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Background: In Multilevel Inverters (MLI) as the number of level increases, there is a proportionate increase in the count of the semiconductor devices that are employed. Methods: This paper deals with an asymmetrical cascaded H-bridge inverter topology with half bridge cells to produce seven level output voltage waveform. Nearest Level Control (NLM) technique is used to produce the switching pulses. The operating principle of the proposed MLI and its performance abilities is verified through MATLAB/Simulink and a prototype is developed to provide the experimental results. Results: Total Harmonic Distortion (THD) is computed for proposed MLI for different types of loads in simulation environment as well as in the developed hardware prototype. Comparison between the proposed MLI and recent topologies demonstrates the advantageous features. Conclusion: The simulation and hardware results confirm the suitability of the proposed seven level MLI as the total component count, and the requirement of DC sources reduces considerably.

The aim of our study was to evaluate the association between levels of blood and urinary cadmium and lipid balance in a group of outdoor workers. The study was conducted on a group of 146 individuals (average age 45,1 ± 8,5). Blood and urinary samples were collected for the detection of total cholesterol, HDL cholesterol, LDL cholesterol, triglycerides, blood cadmium and urinary cadmium. We divided the group of workers into two subgroups according to the task:75 traffic policemen and 71 police drivers. Gender differences were found. The Pearson correlation coefficient showed a positive association between blood and urinary cadmium levels and total cholesterol, LDL and triglycerides levels. Total cholesterol, LDL cholesterol and triglycerides were significantly higher in the group of traffic policemen than in police drivers. In conclusion, the results suggest a statistically significant association between blood and urinary cadmium levels and lipid balance contributing to an increase of the cardiovascular risk.

The aim of the present study is to evaluate whether workers in the sanitary fixtures industry are a category at risk of developing cardiovascular diseases, and in particular, whether chronic noise exposure may play a role in cardiovascular effects in exposed workers. Seventy-five employees engaged in sanitation fixtures production and a control group of sixty-four office workers, who were not exposed to agents that could damage the cardiovascular system, participated in our study. The selected workers completed a clinical-anamnestic questionnaire, and underwent a medical examination, blood pressure test, electrocardiogram (ECG), blood tests, and audiometry. Measurements of environmental noise, dust, and lead were also carried out. The exposed workers, in comparison to the control group, showed a higher frequency of hypertension, systolic and diastolic blood pressure (p

The literature suggests that farmers nowadays are more likely to contract cardiovascular diseases than in the past. This study involved 79 farmers and 64 controls. The workers completed a questionnaire to identify exclusion factors for audiological and cardiovascular risk factors. The participants underwent medical examination, measurement of blood pressure, electrocardiogram, blood tests, audiometry, and measurement of noise exposure. The farmers were found to have a higher prevalence of systolic and diastolic arterial hypertension as well as electrocardiogram (ECG) abnormalities compared with the controls. A significant prevalence of arterial hypertension was detected in the farmers exposed to noise, when compared with those who were not exposed. These results suggest that farmers are at risk of cardiovascular effects and that noise is a cardiovascular risk factor for farmers.

In the assessment of work-related stress it is crucial to find the factors that generate and increase it in order to identify categories of individuals at risk, to plan interventions for prevention, elimination or reduction of risk. The aim of the study is to assess the subjective stress in 68 workers of a large Italian company dealing with human health, through the use of a questionnaire-indicating tool, elaborated by the Italian National Institute for insurance against accidents at work (INAIL) and developed by the Health and Safety Executive (HSE).We studied a final sample of 68 individuals (34 drivers/rescuers and 34 video display unit (VDU) operators). The questionnaire consists of 35 items (divided into six areas) with five possible answers each, that cover working conditions considered potential causes of stress.The drivers/rescuers had a better performance than the VDU operators, especially in the areas "demand", "relationships" and "role". We compared men and women in the two groups, finding that, in VDU operators, women had a better performance than men in all areas, except "role" and "changes", in which the overall scores were the same in men and women. In the drivers/rescuers women showed more critical scores in the items "relationships" and "change".The results show that: the questionnaire-indicating tool is useful, with a demonstrated effectiveness for the occupational physician during the visits and proven validity; additional future efforts should focus on understanding the psycho-social, organizational and individual problems related to stress and the consequent implementation of preventive measures.

Aim: The purpose of this study was to evaluate spirometric lung function parameters in the general population exposed to urban pollution and confirm the existence of an association between exposure to environmental pollutants and effects from these products and which respiratory parameters are associated to urban pollution in general population. Methods: This study is a systematic research of all articles on the assessment of respiratory effects on general population exposed to urban pollution, excluding studies on adolescents and children. The research included articles from January 2008 to May 2009. In the articles included in our meta-analysis, the exposed group is represented by general population aged between 15 and 75 years for both genders, resident in very polluted urban areas, while the control group is represented by general population resident in rural and suburban areas, where pollution is lower. Results: The results confirm the presence of statistically significant effects of urban pollution on the respiratory system for cough, phlegm, shortness of breath/breathlessness, wheezing, FVC, FEV1, PEFR, chronic bronchitis, bronchial asthma, rhinitis, emphysema.