Branislav Jeremic

Electromagnetic field investigation on different cancer cell lines

BackgroundThere is a strong interest in the investigation of extremely low frequency Electromagnetic Fields (EMF) in the clinic. While evidence about anticancer effects exists, the mechanism explaining this effect is still unknown.MethodsWe investigated in vitro, and with computer simulation, the influence of a 50 Hz EMF on three cancer cell lines: breast cancer MDA-MB-231, and colon cancer SW-480 and HCT-116. After 24 h preincubation, cells were exposed to 50 Hz extremely low frequency (ELF) radiofrequency EMF using in vitro exposure systems for 24 and 72 h. A computer reaction-diffusion model with the net rate of cell proliferation and effect of EMF in time was developed. The fitting procedure for estimation of the computer model parameters was implemented.ResultsExperimental results clearly showed disintegration of cells treated with a 50 Hz EMF, compared to untreated control cells. A large percentage of treated cells resulted in increased early apoptosis after 24 h and 72 h, compared to the controls. Computer model have shown good comparison with experimental data.ConclusionUsing EMF at specific frequencies may represent a new approach in controlling the growth of cancer cells, while computer modelling could be used to predict such effects and make optimisation for complex experimental design. Further studies are required before testing this approach in humans.

Locating and clamping of complex geometry workpieces with skewed holes in multiple-constraint conditions

Purpose – The purpose of this paper is to propose a general model for locating and clamping workpieces of complex geometry with two skewed holes under multiple constraints. Design/methodology/approach – Numerous constraints related to application of the proposed model are discussed as prerequisite to design of fixture solution. Based on theoretical model, a fixture was designed and successfully tested in experimental investigation. Experimental results were also verified using FEM simulations. Findings – This study showed that, opposed to conventional approach, novel solution results in significantly smaller fixture dimensions, while providing greater stability. Insertion of mandrels and supports element sub-assemblies into the workpiece holes significantly increases workpiece stiffness through an increased moment of inertia, while the internal support elements largely diminish the problem of thin wall deformation in the workpiece. Practical implications – The fixture designed in this case was actually us...

Towards continuous and real-time attention monitoring at work: reaction time versus brain response

Abstract Continuous and objective measurement of the user attention state still represents a major challenge in the ergonomics research. Recently available wearable electroencephalography (EEG) opens new opportunities for objective and continuous evaluation of operators’ attention, which may provide a new paradigm in ergonomics. In this study, wearable EEG was recorded during simulated assembly operation, with the aim to analyse P300 event-related potential component, which provides reliable information on attention processing. In parallel, reaction times (RTs) were recorded and the correlation between these two attention-related modalities was investigated. Negative correlation between P300 amplitudes and RTs has been observed on the group level (p < .001). However, on the individual level, the obtained correlations were not consistent. As a result, we propose the P300 amplitude for accurate attention monitoring in ergonomics research. On the other hand, no significant correlation between RTs and P300 latency was found on group, neither on individual level. Practitioner Summary: Ergonomic studies of assembly operations mainly investigated physical aspects, while mental states of the assemblers were not sufficiently addressed. Presented study aims at attention tracking, using realistic workplace replica. It is shown that drops in attention could be successfully traced only by direct brainwave observation, using wireless electroencephalographic measurements.

Rolling resistance as the risk factor for fuel consumption

This paper describes a methodical aspect for tyre rolling resistance force measuring and calculating during driving at constant speed, which has been developed at the Institute of Automobiles in Kragujevac in cooperation with faculty of Mechanical Engineering, Kragujevac. The main goal of this paper is to observe the influence of tyre pressure on a vehicles dissipative energy, that is, fuel consumption. Besides the influence on fuel economy, tyre pressure is also of significant importance for vehicle stability during cornering and braking, hence tyre pressure might be considered as a multiple risk factor. To measure the vehicles speed, the DATRON measuring system has been used, while for data acquisition and calculation of rolling resistance force and corresponding power a portable computer and software developed in the Institute of Automobiles was used. Fuel consumption was measured through a series of tests, performed at several different tyre pressures.

Benefits of Instructed Responding in Manual Assembly Tasks: An ERP Approach

The majority of neuroergonomics studies are focused mainly on investigating the interaction between operators and automated systems. Far less attention has been dedicated to the investigation of brain processes in more traditional workplaces, such as manual assembly, which are still ubiquitous in industry. The present study investigates whether assembly workers’ attention can be enhanced if they are instructed with which hand to initiate the assembly operation, as opposed to the case when they can commence the operation with whichever hand they prefer. For this aim, we replicated a specific workplace, where 17 participants in the study simulated a manual assembly operation of the rubber hoses that are used in vehicle hydraulic brake systems, while wearing wireless electroencephalography (EEG). The specific EEG feature of interest for this study was the P300 components’ amplitude of the event-related potential (ERP), as it has previously been shown that it is positively related to human attention. The behavioral attention-related modality of reaction times (RTs) was also recorded. Participants were presented with two distinct tasks during the simulated operation, which were counterbalanced across participants. In the first task, digits were used as indicators for the operation initiation (Numbers task), where participants could freely choose with which hand they would commence the action upon seeing the digit. In the second task, participants were presented with arrows, which served as instructed operation initiators (Arrows task), and they were instructed to start each operation with the hand that corresponded to the arrow direction. The results of this study showed that the P300 amplitude was significantly higher in the instructed condition. Interestingly, the RTs did not differ across any task conditions. This, together with the other findings of this study, suggests that attention levels can be increased using instructed responses without compromising work performance or operators’ well-being, paving the way for future applications in manual assembly task design.

An implementation of infrared thermography in maintenance plans within a world class manufacturing strategy

The objective of the paper is to show the implementation of infrared thermography within World Class Manufacturing (WCM) maintenance strategy. The results from infrared thermography inspections in a food processing and packaging solutions company were presented. Applicability of the infrared thermography, during a two-year period, caused a substantial reduction the potential breakdown in the pilot area. Upon feasibility confirmation, the proposed method was spread to other production equipment of the company.

Static Friction at High Contact Temperatures and Low Contact Pressure

The problem of measuring static friction at high temperatures and low contact pressures is theoretically analyzed, as well as the instruments for the accurate determination of the coefficient of static friction at high temperatures for contact pairs made of steel and bronze. The results of experimental investigation show that at low contact pressure and temperature above 120°C coefficient of static friction dramatically increases. This increase in the coefficient of friction can be of great practical value with regard to the load capacity of contacts where external forces are balanced with friction forces.

Continuous controllable balloon dilation: a novel approach for cervix dilation

BackgroundCervical dilation using mechanical dilators is associated with various complications, such as uterine perforation, cervical laceration, infections and intraperitoneal hemorrhage. To achieve safe and painless cervical dilation, we constructed a new medical device to achieve confident mechanical cervical dilation: a continuous controllable balloon dilator (CCBD).MethodsControlled pumping of incompressible fluid into the CCBD increases the pressure and outer diameter of the CCBD, continuously dilating the cervical canal. The reliability of the CCBD was confirmed in vitro (testing for consistency and endurance, with no detected risk for breakage) and in vivo. A multi-center clinical study was conducted,with 120 pregnant women randomly assigned to one of three groups: Group I,control group, no dilation;Group II,mechanical dilation, Hegar dilator (HeD); and Group III,CCBD. The tissue material for histological evaluation was obtained from the endocervical mucosa before and after dilation using the HeD or CCBD.ResultsThe CCBD dilations were successful and had no complications in all 40 patients of Group III. The cervical tissue was markedly less damaged after CCBD dilation compared with HeD dilation (epithelium damage: 95% (HeD) vs. 45% (CCBD), P <0.001; basal membrane damage: 82.5% (HeD) vs. 27.5% (CCBD), P <0.001; stromal damage: 62.5% (HeD) vs. 37.5% (CCBD), P <0.01). Cervical hemorrhagia was observed in 90% of the patients after HeD dilation versus in 32.5% of the patients after CCBD dilation.ConclusionsThe CCBD should be used as a replacement for mechanical dilators to prevent uterine and cervical injury during cervical dilation.Trial registrationISRCTN54007498

Muscle strength measurement of pelvic floor in women by vaginal dynamometer

INTRODUCTION The pelvic floor is made of a mutually connected system that consists of muscles, connecting tissue and nerve components. Damage to any of these elements creates dysfunction which is exerted through stress, urinary incontinence, prolapse of genital organs and faecal incontinence. OBJECTIVE The primary aim of this study was to present the possibility of objective assessment of pelvic floor muscle force in healthy and sick women using a newly designed instrument, the vaginal dynamometer, as well as to establish the correlation between the values of pelvic floor muscle force obtained by the vaginal dynamometer and digital palpation method. METHODS The study included 90 female patients, age 20-58 years. One group of respondents was made of healthy women (who gave birth, and those who have not given birth), while the other one consisted of sick women (who suffered from incontinence or prolapse of genital organs, operated on or not). The pelvic floor muscle strength of every woman was measured with a newly-constructed device for measuring and monitoring of the pelvic floor muscle force in women, the vaginal dynamometer. Then it was compared with the valid clinical digital palpation (palpation with two fingers) based on the scale for measuring muscle contractions with the digital palpation - the digital pelvic assessment rating scale. The vaginal dynamometer consists of a redesigned speculum which is inserted into the vagina and a sensor for measuring the force. RESULTS Statistically significant linear correlation was found in the values of the measured muscle force with the vaginal dynamometer and ratings produced by digital palpation (r = 0.92; p < 0.001). Mean value of the muscle force of the healthy women measured by the vaginal dynamometer was 1.44 +/- 0.38 daN and that value of the sick women was 0.78 +/- 0.31 daN (t = 8.89 for df = 88; p < 0.001). Mean value of the ratings produced by digital palpation in healthy women was 4.10 (95% of trust limits 3.83-4.37), while the value in sick women was 2.41 (95% of trust limits 2.10-4.16) (Z = -6.38; p < 0.001). CONCLUSION The vaginal dynamometer has been presented as an attempt to overcome the limitations of the previously presented techniques for muscle force measurement. The application of the vaginal dynamometer in clinical practice makes objective and numerical assessment of pelvic floor muscle force possible, independent of the subjective assessment of the examiner. The usage of this instrument enables not only the diagnostics of womens pelvic floor muscle problem, but also the objective monitoring of rehabilitation gynaecological medicine results.

Occupational safety and health education under the lifelong learning framework in Serbia

Serbia is aligning with European Union requirements and the occupational safety and health (OSH) administration is one of the most representative sectors of this alignment. Many efforts were made in this field, by introducing new laws and regulations, but it turned out to be insufficient. OSH professionals need to renovate and strengthen their knowledge in accordance with continuous, updated and improved OSH standards and regulation. Lifelong learning (LLL) programmes can contribute to forming professionals who are always up to date. This paper presents an implemented LLL programme, over the duration of two academic years, dedicated to OSH professionals, and investigates whether this programme will be helpful and accepted by professionals. The results from the study show that the given LLL programme had indeed a positive influence on the professional careers of the participants and that the LLL presents the future trend in OSH education.