Photoelastic Properties of Trigonal Crystals

All possible experimental geometries of the piezo-optic effect in crystals of trigonal symmetry are studied in detail through the interferometric technique, and the corresponding expressions for the calculation of piezo-optic coefficients (POCs) πim and some sums of πim based on experimental data obtained from the samples of direct and X/45°-cuts are given. The reliability of the values of POCs is proven by the convergence of πim obtained from different experimental geometries as well as by the convergence of some sums of POCs. Because both the signs and the absolute values of POCs π14 and π41 are defined by the choice of the right crystal-physics coordinate system, we here use the system whereby the condition S14 > 0 is fulfilled (S14 is an elastic compliance coefficient). The absolute value and the sign of S14 are determined by piezo-optic interferometric method from two experimental geometries. The errors of POCs are calculated as mean square values of the errors of the half-wave stresses and the elastic term. All components of the matrix of elasto-optic coefficients pin are calculated based on POCs and elastic stiffness coefficients. The technique is tested on LiTaO3 crystal. The obtained results are compared with the corresponding data for trigonal LiNbO3 and Ca3TaGa3Si2O14 crystals.

Age and gender characteristics of thoracic aorta elasticity indices in patients with coronary atherosclerosis

Background. Ischemic heart disease (CHD) holds a leading position in the structure of causes of general mortality and in the structure of mortality from cardiovascular diseases. We extended the standard echocardiography with assessment of thoracic aorta elasticity to identify markers of the thoracic aorta elasticity worsen associated with coronary atherosclerosis. When analyzing the data, we identified different clinical characteristics of study participants as one of the main reasons for the difficulty in comparing the data with the results of previous studies, which made it necessary to highlight age and gender characteristics of indicators.Aim. To analyze age and gender characteristics of thoracic aorta elasticity indices in patients with coronary atherosclerosis.Material and methods. An observational analytical cross- sectional clinical trial was conducted from 2016 to 2019. Our study included 109 patients aged 39 to 82 years (mean age 65 ± 9 years, median 66 years), who were divided into 2 groups according to the results of invasive coronarography: 64 patients with coronary atherosclerosis and 45 patients without angiographic signs of coronary atherosclerosis. In the group with coronary atherosclerosis average age was 66 ± 8 years (median 66 years). In the group without coronary atherosclerosis average age was 64 ± 9 years (median 66 years). During transthoracic echocardiography, the following were obtained: coefficient of distensibility, compliance coefficient, elasticity (stiffness) module of Peterson, stiffness index of the ascending thoracic aorta; systolic velocity S, early diastolic velocity E, late diastolic velocity A of the near wall of the ascending aorta, flow velocity propagation (FVP) of the descending thoracic. Analysis of age and gender characteristics of thoracic aorta elasticity indices in patients with coronary atherosclerosis was done.Results. An increase in the stiffness index of the ascending thoracic aorta associated with coronary atherosclerosis occurs in the age group 39–66 years, a decrease in the coefficients of extensibility and compliance, an increase in Peterson’s modulus of elasticity (stiffness) of the as cending thoracic aorta — in the age group 67–82 years. A decrease in the E velocity of the near wall of the ascending thoracic aorta and FVP, associated with coronary atherosclerosis, occurs regardless of belonging to the age group, a decrease in the S velocity — in the age group 39–66 years. A decrease in the compliance coefficient of the ascending thoracic aorta, velocity S of the near wall of the ascending thoracic aorta, associated with coronary atherosclerosis, occurs only in men, an increase in the stiffness index — only in women. A decrease in the extensibility coefficient, an increase in the Peterson’s modulus of elasticity (stiffness), a decrease in the E velocity, and a decrease in CRP associated with coronary atherosclerosis occur regardless of gender.Conclusion. Worsening of the thoracic aorta elasticity in patients with coronary atherosclerosis, assessed using echocardiographic technologies, depends on gender and age.

DEVELOPMENT OF METHODOLOGY FOR TRANSPORTATION FLEET STRUCTURE FORMATION

The paper proposes a methodology for transportation fleet structure formation based on the determination of the standard size fleet by carrying capacity using the criterion of the cost of transportation of 1 ton of cargo, which will be expedient if the number of shipments per day exceeds three times the estimated number of the model range of cars. At a lower intensity of daily shipments, it is necessary to form a standard size range of a vehicle fleet on the basis of a repetition of independent tests. The paper proposes a method of forming the structure of the fleet of vehicles based on determining the size of the fleet using the criterion of the cost of transportation of 1 ton of cargo, which is appropriate if the number of shipments per day exceeds three times the estimated number of cars. With a lower intensity of daily shipments, it is necessary to form a standard size range of the fleet on the basis of repeating independent tests.It has been established that the value of the coefficient of static use of the vehicle's carrying capacity is influenced by the number of intervals for dividing the series of carrying capacity, their length and uniformity, as well as the distribution law of the random value of the item. Violation of the uniformity of the intervals of the series of the carrying capacity of the car, the value of the coefficient can deviate from the average to 6.2% An increase in the number of intervals in a number of carrying capacities of vehicles from 2 to 3 contributes to a rapid increase in the coordination of the density of distribution of the batch volume and shipment to the structure of the vehicle fleet in terms of carrying capacity and is characterized by an increase in the coefficient of compliance on average from 0.65 to 0.75. An increase in the range of carrying capacity up to interval 5 increases the value of the compliance coefficient to 0.8, a further increase in the intervals causes an inversely proportional increase in the compliance coefficient. An increase in the number of car models from 1 to 3 causes a decrease in the cost of transportation in the range of 8% - 11.3%, depending on the degree of use of the vehicle fleet. Further expansion of the model range to 7 units practically does not affect the cost of transportation, and then its growth is observed due to an increase in the duration of downtime while waiting for the proper consignment. It was revealed that an increase in the average weight of a shipment by 2.3 times causes a decrease in the cost of transportation 1.79 times, and with this decrease in the weight of a shipment, an increase in the intensity of growth in the cost of transportation is observed.

Poziom wiedzy i nawyki personelu jako czynniki wpływające na poprawność realizacji higieny rąk w obszarze medycznym

Hand hygiene continues to be the most important part of the strategy to combat healthcare associated infections and the first step in reducing them. Hand hygiene procedures are fully performed by less than half of healthcare workers and research confirms a low compliance coefficient for hygiene (at the level of 1.4–6). The list of factors influencing the adherence to hand hygiene routine protocols (as per WHO guidelines) includes factors related to poor hand hygiene practices, poor hand hygiene practices reported by staff and additional perceived obstacles to good hand hygiene. The following are the barriers and reasons why healthcare workers do not sufficiently adhere to the correct technique of washing and disinfecting hands: forgetting to perform this procedure, excessive workload, haste during routine care activities, lack of a pattern of behavior among other employees and superiors, lack of habits, as well as a shortage of disinfectants and disposable towels in patient rooms, or irritation of the skin of the hands caused by the disinfectant. To sum up, it can be concluded that hand hygiene is and will be an issue that requires continuous action and permanent education of healthcare personnel and recipients of healthcare services. The list of factors causing poor hand hygiene is quite long. It includes, among others, the level of knowledge and habits of medical personnel and requires constant updating, as in the place of confirmed and verified reasons for low rates, newer ones which are specific for the current situation, will appear.

Response of structure models to sinusoidal dynamic action

The use of small-sized models of structures printed on 3-D printers is possible due to the electroelastic properties of ABS plastic. A comparison of their reactions with analogs made of plexiglas, used in studies of concrete structures, was made. The influence of the environment - water or sea sand, support conditions - free support or pinching, shape - simple or complex in planon the response of models from two different materials was investigated. The laboratory setup simulated a dynamic sinusoidal effect using: a digital frequency generator from 1 to 10000 Hz, an acoustic system diffuser, a microphone amplifier, two electrodes, and a computer in a two-channel oscilloscope mode. The vibration characteristics at the base and top of the models were recorded. The experimental system turned out to be sensitive to the shape, methods of fastening elements, the structure as a whole, and the medium of wave propagation. The response was analyzed in terms of the dynamic compliance coefficient and resonance frequencies, reflecting the similarity of the responses of the plexiglas and ABS models. Printing will allow you to adjust the shape and connections of the elements of the models so that they work like mechanical resonators – filters - in a narrow band. No resonances are expected outside this band. In the operated structures, the quality of the element connections is reproduced. Changing the existing rigidity to obtain resonances in a narrow band can serve as a criterion for choosing an effective amplification method.

Infinite Kirchhoff plate on a compact elastic foundation may have arbitrary small eigenvalue

An inhomogeneous Kirhhoff plate composed from semi-infinite strip-waveguide and a compaсt resonator which is in contact with the Winkler foundation of small compliance, is considered. It is shown that for any 0, it is possible to find the compliance coefficient O(2) such that the described plate possesses the eigenvalue 4embedded into continuous spectrum. This result is quite surprising because in an acoustic waveguide (the spectral Neumann problem for the Laplace operator) a small eigenvalue does not exist for any unsubstantial perturbation. A reason of this dissension is explained as well.

AORTIC ELASTICITY AND ENDOTHELIUM MOTOVASCULAR FUNCTION IN PRIMARY HYPOTHYROIDISM

Objective.To compare aortic elasticity and vasomotor endothelial function in hypertensive and normotensive patients with decompensated primary hypothyroidism (PHT) and after medical compensation. Design and methods. 41 women with PHT were examined, 23 (56 %) subjects had concomitant hypertension. Elasticity of aorta was evaluated by compliance coefficient (CC) and pulse wave velocity (PWV), state of vasomotor endothelial function — by vasodilatation coefficient (VDC). Patients were examined twice: during decompensation and after medical compensation.Results. Mean values of CC in patients with decompensated PHT were 2,27 (95 % confidence interval 1,53–3,01) and 2,23 (1,78–2,67) mm2/mm Hg in hypertensives and normotensive, respectively, PWV — 12,2 (10,4–13,9) and 12,9 (11,8–14,0) m/s, VDC — 4,51 (2,91–6,11) and 3,72 (2,06–5,37) CU, respectively (all p > 0,05). Compensation of PHT led to the CC increase up to 4,69 (4,13–5,24) and 4,66 (3,96–5,36) mm2/mm Hg, PWV patients till 8,85 (6,77–10,9) and 7,40 (6,68–8,11) m/s, VDC increase up to 10,7 (9,27–12,2) and 8,94 (7,81–10,1) CU (all p < 0,05).Conclusion. Compensation of PHT is accompanied by improvement of aortic elasticity and vasomotor endothelial function. There are no differences in aortic elasticity and vasomotor endothelial function in hypertensive and normotensive patients during decompensation and after euthyroid state achievement.

The Influence of Multiple Piezoelectric Effects on Elastic Coefficient of Piezoelectric Ceramics

The development of new materials and the performance improvement of existing materials become an important subject from different aspects. In this paper, based on the theoretical research results of multiple piezoelectric effects, the influence of multiple piezoelectric effects on elastic coefficient of piezoelectric ceramics is studied. Theoretical analysis indicates that it is multiple piezoelectric effects that make piezoelectrics have two kinds of elastic and they result in the decrease of elastic compliance coefficients. Experimental validation is performed through PZT-5. Experimental results show that elastic compliance coefficient grows decreased by 0.912 times.