Determination of Fluorescence Polarization and Absorption Anisotropy in Molecular Complexes Having Threefold Rotational Symmetry

The current work concerns investigation of the polarization properties of complex molecular ensembles exhibiting threefold (C3) rotational symmetry, particularly with regard to the interplay between their structure and dynamics of internal energy transfer. We assume that the molecules or chromophores in such complexes possess strongly overlapped spectra both for absorption and fluorescence. Such trimeric structures are widely found in biological preparations, as for example the trimer of C-phycocyanin (C-PC). Higher order aggregates, e.g. hex-amers and three-hexamer rods, are also investigated and compared with the trimer case. The theory addresses both steady-state and 8-pulse excitation and establishes some links between them. Monochromophoric, bichro-mophoric and trichromophoric molecular complexes are individually examined. For steady-state excitation, analytical formulas are reported for the degree of fluorescence polarization and absorption anisotropy. It is shown that the polarization is dependent on the chromophore inclination relative to the symmetry axis, the relative efficiencies of absorption and fluorescence by chromophores of different spectral types, and the rates of energy equilibration. To assess the validity of the theory, it has been applied to C-PC aggregates. Here it was found that different C-PC aggregates provide practically identical polarization response. For S-pulse excitation we give analytical formulas for determination of the fluorescence depolarization, and also the depolarization associated with absorption recovery, both for a monochromophoric trimer and some particular cases of bichromophoric trimer. More complicated systems are analyzed by computer modeling. Thus it transpires that the initial polarization anisotropy r(t = 0) takes the value 0.4 for all considered aggregates; the long-time limit r(t →∞) has about the same value as is associated with steady-state excitation. We also show that with steady-state excitation the degree of fluorescence polarization is practically equal for various C3 aggregates of C-PC, and that the major factor determining the polarization is the chromophore orientation relative to the symmetry axis

Crustal structure below Popocat\'epetl Volcano (Mexico) from analysis of Rayleigh waves

An array of ten broadband stations was installed on the Popocat\'epetl volcano (Mexico) for five months between October 2002 and February 2003. 26 regional and teleseismic earthquakes were selected and filtered in the frequency time domain to extract the fundamental mode of the Rayleigh wave. The average dispersion curve was obtained in two steps. Firstly, phase velocities were measured in the period range [2-50] s from the phase difference between pairs of stations, using Wiener filtering. Secondly, the average dispersion curve was calculated by combining observations from all events in order to reduce diffraction effects. The inversion of the mean phase velocity yielded a crustal model for the volcano which is consistent with previous models of the Mexican Volcanic Belt. The overall crustal structure beneath Popocat\'epetl is therefore not different from the surrounding area, and the velocities in the lower crust are confirmed to be relatively low. Lateral variations of the structure were also investigated by dividing the network into four parts and by applying the same procedure to each sub-array. No well-defined anomalies appeared for the two sub-arrays for which it was possible to measure a dispersion curve. However, dispersion curves associated with individual events reveal important diffraction for 6 s to 12 s periods which could correspond to strong lateral variations at 5 to 10 km depth

Further Remarks on Extra Roots of Rayleigh Equation and Somigliana Waves

The extra roots of the Rayleigh equation for an elastichalfspace contribute to the solution only for large enough values of thePoisson coefficient (a > 0.309). One of them corresponds to leaking modeswith the phase velocity less than the velocity of the longitudinal wave.A similar wave with distinct dispersion may exists in the case where anelastic halfspace is covered by a thin layer with lower velocities of elasticwaves. The thickness of a layer should be not too small in comparisonwith the wave length

Surface wave tomography across Afar, Ethiopia: crustal structure at a rift triple-junction zone

The Afar Depression in northeast Africa contains the rift triple-junction between the Nubia, Arabia and Somalia plates. We analyze Rayleigh wave group velocity from 250 regional earthquakes recorded by 40 broadband stations to study the crustal structure across Afar and adjacent plateau regions in northern Ethiopia. The dispersion velocities are inverted to obtain surface wave tomographic maps for periods between 5 and 25 seconds, sensitive to approximately the top 30 km of the lithosphere. The tomographic maps show a significant low dispersion velocity anomaly (>20%) within the upper crust, below the site of recent dyke intrusions (2005–present) in the Dabbahu and Manda-Hararo magmatic segments. Similar low velocity regions are imaged where magma intrusion in the Afar crust has been inferred over the last decade from seismicity or volcanic eruptions. We invert two group velocity curves to compare the S-wave velocity structure of the crust within an active magmatic segment with that of adjacent areas; the active region has a low velocity zone (Vs ∼ 3.2 km/s), between about 6–12 km, which we infer to be due to the presence of partial melt within the lower crust

THE THEORY OF LEGAL FACTS IN VARIOUS LEGAL SYSTEMS

The article provides an overview of the process of the theory of legal facts formation and development in various legal systems. The perception features of this theory in the continental Western Europe countries, the Anglo-Saxon legal system, as well as in Russia are revealed. The conclusion is made that currently in Russia there is an active development of the theory of legal facts. It is filled with new content and elements. Great importance is attached to the study of large factual systems that identified by Russian jurists

Impact of Field Characteristics on Pneumatic Seed Drill Performance: A Case Study in Eritrea

The efficient use of agricultural machinery significantly improves both the quantity and quality of field operations; therefore, it is essential to optimize operational speed and field time. Factors such as field shape complexities and soil surface roughness (SSR) significantly impact seeding performance. The objective of this research was thus to evaluate how these key factors affect seeder performance: (1) field size and shape, and (2) the interaction of seeder speed and SSR. The performance metrics, effective field capacity (Feff), efficiency (η), and average working speed (va), were analyzed using SAS software. The convexity (Icon) and rectangularity (IR) indices for each plot were calculated using the ArcGIS minimal bounding geometry Data Management tool, while the elevation standard deviation (σe) was computed using Python. The resulting values for Feff, η, and va varied widely, with values ranging from 10.2 to 3.1 ha h-1, 30% to 65.7%, and 5.2 to 17 km h-1, respectively. A va process capability index (Cpk) of 0.22 indicates a significant challenge in meeting the established limits. As the plot run-length increased, the Feff also increased (R2 = 42%), while it decreased with a rising perimeter to area ratio (P/A) (R2 = 51%). Additionally, Feff exhibited an upward trend as the Icon and IR indices rose, while it experienced a decline with greater compactness (Icom) and square perimeter (Isp) indices; albeit these relationships were not statistically significant. Higher roughness levels generally resulted in a decline in η. Furthermore, operating the planter at higher speed on uneven terrain led to a significant decrease in efficiency. Hence, redesigning the plots to minimize border complexities, eliminating topographic abnormalities, and implementing tailored plot-specific pre-sowing procedures, will significantly enhance planter performance

Charlson comorbidity index in predicting deaths in COVID-19 patients

Aim. To assess the clinical performance and factors associated with inhospital mortality in patients with coronavirus disease 2019 (COVID-19).Material and methods. Our results are based on data from hospital charts of inpatients hospitalized in the Asinovskaya District Hospital in the period from March 11, 2020 to December 31, 2020, with a verified COVID-19 by polymerase chain reaction. The study included 151 patients, the median age of which was 66,2 (50- 92) years (women, 91; 60,3%). The study endpoints were following hospitalization outcomes: discharge or death. Depending on the outcomes, the patients were divided into 2 groups: the 1st group included 138 patients (survivors), while the 2nd one included 13 patients (death). To objectify the severity of multimorbidity status, the Charlson comorbidity index was used. The final value was estimated taking into account the patient age by summing the points assigned to a certain nosological entity using a calculator table.Results. Hypertension was recorded in the majority of patients — 79,5%, chronic kidney disease — in 61,1%. The prevalence of type 2 diabetes and coronary artery disease was high — 31,8% each. Prior myocardial infarction was diagnosed in 11,3% of cases. The prevalence of percutaneous coronary intervention and coronary bypass surgery was 5,3% and 3,3%, respectively. Stroke was detected in 9,3% of participants. Prior chronic pulmonary pathologies in COVID-19 patients were rare (asthma — 3,3%, chronic obstructive pulmonary disease — 2,0%). In order to predict the death risk in COVID-19 patients, a logistic regression analysis was performed, which showed that age and Charlson comorbidity index were the most significant predictors.Conclusion. Independent factors of inhospital mortality were age and Charlson’s comorbidity index. The risk assessment model will allow clinicians to identify patients with a poor prognosis at an earlier disease stage, thereby reducing mortality by implementing more effective COVID-19 treatment strategies in conditions with limited medical resources

Application of Surface wave methods for seismic site characterization

Surface-wave dispersion analysis is widely used in geophysics to infer a shear wave velocity model of the subsoil for a wide variety of applications. A shear-wave velocity model is obtained from the solution of an inverse problem based on the surface wave dispersive propagation in vertically heterogeneous media. The analysis can be based either on active source measurements or on seismic noise recordings. This paper discusses the most typical choices for collection and interpretation of experimental data, providing a state of the art on the different steps involved in surface wave surveys. In particular, the different strategies for processing experimental data and to solve the inverse problem are presented, along with their advantages and disadvantages. Also, some issues related to the characteristics of passive surface wave data and their use in H/V spectral ratio technique are discussed as additional information to be used independently or in conjunction with dispersion analysis. Finally, some recommendations for the use of surface wave methods are presented, while also outlining future trends in the research of this topic

Risk factors for heart failure in patients with COVID-19

Aim. To establish risk factors for heart failure (HF) in patients with coronavirus disease 2019 (COVID-19).Material and methods. Medical records of 151 patients treated in an infectious disease hospital from November 3, 2020 to February 2, 2021 with a confirmed diagnosis of COVID-19 were retrospectively selected. The collection of clinical, history and laboratory data were carried out by analyzing electronic medical records. We analyzed information on age, sex, body mass index, smoking, and comorbidities. Following laboratory studies were analyzed: complete blood count, biochemical blood tests, coagulation profile, acute phase proteins (C-reactive protein (CRP), ferritin, lactate dehydrogenase (LDH)), procalcitonin. The diagnosis of HF was confirmed by clinical performance, echocardiography, and elevated levels of the N-terminal pro-brain natriuretic peptide (NT-proBNP). The risk of HF was taken as the endpoint of the study.Results. The studied sample of patients was divided into two groups depending on HF: the 1st group included 46 patients with HF, the 2nd group — 105 patients without HF. The median age was 66,2 (50-92) years (women, 91 (60,3%)). Laboratory indicators, such as the levels of CRP, LDH, procalcitonin, creatinine, bilirubin, differed significantly from each other, and the median values were higher in patients with HF. The neutrophil-to-lymphocyte ratio (NLR) showed significant intergroup differences: in the group of patients with HF, the median was 4,97% vs 3,62% (p=0,011) in the group of patients without HF. There were following most significant predictors increasing the HF risk: age ≥66 years (odds ratio, 8,038, p<0,001), procalcitonin level, which increases the HF risk in patients by 3,8 times (p><0,001), NLR ≥4,11% (p=0,010), thrombocytopenia ≤220×109/l (p=0,010), history of chronic kidney disease (CKD) (p=0,018). Conclusion. The following predictors of HF were established: age ≥66 years, procalcitonin ≥0,09 ng/ml, NLR ≥4,11%, thrombocytopenia ≤220×109/l, history of CKD, LDH ≥685 U/l and creatinine ≥102 µmol/l, international normalized ratio ≥1,19, QTc interval ≥407,5 ms, bilirubin ≤10,7 µmol/l. It is worth noting that the best accuracy values are demonstrated by the Random Forest algorithm (88,5% on the validation set), but the mathematical model of the neural network turned out to be the most sensitive (90,0% on the validation set). Keywords: novel coronavirus infection, heart failure, prognosis>˂0,001), procalcitonin level, which increases the HF risk in patients by 3,8 times (p˂0,001), NLR ≥4,11% (p=0,010), thrombocytopenia ≤220×109/l (p=0,010), history of chronic kidney disease (CKD) (p=0,018).Conclusion. The following predictors of HF were established: age ≥66 years, procalcitonin ≥0,09 ng/ml, NLR ≥4,11%, thrombocytopenia ≤220×109/l, history of CKD, LDH ≥685 U/l and creatinine ≥102 µmol/l, international normalized ratio ≥1,19, QTc interval ≥407,5 ms, bilirubin ≤10,7 µmol/l. It is worth noting that the best accuracy values are demonstrated by the Random Forest algorithm (88,5% on the validation set), but the mathematical model of the neural network turned out to be the most sensitive (90,0% on the validation set)