Time Variability Research Articles

How to better predict the effect of urban traffic and weather on air pollution? Norwegian evidence from machine learning approaches

This paper uses machine learning approaches to predict the association between traffic volume, air pollution, and meteorological conditions. A key focus is on the interaction between these factors. The paper does this using hourly traffic volume, NOx,PM2.5, and weather data for Oslo, Norway. I considered a total of six datasets of the 2019 whole-year data to verify the prediction accuracy of the models. I find that the autoregressive integrated moving average model with exogenous input variables, and the autoregressive moving average dynamic linear model outperform the machine learning models in predicting air pollution. At the same time, I also explored the effect of sampling weather subsets on prediction accuracy. Finally, my study makes optimal policy recommendations for reducing air pollution from traffic volume, after considering the interaction and lagged effects of meteorology, time variables, traffic, and air pollution.

Safety and Efficacy of the Erbium Laser in Debonding Dental Accessories: A Narrative Review.

Objective: This article aims to review the safety and efficacy of the Er:YAG laser in debonding dental accessories. Methods: This review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Articles published between 2010 and 2022 on the removal of dental accessories using erbium laser were searched. The selected articles were then classified according to the accessories used: adhesives, brackets, restorations, or implant crowns. Enamel surface roughness, shear bond strength, adhesive remnant index, duration time (t), pulp chamber temperature (T), morphology (M), and other variables were then noted. Results: The dental accessories and adhesives used were described along with the laser parameters used, such as frequency, pulse width, irradiation time, scanning mode, water-air cooling, and other variables. Conclusions: Laser removal using Er:YAG laser of dental accessories such as brackets, crowns, and veneers is fundamentally safe, time-saving, and does not cause damage to the enamel nor the underlying dentin. However, there was no distinct advantage with laser removal seen, such as those residual adhesives of brackets on the tooth surface and temporary adhesives of restorations.

What time-varying network models based on functional analysis tell us about the course of a patient's problem

Background: Relations among psychological variables are assumed to be complex and to vary over time. Personalized networks can model multivariate complex interactions. The development of time-varying networks allows to model the variation of parameters over time. Objectives: We aimed to determine the value of time-varying networks for clinical practice. Methods: We applied time-varying mixed graphical models (TV-MGM) and time-varying vector autoregressive models (TV-VAR) to intensive longitudinal data of nine participants with depressive symptoms (n = 6) or anxiety (n = 3). Results: Most of the participants showed temporal changes in network topology within the assessment period of 30 days. Time-varying networks of participants with small, medium, and large time variability in edge parameters clearly show the different temporal evolvements of dynamic interactions between variables. The case example indicates clinical utility but also limitations to the application of time-varying networks in clinical practice. Conclusion: Time-varying network models provide a data-driven and exploratory approach that could complement current diagnostic standards by reflecting interacting, often mutually reinforcing processes of mental health problems and by accounting for variation over time. They can be used to generate hypotheses for further confirmatory and clinical testing.

Assessment of dental pulp response to carries via MR T2mapping and histological analysis

ObjectivesThe aim of our study was to assess the correlation between T2 relaxation times and their variability with the histopathological results of the same teeth in relation to caries progression. Materials and methods: 52 extracted permanent premolars were included in the study. Prior to extractions, patients underwent magnetic resonance imaging (MRI) scanning and teeth were evaluated using ICDAS classification. Pulps of extracted teeth were histologically analysed. Results: MRI T2 relaxation times (ms) were 111,9 ± 11.2 for ICDAS 0, 132.3 ± 18.5* for ICDAS 1, 124.6 ± 14.8 for ICDAS 2 and 112. 6 ± 18.2 for ICDAS 3 group (p = 0,013). A positive correlation was observed between MRI T2 relaxation times and macrophage and T lymphocyte density in healthy teeth. There was a positive correlation between vascular density and T2 relaxation times of dental pulp in teeth with ICDAS score 1. A negative correlation was found between T2 relaxation times and macrophage density. There was a positive correlation between T2 relaxation time variability and macrophage and T lymphocyte density in teeth with ICDAS score 2. In teeth with ICDAS score 3, a positive correlation between T2 relaxation times and T2 relaxation time variability and lymphocyte B density was found. Conclusion: The results of our study confirm the applicability of MRI in evaluation of the true condition of the pulp tissue. Clinical relevance: With the high correlation to histological validation, MRI method serves as a promising imaging implement in the field of general dentistry and endodontics.

Real option pricing under the regime-switching model with jumps on a finite time horizon

We consider an irreversible investment decision problem on a finite time horizon where an instantaneous cash flow process of a firm follows a regime-switching jump-diffusion (RSJD) model. The value of a project can be derived from a partial integro-differential equation (PIDE) and then we obtain a closed-form solution of the PIDE. It is proved that the value of the project converges to the solution on an infinite time horizon problem as the lifetime of the project tends to infinity. Moreover, the value function of a real option with a finite expiration date can be evaluated by solving a linear complementarity problem (LCP) under the RSJD model. We apply a 2-step backward differentiation formula (BDF2 method) combined with an operator splitting method to solve the LCP and then it has the second-order convergence rate in the discrete ℓ2-norm with respect to the time and spatial variables. The stability of the proposed method to solve the LCP is also proved in the discrete ℓ2-norm. Finally, a variety of numerical experiments are carried out to determine the optimal investment time and the numerical results on the finite time horizon are analyzed.

Modeling time to death for under-five children in Malawi using 2015/16 Demographic and Health Survey: a survival analysis

BackgroundMalawi has one of the highest under-five mortality rates in Sub Sahara Africa. Understanding the factors that contribute to child mortality in Malawi is crucial for the development and implementation of effective interventions to reduce child mortality. The aim of this study is to use survival analysis in modeling time to death for under-five children in Malawi. In turn, identify potential risk factors for child mortality and inform the development of interventions to reduce child mortality in the country.MethodThis study used data from all births that occurred in the five years leading up to the 2015/16 Malawi Demographic and Health Survey. The Frailty hazard model was applied to predict infant survival in Malawi. In this analysis, the outcome of interest was death and it had two possible outcomes: "dead" or "alive". Age at death was regarded as the survival time variable. Infants who were still alive at the time of the study as of the day of the interview were considered as censored observations in the analysis.ResultsA total of 17,286 live births born during the 5 years preceding the survey were analysed. The study found that the risk of death was higher among children born to mothers aged 30–39 and 40 or older compared to teen mothers. Infants whose mothers attended fewer than four antenatal care visits were also found to be at a higher risk of death. On the other hand, the study found that using mosquito nets and early breastfeeding were associated with a lower risk of death, as were being male and coming from a wealthier household.ConclusionThe study reveals a notable decline in infant mortality rates as under-five children age, underscoring the challenge of ensuring newborn survival. Factors such as maternal age, birth order, socioeconomic status, mosquito net usage, early breastfeeding initiation, geographic location, and child's sex are key predictors of under-five mortality. To address this, public health strategies should prioritize interventions targeting these predictors to reduce under-five mortality rates.

Factors Affecting Performance on a Screening Tool in Persons with Amyotrophic Lateral Sclerosis.

Persons with amyotrophic lateral sclerosis (PALS) are at risk of developing cognitive impairments and frontotemporal dementia (FTD). This study examined the relationship between performance of the ALS-Cognitive Behavioral Screen (ALS-CBS) and the demographic parameters of sex, education, time post-ALS diagnosis, and severity of symptoms. Data were collected retrospectively from 69 participants seen at the Mayo Clinic. Correlations were conducted on the ALS-CBS total scores and subsection scores and the above listed parameters; t-tests were conducted between participant subgroups. No statistically significant relationships or differences occurred between the ALS-CBS or its subsections and the variables measured with exception of age and the attention subsection. Older participants had lower ALS-CBS attention subsection scores. Based on the ALS-CBS scores, most participants had some degree of cognitive impairments: 43 had suspected cognitive impairment, 8 had suspected FTD; 18 fell within the normal range of cognitive function. Overall, the variables of sex, education, time post-diagnosis, and severity of symptoms do not appear to influence ALS-CBS scores. It is recommended cognitive screenings be completed for all PALS due to the high risk for developing cognitive impairments and FTD. Such knowledge can help clinicians develop assessment and treatment plans.

The adsorption properties of the corm tunic structure of Crocus (Iridaceae) and its use as a biomarker for the environmental concentration of uranium

AbstractIn this study, we investigated whether the corm tunic structure, which is the underground part of the Crocus (Iridaceae) plant, can be used for adsorption and recovery/removal of uranium from an aqueous solution. The characterization of this structure, which has not been studied for its interaction with metals before, has been elucidated by point zero charge (PZC), FTIR, and SEM analyses. Extensive investigations were conducted on the adsorption properties of the biomass used and the pH, temperature, time, adsorbent dosage, and uranyl ion concentration variables were optimized. The experimental data were interpreted using theoretical adsorption models. The Langmuir model revealed a maximum adsorption capacity of the material to be 0.286 mol kg−1. Adsorption kinetics were also described using pseudo-first order, pseudo-second order, Elovich, and intra-particular diffusion models. It is shown that the adsorption pH reaches the highest adsorption at the natural pH of the uranium solution. Experimental studies showed that the adsorption was endothermic and spontaneous. It has been shown that this biomaterial can be used as an adsorbent for the removal of uranium as well as a biomarker for determining the environmental uranium concentration.

Comparison of Conventional and Precast Half Slab Work Methods (Case Study: Japfa Office Building Daan – Mogot)

In the construction of vertical buildings, the implementation method used affects the productivity of construction. The development of construction system innovation in Indonesia which continues to grow has led to a new system, one of which is the precast system. Precast systems have been proven to be able to increase productivity in terms of construction time and costs, as well as the value of waste costs, which results in little from conventional methods. The main objective of this study was to compare the efficiency of the method of implementing floor slabs in the field by comparing the variables of field implementation, costs, time, quality control, and material waste costs of the conventional and precast half - slab methods. The analysis was carried out using the unit price is based on the Jakarta Worker’s Wage Unit Price 40 year XXVII - 2021 edition. The index coefficient (conventional) refers to the Minister for Public Works and Human Settlements Regulation No. 1 of 2022, and the index coefficient (precast half slab) refers to SNI 7832:2012. Scheduling was performed using Microsoft Projects. The results show that the precast half - slab method is more efficient than the conventional method.

Characterisation of the stellar activity of M dwarfs

Context. The chromospheric emission estimated in the core of different lines, such as Ca II H & K, Na D1 and D2, and Ha, is not always correlated between lines. In particular, the Ca II H & K and Ha emission time series are anti-correlated for a few percent of the stars, contrary to what is observed on the Sun. This puzzling result has been observed for both solar-type stars and M stars. Aims. Our objective is to characterise these relationships in more detail using complementary criteria, and based on a large set of spectra obtained with HARPS for a large sample of M dwarfs. This should allow to evaluate whether or not additional processes are required to explain the observations. Methods. We analysed the time average and variability of the Ca, Na, and Hα emissions for 177 M stars ranging from subspectral types M0 to M8, paying particular attention to their (anti-)correlations on both short and long timescales as well as slopes between indices. We also computed synthetic Hα time series based on different assumptions of plage properties. We compared our findings with observations in order to evaluate whether or not the main observed properties could be reproduced. Results. The statistical properties of our sample, in terms of correlations and slopes between indices at different timescales, differ from what we previously obtained for FGK stars: there are fewer stars with a null correlation, and the correlations we find show a weaker dependence on timescale. However, there can be a large dispersion from one season to another for stars with a well identified low or negative correlation. We also specify the complex relationship between the average activity levels, with a clear indication of a change in the sign of the slope from the relation between Ca and Hα (and between Na and Ha) for the most massive M dwarfs. In addition, we observe a change in slope in the Na–Ca relation at an intermediate activity level. At this stage, we are not able to find simple plage properties that, alone, are sufficient to reproduce the observations. However, the simulations already allow us to point out that it is not straightforward to compare the temporal variability correlation and the integrated indices. Our findings also demonstrate the need for complex activity patterns to explain some of the observations. Conclusions. We conclude that the relation between the three indices examined here exhibits a large diversity in behaviour over the sample studied. More detailed simulations with complex activity patterns are necessary to understand these observations. This will teach us about plage properties for this type of star.

Harriet Tubman's Deep Voice

Abstract The authors suggest that national investment in the educational utility of automated software comes at an enormous cost, a price paid by the very students that technology aims to convert to history as a lively and accessible field. This “high-tech mimicry” pretends to incarnate the past but instead silences the inflections of time, gender, region, race, or other vocalic variables. Further, the perception that technology is objective or unbiased conceals the vulnerabilities of language models. The authors argue that the illusions of authenticity these bots produce does not bode well for teaching African American history.

Interpreting hydroxychloroquine blood levels for medication non-adherence: a pharmacokinetic study

ObjectiveCharacterise the relationship between hydroxychloroquine (HCQ) blood levels and the number of missed doses, accounting for dosage, dose timing and the large variability in pharmacokinetics (PK) between patients.MethodsWe externally validated...

REGULATIONS OF THE FORMATION OF PROTECTIVE POTENTIAL OF UNDERGROUND STEEL PIPELINES UNDER CONDITIONS OF HETEROGENEOUS ENVIRONMENT

In the work, the modeling of the distribution of the protective potential of electrochemical protection stations is performed by revealed functional dependencies. The initial conditions are adopted for a typical assortment of rolled metal used for underground gas supply. At the initial stage of modeling, the stochastic nature of the change in soil parameters is not taken into account. The distribution of the protective potential of the underground pipeline as a function of two variables (time and distance) showed the mutual influence of neighboring stations on the formation of protective zone. New dependences of the operating parameters of the electrotechnical complex of electrochemical protection on the set of variables characterizing the power source, the physical dimensions of pipeline and the alternative arrangement of active cathodic protection stations (CPS) were obtained. Experimental studies of the modes of electrochemical protection stations at the objects of the gas transportation system of Ukraine confirmed the adequacy of the proposed analytical models. References 16, Figures 3.

ALMA Confirmation of Millimeter Time Variability in the Gamma-Ray Detected Seyfert Galaxy GRS 1734-292

GRS 1734-292 is a radio-quiet galaxy, exhibiting neither intense starburst nor jet activities. However, Fermi-LAT detected this object in the GeV band. The origin of nonthermal activity in this Seyfert galaxy is an intriguing question. We report Atacama Large Millimeter/submillimeter Array observations of GRS 1734-292 at frequencies of 97.5, 145, and 225 GHz. These observations confirmed the millimeter excess within the central ⪅100 pc region and its time variability based on two separate observations conducted 4 days apart. The timescale of variability aligns with the light-crossing time for a compact source smaller than <100 Schwarzschild radius. If we take into account the power-law synchrotron emission originating from the corona (i.e., the hot plasma located above the accretion disk), the millimeter spectrum indicates the coronal magnetic field of ≈10 G and the size of ≈10 Schwarzschild radius. An alternative explanation for this millimeter emission could be synchrotron and free–free emission from disk winds (i.e., fast wide-opening angle outflows from the disk) with the size of ≈10 pc, although it may be difficult to explain the fast variability. Future millimeter observations with higher resolution (<0.″01) will enable the differentiation between these two scenarios. Such observations will provide insights into the acceleration sites of high-energy particles at the core of active galactic nuclei.

TIME-VARYING PARAMETER REGRESSIONS WITH STATIONARY PERSISTENT DATA

We consider local level and local linear estimators for estimation and inference in time-varying parameter (TVP) regressions with general stationary covariates. The latter estimator also yields estimates for parameter derivatives that are utilized for the development of time invariance tests for the regression coefficients. Our theoretical framework is general enough to allow for a wide range of stationary regressors, including stationary long memory. We demonstrate that neglecting time variation in the regression parameters has a range of adverse effects in inference, in particular, when regressors exhibit long-range dependence. For instance, parametric tests diverge under the null hypothesis when the memory order is strictly positive. The finite sample performance of the methods developed is investigated with the aid of a simulation experiment. The proposed methods are employed for exploring the predictability of SP500 returns by realized variance. We find evidence of time variability in the intercept as well as episodic predictability when realized variance is utilized as a predictor in TVP specifications.

Associations between sleep health, negative reinforcement learning, and alcohol use among South Florida college students with elevated internalizing symptoms

Negative reinforcement is proposed to mediate associations between sleep and alcohol use, especially among people with depression and/or anxiety symptoms. Worse sleep (e.g., shorter duration, less efficiency, more irregular timing) exacerbates negative emotions, which alcohol may temporarily relieve. Not yet examined, we propose sleep indirectly impacts early stages of alcohol use via differences in negative reinforcement learning (NRL), since sleep impacts emotion, reward response, and learning. The current study aimed to replicate associations between sleep and alcohol use, test associations with NRL, and examine indirect associations between sleep health and alcohol use via NRL among 60 underage college students (ages 18-20 years, 77% female) varying in depression and anxiety symptoms. Participants wore Fitbit smartwatches and completed daily diaries measuring sleep and substance use for ∼14 days before completing two computer tasks assessing social (SNRL) and monetary (MNRL) negative reinforcement learning. Robust generalized linear models tested direct associations within the proposed model. SNRL performance was positively associated with alcohol use, but no other associations were observed. Statistical mediation models failed to indicate indirect effects of sleep on alcohol use via SNRL or MNRL performance. Post-hoc exploratory models examining depression and anxiety symptoms as moderators of direct associations indicated several interactions. Positive associations between sleep timing variability and alcohol use were weakened at higher anxiety symptom severity and stronger at higher depression symptom severity. The positive association between SNRL performance and alcohol use was also stronger at higher depression symptom severity. Among students with elevated depression symptoms, variable sleep timing and stronger SNRL performance were independently associated with more alcohol use, but indirect effects were not supported. Future research should replicate findings, confirm causality of interactions, and examine sleep timing and behavioral responses to negative social stimuli as targets for improving alcohol-related outcomes among underage college students with elevated depressive symptoms.

Environmental drivers of wheat yield variability across China's production regions: Insights from field experiments

AbstractWheat crops underpin contemporary global food security. Predominant wheat production zones in China include the Huang‐Huai‐Hai‐Plain and the Mid‐Lower Reaches of the Yangtze River, although climatic effects on productive potential across these regions vary markedly in space and time. Here, we conducted field experiments during the wheat season of 2015–2018 to examine environmental effects on growth, with fertilization and irrigation provided at levels ensuring that nutrient and water stress exposure was minimal. Yields in Huang‐Huai‐Hai‐Plain and the Mid‐Lower Reaches of the Yangtze River averaged 8950 and 4818 kg ha−1, respectively. Yield variation across regions was primarily related to spike number per unit area and grain number per spike. Maturity biomass was higher in Huang‐Huai‐Hai‐Plain; this translated into higher grain yields. Lower temperature and longer growing duration between emergence and jointing in Huang‐Huai‐Hai‐Plain afforded higher tillering and spike numbers, whereas higher growth rates from jointing to maturity resulted in higher biomass production in Huang‐Huai‐Hai‐Plain compare with the Mid‐Lower Reaches of Yangtze River. Growth rate, grain numbers and yield were positively correlated with the ratio of daily intercepted solar radiation to mean temperature during jointing to anthesis, termed photothermal quotient. Collectively, our results suggest that growth rate accounted for more variation in biomass production compared with growth duration, and the photothermal conditions in the Mid‐Lower Reaches of the Yangtze River were restrictive for spike development and yield formation. Our results help disentangle drivers of crop growth through the development of agro‐environmental conceptual frameworks, enabling a better understanding of yield variability in space and time.

Delivery Room Resuscitation of Infants with Congenital Diaphragmatic Hernia: Lessons Learned through Video Review

Introduction: Delivery room (DR) interventions for infants with congenital diaphragmatic hernia (CDH) are not well described. This study sought to describe timing and order of DR interventions and identify system factors impacting CDH DR resuscitations using a human factors framework. Methods: This was a single-center observational study of video-recorded CDH DR resuscitations documenting timing and order of interventions. The team used the Systems Engineering Initiative for Patient Safety (SEIPS) model to identify system factors impacting DR resuscitations and time to invasive ventilation. Results: We analyzed 31 video-recorded CDH resuscitations. We observed variability in timing and order of resuscitation tasks. The “Internal Environment” and “Tasks” components of the SEIPS model were prominent factors affecting resuscitation efficiency; significant room and bed spatial constraints exist, and nurses have a significant task burden. Additionally, endotracheal tube preparation was a prominent barrier to timely invasive ventilation. Conclusion: Video review revealed variation in event timing and order during CDH resuscitations. Standardization of the room setup, equipment, and event order and reallocation of tasks facilitate more efficient intubation and ventilation, representing targets for CDH DR improvement initiatives. This work emphasizes the utility of rigorous human factors review to identify areas for improvement during DR resuscitation.

Effects of primary health care and socioeconomic aspects on the dispersion of COVID-19 in the Brazilian Northeast: Ecological study of the first pandemic wave.

The COVID-19 pandemic has had a negative impact on socioeconomic and public health conditions of the population. To measure the temporal evolution of COVID-19 cases in cities near the countryside outside metropolitan areas of northeastern Brazil and the impact of the primary care organization in its containment. This is a time-series study, based on the first three months of COVID-19 incidence in northeastern Brazil. Secondary data were used, the outcome was number of COVID-19 cases. Independent variables were time, coverage and quality score of basic health services, and demographic, socioeconomic and social isolation variables. Generalizable Linear Models with first order autoregression were applied. COVID-19 spreads heterogeneously in cities near the countryside of Northeastern Brazilian cities, showing associations with the city size, socioeconomic and organizational indicators of services. The Family Health Strategy seems to mitigate the speed of progression and burden of the disease, in addition to measures such as social isolation and closure of commercial activities. The spread of COVID-19 reveals multiple related factors, which require coordinated intersectoral actions in order to mitigate its problems, especially in biologically and socially vulnerable populations.

Study on the Energy Absorption Characteristics of Different Composite Honeycomb Sandwich Structures under Impact Energy

A honeycomb structure is a sandwich structure widely used in fuselage, among which the hexagonal honeycomb core is the most widely used. The energy absorption characteristics and impedance ability of the structure are the main reasons that directly affect the energy absorption characteristics of the honeycomb sandwich structure. Therefore, it is necessary to study the out-of-plane mechanical properties of the composite honeycomb sandwich structure. Based on the numerical simulation results, the energy absorption characteristics of several composite honeycomb sandwich structures are verified by drop hammer impact experiments. The research shows that the transient energy absorption characteristics of the composite honeycomb sandwich structure are mainly related to the cell size of the honeycomb structure. The smaller the size of the front cell, the stronger the overall impact resistance; the strength of the composite honeycomb sandwich structure exceeds that of 7075 aluminum alloy-NOMEX and carbon fiber-NOMEX honeycomb sandwich structures. In this paper, the energy absorption characteristics of composite honeycomb sandwich structures under different impact energy are compared and studied. The displacement, force and energy curves of energy absorption characteristics related to time variables are analyzed. The difference in protective performance between the composite honeycomb sandwich structure and existing airframe structure is compared and studied. The optimal structural design parameters of composite honeycomb sandwich under low-speed impact of drop hammer are obtained. The maximum energy absorption per unit volume of the designed honeycomb sandwich structure is 171.7% and 229.8% higher than that of the NOMEX-AL and NOMEX-C structures. The 6.4 mm and 3 mm cell sizes show good characteristics in high-speed buffering and crashworthiness. The composite honeycomb sandwich airframe structure can improve the anti-damage performance of the UAV airframe structure, ensure the same thickness and lightweight conditions as the existing honeycomb sandwich airframe structure, and improve the single-core bearing mode of the existing airframe structure.