Aiškinti pokyčius yra įdomus ir rizikingas užsiėmimas. Dalis pokyčių gali būti apskaičiuojami. Taip veikia, pavyzdžiui, matematikos dėsniai. Dalis pasikeitimų gali būti nuspėjami – todėl mus vilioja ...loterijos ir įvairūs stebuklai. Tačiau didžiausiais stebuklas – mūsų pačių gyvenimas. Jis sunkiai telpa į apskaičiavimus ir spėjimus. Dar didesnė nuostaba apima, kai pradedi mąstyti apie pokyčius, apimančius ne vieno žmogaus, o kartos, amžiaus, tūkstantmečio įvykius.
The option of spectral-acoustic method for coal seam outburst danger prediction based on the influence of outburst danger basic factors on the amplitude-frequency characteristic of acoustic vibration ...median formed when breaking the rock massif by the operating mining equipment is justified. Basic outburst danger factors are: rock pressure, in-situ gas pressure, coal strength.
Abstract
Basic requirements to the methods of current outburst danger prediction are formulated. The methods must be applied in the process of mining not interfering with the works and taking into ...account basic factors that cause the outbursts and they should have scientifically grounded methodology for fast definition of outburst danger criteria under certain mining, geological and engineering conditions. It is shown that geophysical prediction methods can meet the first requirement. Rock pressure, in-situ gas pressure and coal strength are taken as basic factors of outburst danger. Some well-known geophysical method such as a method of acoustic emission, a spectral-acoustic method, a gas analytical method and a temperature method taken separately do not satisfy the second and the third requirements. That is why it is suggested controlling rock pressure by spectral-acoustic method, gas pressure by means of gas analyser on methane concentration at the face of the working while mining coal and coal strength should be measured by a strength measuring device. To improve the accuracy of the prediction a version of spectral-acoustic method based on dependency of amplitude-frequency characteristic median of mining operating equipment noise on average stresses at the section between the source of the noise and geophone. The criterion of outburst danger is substantiated and the algorithm for arranging automated monitoring of coal seam outburst danger is offered.
Hypertension is a leading risk factor for cardiovascular events and death. A reduction in salt intake is among the most cost-effective strategies to reduce blood pressure and the risk of ...cardiovascular diseases. Increasing potassium lowers blood pressure and is associated with lower cardiovascular risk. Adequate iodine intake is important to prevent iodine deficiency disorders. Salt iodization is a key strategy to prevent such deficiency. In Lithuania, no surveys have been performed to directly assess sodium, potassium and iodine consumption. The aim of the present study was to measure sodium, potassium and iodine intake in a randomly selected adult Lithuanian adult population using 24 h urine collections, and to assess knowledge, attitudes and behavior towards salt consumption. Salt and potassium intakes were estimated in 888 randomly selected participants by 24 h urine sodium and potassium excretion and 679 individuals provided suitable 24 h urine samples for the analysis of iodine excretion. Average salt intake was 10.0 (SD 5.3) g/24 h and average potassium intake was 3.3 (SD 1.3) g/24 h. Only 12.5% of participants consumed less than 5 g/24 h of salt. The median value of urinary iodine concentration (UIC) was 95.5 μg/L. Our study showed that average salt intake is twice as high as the maximum level recommended by the World Health Organization while potassium and iodine intakes in Lithuania are below the recommended levels.
A number of tasks for improving the spectral-acoustic method for forecasting dynamic phenomena and controlling stress condition in coalmines is considered. They are: considering the influence of a ...gas factor on the danger indicator, dependence of a relative pressure coefficient on the distance between the source and the receiver of the probing acoustic signal, correct selection of operating frequencies, the importance of developing the techniques for defining the critical value of the outburst danger index The influence of the rock mass stress condition ahead of the preliminary opening face on the relative pressure coefficient defined for installing the sound receiver in the wall of the opening behind the opening face is also justified in the article.
The options of applying spectral-acoustic method of controlling stress state of a rock massif for preventing dynamic phenomena are analyzed in the paper. Two options are based on the dependence of ...relationship of high and low frequencies amplitudes of acoustic signal spectrum of operating equipment on a stress state of a massif in the area between the generator and the receiver of the sound. The difference between these two options is in choosing between high-frequency and low-frequency areas of a source sound spectrum. The drawback of both is in failure to use the whole spectrum of a sound that may cause the error in controlling stress state. To correct this drawback a modified option for applying the method based on the dependence of the median of amplitude and frequency characteristics of a sound on actual stresses is justified. The results of testing the method for controlling stress state of a working face space of a stope in the process of a hard roof directional hydraulic fracturing by hardwaresoftware complex based on RIPAS apparatus are introduced.
To control and manage a stress state of an underground working face space it is important to measure the components of actual stresses. Traditional method for relieving a core-sample with central ...drill is time and labour consuming and is characterized by a lack of accuracy. To improve these issues geophysical methods which do not interfere with mining are to be used for controlling stress state. Acoustic methods are less time and labour consuming. Justification of spectral-acoustic method modification for controlling stress state of a face space is introduced. It is done on the basis of the dependence of the acoustic signal of the operating equipment amplitude-frequency response median on average stresses. The acoustic signal is recorded in the entire sensitivity band of the geophone. The description of a flow chart and operating principle of intrinsically safe portable device for implementing the modification in mines on the seams dangerous on gas and dust and prone to sudden coal and gas outbursts and rock bursts are given. The device operates in three modes: determining amplitudes of background noise and setting signal amplification coefficient; controlling stress state while generating continuous acoustic signal produced by operating mining equipment (combined machine, drilling device, plough-type machine) into the massif; control of stress state during generation a discrete acoustic signal produced by artificial source (heavy hammer strokes) into a massif.
Antimicrobial-resistant pathogens have reached alarming levels, becoming one of the most pressing global health issues. Hence, new treatments are necessary for the fight against antimicrobial ...resistance. Synthetic nanoengineered antimicrobial polymers (SNAPs) have emerged as a promising alternative to antimicrobial peptides, overcoming some of their limitations while keeping their key features. Herein, a library of amphiphilic oxazoline-based SNAPs using cationic ring-opening polymerization (CROP) is designed. Amphipathic compounds with 70% cationic content exhibit the highest activity against clinically relevant Staphylococcus aureus isolates, maintaining good biocompatibility in vitro and in vivo. The mechanism of action of the lead compounds against S. aureus is assessed using various microscopy techniques, indicating cell membrane disruption, while the cell wall remains unaffected. Furthermore, a potential interaction of the compounds with bacterial DNA is shown, with possible implications on bacterial division. Finally, one of the compounds exhibits high efficacy in vivo in an insect infection model.
This paper presents the findings of a research project aimed at reconstructing the subsistence
economy of the Late Bronze Age communities in eastern Lithuania. We focused on examining
...archaeobotanical and zooarchaeological assemblages from three hillforts alongside δ13C and δ15N
stable isotope analysis of plant and animal remains. Our results suggest that local populations
primarily relied on growing domestic plants and animals for their subsistence. By the Late Bronze
Age, they had already adopted a diverse package of cultivated plants, with barley and millet being
the main crops. Also, inhabitants relied on pig and goat/sheep as a primary source for their
protein intake. Finally, δ13C and δ15N measurements suggest that farmers engaged in intensive
agriculture with semi-permanent field systems and moderate application of manure.
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