Heart rate variability (HRV) has been used as a non-invasive marker of the activity of the autonomic nervous system and its spectrum analysis gives a measure of the sympatho-vagal balance. If short segments are used in an attempt to improve temporal resolution, autoregressive spectral estimation, where the mode] order must be estimated, is preferred. In this paper we compare four criteria for the estimation of the 'optimum' model order for an autoregressive (AR) process applied to short segments of tachograms used for HRV analysis. The criteria used were Akaike's final prediction error, Akaike's information criterion, Parzen's criterion of autoregressive transfer function and Rissanen's minimum description length method, and they were first applied to tachograms to verify (i) the range and distribution of model orders obtained and (ii) if the different techniques suggest the same model order for the same frames. The four techniques were then tested using a true AR process of known order p = 6; this verified the ability of the criteria to estimate the correct order of a true AR process and the effect, on the spectrum, of choosing a wrong model order was also investigated. It was found that all the four criteria underestimate the true AR order; specifying a fixed model order was then looked at and it is recommended that an AR order not less than p = 16, should be used for spectral analysis of short segments of tachograms.

Pesq. Vet. Bras. 33(3):319-325, março 2013 319 RESUMO.-[Aspectos clínicos e dinâmica de parasitoses auriculares em bovinos da raça Gir.] Avaliou-se a dinâ-mica da infestação auricular causada por Rhabditis spp. e por Raillietia spp., relacionando-a com a idade dos animais, com a intensidade dos sinais clínicos e com os fatores climáticos. Utilizaram-se 64 bovinos Gir, distribuídos em três grupos: GA -23 bezerros de quatro a seis meses de idade, GB -18 bezerros de sete a 12 meses e GC -23 novilhas de 13 a 33 meses. Foram feitas cinco coletas a cada três meses. A secreção auricular foi coletada utilizando o método de lavagem auricular na orelha direita e um swab na orelha esquerda. Sixty-four Gir cattle were distributed into three groups: GA -23 calves with 4 to 6 months of age; GB -18 calves with 7 to 12 months of age; and GC -23 heifers with 13 to 33 months of age. Five samplings, defined as S1, S2, S3, S4 and S5 were performed every three months from August 2008 to August 2009. The ear secretion was collected using the auricular washing method for the right ear and a swab for the left ear. A clinical assessment of the animals was performed, and they were classified according to the presence and severity of otitis. The highest relative frequency of rhabditosis was 52.2% in GC at the last sampling. In the first sampling, 42.2% of the animals were infested by Raillietia spp. The older cattle were more susceptible to infestations by both parasites. No correlation of Rhabditis spp. and Raillietia spp. parasitism with climate factors was found. The results showed that both parasites could infest Gir cattle, and in most cases, there was no co-infestation. Only older animals parasitized by the nematode showed clinical signs of the disease. maior frequência relativa da rhabditiose encontrada foi de 52,2%, no GC na ultima coleta. Na primeira coleta, 42,2% dos animais estavam infestados pela Raillietia spp. Os bovinos mais velhos foram mais suscetíveis às infestações de ambos os parasitos. Não foi encontrada correlação entre o parasitismo por Rhabditis spp. e por Raillietia spp. e os fatores climáticos. Concluiu-se que ambos os parasitas podem infestar bovinos da raça Gir e na maioria dos casos, não ocorreram infestações simultâneas. Apenas os animais mais velhos, parasitados pelo nematóide, apresentaram sinais clínicos da doença.

The wireless capsule endoscopy has revolutionized early diagnosis of small bowel diseases. However, a single examination has up to 10 h of video and requires between 30-120 min to read. Computational methods are needed to increase both efficiency and accuracy of the diagnosis. In this paper, an evaluation of deep learning U-Net architecture is presented, to detect and segment red lesions in the small bowel. Its results were compared with those obtained from the literature review. To make the evaluation closer to those used in clinical environments, the U-Net was also evaluated in an annotated sequence by using the Suspected Blood Indicator tool (SBI). Results found that detection and segmentation using U-Net outperformed both the algorithms used in the literature review and the SBI tool.

Heart Rate Variability (HRV) series exhibit long memory and time-varying conditional variance. This work considers the Fractionally Integrated AutoRegressive Moving Average (ARFIMA) models with Generalized AutoRegressive Conditional Heteroscedastic (GARCH) errors. ARFIMA-GARCH models may be used to capture and remove long memory and estimate the conditional volatility in 24 h HRV recordings. The ARFIMA-GARCH approach is applied to fifteen long term HRV series available at Physionet, leading to the discrimination among normal individuals, heart failure patients, and patients with atrial fibrillation.

No abstract