ANALYSIS OF UNCERTAINTY IN UNDERWATER MULTIVIEW RECONSTRUCTION

Multiview reconstruction, a method for creating 3D models from multiple images from different views, has been a popular topic of research in the eld of computer vision in the last two decades. Increased availability of high-quality cameras led to the development of advanced techniques and algorithms. However, little attention has been paid to multiview reconstruction in underwater conditions. Researchers in a wide variety of elds (e.g. marine biology, archaeology, and geology) could benefit from having 3D models of seafloor and underwater objects. Cameras, designed to operate in air, must be put in protective housings to work underwater. This affects the image formation process. The largest source of underwater image distortion results from refraction of light, which occurs when light rays travel through boundaries between media with different refractive indices. This study addresses methods for accounting for light refraction when using a static rig with multiple cameras. We define a set of procedures to achieve optimal underwater reconstruction results, and we analyze the expected quality of the 3D models\u27 measurements

Ранние особенности кровообращения у больных с неблагоприятным исходом абдоминального сепсиса (предварительное сообщение)

Aim: to study characteristics of the central hemodynamics (CHD) in patients with severe abdominal sepsis with different outcomes of the disease.Materials and Methods. 18 patients with abdominal sepsis, aged 50.2±3, with the APACHE II and SOFA severity scoring of 13.7±0.8 and 8.4±0.5, respectively, were enrolled in the retrospective study. The CHD was studied using the transpulmonary thermodilution. The following groups were identified: Group 1 (deceased, n=9) and Group 2 (survivors, n=9). The groups did not differ (P>0.05) in age, sex, and the severity of the condition at admission to the ICU. The significance of differences was assessed using the t-test and the chi-squared test. The prognostic value of the parameters was studied using the ROC analysis.Results. On Day 1, the intergroup differences included the average blood pressure (BPav) (85.3±3.3 and 101.6±4.6 mmHg, respectively (P<0.05)) and the cardiac power index (CPI) (306±22 and 429.9±48.9 W/m2, respectively) (Р<0.05). The intergroup difference in the CPI and the global ejection fraction (GEF) persisted on Day 3: 22.3±2.3 and 29.3±1.5%, respectively (P<0.05); there was no other difference. The intergroup difference in the GEF remained on Day 5. On Day 7, the CHD parameters demonstrated no intergroup difference. The SOFA severity scoring in Group 1 patients became greater than that in Group 2 starting from Day 5. According to ROC analysis, BPav (95 mmHg, sensitivity: 88.9%, specificity: 88.9%), CPI (373 W/m2, sensitivity: 88.9%, specificity: 77.8%), and GEF (26.1%, sensitivity: 66.7%, specificity: 77,8%) were the most important predictors of the lethal outcome on Days 1—3 (areas under ROC curves: 0.765—0.840; P<0.05). On days 5—7, the SOFA scoring >7 (sensitivity: 88.9%, specificity: 88.9%) was the most important predictor of the lethal outcome (areas under ROC curves: 0.957—0.994; P<0.05).Conclusion: during the first five days of the intensive treatment of severe sepsis in patients with unfavorable prognosis, a moderate decrease in the cardiac power index and overall cardiac systolic function was registered. The prognostic significance of such parameters as CPI and GEF may become obvious within the first 3 days of the intensive treatment.Цель исследования: изучить особенности центральной гемодинамики (ЦГД) у больных тяжелым абдоминальным сепсисом при различных исходах заболевания.Материалы и методы. В ретроспективное исследование включили 18 больных абдоминальным сепсисом в возрасте 50,2±3 лет с тяжестью состояния по шкале APACHE II 13,7±0,8 балла, SOFA — 8,4±0,5 балла. ЦГД изучали с помощью транспульмональной термодилюции. Выделили группы больных: 1-я (умершие, n=9) и 2-я (выжившие , n=9). Группы не различались (p>0,05) по возрасту, половому составу и тяжести состояния больных при поступлении в отделение реаниматологии. Достоверность отличий оценивали по критерию t-критерию Стьюдента и критерию Хи-квадрат. Прогностическую значимость показателей изучали с помощью ROC-анализа.Результаты. В 1-е сутки межгрупповые отличия выявлены в уровне среднего артериального давления (АДср.) — 85,3±3,3 и 101,6±4,6 мм рт. ст. (р<0,05) и индекса мощности сердца (ИМС) — 306±22 и 429,9±48,9 Вт/м2 (р<0,05). На 3-и сутки сохранялись межгрупповые отличия значений ИМС, проявлялись отличия величины глобальной фракции изгнания сердца (ГФИС) — 22,3±2,3 и 29,3±1,5% (р<0,05); других отличий не было. На 5-е сутки сохранялось межгрупповое отличие значений ГФИС. На 7-е сутки показатели ЦГД не имели межгрупповых отличий. Тяжесть состояния по SOFA у больных 1-й группы становилась больше, чем во 2-й, начиная с 5-х суток. По данным ROC-анализа в 1-3-и сутки наиболее значимыми предикторами летального исхода (площади под ROC-кривыми 0,765—0,840; p<0,05) явились АДср. (95 мм рт. ст., чувствительность 88,9%, специфичность 88,9%), ИМС (373 Вт/м2, чувствительность 88,9%, специфичность 77,8%) и ГФИС (26,1%, чувствительность 66,7%, специфичность 77,8%). На 5—7-е сутки наиболее значимым предиктором летальности (площади под ROC-кривой 0,957—0,994; p<0,05) становилась тяжесть состояния по шкале SOFA >7 баллов (чувствительность 88,9%, специфичность 88,9%).Заключение: в течение первых 5-и суток интенсивного лечения тяжелого сепсиса у больных с неблагоприятным прогнозом заболевания отмечено умеренное снижение показателей мощности и общей систолической функции сердца. Прогностическая значимость таких показателей, как ИМС и ГФИС, может проявляться в первые трое суток интенсивного лечения

Eddies in the Western Arctic Ocean From Spaceborne SAR Observations Over Open Ocean and Marginal Ice Zones

The Western Arctic Ocean is a host to major ocean circulation systems, many of which generate eddies that can transport water masses and corresponding tracers over long distances from their formation sites. However, comprehensive observations of critical eddy characteristics are currently not available and are limited to spatially and temporally sparse in situ observations. Here we use high‐resolution spaceborne synthetic aperture radar measurements to detect eddies from their surface imprints in ice‐free sea surface roughness, and in sea ice patterns throughout marginal ice zones. We provide the first estimate of eddy characteristics extending over the seasonally ice‐free and marginal ice zone regions of the Western Arctic Ocean, including their locations, diameters, and monthly distribution. Using available synthetic aperture radar data, we identified over 4,000 open ocean eddies, as well as over 3,500 eddies in marginal ice zones from June to October in 2007, 2011, and 2016. Eddies range in size between 0.5 and 100 km and are frequently found over the shelf and near continental slopes but also present in the deep Canada Basin and over the Chukchi Plateau. We find that cyclonic eddies are twice more frequent compared to anticyclonic eddies at the surface, distinct from the dominating anticyclonic eddies observed at depth by in situ moorings and ice‐tethered profilers. Our study supports the notion that eddies are ubiquitous in the Western Arctic Ocean even in the presence of sea ice and emphasizes the need for improved ocean observations and modeling at eddy scales

Eddies in the Western Arctic Ocean From Spaceborne SAR Observations Over Open Ocean and Marginal Ice Zones

The Western Arctic Ocean is a host to major ocean circulation systems, many of which generate eddies that can transport water masses and corresponding tracers over long distances from their formation sites. However, comprehensive observations of critical eddy characteristics are currently not available and are limited to spatially and temporally sparse in situ observations. Here we use high‐resolution spaceborne synthetic aperture radar measurements to detect eddies from their surface imprints in ice‐free sea surface roughness, and in sea ice patterns throughout marginal ice zones. We provide the first estimate of eddy characteristics extending over the seasonally ice‐free and marginal ice zone regions of the Western Arctic Ocean, including their locations, diameters, and monthly distribution. Using available synthetic aperture radar data, we identified over 4,000 open ocean eddies, as well as over 3,500 eddies in marginal ice zones from June to October in 2007, 2011, and 2016. Eddies range in size between 0.5 and 100 km and are frequently found over the shelf and near continental slopes but also present in the deep Canada Basin and over the Chukchi Plateau. We find that cyclonic eddies are twice more frequent compared to anticyclonic eddies at the surface, distinct from the dominating anticyclonic eddies observed at depth by in situ moorings and ice‐tethered profilers. Our study supports the notion that eddies are ubiquitous in the Western Arctic Ocean even in the presence of sea ice and emphasizes the need for improved ocean observations and modeling at eddy scales

Diagnosis of Skin Vascular Complications Revealed by Time-Frequency Analysis and Laser Doppler Spectrum Decomposition

Nowadays, photonics-based techniques are used extensively in various applications, including functional clinical diagnosis, progress monitoring in treatment, and provision of metrological control. In fact, in the frame of practical implementation of optical methods, such as laser Doppler flowmetry (LDF), the qualitative interpretation and quantitative assessment of the detected signal remains vital and urgently required. In the conventional LDF approach, the key measured parameters, index of microcirculation and perfusion rate, are proportional to an averaged concentration of red blood cells (RBC) and their average velocity within a diagnostic volume. These quantities compose mixed signals from different vascular beds with a range of blood flow velocities and are typically expressed in relative units. In the current paper we introduce a new signal processing approach for the decomposition of LDF power spectra in terms of ranging blood flow distribution by frequency series. The developed approach was validated in standard occlusion tests conducted on healthy volunteers, and applied to investigate the influence of local pressure rendered by a probe on the surface of the skin. Finally, in limited clinical trials, we demonstrate that the approach can significantly improve the diagnostic accuracy of detection of microvascular changes in the skin of the feet in patients with Diabetes Mellitus type 2, as well as age-specific changes. The results obtained show that the developed approach of LDF signal decomposition provides essential new information about blood flow and blood microcirculation and has great potential in the diagnosis of vascular complications associated with various diseases