Numerical simulations of bone remodelling and formation following nucleotomy

Nucleotomy is the gold standard treatment for disc herniation and has proven ability to restore stability by creating a bony bridge without any additional fixation. However, the evolution of mineral density in the extant and new bone after nucleotomy and fixation techniques has to date not been investigated in detail. The main goal of this study is to determine possible mechanisms that may trigger the bone remodelling and formation processes. With that purpose, a finite element model of the L4–L5 spinal segment was used. Bone mineral density (BMD), new tissue composition, and endplate deflection were determined as indicators of lumbar fusion. A bone-remodelling algorithm and a tissue-healing algorithm, both mechanically driven, were implemented to predict vertebral bone alterations and fusion patterns after nucleotomy, internal fixation, and anterior plate placement. When considering an intact disc height, neither nucleotomy nor internal fixation were able to provide the necessary stability to promote bony fusion. However, when 75% of the disc height was considered, bone fusion was predicted for both techniques. By contrast, an anterior plate allowed bone fusion at all disc heights. A 50% disc-height reduction led to osteophyte formation in all cases. Changes in the intervertebral disc tissue caused BMD alterations in the endplates. From this observations it can be drawn that fusion may be self-induced by controlling the mechanical stabilisation without the need of additional fixation. The amount of tissue to be removed to achieve this stabilisation remains to be determined

Behaviour of Ultra-Short Radio Waves Refraction in the Lower Atmospheric Layer of the Coastal Zone of the Bolshye Yeravninsky Lakes

Поступила: 10.10.2023. Принята в печать: 04.02.2024.Received: 10.10.2023. Accepted: 04.02.2024.Особенностью ультракоротких волн является тот факт, что на их распространение оказывают влияние погодные условия. Метеорологические неоднородности атмосферы вызывают искривление (рефракцию) траектории луча УКВ. Измерения метеопараметров на h1 = 2 и h2 = 10 м проводились с использованием атмосферно-почвенного измерительного комплекса, установленного в прибрежной зоне Больших Еравнинских озер Республики Бурятия на Лесостепном мерзлотно-экологическом стационаре «Еравнинский». Установлено, что в нижнем десятиметровом слое тропосферы наблюдается сильная суточная изменчивость градиента рефракции и разброс значений градиента рефракции составляет от –0,820 до +0,307 N-единиц. Обнаружено, что в летнее время в данной местности наблюдаются метеорологические условия, благоприятствующие появлению сверхрефракции.The propagation of ultra-short waves is influenced by weather conditions. Meteorological inhomogeneities in the atmosphere cause refraction of the ultra-short wave beam. Measurements of meteorological parameters at h1 = 2 and h2 = 10 m have been carried out using an atmospheric-soil measuring complex installed in the coastal zone of Big Eravninsky Lakes at the Forest-Steppe permafrost-ecological station “Eravninsky” in Buryatia. There is a strong daily variability of the refractive gradient, and the refractive gradient values scatter ranges from –0.820 to +0.307 N-units In the lower ten-meter layer of the troposphere. It is discovered that in summer, meteorological conditions favorable for the superrefraction appearance are observed in this area.Работа выполнена в рамках бюджетного проекта № 0270-2024-0004 «Развитие радиофизических методов исследования динамики поверхности суши, водоемов и атмосферы Земли в СНЧ-СДВ-ДВ-СВ и СВЧ диапазонах радиоволн».The Ministry of Education and Science of the Russian Federation, budget project No. 0270-2024-0008 supported this work