13 research outputs found
DEVELOPMENT OF A PATIENT-SPECIFIC OCULAR MODEL FOR RISK ASSESSMENT OF GLAUCOMA DEVELOPMENT AND PROGRESSION
No full textGlaucoma is the leading cause of blindness worldwide. Once the retinal ganglion cell axons are lost they cannot be cured. Therefore, preventative risk assessment measures are important. To be able to perform these tasks, one needs to understand the mechanism behind the axonal blockage that leads to glaucoma. Biomechanical factors are thought to play a role in glaucoma, but the specific mechanism is not explored. In a Finite Element (FE) ocular model, the complex shape of the optic nerve components can be modeled and relevant mechanical quantities, such as stresses and strains due to intraocular (IOP) and/or intracranial (ICP) pressure, can be estimated and their effects assessed. Furthermore, optic nerve head (ONH) morphology and especially lamina cribrosa shape and properties, which are tightly linked to Glaucoma onset and development, vary greatly between individuals. This consequently suggests the development of patient-specific FE ocular models.
A method to generate patient-specific ocular models was contrived based on the geometry extracted from Optical Coherence Tomography (OCT) scans. Specifically, retinal layers were segmented using intensity and graph-based algorithms and the segmented layers were then reconstructed with a thin plate spline method. Finally, solid models were created from the reconstructed surfaces and meshed with tetrahedral elements. The geometric details of the generated ONH model correlate well with those of generic models from pertinent literature and special attention was paid to meshing so that the optic nerve region of the ocular model exhibits analysis-suitable element quality. The suggested reconstruction method is semiautomatic and although we aimed to fully capture the complete ONH region, some anatomical structures, which are generally considered relevant and important, could not be extracted from OCT images in vivo. These include the pia arachnoid complex (dura mater and pia mater) that contains cerebrospinal fluid material and is considered to exert ICP. These were handled by carrying out a parametric analysis, using generic models with linear elastic material properties, to establish the degree of importance of the pia arachnoid complex. It was found that pia and dura mater properties can affect post laminar neural tissue and lamina cribrosa biomechanics. As it is currently infeasible to obtain high-quality patient-specific geometries for the pia arachnoid complex in vivo, we embed generic models of the pia and dura mater in our patient-specific ONH model. Viscoelastic material properties of dura mater and sclera were additionally retrieved from physical unidimensional tensile stress-relaxation tests. The influence of viscoelastic material properties at certain levels of ICP/IOP with a generic ocular model was examined, and results indicated, as expected, the importance of viscoelastic properties. Parametric analysis of patient-specific models was performed via the principal component analysis method deriving statistical shape models (SSM). Qualitative, quantitative and biomechanical assessments were performed with the aid of the generated SSM. For the biomechanical assessment, finite element modeling was employed and several patient-specific models, based on SSM shape modes, were generated and tested. We anticipate further enhancements and developments for this approach in the future. Based on the so far obtained results, we find evidence that patient-specific, anatomically detailed 3D ocular models allow for a better understanding of employed biomechanics and can benefit glaucoma risk assessment
“Эзэн Чингис хааны билиг сургаал”-ын судлагдсан байдал: Studies on “Chingis khaany bilig surgaal”
No full textIn this article, author examines the scientific and research studies on “Chingis khaany bilig surgaal”. The scholars [Sh.Choimaa, E.Purevjav, Kh.Namjil, G.Akim] and source studies have have divided the work into the following: 1. Folklore - intellectual prowess and superiority of proverbs 2. Natural intelligence and wisdom of Ezen bogda 3. Life experience, learning from others and the wise men that use his mind to call upon past teachings. Also professor G.Munkh has classified it: 1. Khutag bilig (his sayings and teachings) 2. Öv bilig (expressed his ideas enriching others teachings) 3. Örgömöl bilig (Chingis khan’s teaching and sayings to his sons, successors, generals and ministers; others’ sayings related to his success and deed) 4. Ish bilig (quotes on Chingis khan’s concepts based on historical source materials) These classifications are helpful to do the further investigations
Brillouin Biosensing of Viscoelasticity across Phase Transitions in Ovine Cornea
No full textNoninvasive in situ monitoring of viscoelastic characteristics of corneal tissue at elevated temperatures is pivotal for mechanical property-informed refractive surgery techniques, including thermokeratoplasty and photorefractive keratectomy, requiring precise thermal modifications of the corneal structure during these surgical procedures. This study harnesses Brillouin light scattering spectroscopy as a biosensing platform to noninvasively probe the viscoelastic properties of ovine corneas across a temperature range of 25–64 °C. By submerging the tissue samples in silicone oil, consistent hydration and immiscibility are maintained, allowing for their accurate sensing of temperature-dependent mechanical behaviors. We identify significant phase transitions in the corneal tissue, particularly beyond 40 °C, likely due to collagen unfolding, marking the beginning of thermal destabilization. A subsequent transition, observed beyond 60 °C, correlates with collagen denaturation. These phase transformations highlight the cornea’s sensitivity to both physiologically reversible and irreversible viscoelastic changes induced by mild to high temperatures. Our findings underscore the potential of the Brillouin biosensing technique for real-time diagnostics of corneal biomechanics during refractive surgeries to attain optimized therapeutic outcomes
Critical Assessment on the Stability and Convergence of the Conventional Gear Tooth Contact Analysis
No full textMathematical modeling of gear engagement is crucial during design to ensure optimal performance in manufacturing. This study reproduces the conventional tooth contact analysis (TCA) model, highlighting convergence issues in parallel-axis gears and limitations in local synthesis methods. The research critically analyzes the TCA method, which solves five nonlinear equations to assess performance and accuracy. Simulations replicate the conditions of previous studies to ensure valid comparisons. Initial guess values are randomly generated within a specific range to guide the iterative process toward convergence, with this range progressively narrowed to improve computational efficiency and accuracy. Results indicate that the TCA approach is highly sensitive to initial guess values, particularly the starting angular position. Convergence issues arise from the complexity of nonlinear equations and multiple roots. This can lead to divergence or reverting to the initial guess when values deviate significantly from the true solution
Монголчуудын бүхэл шүүс хөндөхийн ёс учир хийгээд “хишиг хүртээх” зан үйлийн уламжлал: Ritual tradition of sharing meat and the Mongolians’ custom of meat cutting
No full textThe author discusses the ancient ritual tradition of sharing meat and the Mongolians’ custom of meat cutting which holds symbolic meaning as analyzed from ‘Chingis-un hishigyn deej’. Since early times, Mongolians have had a unique ritual tradition and custom of sharing meat depending on ranks in a tribe. Also there are special rules regarding which bones should be eaten by whom
New Data on the Type Species of the Genus Lixodessa Gozmany, 1957 (Lepidoptera, Gelechiidae)
No full textThe data are presented on finding Lixodessa ochrofasciella (Toll.) in Western Siberia (vil. Chingis, Novosibirsk Region) and in Latvia (town of Kandava). This species was known formerly only in the Ukraine (Ternopol' Region) and in Hungary. Gozmany's (1957) statement on distribution of the given species in Poland is erroneous. Redescription of L. ochrofasciella (Toll.) genitals is given. Contrary to the opinion of Wolff (1958), the author supports independence of the genus Lixodessa Gozm
Mechano-Chemistry across Phase Transitions in Heated Albumin Protein Solutions
No full textThe presence of certain proteins in biofluids such as synovial fluid, blood plasma, and saliva gives these fluids non-Newtonian viscoelastic properties. The amount of these protein macromolecules in biofluids is an important biomarker for the diagnosis of various health conditions, including Alzheimer’s disease, cardiovascular disorders, and joint quality. However, existing technologies for measuring the behavior of macromolecules in biofluids have limitations, such as long turnaround times, complex protocols, and insufficient sensitivity. To address these issues, we propose non-contact, optical Brillouin and Raman spectroscopy to assess the viscoelasticity and chemistry of non-Newtonian solutions, respectively, at different temperatures in several minutes. In this work, bovine and human serum albumin solution-based biopolymers were studied to obtain both their collective dynamics and molecular chemical evolution across heat-driven phase transitions at various protein concentrations. The observed phase transitions at elevated temperatures could be fully delayed in heated biopolymers by appropriately raising the level of protein concentration. The non-contact optical monitoring of viscoelastic and chemical property evolution could represent novel potential mechano-chemical biomarkers for disease diagnosis and subsequent treatment applications, including hyperthermia
"T'a-li-han" (塔里寒)
No full textTaoist Ch'ang-ch'un's Travels is one of the best travel stories in China. It is also an extremely important material on the historical geography of Central Asia in the Middle Ages. Emile Bretschneider, Wang Kuo-wei and Arthur Waley have made considerable contributions toward identifications of various place names appearing in the Travels and the routes followed by the Taoist and his followers. It was the late Professor Michiyo Naka who, for the first time, pointed out confusion in the chronology of Chingis Khan's expeditions into Central Asia and corrected the errors in both Persian and Chinese histories of the time, and the main source he used for this purpose was the Travels. There remain, however, a few points that have not yet been clarified; the location of T'a-li-han, the place where the Taoist was received in audience by Chingis Khan, etc. The present author tries to identify T'a-li-han not with the present Taliqan but with Kunduz and to prove that Ch'ang-ch'un did never go into or beyond the Hindu-kush
Early Hungarian Information on the Beginning of the Western Campaign of Batu (1235–1242)
No full textThe author of this article examines the gradual accumulation of information in the Hungarian Kingdom about the Mongol Western Campaign and the corresponding propagation of this information in Western Europe. The primary information was brought to Europe by the Dominican friar Julian after his return from his travel to the Volga Magyars at the end of 1235. The letter of friar Julian written at the beginning of 1238 is replete with information about Mongol tactical warfare, previous military campaigns of Chingis Khan and Jochi, and the first Mongol conquest in the early stages of the Western Campaign of Batu. He also brought an oral report of the Prince of Vladimir on the Mongol plans to attack the Hungarian Kingdom. Soon the content of Julian’s letter became known in Western Europe. The Hungarian King Béla IV started to make preparations for the imminent Mongol invasion and attempted to organise resistance
Tatars of the Jochid Ulus: the formation and development of an ethnopolitical identity in the 13th–15th centuries
No full textResearch objectives: To analyze the processes behind the formation and development of the Tatar ethnopolitical community in the Ulus of Jochi in the XIII–XV centuries.
Research materials: The author of the article examines a variety of sources that reflect the progressive development of the Tatar ethnopolitical community in the Ulus of Jochi during the XIII–XV centuries.
Results and novelty of the research: The Tatars of the Jochid Ulus during the XIII–XV centuries were usually studied from a socio-political point of view, with little attention being paid to the study of mental structures. Nevertheless, the formation of the ethnopolitical community of the Tatars – something which determines the mental universe of the population of the Ulus of Jochi – deserves and receives here more intensive study.
The Mongol invasion brought not only destruction to the countries of Eurasia, but also led to the formation of a new Mongol Empire, and at the end of the XIII century, the successor Chingisid states. In all these khanates, there was a process of formation of their statehood and ethnopolitical consolidation. In the Ulus of Jochi, this process was associated with the formation of the Tatar ethnopolitical community. It turns out that during the conquests of Chingis Khan and his heirs in different countries of Eurasia from the Near and Middle East to Central Asia and Eastern Europe, Tatars were present among the troops of the Khans, playing the role of a military aristocracy. Due to these objective and other subjective reasons, the Tatar identity became the leading one in the Jochid Ulus, manifesting itself in the ideas that the Jochid Ulus was a country of the Tatars, the term itself becoming synonymous with the military service aristocracy. Tatars were also understood as Turkic nomadic people with their own clan structure
