ESS - FIS - Física
Permanent URI for this community
Browse
Browsing ESS - FIS - Física by Title
Now showing 1 - 10 of 185
Results Per Page
Sort Options
- Activation timing of soleus and tibialis anterior muscles during sit-to-stand and stand to sit in post-stroke vs healthy subjectsPublication . Augusta Silva; Santos, Rubim; Pinheiro De Sousa, Andreia Sofia; Pinheiro, Ana Rita; Ferraz, Joana; Tavares, João Manuel; Sousa, FilipaSit-to-stand (SitTS) and stand-to-sit (StandTS) are very important functional tasks that become compromised in stroke patients. As in other voluntary movements, they require an adequate postural control (PC) involving the generation of anticipatory postural adjustments (APAs). In order to give clues for more efficient and directed rehabilitation programs, a deeper knowledge about APAs during challenging and daily life movements is essential. To analyze the activation timing of tibialis anterior (TA) and soleus (SOL) muscles during SitTS and StandTS in healthy subjects and in post-stroke patients. Methods: Two groups participated in this study: one composed by ten healthy subjects and the other by ten subjects with history of stroke and increased H-reflex. Electromyographic activity (EMGa) of SOL and TA was analyzed during SitTS and StandTS in the ipsilateral (IPSI) and the contralateral (CONTRA) limb to the side lesion in stroke subjects, and in one limb in the healthy subjects. A force plate was used to identify the movement onset. In both sequences, in the stroke group SOL activation timing occurred prior to movement onset, contrary to the pattern observed in the healthy subjects. Statistical significant differences were found in SOL activation timings between each lower limbs of the stroke and healthy groups, but no significant differences were found between the IPSI and the CONTRA limb. The TA activation timing seems to be delayed in the CONTRA limb when compared to the healthy subjects and showed also a better organization of TA timing activation in StandTS when compared to SitTS. Compared to healthy subjects, APAs seems to be altered in both limbs of the post-stroke subjects, with the SOL activation timing being anticipated in both SitTS and StandTS.
- Activation timings of the scapular stabilizers in subjects with a stroke affecting the right versus left hemispheresPublication . Ferreira, S.; Silva, Cláudia; Silva, A.; Carvalho, Paulo; Santos, RubimLesions affecting the right hemisphere influence the ability to plan the virtual reaching trajectory and, consequently the postural control. On the other hand, left hemisphere lesions affect the ability to select the adequate motor program to reach the target. This study aimed to explore the existence of differences at the activation timings and sequence of activation of the scapular stabilizers, mainly the serratus anterior, superior, middle and inferior trapezius fibers, in relation to the anterior deltoid, in subjects with a stroke affecting the right versus left hemispheres, during reaching. Besides, it aimed to establish comparisons between both sides of each subject and a group of subjects without of each subject and a group of subjects without pathology.
- Acupuncture effect on reaction-time changes in Parkinson’s disease patients—Case study seriesPublication . Pereira, Catarina Ramos; Greten, Henry J.; Santos, Rubim; Reis, Ana Mafalda; Ramos, Bruno; Santos, Maria João; Machado, Jorge; Criado, Maria BegoñaParkinson’s Disease (PD) is a progressive neurodegenerative condition associated with deficit in reaction time which can lead to falls, resulting in limited independence, diminished quality of life, heightened rates of institutionalization and increased healthcare costs. We aimed to examine the effects of an acupuncture protocol in motor time response after an auditory stimulus. Methods: This study employed a case series design. Reaction time to exposed rhythmic and random auditory stimuli outcomes were evaluated at six different moments over a month-long acupuncture treatment protocol using the MP 36 system from Biopac Systems. Results: We observed a tendency to have more pronounced improvements in the time response in the more affected side of the body compared with the contralateral one. Patients tended to show better values of response to random auditory stimuli compared to rhythmic auditory ones. We also observed a tendency to obtain better results when considering the accumulative effects of the acupuncture protocol. Conclusions: Our findings indicated a possible role of reaction time as a sensitive and useful tool for motor function assessment in PD patients. Also, from our results, we concluded that the acupuncture protocol used may lead to an improvement in efficacy of motor response after aleatory and rhythmic stimulus; we also found a tendency for a higher efficacy of acupuncture in random stimuli responses in the first stages of the disease. However, further in-depth research, including a statistical evaluation with a larger participant pool, is necessary to validate and confirm these promising results.
- Acute effects of physical exercise with microcurrent in the adipose tissue of the abdominal region: A randomized controlled trialPublication . Noites, Andreia; Moreira, Anabela; Melo, Cristina; Faria, Miriam; Vilarinho, Rui; Freitas, Carla; Monteiro, Pedro; Carvalho, Paulo; Adubeiro, Nuno; Sousa, Maria; Santos, Rubim; Nogueira, LuisaIncreased abdominal fat and sedentary lifestyles contribute to cardiovascular disease risk. Low-intensity electrical current (microcurrent) on the abdominal region, associated with physical exercise, appears to be an innovative method to increase the lipolytic rate of abdominal adipocytes, in order to reduce abdominal fat. This study aimed to analyze the acute effects of microcurrent associated with an aerobic exercise program in healthy subjects in lipolysis. A double-blinded, randomized controlled trial was developed and conducted in a higher education school. Eighty-three healthy subjects, aged between 18 and 30 years old and with a 18.5 to 29.9 kg/m2 body mass index were randomly assigned either to an experimental or to a placebo group. Subjects received a trans-abdominal microcurrent stimulation for 40 min with (experimental group) or without (placebo group) electrical current, followed by a single aerobic exercise session (60 min at 45–55% VO2max intensity). Lipolytic activity (serum glycerol), abdominal fat (waist circumference, abdominal skinfold, ultrasonography), and serum lipid profile (serum triglyceride, total cholesterol, low-density lipoprotein cholesterol and high-density lipoprotein cholesterol) were evaluated in all subjects. Physical activity (International Physical Activity Questionnaire) and dietary intake (food-frequency questionnaire) questionnaires were applied. After the intervention, lipolytic rate was significantly higher (p = 0.003) in the experimental group (mean = 0.15) than in the placebo group (mean = 0.09). Glycerol results showed a statistically significant increase between baseline and after the intervention for both experimental group (p = 0.001) and the placebo group (p = 0.001). Combined use of microcurrent and physical aerobic exercise had an acute effect enhancing lipolytic rate comparing to exercise alone, in young healthy subjects.
- Ajustes posturais antecipatórios no movimento de alcançar em indivíduos pós-acidente vascular encefálicoPublication . Ferreira, Sílvia; Silva, Cláudia C.; Carvalho, Paulo; Silva, Augusta; Santos, RubimPretendeu-se verificar a existência de alterações nos timings de activação dos músculos estabilizadores da omoplata em indivíduos pós-acidente vascular encefálico e a sua relação com a velocidade. Metodologia: Amostra (n = 17) dividida nos Grupos 1 (n = 10 indivíduos sem patologia) e 2 (n = 7 indivíduos pós-acidente vascular encefálico). Análise electromiográfica e cinemática no alcance de um copo. Resultados: Nas fibras inferiores do trapézio esquerdo (p = 0,043) e grande dentado bilateralmente (p = 0,028), encontraram-se diferenças entre os Grupos. Não se verificou uma relação com a velocidade. Conclusões: Foram encontrados ajustes posturais antecipatórios em alguns dos músculos.
- Alterações no recrutamento dos músculos abdominais em indivíduos com história de dor lombopélvica em movimentos do membro superiorPublication . Carvalho, Paulo; Moreira, Camilo; Santos, Rubim; Boas, João Paulo VilasVerificar se existem alterações no padrão de recrutamento do transverso do abdómen/oblíquo interno, recto abdominal e oblíquo externo em indivíduos com história de dor lombopélvica.
- An all-digital coincidence-selection and coincidence-trigger generation for a small animal RPC-PET cameraPublication . Clemêncio, Filomena; Loureiro, Custodio F. M.; Landeck, JorgeThe time resolution for gamma photon pairs of a detector based on resistive plate chamber technology is close to 300 ps FWHM. This allows a tight time window for coincidence detection, reducing the number of random coincidences observed and the overall noise of the acquired image. We implemented, inside a Xilinx Virtex-5 field programmable gate array, a fully programmable coincidence-trigger system with sub-nanosecond resolution and low latency for a small animal RPC-PET camera being built. An automatic procedure to construct a histogram of coincidences was implemented that helps characterizing the camera and allows compensating for different delays in the time channels. The time window for coincidences can then be placed at the optimal position helping rejecting coincidences from undesired sources.
- An easy procedure for calibrating data acquisition 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 relative 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 rich 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.
- 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.
- Análise cinemática do membro superior durante a atividade de beber em pessoas com sequelas de Acidente Vascular EncefálicoPublication . Vieira, Marisa; Santos, Rubim; Sousa, HelenaEste estudo pretende descrever todas as fases do gesto de beber num grupo de indivíduos após Acidente Vascular Encefálico (AVE), através de uma análise cinemática. Os indivíduos produziram movimentos lentos, menos suaves, com número elevado de unidades motoras e picos de velocidade com valores bastante superiores ao observado em indivíduos saudáveis e houve um grande deslocamento do tronco na fase de alcance e beber.