for older adults undermine quality of care. These workers are part of the health sector workforce, and also participate in a larger labor market of jobs requiring minimal formal education and brief training. The Brandeis Front-line Health Worker Survey queried a random sample of U.S. residents screened for holding patient-facing jobs in the health sector between the survey date (Summer 2022) and five years prior (2017), generating information on a retrospective longitudinal cross section of US health sector workers. Respondents reporting occupations in Bureau of Labor Statistics Job Zones 1 and 2 were identified as participating in low-preparation labor markets. About half of low-preparation health sector workers reported work in nursing homes, residential settings, or home care. We estimated annual rates of transition into and out of heath sector employment for all low-preparation health workers for years prior to and during the pandemic. Descriptive logistic regressions showed the relationship of job churn to gender, caregiver status, and previous employment pattern. Despite concerns about health workforce stability as the pandemic wound down, low-preparation workers exhibited about the same year-to-year transition rates out of (and back into) the health sector throughout the period. This suggests that the Great Resignation in healthcare is a continuing pattern rather than a pandemic phenomenon. Employers and public policy makers setting wages and working conditions should recognize that front-line workers have, and have always had, alternatives beyond the health sector.

Comparison of imputation methods for univariate categorical longitudinal data

AbstractThe life course paradigm emphasizes the need to study not only the situation at a given point in time, but also its evolution over the life course in the medium and long term. These trajectories are often represented by categorical data. This article aims to provide a comprehensive review of the multiple imputation methods proposed so far in the context of univariate categorical data and to assess their practical relevance through a simulation study based on real data. The primary goal is to provide clear methodological guidelines and improve the handling of missing data in life course research. In parallel, we develop the MICT-timing algorithm, which is an extension of the MICT algorithm. This innovative multiple imputation method improves the quality of imputation in trajectories subject to time-varying transition rates, a situation often encountered in life course data.

Закономерности массообменных процессов при криоконцентрировании обезжиренного молока

Low-temperature concentration of milk and dairy products is a prospective alternative to such traditional concentration methods as evaporation or membrane technologies. This energy-effective method preserves the native properties of dairy raw materials. In this research, the kinetics of moisture freezing made it possible to determine the effect of time, temperature, and composition on the amount of frozen ice on the cooled surface. The study featured the main physical and chemical parameters of milk, i.e., water, fat, protein, and solids. Chromel-copel thermoelectric converters were used to identify the freezing temperature. Experimental laboratory equipment made it possible to describe the kinetics of low-temperature concentration. The ice growth rate curves were similar and not linear at temperatures between –2 and –8°C. At all temperature conditions, the solids increased together with the freezing time as the coolant temperature went down. The experiment yielded a regression equation that revealed the mass fraction of solids in concentrated skim milk depending on the temperature and freezing time. The temperature and freezing time affected the transition rate of milk solids into ice. The coolant temperature had the greatest effect on the cryoconcentration of skim milk. When the temperature of the coolant was reduced from –2 to –8℃, it increased the share of solids in the finished product and sped up its transition into ice. The optimal temperature for milk concentration in the experimental capacitive-type crystallizer proved to be –4°C.

Molecular epidemiology, evolution, and transmission dynamics of raccoon rabies virus in Connecticut.

In North America, raccoon rabies virus (RRV) is a public health concern due to its potential for rapid spread, maintenance in wildlife, and impact on human and domesticated animal health. RRV is an endemic zoonotic pathogen throughout the eastern USA. In 1991, an outbreak of RRV in Fairfield County, Connecticut, spread through the state and eventually throughout the Northeast and into Canada. Factors that contribute to, or curb, RRV transmission should be explored and quantified to guide targeted rabies control efforts, including the size and location of buffer zones of vaccinated animals. However, population dynamics and potential underlying determinants of rabies virus diversity and circulation in Connecticut have not been fully studied. In this study, we aim to (i) investigate RRV source-sink dynamics between Connecticut and surrounding states and provinces, (ii) explore the impact of the Connecticut River as a natural barrier to transmission, and (iii) characterize the genomic diversity and transmission dynamics in Connecticut. Using RRV whole-genome sequences collected from various host species between 1990 and 2020, we performed comparative genetic and Bayesian phylodynamic analyses at multiple spatial scales. We analyzed 71 whole-genome sequences from Connecticut, including 21 recent RRV specimens collected at the Connecticut Veterinary Medical Diagnostic Laboratory that we sequenced for this study. Our analyses revealed evidence of RRV incursions over the US-Canada border, including bidirectional spread between Quebec and Vermont. Additionally, we highlighted the importance of Connecticut and New York in seeding RRV transmission in eastern North America, including two introduction events from New York to Connecticut that resulted in sustained local transmission. While RRV transmission does occur across the Housatonic and Connecticut Rivers, we demonstrated the distinct presence of spatial structuring in the phylogenetic trees and characterized the directionality of RRV migration. The significantly higher mean transition rates from locations east to west of the Connecticut River, compared to west to east, may be leveraged in directing interventions to fortify these natural barriers. Ultimately, the findings of these international, regional, and state analyses can inform targeted control programs, vaccination efforts, and enhanced surveillance at borders of key viral sources and sinks.

Evolution from 3-D to 2-D of a confined hydrogen atom dipole dependent properties when compressed by two parallel planes

Abstract The confinement of an atom by two parallel planes produces changes in the spectra and dipole-dependent electronic properties when evolving from large – 3-D – to narrow – 2-D – inter-plane separation. In this work, the behavior of the dipole electronic properties of a hydrogen atom located half the distance between two impenetrable parallel planes is studied as a function of the inter-plane separation
using the energies and wave functions reported previously by the author [Physica Scripta 99, 065416 (2024)]. The evolution of the line intensities, transition rates, life times, polarizability, and the mean excitation energy are reported as a function of the inter-plane separation. We find that as the inter-plane separation is reduced, all the electronic properties are affected by the shifting of the electronic spectra towards the short wave-length region (EUV) with a boost of the photo-luminosity intensity, reduction of the static polarizability and life-time of the 2s and 2p states, increase of the mean excitation energy, and transition rates for characteristic plane separations. Our numerical results agree, in the limiting cases, to the analytical solutions for a free atom for large inter-plane separations and to those of a 2-D atom for small inter-plane separation, as well as to available experimental data.

Large Scale Synthesis of Red-Emitting Quantum Dots for Efficient and Stable Light-Emitting Diodes.

It is known that large-scale synthesis of emitters affords colloidal quantum dot (CQD) materials with a great opportunity toward the mass production of quantum dot light-emitting diodes (QLEDs) based commercial electronic products. Herein, an unprecedented example of scalable CQD (> 0.5 kilogram) is achieved by using a core/shell structure of CdZnSe/ZnSeS/CdZnS, in which CdZnSe, ZnSeS, and CdZnS alloys are used as the inner core, transition layer and outermost shell, respectively. It exhibits a high fluorescence quantum yield (>90%), a robust excited state, and a fast radiative transition rate. The investigation of morphology and surface state reveals the possible reasons for such excellent optical properties, which include uniform size distribution, no undesired byproducts, and high defect tolerance. The QLEDs exhibit a peak external quantum efficiency of over 21%, a high luminance of over 9.5×104cd m-2, and a long lifetime of over 1.0×106 h, corresponding to the state-of-the-art performance among the QLEDs based on the large-scale synthesis of CQDs. Therefore, it is believed that an efficient and reliable strategy is provided toward the large-scale synthesis of CQDs, which can be used as emitters in the QLEDs-based commercial electronic devices and make the mass production of these products a reality.

Effects of Temperature and Random Forces in Phase Transformation of Multi-Stable Systems.

Multi-stable behavior at the microscopic length-scale is fundamental for phase transformation phenomena observed in many materials. These phenomena can be driven not only by external mechanical forces but are also crucially influenced by disorder and thermal fluctuations. Disorder, arising from structural defects or fluctuations in external stimuli, disrupts the homogeneity of the material and can significantly alter the system's response, often leading to the suppression of cooperativity in the phase transition. Temperature can further introduce novel effects, modifying energy barriers and transition rates. The study of the effects of fluctuations requires the use of a framework that naturally incorporates the interaction of the system with the environment, such as Statistical Mechanics to account for the role of temperature. In the case of complex phenomena induced by disorder, advanced methods such as the replica method (to derive analytical formulas) or refined numerical methods based, for instance, on Monte Carlo techniques, may be needed. In particular, employing models that incorporate the main features of the physical system under investigation and allow for analytical results that can be compared with experimental data is of paramount importance for describing many realistic physical phenomena, which are often studied while neglecting the critical effect of randomness or by utilizing numerical techniques. Additionally, it is fundamental to efficiently derive the macroscopic material behavior from microscale properties, rather than relying solely on phenomenological approaches. In this perspective, we focus on a paradigmatic model that includes both nearest-neighbor interactions with multi-stable (elastic) energy terms and linear long-range interactions, capable of ensuring the presence of an ordered phase. Specifically, to study the effect of environmental noise on the control of the system, we include random fluctuation in external forces. We numerically analyze, on a small-size system, how the interplay of temperature and disorder can significantly alter the system's phase transition behavior. Moreover, by mapping the model onto a modified version of the Random Field Ising Model, we utilize the replica method approach in the thermodynamic limit to justify the numerical results through analytical insights.