Bayesian on-line anticipation of critical transitions

The design of reliable indicators to anticipate critical transitions in complex systems is an important task in order to detect a coming sudden regime shift and to take action in order to either prevent it or mitigate its consequences. We present a data-driven method based on the estimation of a parameterized nonlinear stochastic differential equation that allows for a robust anticipation of critical transitions even in the presence of strong noise levels like they are present in many real world systems. Since the parameter estimation is done by a Markov Chain Monte Carlo approach we have access to credibility bands allowing for a better interpretation of the reliability of the results. By introducing a Bayesian linear segment fit it is possible to give an estimate for the time horizon in which the transition will probably occur based on the current state of information. This approach is also able to handle nonlinear time dependencies of the parameter controlling the transition. In general the method could be used as a tool for on-line analysis to detect changes in the resilience of the system and to provide information on the probability of the occurrence of a critical transition in future.

Fractal analysis of images in medicine and morphology: basic principles and methodologies

Background. Fractal analysis is an informative and objective method of mathematical analysis that can complement existing methods of morphometry and provides a comprehensive quantitative assessment of the spatial configuration of irregular anatomical structures. Objective: a comparative analysis of fractal analysis methods used for morphometry in biomedical research. Methods. A comprehensive analysis of morphological studies, based on fractal analysis. Results. Different types of medical images with different preprocessing algorithms can be used for fractal analysis. The parameter determined by fractal analysis is the fractal dimension, which is a measure of the complexity of the spatial configuration and the degree of filling of space with a certain geometric object. The most known methods of fractal analysis are the following: box counting, caliper, pixel dilation, "mass-radius", cumulative intersection, grid intercept. The box counting method and its modifications is the most commonly used method due to the simplicity and versatility. Different methods of fractal analysis have a similar principle: fractal measures (different geometric figures) of a certain size completely cover the structure in the image, size of fractal measure is iteratively changed, and the minimum number of fractal measures covering the structure is calculated. Methods of fractal analysis differ in the type of fractal measure, which can be a linear segment, a square of a fractal grid, a cube, a circle, a sphere etc. Conclusion. The choice of the method of fractal analysis and image preprocessing method depends on the studied structure, features of its spatial configuration, the type of image used for the analysis, and the aim of the study.

OV13 LAPAROSCOPIC APPROACH IN EMERGENCY HERNIA SURGERY: MANAGEMENT OF ACUTE SMALL BOWEL OBSTRUCTION SECONDARY TO STRANGULATED OBTURATOR HERNIA

Aim Acute small bowel obstruction secondary to strangulated obturator hernia is a rare condition, with high rates of morbidity and mortality in the absence of prompt diagnosis and intervention. We aim to describe a case with the above presentation, managed using a minimally-invasive approach with positive outcomes. Material and Methods We describe a case of an 82-year-old female who presented with acute small bowel obstruction secondary to strangulated obturator hernia on cross-sectional imaging. Results The patient underwent emergency surgery using laparoscopic approach for repair of obturator hernia and assessment of obstructed small bowel. Our approach involved identification and reduction of small bowel loop. A transabdominal preperitoneal approach was made to obturator hernia and ischaemic sac was reduced followed by closure of defect with a plug of biologic mesh. A linear segment of ischaemic small bowel was oversewn. Total operative time was 90 minutes. Conclusions Minimally-invasive surgery is an important tool in the armamentarium of the acute care surgeon. A laparoscopic approach will reduce the insult of intervention in already physiologically deplete patients. This case demonstrates the feasibility of laparoscopy for small bowel obstruction secondary to strangulated obturator hernia in the acute setting, requiring advanced laparoscopic skill as demonstrated in this video.

Macro and micro analysis on coal-bearing soil slopes instability based on CFD-DEM coupling method

By combining the discrete element method (DEM) with computational fluid dynamics (CFD), this study proposes a three-dimensional CFD–DEM fluid–solid coupling microscopic computational model for analyzing the micromechanisms of instability and failure in a coal-bearing soil slope during rainfall. The CFD–DEM fluid–solid coupling model indicated that the main failure mode of the coal-bearing soil slopes was rainwater washing, and the slope sliding surface was predicted as an approximately linear segment. The adaptability of this numerical method was verified by comparing its results with those of rain-washed slopes in an outdoor model test. Rainfall changed the microscopic parameters such as the force chain, coordination number, and porosity of the slope soil particles. The porosity of the slope’s top particles increased from 0.35 in the initial state to 0.80 in the unstable state. This change was directly related to the macroscopic mechanics of the slope soil. By analyzing the changes in the microscopic parameters of the particles, the failure evolution law of the coal-bearing soil slopes during rainfall was explored from a microscopic perspective. This study not only provides a theoretical basis for the protection design and construction of coal-bearing soil slopes in the region but can also analyze macroscopic mechanical laws of discrete media from a micro–macro perspective in geotechnical engineering.

The introduction of a mandatory mask policy was associated with significantly reduced COVID-19 cases in a major metropolitan city

Background Whilst evidence of use of face masks in reducing COVID-19 cases is increasing, the impact of mandatory use across a large population has been difficult to assess. Introduction of mandatory mask use on July 22, 2020 during a resurgence of COVID-19 in Melbourne, Australia created a situation that facilitated an assessment of the impact of the policy on the epidemic growth rate as its introduction occurred in the absence of other changes to restrictions. Methods and findings Exponential epidemic growth or decay rates in daily COVID-19 diagnoses were estimated using a non-weighted linear regression of the natural logarithm of the daily cases against time, using a linear spline model with one knot (lspline package in R v 3.6.3). The model’s two linear segments pivot around the hinge day, on which the mask policy began to take effect, 8 days following the introduction of the policy. We used two forms of data to assess change in mask usage: images of people wearing masks in public places obtained from a major media outlet and population-based survey data. Potential confounding factors (including daily COVID-19 tests, number of COVID-19 cases among population subsets affected differentially by the mask policy–e.g., healthcare workers) were examined for their impact on the results. Daily cases fitted an exponential growth in the first log-linear segment (k = +0.042, s.e. = 0.007), and fitted an exponential decay in the second (k = -0.023, s.e. = 0.017) log-linear segment. Over a range of reported serial intervals for SARS-CoV-2 infection, these growth rates correspond to a 22–33% reduction in an effective reproduction ratio before and after mandatory mask use. Analysis of images of people in public spaces showed mask usage rose from approximately 43% to 97%. Analysis of survey data found that on the third day before policy introduction, 44% of participants reported “often” or “always” wearing a mask; on the fourth day after, 100% reported “always” doing so. No potentially confounding factors were associated with the observed change in growth rates. Conclusions The mandatory mask use policy substantially increased public use of masks and was associated with a significant decline in new COVID-19 cases after introduction of the policy. This study strongly supports the use of masks for controlling epidemics in the broader community.

Extraction, Characterization, and Applications of Pectins from Plant By-Products

Currently, pectins are widely used in the cosmetic, pharmaceutical, and food industries, mainly as texturizing, emulsifying, stabilizing, and gelling agents. Pectins are polysaccharides composed of a large linear segment of α-(1,4) linked d-galactopyranosyluronic acids interrupted by β-(1,2)-linked l-rhamnoses and ramified by short chains composed of neutral hexoses and pentoses. The characteristics and applications of pectins are strongly influenced by their structures depending on plant species and tissues but also extraction methods. The aim of this review is therefore to highlight the structures of pectins and the various methods used to extract them, including conventional ones but also microwave heating, ultrasonic treatment, and dielectric barrier discharge techniques, assessing physico-chemical parameters which have significant effects on pectin characteristics and applications as techno-functional and bioactive agents.

Assessing Calcium and Magnesium Nutritional Status With the Hair Median Derivatives Bioassay

Objectives Short-term biological indicator of urinary Mg and Ca excretion helps us to assess human body Mg and Ca nutritional status. In this study, we used the long-term biological indicator tissue of hair to assess Mg and Ca human body nutritional status. Methods Hair Mg and Ca were analyzed in 1073 healthy white adult Caucasians [734 women (♀) and 339 men (♂)] consuming common mid-European diet, with the ICP MS. The log transformed data on hair magnesium and calcium were analyzed with median derivatives bioassay. Results The median values (μg·g−1) were ♀Mg 137.2 and ♂Mg 47.1, and ♀Ca 1721.4 and ♂Ca 492.0, respectively. The linear (adequate) reference ranges of the sigmoid saturation curve for magnesium were ♀Mg 29.7–270.6 and ♂Mg 20.5–90.2, whereas these ranges for calcium were ♀Ca 487.7–4426.8 and ♂Ca 261.1–816.4. The magnesium to calcium (Mg/Ca) ratio in women appears fairly constant along the sigmoid linear segment range (about 0.067), and in difference to the constantly increasing Mg/Ca ratio in men - from 0.078 at the start of the linear segment to 0.096 at the median and 0.1105 before leveling at the top of the curve. Conclusions Women tend to accumulate much more Ca in their hair than men. The results suggest how hair Mg concentration should not be below 29.7 and 20.5 or above 270.6 and 90.2 μg·g−1 in women and men, respectively. Similarly, Ca hair concentrations should be not below 487.7 and 261.1 and higher than 4456.8 and 816.4 in women and men, respectively. The possible health effects of the observed sex related metabolic difference between men and women remains to be elucidated. Funding Sources The authors received no specific funding for this work.

Planning models for optimal routing of radial distribution systems

<span>This paper presents three planning models for optimal routing of radial distribution systems. In the first two models, the cost function includes capital cost of lines, energy loss cost, and bays cost. The constraints equations include power balance equations, voltage drop equations, radiality equations, logic equations, thermal limit equations, and bus voltage limit equations. The first model considers the energy loss equation in its quadratic form while the second model approximates the energy loss equation of each cable size by a simple linear segment considering the economic loading of each cable size. In the third model, two sub-models are used where the first one gets the optimal radial network configuration regardless of the cable sizes and voltage constraints. In the second sub-model the best cable size on each selected line of the first model is determined to minimize the system costs while considering the bus voltage limit constraint and thermal limit constraint. Verification of the proposed planning models has been made using a real 11 kV 34-bus distribution network with 68 initial lines.</span>

A new methodology to detect changes in displacement rates of slow-moving landslides using InSAR time series

&lt;p&gt;Regional-scale landslide deformation can be measured using satellite-based synthetic aperture radar interferometry (InSAR). Our study focuses on the quantification of displacements of slow-moving landslides that impact a hydropower dam and reservoir in the tropical Ecuadorian Andes. We constructed ground surface deformation time series using data from the Copernicus Sentinel-1 A/B satellites between 2016 and 2020. We developed a new approach to automatically detect the onset of accelerations and/or decelerations within each active landslide. Our approach approximates the movement of a pixel as a piecewise linear function. Multiple linear segments are fitted to the cumulative deformation time series of each pixel. Each linear segment represents a constant movement. The point where one linear segment is connected to another linear segment represents the time when the pixel&amp;#8217;s rate of movement has changed from one value to another value and is referred to as a breakpoint. As such, the breakpoints represent moments of acceleration or deceleration. Three criteria are used to determine the number of breakpoints: the timing and uncertainty of the breakpoints, the confidence intervals of the fitted segments&amp;#8217; slopes, and the Akaike Information Criterion (AIC). The suitable number of breakpoints for each pixel (i.e., the number of accelerations or decelerations) is determined by finding the largest number of breakpoints that complies with the three listed criteria. The application of this approach to landslides results in a wealth of information on the surface displacement of a slope and an objective way to identify changes in displacement rates. The displacement rates, their spatial variation, and the timing of acceleration and deceleration can further be used to study the physical behavior of a slow-moving slope or for (regional) hazard assessment linking the onset of change in displacement rate to causal and triggering factors.&lt;/p&gt;