ESS - FIS - Comunicações em eventos científicos
Permanent URI for this collection
Browse
Recent Submissions
- The influence of job rotation on wrist position sense: a preliminary study among assembly workers in a real-life occupational settingPublication . Santos, Joana; Mesquita, Inês; Monteiro, Pedro; Santos, Rubim; Baptista, João Santos; Vaz, MárioThe effectiveness of job rotation in industrial environment is still controversial, namely during tasks with high functional similarity, as assembly tasks. Thus, the aim of this study was to investigate the influence of job rotation on wrist position sense acuity among experienced assembly workers. Eight healthy assembly workers divided in two groups (four assembly workers performed task rotation and four assembly workers performed tasks with no rotation) participated in this field study. Manifestations of muscle fatigue of wrist flexors and extensors muscles were obtained by surface electromyography during a standardized test contraction, while wrist position sense errors were assessed by electrogoniometry. After a workweek, d espite not statistically significant, wrist flexors muscles in the no rotation group showed EMG signs of fatigue. The two groups showed a trend to increase position error for flexion after a workweek. Future research should include a higher number of participants and other techniques to evaluate muscle fatigue and their impact on positon sense acuity.
- Manifestations of muscle fatigue during repetitive low-moderate intensity work: a brief reviewPublication . Santos, Joana; Monteiro, Pedro; Miguel, Alberto Sérgio; Santos, Rubim; Baptista, J. Santos; Vaz, MárioMuscle fatigue is a complex phenomenon that has been suggested to be an important precursor for work-related upperlimb musculoskeletal disorders. The assembly work is an example of low-moderate intensity work with elevated risk of muscle fatigue development. This review was performed to summarise and analyse the studies that investigated the influence of work requirements on muscle fatigue development in workplaces or experimental setting. This review was based on relevant articles published from 2000 to 2013 in the research platform Web of Knowledge. The studies included in this review were performed in humans and assess peripheral muscle fatigue in upper limbs during occupational activities. The search yielded 103 articles and 10 were included, according to inclusion criteria. Few studies were conducted in real work environment and the most common methods used to assess muscle fatigue were surface electromyography (EMG). The work duration and intensity level were the determinants of muscle fatigue that had more consistent results in terms of EMG- based parameters. In the studies that report subjective measurement of muscle fatigue, the subjective ratings increase. More research is needed to understand the impact of work requirements on muscle fatigue and work-related performance.
- Analysis of the backpack loading effects on the human gaitPublication . Machado, Leandro; P. de Castro, Marcelo; Abreu, Sofia; Sousa, Helena; Gonçalves, Pedro; Sousa, Filipa; Santos, Rubim; Pinto, Viviana; Vaz, Mário; Boas, J. Paulo VilasGait is a simple activity of daily life and one of the main abilities of the human being. Often during leisure, labour and sports activities, loads are carried over (e.g. backpack) during gait. These circumstantial loads can generate instability and increase biomechanical stress over the human tissues and systems, especially on the locomotor, balance and postural regulation systems. According to Wearing (2006), subjects that carry a transitory or intermittent load will be able to find relatively efficient solutions to compensate its effects. These are dependent upon the walking distance and of the load characteristics - size, weight and location relatively to the body (Hsiang, 2002).Thus, these solutions should become a concerning factor (Koh, 2009) and a topic of scientific research, particularly in what concerns the inventory of its biomechanical effects and the possible strategies to be developed in order to minimize its effects. The aim of the present study was to analyze the effects of an occasional dorso-lombar load during the gait through the use of a backpack.
- An easy procedure for calibrating data systems using interleavingPublication . Clemêncio, Filomena; Loureiro, Custódio F. M.; Correia, Carlos M. B. A.Interleaving data acquisition channels is a well-known and interesting technique to achieve higher acquisition rates. However, to obtain the expected benefits, a careful look at the interleaving technique and to mismatches that can lead to unwanted harmonic distortion and noise is essential. In this paper we discuss the methods used to interleave existing high-speed, 250 MSPS 8-bit acquisition channels, and the results obtained. The methods presented allowed a good channel calibration in amplitude (amplitude mismatch under 0.1 lsb) and in time (time mismatch between acquisition channels in the ps range, under the specified maximum jitter for the ADC used). A dynamic, by software, amplitude level signal-dependent adjustment procedure is also suggested for signals with reach frequency content that can substantially improve the quality of the acquired signal when using interleaved channels. The techniques presented provide good results even in the presence of noise.
- A data acquisition architecture for a RPC-based small animal petPublication . Clemêncio, Filomena; Loureiro, Custódio F. M.; Correia, Carlos M. B. A.On-going work suggests that a RPC-based small animal pet camera can be built with a FWHM resolution below 0.5 mm and at a very competitive cost. The camera being developed demands a high-resolution data acquisition system along with very good trigger coincidence detection and on-line data reduction. In this paper the actual system specifications are given and a solution is discussed. The elected solution includes the development of four similar data acquisition modules, each with 16 channels based on 12-bit, 70 MSPS ADCs with LVDS outputs, dedicated memory, trigger logic, processing unit, and a USB 2.0 interface. The trigger and data processing logic of each module were placed inside a Xilinx-4 Virtex FGPA. The proposed solution allows a cheap and efficient system to be constructed in a PC-centric way.
- A rising risk to human health: assessment of light pollution on two dark sky regions of PortugalPublication . Lima, Raul Cerveira; Cunha, José Pinto da; Peixinho, NunoBad public and private artificial light planning is the main cause for light pollution (LP). Night illumination is part of modern societies, reaching increasing levels with consequences on various fields that only recently began to be studied. Residents of large cities are almost totally deprived from a starry night. UNESCO, UNTWO and IAU’s Declaration in Defence of the Night Sky and the Right to Starlight state that “an unpolluted night sky that allows the enjoyment and contemplation of the firmament should be considered an inalienable right equivalent to all other socio-cultural and environmental rights. Hence the progressive degradation of the night sky must be regarded as a fundamental loss” and that “the intelligent use of artificial lighting that minimizes sky glow and avoids obtrusive visual impact on both humans and wildlife should be promoted. This strategy would involve a more efficient use of energy so as to meet the wider commitments made on climate change, and for the protection of the environment”(Marín & Jafari, 2007).The observation and study of the night sky both at professional and casual or amateur levels is the first to be affected by light pollution thus being the primary reason to study LP until recently. However, other LP effects are already known to affect the human being such as modifications of the circadian rhythm(Stevens, 2006). More recent studies suggest LP as a risk factor for human breast and prostate cancer(Haim & Portnov, 2013). Other direct and indirect effects on the environment include natural resources consumption and effects on biodiversity, namely nocturnal fauna(Rich & Longcore, 2005).The creation of dark-skies protected areas is one form to preserve the night sky of some regions that still have a good dark sky quality. It is also a way to draw the attention of public and stakeholders to this growing problem. More than a local effect caused mainly by large urban centres, light pollution propagates to regions that are tensor more kilometres away from those populated regions, affecting places once with good night sky quality even a few years ago. Two examples of regions in Portugal that offer good dark skies are, at the north of the country, the Peneda-Gerês National Park and, at the south, the Alentejo’s region of Alqueva, both commonly known to have good dark skies but that have not been previously measured. The latter got its classification as «dark sky reserve» based on the values of night sky brightness obtained for this work.
- Influência da exposição profissional a vibrações corpo inteiro no equilíbrio de manobradores de máquinas de terraplanagemPublication . Ferreira, Flávia; Vila-Chã, Carolina; Santos, Rubim; Santos, JoanaPostural instability due exposure to whole body vibrations (WBV) is very common among earthmoving machine operators. The aim of this study was to analyze the influence of occupational exposure to WBV in the postural stability. The study included two groups of healthy volunteers, which included six experienced earthmoving machine operators (exposed group) and five students recruited from an University (non exposed group). The standing balance was assessed by measuring the centre of pressure (CoP) displacement in a single-task (eyes-open/eyes-closed) during two experimental sessions at the beginning and at the end of the week. In general, the results showed that the standing balance of exposed group was worse than the non exposed group, in the CoP displacement in the medium-lateral direction, which may be due to the vibration input was, predominantly, in the y-axis. However, the results also demonstrated that exposed group developed body compensatory strategies associated to duration of exposure and years performing similar tasks. This evidence was an important contribute to further studies and to plan future ergonomic interventions related to work organization factors as work/rest schemes.
- Influência da exposição profissional a vibrações corpo inteiro na proprioceção em manobradores de máquinas de terraplanagemPublication . Domingues, Ana Raquel; Vila-Chã, Carolina; Santos, Rubim; Santos, JoanaOccupational exposure to whole body vibrations (WBV) has been identified as a risk factor for the development of low back injuries. Besides others negative health effects, WBV can cause proprioceptive deficits. Thus, the aim of this study was evaluate the impact of the WBV on trunk proprioception of earthmoving machines operators in an extractive industry. The study included twelve healthy subjects, seven experienced operators of earthmoving machinery and five recruited students from the university. Two experimental sessions at the beginning and at the end of the week were performed and trunk position sense absolute errors were assessed for all participants with the active movement reproduction test using a high speed camera (Casio EX-FC 100), for subsequent motion analysis with Kinovea 0.8.24 software. Data analysis demonstrated that the exposed group had higher absolute errors at the beginning and at the end of the week than non exposed group. These results suggest that vibration can alter sensory messages of the skin and muscles receptors and, consequently, change the sensation of the individual position. The implementation of postural reeducation strategies for workers exposed of WBV, can reduce the negative effects on proprioceptive ability.
- Pré-teste e validação de um procedimento para a análise de movimentos de reposicionamento da coluna lombarPublication . Ramos, Diana; Santos, Rubim; Rodrigues, MatildeMobile devices are becoming more common between young people, both for personal and school use. However, during the use of these equipment, they can adopt awkward postures for long periods, contributing for musculoskeletal disorders. The project “Mobile Devices, what risks?” intends to better characterize this problem. This study aims to test and validate a procedure to determine and analyse the repositioning movements of the lumbar spine during a sitting posture. For this analysis, two different systems were used: tri-axial accelerometers system; video recording. The study showed that both methods can be used to identify repositioning movements. However, better results for inter and intrareliability were found for the accelerometer system.
- Atividade do músculo solear nos dois membros inferiores em sujeitos com acidente vascular encefálico-sub-fase média de apoio da marchaPublication . Silva, Augusta; Santos, Rubim; Sousa, FilipaO objetivo da presente investigação foi estudar as diferenças de magnitude da atividade electromiográfica do músculo solear, durante a sub-fase média de apoio da marcha, entre os dois membros inferiores em indivíduos com acidente vascular encefálico. Foi constituída uma amostra, de forma não probabilística voluntária de cinco indivíduos com alterações neuro-motoras por AVE. O sinal electromiográfico foi recolhido e tratado pelo sistema Biopac MP 150 Worksation, e o software de apoio Acqknowledge® versão 3.9. foi utilizada uma Plataforma de forças e respectivo amplificador Bertec AM6300. Foi utilizada a versão adaptada para a população portuguesa da Fugl-Meyer AssessmentfsensorimotorRecoveryafterStroke. Para determinar o onset do sinal electromiográfico foi identificado o seu valor de atividade basal. O sinal da plataforma de forças foi normalizado ao peso e à velocidade da marcha dos sujeitos. Para a análise estatística das variáveis em estudo foi utilizado o software SPPS®. O intervalo de confiança utilizado foi de 95%, com um nível de significância de 0,05. Os resultados permitem-nos verificar uma tendência para uma diminuição da atividade electromiográfica do músculo solear no membro inferior menos comprometido. Não foram encontradas diferenças estatisticamente significativas para a atividade eletromiográfica do músculo solear entre os dois membros inferiores na sub-fase média de apoio da marcha nos sujeitos com AVE.