The impact of legionellosis into fatal outcomes of pneumonia in Irkutsk

Aim. To study the diagnosis of legionellosis in patients who died because of pneumonia in Irkutsk (2016-2018).Materials and Methods. We performed 65 autopsies of patients who died from pneumonia in Irkutsk (2016-2018), studied their case histories, and interrogated 510 tap water samples for Legionella pneumophila by means of inoculation and polymerase chain reaction.Results. Among 65 fatal pneumonia outcomes registered in Irkutsk during 2016-2018, legionellosis has been confirmed in three cases (4.6%). Two of these patients were at the late stages of HIV infection while the third, 74-yearold, patient had multiple comorbid conditions. Nosocomial infection was suspected in one of these cases. None of these three patients left Irkutsk during the last month of their life. The assumed transmission factor was tap water, as Legionella pneumophila was found in tap water samples collected in 2013 and 2015.Conclusion. Patients with severe pneumonia need screening for legionellosis to perform the correct treatment, particularly during COVID-19 pandemic.

Impact of Modifier Oxides on Mechanical and Radiation Shielding Properties of B2O3-SrO-TeO2-RO Glasses (Where RO = TiO2, ZnO, BaO, and PbO)

The influence of modifier oxides (TiO2, ZnO, BaO, and PbO) on the mechanical and radiation shielding properties of boro-tellurate glasses is investigated. Samples with a composition of B2O3-SrO-TeO2-RO (RO represents the modifier oxides) were fabricated using the melt quench method, and their physical, mechanical, and radiation attenuation parameters were reported. For this aim, Monte Carlo simulation was employed to predict the radiation attenuation parameters, while the Makishima-Mackenzie model was adopted to determine the mechanical properties. The tightly packed structure with better cross-linkage density is possessed by the Ti-containing glass (SBT-Ti) system among the titled glass batch. The higher Poisson and micro-hardness values of the SBT-Ti glass indicate its structure’s reduced free volume and better compactness. For the glass with PbO, the linear and mass attenuation coefficients are highly increased compared to those glasses doped with TiO2, ZnO, and BaO. The thinner half-value layer was reported at 0.015 MeV, taking values 0.006, 0.005, 0.004, and 0.002 for samples with TiO2, ZnO, BaO, and PbO, respectively. SBT-Pb sample (with PbO) has a thinner HVL compared to other fabricated glass samples. The fabricated glasses’ thickness (Deq) equivalent to 1 cm of lead (Pb) was reported. The results demonstrated that Deq is high at low energy and equals 11.62, 8.81, 7.61, 4.56 cm for SBT-Ti, SBT-Zn, SBT-Ba, and SBT-Pb glass samples, respectively. According to the Deq results, the fabricated glasses have a shielding capacity between 30 and 43% compared to the pure Pb at gamma-ray energy of 1.5 MeV. At high energy (8 MeV), the transmission factor values for a thickness of 1 cm of the fabricated samples reach 88.68, 87.83, 85.95, and 83.11% for glasses SBT-Ti, SBT-Zn, SBT-Ba, and SBT-Pb, respectively.

Method for synthesis of matching devices for broadband radio engineering systems with unstable load impedance based on the method of real frequencies

The aim of this work is to develop a method for the synthesis of matching devices for broadband radio engineering systems with varying impedance in different operating conditions. To achieve this goal, a criterion (complex criterion) is proposed for minimizing the value of the modulus of the sensitivity invariant of the reflection coefficient function to a change in the load impedance with restrictions on the square of the deviation of the power transmission ratio from a given level. It is proposed to use a combination of methods of real frequencies together with the shown complex criterion, which made it possible to implement an effective approach to the synthesis of matching devices for broadband radio engineering systems with an unstable load impedance. To verify the approach, a matching device was synthesized, which made it possible to reduce the loss of the power transmission factor level transmitted to the UHF/VHF antenna of the AD-44 / CW-TA-30-512 range when it is located in various operating conditions by at least 50 % in relation to losses obtained with a standard matching device.

Mitigation strategies and compliance in the COVID-19 fight; how much compliance is enough?

The U.S. with only 4% of the world’s population, bears a disproportionate share of infections in the COVID-19 pandemic. To understand this puzzle, we investigate how mitigation strategies and compliance can work together (or in opposition) to reduce (or increase) the spread of COVID-19 infection. Building on the Oxford index, we create state-specific stringency indices tailored to U.S. conditions, to measure the degree of strictness of public mitigation measures. A modified time-varying SEIRD model, incorporating this Stringency Index as well as a Compliance Indicator is then estimated with daily data for a sample of 6 U.S. states: New York, New Hampshire, New Mexico, Colorado, Texas, and Arizona. We provide a simple visual policy tool to evaluate the various combinations of mitigation policies and compliance that can reduce the basic reproduction number to less than one, the acknowledged threshold in the epidemiological literature to control the pandemic. Understanding of this relationship by both the public and policy makers is key to controlling the pandemic. This tool has the potential to be used in a real-time, dynamic fashion for flexible policy options. Our methodology can be applied to other countries and has the potential to be extended to other epidemiological models as well. With this first step in attempting to quantify the factors that go into the “black box” of the transmission factor β, we hope that our work will stimulate further research in the dual role of mitigation policies and compliance.

The effect of singers masks on the impulse dispersion of aerosols during singing

Background: During the Covid-19 pandemic, singing activities were restricted due to several super-spreading events which have been observed during rehearsals and vocal performances. However, it has not been clarified how the aerosol dispersion, which has been assumed to be the leading transmission factor, could be reduced by masks which are specially designed for singers. Material and Methods: 12 professional singers (10 of the Bavarian Radio-Chorus and two freelancers, 7 females and 5 males) were asked to sing the melody of the ode of joy of Beethovens 9. symphony Freude schoener Goetterfunken, Tochter aus Elysium in D-major without masks and afterwards with five different singers masks, all distinctive in their material and proportions. Every task was conducted after inhaling the basic liquid from an e-cigarette. The aerosol dispersion was recorded by three high-definition video cameras during and after the task. The cloud was segmented and the dispersion was analyzed for all three spatial dimensions. Further, the subjects were asked to rate the practicability of wearing the tested masks during singing activities using a questionnaire. Results: Concerning the median distances of dispersion, all masks were able to decrease the impulse dispersion of the aerosols to the front. In contrast, the dispersion to the sides and to the top was increased. The evaluation revealed that most of the subjects would reject performing a concert with any of the masks. Conclusion: Although, the results exhibit that the tested masks could be able to reduce the radius of aerosol expulsion for virus-laden aerosol particles, there are more improvements necessary to enable the practical implementations for professional singing.

The Role of La2O3 in Enhancement the Radiation Shielding Efficiency of the Tellurite Glasses: Monte-Carlo Simulation and Theoretical Study

The radiation shielding competence was examined for a binary glass system xLa2O3 + (1 − x) TeO2 where x = 5, 7, 10, 15, and 20 mol% using MCNP-5 code. The linear attenuation coefficients (LACs) of the glasses were evaluated, and it was found that LT20 glass has the greatest LAC, while LT5 had the least LAC. The transmission factor (TF) of the glasses was evaluated against thicknesses at various selected energies and was observed to greatly decrease with increasing thickness; for example, at 1.332 MeV, the TF of the LT5 glass decreased from 0.76 to 0.25 as the thickness increased from 1 to 5 cm. The equivalent atomic number (Zeq) of the glasses gradually increased with increasing photon energy above 0.1 MeV, with the maximum values observed at around 1 MeV. The buildup factors were determined to evaluate the accumulation of photon flux, and it was found that the maximum values for both can be seen at around 0.8 MeV. This research concluded that LT20 has the greatest potential in radiation shielding applications out of the investigated glasses due to the glass having the most desirable parameters.

RADIOLOGICAL EVALUATION OF LEAD APRON INTEGRITY IN FIVE SELECTED HOSPITALS IN ABUJA, NIGERIA

Background: The general consensus is that any exposure to ionising radiation carries a risk. Diagnostic radiology is the largest (87%) contributor to man-made ionising radiation, therefore any economical and socially acceptable means of reducing dose without compromising the diagnostic value of the procedure must be worth implementing. Aim: This study is aimed at evaluating lead apron integrity in five selected Hospitals in Abuja, Nigeria. Methodology: The methodology approach includes the application of a large area beam for transmission measurement with the placement of OSLD before and behind the ten (10) lead aprons to determine the entrance and exit dose as well as the transmission factor. In this study, a lead apron consisting of 0.25mm and 0.35mm thickness were examined. Results: The result shows that the transmittance factor of the entrance and exit dose through the lead equivalent aprons is directly proportional to the age of the apron with NHA1 having the highest transmission factor (0.83) and oldest age (16 years). WGH2 has the lowest transfer factor (0.12) and the least age (1 year). Conclusion: Lead aprons loses their attenuation capability over time and should be replaced after 15 years at most for effective protection against ionizing radiation.

ANALYSIS OF CHANGES IN REGULATION OF NATURAL ILLUMINATION IN ACCORDANCE WITH STATE CONSTRUCTION REGULATIONS

This paper presents a novel automated approach and describes in details developed software for problem solution of typical tasks of civil defence concerning assessment of the radiological situation, calculation of impact zone center, determination of transmission factor of multilayered inter-floor covering, determination of potential irradiation exposure of the population and civil defence personnel assets, along with determination of possible duration of people presence on contaminated ground. Developed software confers a possibility to determine borders of destruction zones, dimensions of fire areas, automatically construct a graph of nuclear destruction center, areas of destruction zones, determine excessive pressure on the territory of the object, destruction level of object elements, areas of destruction zones, in which the object is located, population number and deaths within destruction borders in accordance with standard methodology. Based on carried out research findings it was determined that developed software boosts solution of typical civil defence problems concerning assessment of the radiological situation approximately by ten times and increases computational accuracy by 10% owing to the absence of approximation during calculation conduction. Furthermore, such software can be used for simplification of students’ papers grading by lecturers during their taking a subject of Civil defence. Described software can be used not only as part of educational process of Civil defence subject, but also by corresponding dedicated government agencies in the matter of civil defence for prompt and accurate assessment of radiological situation and calculation of irradiation exposure of the population in regions.

Gamma Ray Shielding Properties of Yb3+-Doped Calcium Borotellurite Glasses

This research work aims to investigate the radiation shielding ability of a Yb3+-doped calcium borotellurite glass system. The system has the basic composition of CaF2–CaO–B2O3–TeO2–Yb2O3 but is denoted as TeBYbn for simplicity. The effect of increasing the TeO2 content in the glasses from 10 to 54 mol% was investigated, with five different chosen compositions and densities. The Phy-X/PSD program was used to investigate the mass attenuation coefficient (µ/ρ) of the samples. The mass attenuation coefficients were theoretically determined by using an online software for the calculation of shielding parameters. Other parameters were then calculated and analyzed, such as the linear attenuation coefficient (µ), transmission factor (TF), radiation protection efficiency (RPE), effective atomic number (Zeff), and mean free path (MFP). TeBYb5, the glass with the greatest TeO2 content, was shown to have the greatest µ/ρ; however, at greater energies, the differences between the values are practically negligible. µ was shown to increase with density, such as from 0.386 cm−1 to 0.687 cm−1 for TeBYb1 and TeBYb5 at 0.284 MeV, respectively. The least TF was found for samples with a thickness of 1.5 cm, proving an inverse correlation between the thickness of the sample and the TF. The HVL and TVL of the glasses decreased as the density of the samples increased, which means that TeBYb1 is the least effective out of the investigated glasses. The five samples proved to have a lower MFP than some other shielding glasses, demonstrating their capabilities as radiation shields. Based on the calculated parameters, TeBYb5 indicated the greatest photon attenuation ability.