CONDITIONS VULNERABILITY IDENTIFICATION OF NATURAL AND TECHNICAL OBJECTS BASED ON LINEAR SPLINE INTERPOLATION OF INTERFACE TRAFFIC INTENSITY

The method of application of spline interpolation in solving the problems of identification of abnormal states (A-events) in information data flows and classification of the specified events in the control of natural and technical objects (PTO) is considered. The approach is based on the representation of the intensity of interface traffic by piecewise linear splines and implemented using a modeling stand. At the first stage, descriptions are generated and formed in the form of linear splines representing the states of controlled objects, one of which is subject to external disturbance. At the second stage, the generated descriptions of splines are used to assess discrepancies between the studied distributions and the influence of a number of factors on the reliability of decisions made using probabilistic modeling methods in the Anylogic environment.

Lipids Changes After Switch from TDF to TAF in the OPERA Cohort: LDL-cholesterol and Triglycerides

Background Increases in lipids have been observed in people living with HIV (PLWH) switching from tenofovir disoproxil fumarate (TDF) to tenofovir alafenamide (TAF). We assessed changes in low-density lipoprotein cholesterol (LDL-C) and triglycerides (TG) following a switch from TDF to TAF. Methods Adults with ≥1 lipid measure before and after switch from TDF-to-TAF were identified in the OPERA® cohort. Multivariable linear regression using generalized estimating equations were used to estimate predicted changes in lipids over time on TAF, modeled flexibly with linear splines. Results 6,451 PLWH switched from TDF-to-TAF, of whom 4,328 maintained all other agents. LDL-C increased significantly by 1.40 mg/dL/month over the first 3 months on TAF, by 0.33 mg/dL/month between 3-9 months and plateaued beyond 9 months. TG increased significantly by 3.52 mg/dL/month over the first 3 months of TAF, by 0.91 mg/mL/month between 3-9 months, and by 0.72 mg/mL/month between 9-16 months but decreased thereafter. Similar patterns were observed in analyses restricted to PLWH who switched from TDF-to-TAF but maintained all other agents. Discussion TDF-to-TAF switch was associated with LDL-C and TG increases over the first 9 to 16 months on TAF. The dynamic patterns observed cannot be attributed to changes in other agents.

World War II cohorts and diabetes mellitus, coronary heart disease and cerebrovascular disease later in life: An observational cohort study based on German claims data

BackgroundThis study applied a data-driven approach to explore whether being born during or around World War II affects the risk of morbidity later in life.MethodsIncident diagnoses were explored for diabetes (ICD-10 code E10-E14; 75,487 persons/12,905 incident cases), cerebrovascular disease (CeVD; I6; 79,829/11,664), and coronary heart disease (CHD; I20-I25; 89,657/11,116) for birth cohorts 1935-1950, using German health-claims data from 2004-2015. The data include quarterly information of the inpatient and outpatient treatment. We applied recursive partitioning methods with the aim of splitting the sample into birth cohorts with different risk profiles in terms of the incidence of diabetes, CeVD, and CHD. We performed Cox proportional hazard models to explore the transition into diabetes, CeVD, and CHD, accounting for birth cohort and gender. We used the median cut-points from the recursive partitioning analysis on the birth cohort indicator to define linear splines and present the yearly slopes of the linear splines.ResultsBased on the results from recursive partitioning method we defined four groups of birth cohorts depending on the disease of interest (diabetes: 1/35-10/37, 11/37-11/41, 12/41-10/44, 11/44-12/50; CHD: 1/35-5/37, 6/37-4/41, 10/44-12/50; CeVD: 1/35-6/37, 7/37-6/40, 7/40-12/43, 1/44-12/50). We found a general decline in cohort incidence for all three diseases, however, there was a discontinuation for diabetes among birth cohorts 12/41-10/44 (yearly slope=-0.01, p=0.584), and a deceleration for cohorts 11/44-12/50 for CeVD.ConclusionsWe identified risk periods associated with WWII that interfered with the cohort decline in the risk of diabetes and CeVD, stressing the importance of a beneficial early-life environment.Availability of dataThe scientific research institute of the AOK (WIdO) has strict rules regarding data sharing because of the fact that health claims data are a sensible data source and have ethical restrictions imposed due to concerns regarding privacy. Anonymized data are available to all interested researchers upon request. Interested individuals or an institution who wish to request access to the health claims data of the AOK, please contact the WIdO (webpage: http://www.wido.de/, mail: [email protected]).

Estimating Urine Albumin-to-Creatinine Ratio from Protein-to-Creatinine Ratio: Development of Equations using Same-Day Measurements

BackgroundUrine albumin-to-creatinine ratio (ACR) and protein-to-creatinine ratio (PCR) are used to measure urine protein. Recent guidelines endorse ACR use, and equations have been developed incorporating ACR to predict risk of kidney failure. For situations in which PCR only is available, having a method to estimate ACR from PCR as accurately as possible would be useful.MethodsWe used data from a population-based cohort of 47,714 adults in Alberta, Canada, who had simultaneous assessments of urine ACR and PCR. After log-transforming ACR and PCR, we used cubic splines and quantile regression to estimate the median ACR from a PCR, allowing for modification by specified covariates. On the basis of the cubic splines, we created models using linear splines to develop equations to estimate ACR from PCR. In a subcohort with eGFR<60 ml/min per 1.73 m2, we then used the kidney failure risk equation to compare kidney failure risk using measured ACR as well as estimated ACR that had been derived from PCR.ResultsWe found a nonlinear association between log(ACR) and log(PCR), with the implied albumin-to-protein ratio increasing from <30% in normal to mild proteinuria to about 70% in severe proteinuria, and with wider prediction intervals at lower levels. Sex was the most important modifier of the relationship between ACR and PCR, with men generally having a higher albumin-to-protein ratio. Estimates of kidney failure risk were similar using measured ACR and ACR estimated from PCR.ConclusionsWe developed equations to estimate the median ACR from a PCR, optionally including specified covariates. These equations may prove useful in certain retrospective clinical or research applications where only PCR is available.

Application of linear splines to simulate daily changes in insolation

The paper shows the possibility of using linear splines in modeling the daily change in solar radiation. The calculations were based on the generally accepted cosine expression used for modeling insolation changes on the surface of lakes and the ocean. The equation parameters are set for the conditions of Sevastopol (44°35'N, 33°30' E): the maximum height of the sun above the horizon is about 68 degrees, the day length is 15 hours. The model curve was divided into three sections. For the early morning hours and late evening, the sunlight intensity is low and is below the “compensation point” of photosynthesis. So these areas were not considered during modeling. Three sites: the increase in irradiation from 6 to 12 hours, the maximum irradiation from 12 to 14 hours, and the decrease in irradiation from 14 to 20 hours are described by linear equations. It is shown that the deviations in the description of the data of the dependence of the sunlight intensity on the time of day by linear splines from the generally accepted formula in the form of a cosine do not exceed 5%. An example of experimental data of linear growth of productivity of A. platensis culture is given. Based on the assumption that the growth rate of microalgae culture is proportional to the amount of energy absorbed, the linear increase in productivity can be explained by a linear increase in the intensity of sunlight.

Modeling of photosynthesis light curves by linear splines

The paper presents an example of the linear splines use to describe the photosynthesis light curves for microalgae culture. The main mathematical models of the relationship between photosynthesis rate and light are listed. Based on the previously formulated basic principles of modeling microalgae photobiosynthesis, a mathematical model is proposed that describes the dependence of the assimilation number of chlorophyll a on the value of the light flux by linear splines. The advantage of the proposed approach is a clear definition of the point of change of the limiting factor. It is shown that light-limited photosynthesis rate is determined not only by external irradiation, but also by the concentration of chlorophyll a. The light-saturated rate depends on the amount of a key enzyme complex, which limits the rate of energy exchange reactions in the cell. Verification of the proposed model on the example of the diatom microalgae Skeletonema costatum was carried out. It is shown that the higher the degree of cell adaptation to high irradiation, the better the photosynthesis curve is described by linear splines. If S. costatum cells are adapted to low irradiation, deviations of experimental data from the idealized broken line are observed, which are caused by changes in the pigment composition. When the experimental data are normalized, the cell adaptation factor is reduced, all points are described by a single broken line, which indicates the universality of the proposed approach.