Continuous Independent Variables Research Articles

Should businesses take a stand? Effects of perceived psychological distance on consumers’ expectation and evaluation of corporate social advocacy

ABSTRACT Nowadays companies are increasingly engaging in social-political issues. In light of the Construal Level Theory, this study examined the polarizing/depolarizing effects of perceived psychological distance on consumers’ expectation of corporate social advocacy and evaluations among consumers from different partisan identities. A between-subjects experiment (N = 296) with a continuous independent variable – perceived psychological distance – was employed. The study found that consumers with a closer perceived psychological distance to the company tended to have a higher expectation of corporate social advocacy. However, perceptions of psychological distance resulted in mixed effects regarding people’s attitudes and buycott/boycott intentions, where consumer-company identification mediated these relationships. Theoretical and practical implications are discussed.

“Chronic urticaria and obstructive sleep apnea: Is there a significant association?”

BackgroundFew studies have explored the association between obstructive sleep apnea (OSA) and chronic urticaria (CU). Our study aims to fill this gap by determining the frequency of the risk categories for OSA and how they might correlate with the specific CU patient reported outcome measures urticaria activity score (UAS7), urticaria control test (UCT) and CU quality of life questionnaire (CU-Q2oL). MethodsWe conducted a cross-sectional study involving a cohort of 171 Latin American CU patients. Descriptive statistics were used to determine frequency and proportions for demographic and clinical variables, while a chi-squared test for association between STOP-Bang OSA questionnaire categories and both UAS7 and UCT categories was performed to analyze how such variables interact. To further assess the strength of the correlation a Cramer's V coefficient was reported. Finally, a Kendall-Tau b correlation coefficient was performed to measure the correlation between the STOP-Bang score and other independent continuous variables. ResultsThe average STOP-Bang score was 2.5, with 24% and 21% of patients falling into the intermediate and high-risk category for moderate-to-severe OSA, respectively. There was a strong statistically significant association (Cramer's V = 0.263; p = .000) between UAS-7 categories and STOP-Bang risk categories. A similar pattern of strong significant association (Cramer's V = .269; p = .002) was observed between UCT categories and STOP-Bang risk categories. A weak positive correlation between the STOP-Bang score and the CU-Q2oL average score (τb = 0.188, p = .001) was identified. Overall, 72.5% patients reported limitations with respect to sleep in a varied degree according to the CU-Q2oL. ConclusionsOur results suggest that a considerable proportion of patients with CU are at intermediate to high risk for OSA. Higher disease activity, poor CU control, and worse quality of life were all found to be associated with an increased risk. Additional studies are needed to determine the exact link between these conditions, and to determine whether screening and treatment for OSA might benefit patients with CU.

Cyclothymic Temperament is Associated with Poor Medication Adherence and Disordered Eating in Type 2 Diabetes Patients: A Case-Control Study.

IntroductionPoor medication adherence and disordered eating are major self-care problems in patients with type 2 diabetes that worsen glycemic control and increase the risk of developing severe diabetes complications. Affective temperament, which remains mostly unchanged throughout life, is speculated to predict poor treatment response and high comorbidity. The aim of this study was to explore the link between affective temperament and poor glycemic control due to insufficient self-care.MethodsThis single-center case–control study involved 77 outpatients divided into the ‘poor glycemic control’ group (n = 52) and the ‘better glycemic control’ group (n = 25) based on their mean glycated hemoglobin (HbA1c) levels over the past 12 months. All participants underwent one-on-one interviews during which they completed the following psychometric questionnaires: (1) the Mini-International Neuropsychiatric Interview 5.0.0; (2) the Temperament Evaluation of Memphis, Pisa, and San Diego Auto-questionnaire; (3) a researcher-designed single question for assessing subclinical stress-induced overeating; and (4) the Morisky Medication Adherence Scale. The difference between two continuous independent variables was determined using Student’s t test. Discrete variables were compared using the Chi-square (χ2) or Fisher’s exact test. Multiple testing corrections were performed using the false discovery rate.ResultsThose outpatients in the poor glycemic control group exhibited significantly more stress-induced overeating (χ2 = 1.14, q statistic = 0.040) and poor medication adherence (t = 3.70, q = 0.034) than those in the better glycemic control group. However, there were no significant differences between the two groups in terms of affective temperaments, clinical eating disorders, or diabetes-specific distress. Patients with stress-induced overeating (t = − 2.99, p = 0.004) and poor medication adherence (t = − 4.34, p = 0.000) exhibited significantly higher scores for cyclothymic temperament than their counterparts.ConclusionCyclothymic temperament is significantly associated with disordered eating and/or poor medication adherence in patients with type 2 diabetes and is possibly linked to poor glycemic control.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13300-021-01121-y.

Characteristic Lie algebras of integrable differential-difference equations in 3D

The purpose of this article is to discuss an algebraic method for studying integrable differential-difference lattices with two discrete and one continuous independent variables. The main idea is based on the hypothesis that any integrable equation of this type admits an infinite sequence of reductions, which are Darboux integrable systems of differential-difference equations with two independent variables. To detect the Darboux integrability property of the reductions the authors use the characteristic Lie–Rinehart algebras. The hypothesis is confirmed by integrable three-dimensional lattices from the list given by Ferapontov et al (2015 Int. Math. Res. Not. 2015 4933). The required reductions are found for these lattices. Characteristic algebras corresponding to small-order reductions are described, integrals are calculated in both directions, which proves Darboux integrability. The approach might be useful for the integrable classification in 3D.

The relationship between quality of life and fear of Turkish individuals during the COVID-19 pandemic: A cross-sectional study

ObjectiveIn this study, it was aimed to determine the relationship between quality of life and the fear experienced due to the COVID-19 pandemic. MethodThis cross-sectional descriptive study was conducted with a total of 1060 participants from Turkey's 65 provinces. The research data were collected through an online questionnaire consisting of three parts: “Personal Information Form”, “The Fear of COVID-19 Scale (FCS)” and “World Health Organization Life Quality Scale-Short Form (WHOQOL-BREF)”. Independent two-group t-test (Student's t-test), and one-way ANOVA test were used to compare the means of groups. The Pearson Correlation Coefficient was calculated to determine the level of correlation between two independent continuous variables. A value of p < .05 was accepted as the threshold for statistical significance. ResultsThe fear levels of women, married individuals and primary school graduates were found to be high, while quality of life was low among participants with poor economic status, those with COVID-19 symptoms and subjects who had been in close contact with a COVID-19-positive patient. In addition, there was an inverse relationship between the level of fear related to COVID-19 and quality of life (physical and psychological health). Practice implicationsNurses are recommended to develop new care and evaluation strategies that will cover psychosocial and economic areas, as well as physical health, in order to protect and maintain the well-being of individuals during the COVID-19 pandemic.

Looking at knock-on effects: univariable, multivariable linear regression.

Linear regression is used to describe the relationship between a continuous dependant variable of interest (outcome) and other patient characteristics or predictors (independent continuous, categorical or dichotomous variables). Fitting a linear regression model estimates a constant, predictor coefficients and their corresponding 95% confidence intervals (95%CI). In a univariable analysis only one independent variable is included in the model and the model shows the association between that variable and the outcome, without any consideration of other characteristics. In a multivariable analysis more than one predictor is included in the model.

Generalized symmetries and integrability conditions for hyperbolic type semi-discrete equations * *To the memory of A B Shabat and R I Yamilov.

In the article differential-difference (semi-discrete) lattices of hyperbolic type are investigated from the integrability viewpoint. More precisely we concentrate on a method for constructing generalized symmetries. This kind integrable lattices admit two hierarchies of generalized symmetries corresponding to the discrete and continuous independent variables n and x. Symmetries corresponding to the direction of n are constructed in a more or less standard way while when constructing symmetries of the other form we meet a problem of solving a functional equation. We have shown that to handle with this equation one can effectively use the concept of characteristic Lie–Rinehart algebras of semi-discrete models. Based on this observation, we have proposed a classification method for integrable semi-discrete lattices. One of the interesting results of this work is a new example of an integrable equation, which is a semi-discrete analogue of the Tzizeica equation. Such examples were not previously known.

Flexural optimization of slag-based geopolymer concrete beams modified with corn cob ash

This study investigated the flexural strength of geopolymer concrete (GPC) beams produced with ground granulated blast furnace slag (GGBFS) and corn cob ash (CCA). The design of experiment (DOE), Box-Behnken design (BBD) of the response surface methodology (RSM), was used to optimize the strength. GGBFS was replaced at 0, 20, and 40 wt. % of CCA. The mixes were activated with 14 molar concentration (14 M) of both sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) solutions. The mix design properties such as alkaline liquid to binder ratio, binder to aggregate ratio, binder ratio, and curing time were statistically applied as continuous (independent) variables to optimize the response factor (flexural strength). Compared with the control sample (Portland cement concrete), GPC exhibited higher compressive and flexural strengths at up to 40 wt. % of CCA replacement. The models predicted the response of flexural strength with less than 5% variability. Besides, the correlation between the experimental and the optimized flexural strength yielded a high precision with 99.6% “R2”. Therefore, this study's response models would be advantageous in the optimization of mix design proportions for obtaining target flexural strength of GPC beams produced with GGBFS and CCA.

Factors influencing depression in primary caregivers of patients with dementia in China: A cross-sectional study

This study aims to estimate the prevalence and factors of depression in primary caregivers of people with dementia in China, based on a biopsychosocial medical model. A sample of 285 caregiver-patient dyads was recruited from a tertiary psychiatric hospital in Nanjing, between December 2018 and November 2019. The prevalence of depression among primary caregivers of people with dementia was 42.8%. Binary logistic regression analyses revealed that caregivers’ gender (OR=4.692), social support (OR=0.131), health condition (OR=12.994), extraversion (OR=0.102) and neuroticism (OR=2.978) were predictive of depression in those caregivers. Of the above, health condition was the major factor associated with caregiver's depression. The Box-Tidwell method was used to show a linear relationship between continuous independent variables and dependent variable logit conversion values (p = 0.0045). Suggestions are provided to develop support service programs and interventions tailored to caregivers, to help meet their basic substance and mental health needs. (147 words).

Topology Optimization Design of Adjustable Thermal Expansion Metamaterial Based on Independent Continuous Variables

This paper presents a topology optimization method to construct adjustable thermal expansion metamaterials. The negative thermal expansion (NTE) and extreme positive thermal expansion (EPTE) microstructures are designed, respectively. First, the effective elastic modulus and the effective thermal expansion coefficient of microstructure are derived by the multiscale asymptotic homogenization theory based on the periodic characteristics of the metamaterial. Second, a topology optimization model aiming at extreme thermal expansion coefficient is established and solved based on independent continuous topological variables, which is subjected to the effective elastic modulus and structure weight fraction. Then a cross-precision progressive optimization method is provided to save the computation time and make a smoother boundary. In addition, the specific topological feature for the initial configuration is discussed. Five holes are the necessary condition to obtain adjustable thermal expansion metamaterials for four-axisymmetric structures. Finally, a transformation strategy from NTE to EPTE and the change law of thermal expansion coefficient bounds with effective elastic modulus are studied. Numerical examples show that the NTE and EPTE can be designed in the range of effective elastic modulus from 0.01 to 0.05. The proposed method provides a reference for the novel configuration design of metamaterials.

BRACHIAL-ANKLE PULSE WAVE VELOCITY IS INVERSELY ASSOCIATED WITH OBESITY IN A HEALTHY CHINESE POPULATION

Objective: Obesity is generally considered undesirable on account of its association with metabolic syndrome and other risk factors for cardiovascular disease. However, obese subjects paradoxically appear to have better outcome following certain interventions (eg vascular interventions in heart failure) compared to non-obese subjects, suggesting a vascular protective effect of obesity (obesity paradox). This study aimed to quantify the association between indices of obesity and arterial stiffness as measured by brachial-ankle pulse wave velocity (baPWV) in a healthy Chinese population. Design and method: Normal individuals (n = 858) attending a health assessment clinic for cardiovascular disease screening at Ruijin Hospital North, Shanghai, China, between April 2017 and June 2018, had measurements of baPWV (Omron, BP-203RPEIII VP-1000) and brachial systolic (SP), diastolic (DP), mean (MP) and pulse pressure (PP). Subjects were divided into 3 groups according to their Body Mass Index (BMI, kg/m2): BMI less than 24, normal; 24–28, overweight; greater than 28, obese (using Chinese guidelines). Results: All brachial pressures were significantly higher as BMI increased. baPWV increased significantly when the normal group was compared with overweight or obese groups (p &lt; 0.001). However, no differences were apparent between the overweight and obese group, with baPWV being lower in the obese group with higher BMI. Using baPWV as the independent continuous variable in multiple linear regression, age, MP and heart rate were all positively associated with baPWV, whereas BMI was negatively associated with baPWV after adjusting for confounding factors (β=-0.104, p &lt; 0.001). A negative linear relationship between BMI class and baPWV was only apparent for males less than50 years (p = 0.01) and females of age above 50 years (p &lt; 0.01). Conclusions: baPWV, as a measure of arterial stiffness, is higher for similar SP values in the normal individuals when compared to those in overweight and obese groups, consistent with the “obesity pardox”. The disparate effects of BMI on baPWV are likely due to sex differences that affect arterial stiffness in older overweight and obese individuals.

Optimizing the Rheology of Concrete modified with High Silica and Alumina Precursor for Normal Workability in the Built Environment

Concrete performance in its fresh state is not only pertinent for proper concrete placement, consolidation, and finishing but also its properties in its hardened state. Thus, this study optimized the rheology of concrete modified with high silica and alumina precursor (cashew nutshell ash (CNA)). Cashew nutshell was recycled, and the ash obtained was used at 5, 10, and 15 wt.% of cement using the concrete mix designs of grades C 25-40 to attain the target strengths of 25-40 MPa at 28 days. Both slump and its corresponding compressive strength were determined. Moreover, the concrete slump was optimized using the experimental mix design properties (EMDPs) such as cementitious materials, water/cementitious materials, and cementitious materials/aggregate ratios, as independent (continuous variables). The findings showed that EMDPs influenced the rheology of fresh concrete, significantly, hence yielding an optimized high precision with 99 % R2. Therefore, the model can be used to predict the normal workability of the concrete incorporating CNA in the built environment.

A 180-day mortality predictive score based on frailty syndrome in elderly patients with sepsis: a Logistic regression analysis model

To establish a 180-day mortality predictive score based on frailty syndrome in elderly sepsis patients [elderly sepsis score (ESS)]. A prospective study for sepsis patients aged 60 years and above who were admitted to a medical intensive care unit of the General Hospital of Southern Theatre Command from January 1st, 2018 to December 31st, 2018 was conducted. Univariate analysis was performed on 19 independent variables including gender, age, body mass index (BMI), tumor, charlson comorbidity index (CCI), activity of daily living (ADL), instrumental activity of daily living (IADL), mini-mental state examination (MMSE), geriatric depression scale (GDS), clinical frail scale (CFS), sequential organ failure assessment (SOFA), Glasgow coma scale (GCS), acute physiology and chronic health evaluation (APACHE II, APACHE IV), modified NUTRIC score (MNS), multiple drug resistance (MDR), mechanical ventilation (MV), continuous renal replacement therapy (CRRT) and palliative care. Continuous independent variables were converted into classified variables. Multivariate binary regression analysis of risk factors was conducted to screen independent risk factors which affecting 180-day mortality in elderly sepsis patients. Then a 180-daymortality predictive score was established, and the discrimination of the mortality of patients using CFS, SOFA, GCS, APACHE II, APACHE IV, MNS scores were compared. A total of 257 patients were enrolled, with a 180-day mortality of 60.7%. Univariate analysis showed that age, tumor, CCI, ADL, IADL, MMSE, CFS, SOFA, GCS, APACHE II, APACHE IV, MNS, MDR, MV, CRRT, palliative care were risk factors of 180-day mortality in elderly sepsis patients [age: odds ratio (OR) = 1.027, 95% confidence interval (95%CI) was 1.005-1.050, P = 0.018; tumor: OR =2.001, 95%CI was 1.022-3.920, P = 0.043; CCI: OR = 1.193, 95%CI was 1.064-1.339, P = 0.003; ADL: OR = 0.851, 95%CI was 0.772-0.940, P = 0.001; IADL: OR = 0.894, 95%CI was 0.826-0.967, P = 0.005; MMSE: OR = 0.962, 95%CI was 0.937-0.988, P = 0.004; CFS: OR = 1.303, 95%CI was 1.089-1.558, P = 0.004; SOFA: OR = 1.112, 95%CI was 1.038-1.191, P = 0.003; GCS: OR = 0.918, 95%CI was 0.863-0.977, P = 0.007; APACHE II: OR = 1.098, 95%CI was 1.053-1.145, P < 0.001; APACHE IV: OR = 1.032, 95%CI was 1.020-1.044, P < 0.001; MNS: OR = 1.315, 95%CI was 1.159-1.493, P < 0.001; MDR: OR = 2.029, 95%CI was 1.197-3.437, P = 0.009; MV: OR = 6.408, 95%CI was 3.480-11.798, P < 0.001, CRRT: OR = 2.744, 95%CI was 1.529-4.923, P = 0.001, palliative care: OR = 5.760, 95%CI was 2.177-15.245, P < 0.001]. By binary regression analysis, CFS stratification (OR = 1.934, 95%CI was 1.267-2.953, P = 0.002), MV (OR = 4.531, 95%CI was 2.376-8.644, P < 0.001), CRRT (OR = 2.471, 95%CI was 1.285-4.752, P = 0.007), palliative care (OR = 6.169, 95%CI was 2.173-17.515, P = 0.001) were independent risk factors of 180-day mortality in elderly patients with sepsis. The model of "ESS = 0.660×CFS stratification+1.511×MV+0.905×CRRT+1.820×palliative care" was established. Receiver operating characteristic curve (ROC curve) analysis showed that the area under the ROC curve (AUC) for predicting 180-day mortality by ESS was 0.785 (95%CI was 0.730-0.834, P < 0.001). When the best cut-off value was 2.2 points, its sensitivity was 78.9%, specificity was 70.3%, the positive predictive value was 80.4%, and the negative predictive value was 68.3%. Simplified ESS was defined as "0.5×CFS stratification+1.5×MV+1×CRRT+2×palliative care". ROC curve analysis showed that AUC for predicting 180-day mortality by simplified ESS was 0.784 (95%CI was 0.729-0.833, P < 0.001). When the best cut-off value was 2.0 points, sensitivity was 76.9%, specificity was 70.3%, the positive predictive value was 80.0%, and the negative predictive value was 66.4%. Compared with CFS, SOFA, GCS, APACHE II, APACHE IV and MNS, ESS had a significant difference in discriminating 180-day mortality in elderly patients with sepsis (AUC was 0.785 vs. 0.607, 0.607, 0.600, 0.664, 0.702, 0.657, 95%CI: 0.730-0.734 vs. 0.537-0.678, 0.537-0.677, 0.529-0.671, 0.598-0.730, 0.638-0.766, 0.590-0.725, all P < 0.05). CFS, MV, CRRT, and palliative care are independent risk factors of 180-day mortality in elderly patients with sepsis. We established ESS based on these risk factors. The ESS model has good discrimination and can be used as a reference and assessment tool for prediction and treatment guidance in elderly patients with sepsis.

Evaluation of Performance of MLP Neural Networks and RBF Neural Networks in Adjusting Time Series of the Development of the Trade Balance between the USA and the PRC

Artificial neural networks are widely used for predicting values, for solving possible future problems and are able to provide various solutions in problem estimation, regression or optimisation. They are useful for predicting time series too. The aim of the paper is to analyse and evaluate the performance of multilayer neural networks (hereinafter referred to as "MLP") and neural networks of radial basis function (hereinafter referred to as "RBF) in adjusting time series on the example of the trade balance between the United States and the People's Republic of China. Regression was performed using neural structures. We generated multilayer perceptron networks and neural networks of radial basis function and we generated two sets of artificial neural networks. Time was the continuous independent variable. We determined the trade balance of the USA and the PRC as a dependent variable. We can state that due to the great simplification of reality, it is not possible to predict the emergence of extraordinary situations and their impact on the trade balance of the USA and the PRC. We can state that when an adjusted time series is derived from a single variable, time, RBFs perform better than MLPs. In order to make the prediction more accurate and its calculation easier, it seems appropriate to use RBF networks, which brings a relatively high degree of accuracy.

Predictive utility of the Minnesota Multiphasic Personality Inventory-2-RF (MMPI-2-RF) in differentiating psychogenic nonepileptic seizures and epileptic seizures in male veterans

ObjectiveWhile psychogenic nonepileptic seizures (PNES) and epileptic seizures (ES) often present similarly, they are etiologically distinct, and correct diagnosis is essential for ensuring appropriate treatment and improving outcomes. The Minnesota Multiphasic Personality Inventory-2-RF (MMPI-2-RF) may assist in differential diagnosis, but prior investigations have been limited by disproportionately female samples, inconsistent accounting for profile invalidity, and limited intra-scale variability from dichotomizing variables. The current investigation addressed these gaps by assessing diagnostic utility of the MMPI-2-RF in differentiating PNES and ES in a male sample of veterans while conservatively accounting for profile invalidity and using a statistical approach that allows for consideration of continuous independent variables to better appreciate intra-scale variance. MethodOne hundred and forty-four veterans completed the MMPI-2-RF and were diagnosed with PNES (57.6%) or ES (42.4%) by a board-certified neurologist following continuous video-EEG monitoring. Participants with validity scores falling in the definitely or likely invalid ranges were excluded to ensure construct validity among clinical/substantive scales. Independent samples t-tests assessed differences in MMPI-2-RF variables by diagnostic groups. Hierarchical stepwise logistical regressions assessed predictive utility of MMPI-2-RF indices. A clinical calculator was derived from regression findings to help with diagnostic prediction. ResultsMales with PNES endorsed significantly higher scores on F-r, FBS-r, RBS, RC1, RC7, HPC, and NUC (medium to large effect sizes). The regression block that contained validity, restructured clinical (RC1), and substantive scales (GIC, SUI) had a hit rate of 75.69%, which was an improvement from the baseline model hit rate of 57.64%. Higher endorsement on RC1 and lower reporting on GIC significantly predicted PNES diagnosis for males. ConclusionsMinnesota Multiphasic Personality Inventory-2-RF improved diagnostic accuracy of PNES versus ES among male veterans, and RC1 (somatic complaints) emerged as a significant predictor for males with PNES, in line with hypotheses. Several clinical/substantive scales assisted with differential diagnosis after careful accounting for profile validity. Future studies can validate findings among males outside of veteran samples.

Linear Regression in Medical Research.

Linear Regression in Medical Research.

TRAITS OF PATIENTS SEEN VIA TELEMEDICINE VERSUS IN-PERSON FOR NEW PATIENT VISITS IN A FERTILITY PRACTICE

Integration of telemedicine (TM) into reproductive endocrinology and infertility (REI) is quickly occurring due to changes in the practice environment and recently, COVID19. However, no US studies have investigated telemedicine’s impact on REI practices. This study aimed to evaluate differences in demographics, time to treatment initiation, clinical outcomes, and dropout rates between patients using telemedicine relative to in-person (IP) visits. Retrospective cohort study. All new patients seen via TM (between June 2017 to February 2020) at an academic practice were compared with control new IP visits (seen in 2019). The following were evaluated for each new patient encounter by visit type (TM or IP): demographics, cancellation, distance to clinic, infertility diagnosis, duration of infertility, time to treatment initiation, number of clinic-contacts (i.e. number of e-messages or phone calls from patient) prior to treatment start, and dropout rate. We performed t-test analysis by group for continuous independent variables and Chi-square analyses by group for categorical independent variables. Binary logistic regression analysis was performed to estimate the odds of initiating treatment in the TM group. Seventy-one patients were identified in the TM group, and 71 followed in the IP group. The average age of the IP and TM groups was similar, at 33.5 ± 5.0 and 33.2 ± 5.2, respectively (p=0.723). There were no differences between groups in the following: BMI (p=0.723), area deprivation index (p=0.235), and treatment recommended (e.g. ovulation induction, IVF, surgery, etc.) (p=0.475). There were no differences between the TM and IP groups in: treatment dropout rates (p=0.075), cancellation rates (p=0.379), time to treatment initiation (mean 74.82 days in TM group; 77.5 days in IP group; p = 0.315), or number of times the patient contacted the clinic prior to treatment start (p=0.153). Of those who became pregnant, time to positive pregnancy test was not significantly different between the TM (n=11, mean 176.4 days) and IP groups (n=19, mean 226.45 days) (p=0.368). Compared to IP patients, TM patients were significantly more likely to live further away (mean 223.6 miles vs 69.28 miles, p = 0.006) and have a longer duration of infertility (mean 41.9 months vs 19.49 months, p = 0.006). The lengths of TM appointments were significantly shorter than IP visits (mean 56.3 ± 9.1 minutes vs 59.3 ± 4.6 minutes, p < 0.001) and much less likely to contain documentation of height or weight (p=0.001). In the TM group, age and distance from clinic were not significantly associated with likelihood of dropping out of treatment (p=0.467). Telemedicine appears to be of particular interest to patients who live further from clinics and have longer durations of infertility, and it could help reduce visit times. Patients seen in person and via telemedicine are equally likely to pursue treatment. Telemedicine consultation for new-patient visits is feasible in REI practice and is especially useful in areas with limited access to fertility specialists and beyond in a post-COVID landscape.

Application of logistic regression equation analysis using derivatives for optimal cutoff discriminative criterion estimation

Background: Sigmoid curve function is frequently applied for modeling in clinical studies. The main task of scientific research relevant to medicine is to find rational cutoff criterion for decision making rather than finding just equation for probability calculation. The objective of this study is to analyze the specific features of logistic regression curves in order to evaluate critical points and to assess their implication for continuous predictor variable dichotomization in order to provide optimal cutoff criterion for decision making. Methods: Second order and third order derivatives were used to analyze estimated logistic regression function, critical values of independent continuous variable that correspond to zero points of second and third derivative were calculated for each logistic regression equation. Using those values continuous predictors of each logistic regression equations were converted into dichotomized scales using 1 value that correspond to second order derivative and 2 values that correspond to zero points of third derivative then receiver operating characteristics of estimated equations with dichotomized predictor were assessed. Results: Sigmoid curve of logistic regression has the same structure with inflection point corresponding probability 0.5 (zero value of second derivative) and maximal torsion (zero values of third derivative) corresponding 0.2113 and 0.7886 probability values. Thresholds accounting for predictor values that correspond to zero values of second and third derivative provide estimation of logistic regression applying dichotomized predictor with optimal ratio of sensitivity, specificity and overall accuracy with maximal area under curve. Conclusion: Analysis of logistic regression equation with continuous predictor applying derivatives help to choose optimal thresholds that provide maximally effective discriminative functions with priority sensitivity or specificity. Using this dichotomization discriminative function can be adjusted to the needs of particular task or study depending which characteristic is in priority – sensitivity or specificity.

The geometry of convergence in numerical analysis

<p style='text-indent:20px;'>The domains of mesh functions are strict subsets of the underlying space of continuous independent variables. Spaces of partial maps between topological spaces admit topologies which do not depend on any metric. Such topologies geometrically generalize the usual numerical analysis definitions of convergence.

Impact speed and the risk of serious injury in vehicle crashes

The current guiding philosophies in road safety have stated aims of zero deaths and serious injuries. Speed has previously been highlighted as a key factor in the outcome of a crash but the literature to date has yet to provide a robust relationship between impact speed and the risk of serious injury for crashes other than pedestrian crashes. This study aimed to determine the relationship between impact speed and the risk of serious injury in light vehicle crashes.Crash data from the US based National Automotive Sampling System – Crashworthiness Data System collected from 2011 to 2015 were used in the analysis when there was a known impact speed from an event data recorder (EDR) and a known injury outcome. The analysis was conducted at the vehicle level. Data from a total of 1274 vehicles were used in logistic regressions, with the presence or absence of a serious injury as the binary dependent variable, and impact speed as the continuous independent variable. Individual risk curves were produced for front, side, rear and head on impacts. Impact speed was found to have a highly significant positive relationship to risk of serious injury for all impact types examined. The risk of serious injury reaches 1% at 28 km/h for head on impacts, 51 km/h for side impacts, 64 km/h for front impacts, and 67 km/h for rear impacts. The results emphasise the importance of measures that reduce impact speeds, be they road designs, vehicle technologies or enforced speed limit reductions, and highlight the need to prevent head on impacts.