Using mathematical modeling, we studied the influence of defects in the Treacy compressor diffraction gratings on wavefront quality and compared the results with an analytical model. We obtained good qualitative agreement: distortions from substrate defects and writing-system aberrations add and lead to a noticeable reduction of the Strehl ratio in the focal plane. Modeling showed that the second and third compressor gratings contribute most to the degradation, and rotating these gratings by 180 degrees about the normal can markedly improve or worsen the resulting wavefront. We demonstrate that an optimal grating orientation combined with adaptive optics substantially reduces unwanted effects and restores the beam's high peak intensity. The practical significance of this work is the recommendation to account for and compensate large-scale defects when designing and operating large apertures in chirped pulse amplification systems to ensure maximum peak intensity and stable compression in multi-petawatt lasers.
AIM: to identify risk factors affecting the anal incontinence (AI) in Crohn’s disease. P ATIENTS AND METHODS: a retrospective study included 191 patients with perianal fistulizing Crohn’s disease in February 2017 — September 2024. Sphincter function was assessed via Wexner’s scale and sphincterometry. The incontinence symptoms were revealed in 118/155 (76%) patients. AI according sphincterometry was fixed in 175/191 (90%) cases. Associations were examined between: clinical/ anamnestic parameters, incontinence symptoms, anal sphincter insufficiency (sphincterometry -confirmed), and risk factor effects on sphincter tone/voluntary contraction. RESULTS: previous anal surgery, regardless of the number of operations, increases the likelihood of AI confirmed by sphincterometry (odds ratio (OR) = 4.1; 95% confidence interval (CI): 1.27–13.2; p = 0.02). When analyzing individual sphincterometry data, the effect of the duration of the perianal disease (OR = 1.11; 95% CI: 1–1.22; p = 0.04) and the number of fistula-related abscesses (OR = 1.49; 95% CI: 1.13–1.97; p = 0.005) on the reduction of maximum anal squeeze pressure was revealed. According to data obtained, the risk of a decrease in the maximum anal squeeze pressure increased in patients with chronic perianal lesions for more than 5.5 years (OR = 2.74; 95% CI:1.24–6.06, p = 0.012), as well as in patients with 2 or more actively draining collections (OR = 2.36; 95% CI:1.39–4.31, p = 0.005). CONCLUSION: analysis of predictors for anal incontinence in patients with Crohn’s disease-related perianal lesions will help develop optimal treatment strategy for these patients, thus highlighting the need for further research in this area.
In nuclear medicine, radiopharmaceutical drugs (RPDs) containing the technetium isotope Tc-99m are used to treat oncological diseases, such as brain, thyroid, and salivary gland cancer, as well as for diagnostic studies of the cardiovascular system. These RPDs are created using a molybdenum-technetium Tc-99m generator. To determine the main parameters of complex protection for a designed transport container of a technetium generator for the production of RPDs in accordance with the GMP standard. Eighteen container material options were considered. To assess the protective characteristics of the container, we used the MicroShield v. 8.01 software. Transport indices and categories of all container options were determined taking into account the calculated rate of equivalent doses for gamma radiation from the Mo-99/Tc-99m sorption column and the nominal source activity. We have simulated an advanced protective container for the Tc-99m generator. The best protective characteristics are noted for the option combining tungsten and lead 2.5 and 3.5 cm thick, respectively. This complex design of the protective container ensures the safe operation and transportation of the Tc-99m generator.
A combined mathematical model was developed for the regional-scale dynamics of gaseous admixtures and aerosols in the atmosphere. The model incorporates the following modules: thermo-hydrodynamic equations for meso-scale atmospheric processes in the non-hydrostatic approximation; transport of gaseous admixtures and aerosols, with allowance for photochemical transformation and binary homogeneous nucleation; and kinetic processes of condensation/evaporation and coagulation. Particular emphasis is given to the mechanisms of new-particle formation through binary homogeneous nucleation of drops of sulfuric acid and water vapor. By using this model, numerical experiments were performed to investigate spatio-temporal variations in the concentrations of gaseous admixtures and aerosols, as well as the formation of fine aerosol clusters in the Lake Baikal (Russia) and Antwerp (Belgium) areas due to strong industrial emission sources. The results of the numerical experiments are analyzed.
— The longitudinal distribution and characteristic features of sunspot groups during the end of the descending branch of Solar Cycle 24 are analyzed. The main activity turned out to be concentrated in the 60° longitude band, whose position coincided in the northern and southern hemispheres. We obtained a synodic rotation period of the activity zone of 26.6 days, which is shorter than during the corresponding phase of the previous cycles and is probably related to the variation not only in latitude but also in the depth of the active longitude source localization. The groups of sunspots observed in the active longitude zone are characterized by a more compact latitudinal distribution and an increased number of not only large sunspots but also small ones with areas smaller than 50 Msh. Furthermore, the lifetime of small sunspots in this area is longer in contrast to similar sunspots found elsewhere on the solar surface. This indicates a common source of sunspot generation in the active longitude zone. The analysis of the rotation rate of individual sunspot groups with areas larger than 150 Msh in the active longitude zone by the solar disk showed that only a portion of them rotate at a rate close to that of the active longitude zone itself, while another portion rotate at the Carrington rate characteristic of sunspot groups outside the active longitude zone. We assume that this can be due to the different depths of the bases of the different sunspot groups and to the difference in the localization of the sunspot bases and the active longitude source. As a result, only a portion of the groups can consistently receive magnetic flux from a faster rotating source, which leads to an acceleration of their rotation.
