Random Time Points Research Articles

7899 Mixture Of Urinary Concentrations Of Phenols And Phthalate Metabolites In Relation To Serum Levels Of Lipid Biomarkers Among Pregnant Women: Results From The EARTH Study

Abstract Disclosure: X. Shen: None. M. Génard-Walton: None. P.L. Williams: None. T. James-Todd: None. J.B. Ford: None. K.M. Rexrode: None. D. Zhang: None. J.E. Chavarro: None. R.B. Hauser: None. L. Minguez Alarcon: None. Given the limited evidence on endocrine-disrupting chemicals (EDCs), evaluated as mixture, in relation to lipid biomarkers during pregnancy, we examined whether mixtures of urinary concentrations of bisphenol A (BPA), parabens and phthalate metabolites were associated with serum lipid levels among 175 pregnant women who enrolled in Environment and Reproductive Health (EARTH) Study from 2005 to 2017. The outcomes were assessed at one random timepoint pre women during pregnancy, including serum levels of total triglycerides, total cholesterol, high-density lipoprotein (HDL), non-HDL, and low-density lipoprotein (LDL). We grouped the chemical biomarkers [di(2-ethylhexyl) phthalate (DEHP) metabolites and BPA; other phthalate metabolites; parabens] assessed in urine collected at the same time and applied Bayesian Kernel Machine Regression (BKMR) and quantile g-computation to evaluate the associations while adjusting for confounders [urine specific gravity, age, pre-pregnancy body mass index (BMI), race, education level, infertility diagnosis, mode of conception, number of babies in this pregnancy and trimester]. In the adjusted BKMR models, we found no associations between the overall chemical biomarker mixture and lipid levels for example total cholesterol [mean difference (95% CRI, credible interval) = 0.02 (-0.31, 0.34)] and LDL [mean difference (95% CRI) = 0.10 (-0.22, 0.43)] when comparing concentrations at the 75th to the 25th percentile. When stratified by BMI, we found suggestive positive relationships between the paraben group and total cholesterol and LDL among women with high BMI [mean difference (95% CRI) = 0.16 (-0.23, 0.55) and 0.16 (-0.25, 0.57)], but not among women with low BMI [mean difference (95% CRI) = -0.02 (-0.16, 0.12) and -0.02 (-0.15, 0.12)]. Among the paraben group, propylparaben was driving the associations among high BMI group [mean difference (95% CRI) = 0.25 (-0.26, 0.75) and 0.35 (-0.25, 0.95)], but not among low BMI group [mean difference (95% CRI) = 0.00 (-0.06, 0.07) and 0.00 (-0.07, 0.07)]. In addition, we found suggestive positive associations of DEHP metabolites and BPA group with total cholesterol, non-HDL and LDL among women with lower BMI, but none of the chemicals was identified as an important contributor to these associations. This study highlights that the associations between EDCs and cardiovascular biomarkers, such as circulating lipids, differ by BMI among pregnant women. Presentation: 6/1/2024

Anti-Müllerian hormone as a promising novel biomarker for litter size in Romanov sheep.

Anti-Müllerian hormone (AMH) is a hormone produced by growing preantral and antral follicles of the ovary. AMH is accepted as an important biomarker for fertility and superovulation parameters in livestock species. This study aimed to evaluate changes in serum AMH level in the oestrous cycle, repeatability of AMH, the effect of age on serum AMH level and the effects of AMH on litter size in Romanov sheep. In the study, a total of 36 Romanov sheep were used as animal material. First blood samples (0th day) were collected from 36 ewes to evaluate AMH and progesterone levels. Second blood samples were collected randomly from 20 ewes 9 days after first sampling to compare AMH levels at two different periods of the oestrous cycle in Romanov ewes. The ewes were categorized into three groups as low, medium and high AMH based on their first AMH levels. Results indicated that serum AMH level did not change during the oestrous and dioestrous phases of the oestrous cycle and two random time points of the oestrous cycle (p > .05). Pearson correlation analysis revealed that there is a high (r = .95) and significant (p < .001) correlation between AMH levels at the 0th (AMH-1) and 9th (AMH-2) days. The effect of AMH level on litter size was found to be significant. Litter size was significantly higher in the high AMH group than in the low AMH group (p < .05). In addition, the age of ewes did not affect serum AMH levels (p > .05). ROC analysis indicates that AMH cut-off value >320 pg/mL with 70% sensitivity and 100% specificity can be used for litter size in Romanov ewes. In conclusion, AMH is highly repeatable and its serum AMH level did not change during the oestrous cycle in Romanov sheep. In addition, AMH affects litter size and can be reliably used as a marker for litter size in Romanov sheep.

A study on N-policy BMAP/G/1 queueing system

This study presents a simple approach for analyzing the BMAP/G/1 queueing system under N policy. In this policy, the server goes idle at the end of a busy period and the queue length is checked at every arrival moment. The idle server starts serving customers when the queue length reaches or above a predetermined number, namely N, and keeps doing so until the system is completely empty. We first use a simple sequential substitution approach to derive the system length distribution at departure epoch. A comparative study is also conducted to highlight the benefits and strength of our straightforward approach to that of the RG-factorization technique and the roots finding method. We extract the distribution of system length at a random time point by utilizing the remaining service time of a customer who is currently being served as the supplementary variable. The probability density function of the sojourn time distribution for an arbitrary customer of an incoming batch is also computed. We propose an expected linear cost function to estimate the optimal value of N at minimum cost. The validity of our analytic technique has been shown through a variety of numerical examples involving different service time distributions.

Universal Glycosyltransferase Continuous Assay for Uniform Kinetics and Inhibition Database Development and Mechanistic Studies Illustrated on ST3GAL1, C1GALT1, and FUT1.

Chemical systems glycobiology requires experimental and computational tools to make possible big data analytics benefiting genomics and proteomics. The impediment to tool development is that the nature of glycan construction and mutation is not template driven but rests on cooperative glycosyltransferase (GT) catalytic synthesis. What is needed is the collation of kinetics and inhibition data in a standardized form to make possible analytics of glycan and glycoconjugate synthesis, mechanism extraction, and pattern recognition. Currently, kinetics assays in use for GTs are not universal in processing nucleoside phosphate UDP, GDP, and CMP donor-based glycosylation reactions due to limitations in accuracy and large substrate volume requirements. Here we present a universal glycosyltransferase continuous (UGC) assay able to measure the declining concentration of the NADH reporter molecule through fluorescence spectrophotometry and, therefore, determine reaction rate parameters. The development and parametrization of the assay is based on coupling the nucleotide released from GT reactions with pyruvate kinase, via nucleoside diphosphate kinase (NDK) in the case of NDP-based donor reactions. In the case of CMP-based reactions, the coupling is carried out via another kinase, cytidylate kinase in combination with NDK, which phosphorylates CMP to CDP, then CDP to CTP. Following this, we conduct kinetics and inhibition assay studies on the UDP, GDP, and CMP-based glycosylation reactions, specifically C1GAlT1, FUT1, and ST3GAL1, to represent each class of donor, respectively. The accuracy of calculating initial rates using the continuous assay compared to end point (noncontinuous) assays is demonstrated for the three classes of GTs. The previously identified natural product soyasaponin1 inhibitor was used as a model to demonstrate the application of the UGC assay as a standardized inhibition assay for GTs. We show that the dose response of ST3GAL1 to a serial dilution of Soyasaponin1 has time-dependent inhibition. This brings into question previous inhibition findings, arrived at using an end point assay, that have selected a seemingly random time point to measure inhibition. Consequently, using standardized Km values taken from the UGC assay study, ST3GAL1 was shown to be the most responsive enzyme to soyasaponin1 inhibition, followed by FUT1, then C1GALT1 with IC50 values of 37, 52, and 886 μM respectively.

Comparison of serum anti-Müllerian hormone between unilateral and bilateral ovarian endometriomas during follicular, luteal, and random menstrual phases: a retrospective study.

Over the last two decades, serum levels of anti-Müllerian hormone (AMH) have been shown to be reliable markers of ovarian reserve. This study aimed to compare baseline serum AMH levels and well-controlled clinical factors between patients with unilateral and bilateral ovarian endometriomas during the menstrual phase. We conducted a retrospective study. We enrolled 136 patients aged 18 to 36 years who were diagnosed with unilateral or bilateral ovarian endometriomas. Serum AMH levels of all patients and their latest two to three menstrual cycles were measured before surgery for ovarian endometriomas. The latest menstrual cycle length ranged from 26 to 30 days. Patients with irregular menstruation, a recent medication history of hormonal drugs other than oral contraceptive pills, a previous history of ovarian surgery, or any medical history influencing ovarian function were excluded. Of the 136 patients, 76 (55.9%) had unilateral ovarian endometriomas and 60 (44.1%) had bilateral ovarian endometriomas. Serum AMH levels were not significantly different between the two groups in the follicular phase, luteal phase, or at any random time point. Serum AMH levels were not significantly different between unilateral and bilateral ovarian endometriomas in the follicular and luteal phases, or at any random time during the menstrual cycle when various confounding factors were excluded.

Impact of amiodarone use on metoprolol concentrations, α-OH-metoprolol concentrations, metoprolol dosing and heart rate: A cross-sectional study.

Small studies suggest that amiodarone is a weak inhibitor of cytochrome P450 (CYP) 2D6. Inhibition of CYP2D6 leads to increases in concentrations of drugs metabolized by the enzyme, such as metoprolol. Considering that both metoprolol and amiodarone have β-adrenergic blocking properties and that the modest interaction between the two drugs would result in increased metoprolol concentrations, this could lead to a higher risk of bradycardia and atrioventricular block. The primary objective of this study was to evaluate whether metoprolol plasma concentrations collected at random timepoints from patients enrolled in the Montreal Heart Institute Hospital Cohort could be useful in identifying the modest pharmacokinetic interaction between amiodarone and metoprolol. We performed an analysis of a cross-sectional study, conducted as part of the Montreal Heart Institute Hospital Cohort. All participants were self-described "White" adults with metoprolol being a part of their daily pharmacotherapy regimen. Of the 999 patients being treated with metoprolol, 36 were also taking amiodarone. Amiodarone use was associated with higher metoprolol concentrations following adjustment for different covariates (p = .0132). Consistently, the association between amiodarone use and lower heart rate was apparent and significant after adjustment for all covariates under study (p = .0001). Our results highlight that single randomly collected blood samples can be leveraged to detect modest pharmacokinetic interactions.

Branching processes in random environments with thresholds

AbstractMotivated by applications to COVID dynamics, we describe a model of a branching process in a random environment $\{Z_n\}$ whose characteristics change when crossing upper and lower thresholds. This introduces a cyclical path behavior involving periods of increase and decrease leading to supercritical and subcritical regimes. Even though the process is not Markov, we identify subsequences at random time points $\{(\tau_j, \nu_j)\}$ —specifically the values of the process at crossing times, viz. $\{(Z_{\tau_j}, Z_{\nu_j})\}$ —along which the process retains the Markov structure. Under mild moment and regularity conditions, we establish that the subsequences possess a regenerative structure and prove that the limiting normal distributions of the growth rates of the process in supercritical and subcritical regimes decouple. For this reason, we establish limit theorems concerning the length of supercritical and subcritical regimes and the proportion of time the process spends in these regimes. As a byproduct of our analysis, we explicitly identify the limiting variances in terms of the functionals of the offspring distribution, threshold distribution, and environmental sequences.

Some stability results on non-linear singular differential systems with random impulsive moments

This paper studies the exponential stability for random impulsive non-linear singular differential systems. We established some new sufficient conditions for the proposed singular differential system by using the Lyapunov function method with random impulsive time points. Further, to validate the theoretical results' effectiveness, we finally gave two numerical examples that study with graphical illustration and an additional example involving matrices with complex entries, proving the results to be true in that case as well.

International Phase IV Field Study for the Reliability and Validity of the European Organisation for Research and Treatment of Cancer Thyroid Cancer Module EORTC QLQ-THY34.

Purpose: The aim of this study was to validate the new European Organisation for Research and Treatment of Cancer Quality of Life Thyroid Cancer Module (EORTC QLQ-THY34). Methods: We enrolled 437 thyroid cancer patients from 17 countries. One group (n = 303), undergoing treatment or best supportive care, completed the questionnaires at three time points (before therapy [t1], 6 weeks later [t2], and 6 months after t2 [t3]). A second group (survivors ≥2 years after diagnosis, n = 134) completed it at a random baseline time point and a second time 1 week later. We determined internal consistency (using Cronbach's alpha), the scale structure (with confirmatory factor analysis), and discriminant validity (using known-group comparisons). Group 1 data were used to assess responsiveness and group 2 data to determine test-retest reliability using intra-class correlations (ICC). Results: All 34 items fulfilled the criteria to be kept in the questionnaire. Cronbach's alpha was >0.70 in 8 of the 9 multi-item scales. All standardized factor loadings exceeded 0.40, confirming the proposed scale structure. The ICC was >0.70 in all scales expressing good test-retest reliability. Differences in scale scores between patients with different histology were >5 points in all scales. In all but one of the pre-specified scales (Dry Mouth), changes over time were ≥|4| points between at least two time points. Conclusion: The EORTC QLQ-THY34 with its 9 multi-item and 8 single-item scales is a reliable and valid tool to measure quality of life in thyroid cancer patients and can be used in future trials and studies.

P-595 What to expect from “standard vaginal progesterone regimen” in Hormone Replacement Therapy Frozen Embryo Transfer (HRT-FET) – do different products result in different serum levels?

Abstract Study question Do luteal serum progesterone levels (P4) vary in relation to time of blood sampling, the type and dosing of vaginal progesterone products used for HRT-FET? Summary answer Significant differences in luteal serum P4 levels exist between time of blood sampling as well as between different vaginal progesterone products and the administration regimen. What is known already Mid-luteal P4 levels below 9-11 ng/ml have been shown to negatively affect reproductive outcomes in HRT-FET cycles. Formulations of vaginal progesterone products differ as progesterone can be suspended in vegetable hard fat, in a vegetable lipophile liquor, be prepared in an oil-in-water emulsion carrier, or mixed in a tablet. Moreover, dosing regimens vary from one to three times daily, and BMI, age, and parity affect serum P4 levels; importantly, no consensus exists in terms of optimal time point to measure P4 in relation to administration, the specific serum P4 cut-off level to use or the most optimal vaginal progesterone product. Study design, size, duration Cohort study including 488 HRT-FET blastocyst transfers performed from January 2020 to November 2022 in patients undergoing a “standard vaginal progesterone regimen”. Each patient participated only once in the study. To compare the vaginal progesterone product used in the present study, we reviewed the most recent literature, including data from six studies, using three different products in six different regimens; all studies were cohort studies, including between 227 -1150 patients undergoing a “standard” HRT-FET protocol. Participants/materials, setting, methods A total of 488 patients in a public Fertility Clinic underwent HRT-FET, including endometrial preparation with oral oestradiol (6mg/24hours), followed by vaginal micronized progesterone, 400mg/12hours (Cyclogest®). Blood sampling on the blastocyst transfer day was standardised to two to four hours after progesterone administration. In contrast, P4 was measured randomly on the day of pregnancy testing. For comparison a review of the literature from six HRT-FET cohort studies using either Crinone®, Utrogestan® or “PIVET”-pessaries was performed. Main results and the role of chance The mean serum P4 (2-4 hours after administration) on the day of blastocyst transfer in our cohort was 15.4 ±6.6ng/ml. On the day of pregnancy testing (random time points) serum P4 levels were divided into four groups, depending on the time from progesterone administration to blood sampling: &amp;lt;2hours, &amp;gt;2&amp;lt;4hours &amp;gt;4&amp;lt;6hours and &amp;gt;6hours.The mean P4 levels were 14.7 ±6.3ng/ml, 15.6 ±5.8ng/ml, 14.3 ±4.9ng/ml and 12.9 ±6.4, respectively, and a significant difference was seen, between P4 levels measured 2-4 hours and &amp;gt;6 hours after vaginal administration (p = 0.03). As regards the product, the mean P4 levels in this study (Cyclogest®) was significantly different from the reviewed P4 levels of other “standard” HRT-FET cohorts, using three different products (Uterogestan®, Crinone® and the “PIVET-pessary”) 12.1 ±7.0ng/ml (p &amp;lt; 0.001), 7.6 ±3.2ng/ml (p &amp;lt; 0.001) and 29.3 ±20.3ng/ml (p &amp;lt; 0.001), respectively. As regards the dose, a significant difference in P4 levels was seen between dosing regimens in two cohorts when using the same product (Crinone®) 90mg x 3 vs. 90 mg x 2; 11.3 ±4.7ng/ml and 7.6 ±3.2ng/ml, respectively, p &amp;lt; 0.001. Interestingly, when comparing another product (Utrogestan®) used in different dosing regimens, 400mg x 2 vs. 200mg x 3, no difference in P4 levels was seen, 12.1 ±7.0ng/ml and 11.3 ±5.1ng/ml, P = 0.09. Limitations, reasons for caution In HRT-FET serum P4 levels reflect the exogenous administration, only, and P4 fluctuations depend on the route and number of administrations, as well as absorption and metabolization. The reviewed data used for this comparison between different progesterone products and regimens derive from cohorts with different characteristics and blood sampling timings. Wider implications of the findings Luteal serum P4 measurement is important, however, standardization of blood sampling in relation to the latest vaginal progesterone administration is mandatory to obtain correct levels. Clinicians should be aware of the significant differences in P4 levels related to dose and vaginal absorption between different types of vaginal progesterone products. Trial registration number EudraCT no.: 2019-001539-29

Markov-modulated marked Poisson processes for modeling disease dynamics based on medical claims data.

We explore Markov-modulated marked Poisson processes (MMMPPs) as a natural framework for modeling patients' disease dynamics over time based on medical claims data. In claims data, observations do not only occur at random points in time but are also informative, that is,driven by unobserved disease levels, as poor health conditions usually lead to more frequent interactions with the health care system. Therefore, we model the observation process as a Markov-modulated Poisson process, where the rate of health care interactions is governed by a continuous-time Markov chain. Its states serve as proxies for the patients' latent disease levels and further determine the distribution of additional data collected at each observation time, the so-called marks. Overall, MMMPPs jointly model observations and their informative time points by comprising two state-dependent processes: the observation process (corresponding to the event times) and the mark process (corresponding to event-specific information), which both depend on the underlying states. The approach is illustrated using claims data from patients diagnosed with chronic obstructive pulmonary disease by modeling their drug use and the interval lengths between consecutive physician consultations. The results indicate that MMMPPs are able to detect distinct patterns of health care utilization related to disease processes and reveal interindividual differences in the state-switching dynamics.

Characterization Results on Lifetime Distributions by Scaled Reliability Measures Using Completeness Property in Functional Analysis

In this article, using the scaled (weighted) residual life variable, some scaled measures, the scaled mean residual life and the scaled hazard rate, are introduced. Several scales are considered as examples of the derivation of the scaled measures. The measures are developed for the case of a weighted residual life at a random time, and it is shown that the measures are scale-free in these cases. This property proves useful in situations where a relative comparison of the lifetime distribution is studied. Some characterization properties are derived in terms of scaled measures evaluated at some sequences of random time points that follow a typical distribution. Examples are used to illustrate, examine, and satisfy the obtained characterizations.

Sex Hormones and Calcitonin Gene-Related Peptide in Women With Migraine: A Cross-sectional, Matched Cohort Study.

Sex hormones may modulate calcitonin gene-related peptide (CGRP) release in the trigeminovascular system. We studied CGRP concentrations in plasma and tear fluid in female participants with episodic migraine (EM) and a regular menstrual cycle (RMC), female participants with EM and combined oral contraception (COC), and female participants with EM in the postmenopause. For control, we analyzed 3 corresponding groups of age-matched female participants without EM. Participants with an RMC had 2 visits: during menstruation on menstrual cycle day 2 ± 2 and in the periovulatory period on day 13 ± 2. Participants with COC were examined at day 4 ± 2 of the hormone-free interval (HFI) and between days 7 and 14 of hormone intake (HI). Postmenopausal participants were assessed once at a random time point. Plasma and tear fluid samples were collected at each visit for determination of CGRP levels with an ELISA. A total of 180 female participants (n = 30 per group) completed the study. Participants with migraine and an RMC showed statistically significantly higher CGRP concentrations in plasma and tear fluid during menstruation compared with female participants without migraine (plasma: 5.95 pg/mL [IQR 4.37-10.44] vs 4.61 pg/mL [IQR 2.83-6.92], p = 0.020 [Mann-Whitney U test]; tear fluid: 1.20 ng/mL [IQR 0.36-2.52] vs 0.4 ng/mL [IQR 0.14-1.22], p = 0.005 [Mann-Whitney U test]). In contrast, female participants with COC and in the postmenopause had similar CGRP levels in the migraine and the control groups. In migraine participants with an RMC, tear fluid but not plasma CGRP concentrations during menstruation were statistically significantly higher compared with migraine participants under COC (p = 0.015 vs HFI and p = 0.029 vs HI, Mann-Whitney U test). Different sex hormone profiles may influence CGRP concentrations in people, with current or past capacity to menstruate, with migraine. Measurement of CGRP in tear fluid was feasible and warrants further investigation.

An optimal ordering inventory policy when the purchase price follows a discrete-time Markov chain

Most of the time retailers are offered discount prices that are occurring at random points in time. One such scenario is the supplier offering discounts to the retailers to increase market share, cash flow, and to reduce the inventory of specific items. Surprisingly no models exist in the literature survey to model the randomly occurring discount price under discrete time. The primary objective of this article is to develop an optimal inventory policy for a retailer when the discount price arrives randomly and the time variable is discrete. Under such a scenario, the optimal inventory policy can be obtained by considering the variations in the purchase price as a discrete-time Markov chain. The renewal reward theorem is used to derive the expected profit per unit of time. To illustrate the application of the developed model a real case study is considered. The optimal solution of the developed model is compared with the EOQ policy and found that the developed model solution provides better profit. This justifies the significance of the developed model. The inventory manager can use the developed model as a tool to obtain the optimal solution for any two price problems that repeat randomly.

Three-Dimensional Printed Polycaprolactone Mesh in Pediatric Cranial Vault Remodeling Surgery.

The surgical management of craniosynostosis has greatly evolved with improvements in both technology and understanding of the disease process. Some drawbacks remain regarding bone regeneration within the surgical bony gaps. Generally, bony gaps improve in the 12 to 24 months after surgery, but some gaps may remain for longer and cause deformity and/or require additional bony reconstruction. These considerations make tissue-engineered bone very attractive. Novel 3-dimensional printed bioresorbable mesh implants made of Polycaprolactone (PCL) can be used to fill the surgical bony defects. The authors seek to investigate how the use of a 3-dimensional printed biodegradable PCL mesh applied to bony defects in cranial vault surgery affects bone healing. Case series analysis of 8 pediatric patients who have undergone surgical intervention using PCL mesh implants for reconstruction of bony defects during craniosynostosis correction surgery. Radiological evaluation of 3 patients at random time points between 9 and 12 months postoperative revealed persistent bony gaps in areas where PCL mesh was laid. One patient who underwent a subsequent cranial vault surgery at 9 months was found to have less bone regeneration in the defect area where PCL mesh was used when compared with an adjacent area where a particulate bone graft was used. Based on our experience, the use of PCL mesh on its own did not augment bone regeneration. It is possible that a greater amount of time or increased vascularization of the scaffold is required, which supports the concept of regenerative matching axial vascularization or the further addition of osteogenic factors to increase the rate of bone formation.

Have a good day! An experience-sampling study of daily meaningful and pleasant activities.

We organize our daily lives with a relatively high degree of freedom. Some things must be done; others are optional. Some we find meaningful, some pleasant, some both, and some neither. The present study looks at such evaluations of daily activities and how they relate to perceived meaning in life. Sixty-two students from an Austrian university first completed the meaningfulness scale from the Sources of Meaning and Meaning in Life Questionnaire (SoMe). They then participated in a 1-week experience-sampling assessment, wherein they completed a short questionnaire at five random time-points per day. They indicated their current activity and then reported, on a 6-point Likert scale, how pleasant and meaningful they perceived it to be. Activities could thus be categorized as meaningful, pleasant, both, or neither. Results reflected that activities grouped under culture/music, communication, intimacy, and sports are experienced as both highly meaningful and pleasant. A two-level hierarchical linear regression suggested that people with high trait meaningfulness experience their daily activities as more meaningful than people with lower trait meaningfulness if they also enjoy what they are doing. People with low trait meaningfulness, however, tended to experience their daily activities as rather meaningless, even if they enjoyed them very much. Thus, when looking for advice on how to have a good day, clarifying one's meaning in life seems to represent the best starting point.

Stochastic Model of Emotional Stress Development in the Educational Process

The aim of the study is the development of mathematical models that describe the reaction of the individual to the occurrence of stresses of various nature, including those that appear during the implementation of the educational process. The complexity of developing such a model is confirmed by the lack of theoretical results to substantiate the classic experiments of Holmes and Rae on the effect of stress on personality. In this regard, the task is to develop such a mathematical model that would allow not only to give a theoretical explanation of the experimental results used in the Holmes and Rae stress calculator, but also to become a tool for studying the effect of stress on a person in other conditions, including in the process of educational activities of both the teacher and the learner.The research method consists in a mathematical description of the process of occurrence of stresses that develop over time, and it is believed that stresses occur at random times and are characterized by relative stress values indicated in the classical table of Holmes and Rae. The need to involve these results is that they allow us to confirm the correspondence of the developed theoretical mathematical models to already known practical results. The following main assumptions are accepted in the paper. It is believed that a person is exposed to stresses that can occur at random localized points in time and are interpreted as a sequence of points on the time axis, the number and location of which is random. The response of a person to a particular stress is described by a decreasing exponential function of three arguments – current time, random time of stress occurrence, and stress magnitude. The reaction of the individual to a sequence of stresses is the sum of the responses of the person to individual stresses, i.e. it is assumed that the personality exhibits the properties of linearity. In the process of developing a mathematical model, the distribution of the number of random stresses is substantiated according to the Poisson law, which is used to describe the occurrence of random events with a distinct discreteness. The paper introduces one of the key indexes - the coefficient of emotional load, equal to the ratio of the mathematical expectation of everyday stressful background and the mathematical expectation of the sum of this background and additional stress. The response of a person to a particular stress is described by an exponential response function widely used in natural science applications. The total relative value of processed, experienced, random relative values of stress, as well as their non-random mathematical expectations, is introduced into consideration.The new results of the study are: – development of a stochastic mathematical model for the development of stresses over time, depending on the parameters included in the model. It is shown that the behavior of a person’s reaction to stress, predicted by a mathematical model, corresponds to the previously mentioned experimental results. – a study of the behavior in time of a person’s reaction to stress for a situation that was not previously considered and in which the person is affected by a single stress of great intensity, as well as regular emotional imposition.In conclusion, it is noted that the developed model not only makes it possible to theoretically explain the experimental data, but also significantly expand the scope of the studied effect of stress on personality. Thus, it turned out to be possible to predict the impact of a single impact, as well as to indicate a way to account for periodic intentional exposure (emotional suppression). In addition, the results can be used in the study of emotional stresses in the educational process in order to predict and consider them in practical activities.

Engagement with social media content results in lower appearance satisfaction: An experience sampling study using a wrist-worn wearable and a physical analogue scale

Social media use is consistently associated with more negative body image, but much of this literature is cross-sectional and/or lacks ecological validity. To overcome these limitations, we examined associations between everyday social media engagement and appearance satisfaction using an experience sampling method. Fifty participants from Central Europe completed a 14-day experience sampling phase in which they reported their appearance satisfaction at two random time-points each day, as well as following active engagement with social media content, using a wrist-worn wearable and a physical analogue scale (PAS; i.e., angle of a participant’s forearm between flat and fully upright as a continuous response scale). Results indicated that engagement with social media content was significantly associated with lower appearance satisfaction. Additionally, we found that engagement with the content of known others was associated with significantly lower appearance satisfaction than engagement with the content of unknown others. These effects were stable even after controlling for participant demographics, active vs. passive daily social media use, and body image-related factors. These results provide evidence that everyday social media engagement is associated with lower appearance satisfaction and additionally provides preliminary support for the use of a PAS in body image research using an experience sampling method.

Better Together. Group versus individual Cognitive-Behavioral Therapy for tinnitus: A Multiple-Baseline Single-Case Experimental Design.

Chronic tinnitus is effectively treated through cognitive-behavioral therapy (CBT). Both group and individual CBT for tinnitus are effective, but no study has directly compared the two. The current study explores group versus individual CBT for tinnitus. A multiple-baseline single-case experimental design was employed to observe changes within/between individual and group treatments. Six participants started a 10-week CBT protocol and were equally divided into individual or group treatment. Participants were exchanged between treatments at random time points. Diary data included 14 variables on tinnitus experience (e.g. annoyance and distraction) and wellbeing (e.g. happiness and stress). Five male participants (59- to 67-year-old) completed treatment. Randomization tests comparing means between individual and group treatments did not reveal significant differences. Analysis of data overlap and trend (Tau-U) revealed minor significant improvements for seven variables (50%) in group treatment as compared to individual treatment. Diminished happiness and activity levels were observed in participants who went from group to individual treatment. Low effect sizes and homogeneity of sample restrict the generalizability of data. Group CBT indicated potential benefits when compared to individual CBT. Social learning may be an underlying process in group delivery boosting tinnitus recovery. Findings are limited to male patients with chronic disabling tinnitus.

Risk Factors for Fear of Recurrence in Head and Neck Cancer Patients.

Fear of recurrence (FoR) affects the quality of life of head and neck cancer survivors. Identification of factors predisposing to FoR may help to recognize and treat patients at risk. For this exploratory study, 101 disease-free head and neck cancer survivors completed a cross-sectional survey in 2017 that included the FoR questionnaire at a random point in time during their follow-up. Additionally, the patients were asked to choose their favorite among four follow-up schedules with or without systematic imaging and varying frequency of visits. Elevated FoR was present in 36.6% of patients. Females and patients ≤65 years showed significantly higher FoR overall scores than males (score difference 3.40; CI 0.49-6.32; p=0.022) and patients >65 years (score difference 4.25; CI 1.58-6.92; p=0.002). A history of cancer recurrence or second primary malignancy increased the relative risk (RR) for elevated FoR (RR 1.7; CI 1.01-2.86; p=0.046). Tumor stage and treatment modality were not significantly associated with elevated FoR or FoR overall score. Higher FoR overall scores were recorded in patients who favored intensive follow-up plans (mean overall FoR score 18 vs. 15; SD 7.7; p=0.076) and systematic imaging in follow-up (17 vs. 13, SD 7.1; p=0.034). Fear of recurrence in head and neck cancer patients is associated with female sex, younger age, and history of a past recurrence or second primary malignancy. Due to its high prevalence, it should be addressed in clinical practice and future research. NA Laryngoscope, 133:1630-1637, 2023.