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Browsing by Author "Barros, Pedro"

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  • Day-night differences in Cunene horse mackerel (Trachurus trecae) acoustic relative densities off Angola
    Publication . Velho, Filomena Vaz; Barros, Pedro; Axelsen, Bjorn Erik
    The assessment and the management of the Cunene horse mackerel in Angola rely heavily on abundance estimates from hydroacoustic surveys. Acoustic data collected from 1994 to 1999 were analysed to quantify diurnal variation in relative acoustic densities at 38 kHz. The nautical-area scattering coefficient (s(A), m(2) nautical mile(-2)) was characterized by clear day night differences: s(A) values recorded during the day were significantly higher (mean s(A): 135 m(2) nautical mile(-2)) than the corresponding night-time values (mean s(A) 83 m(2) nautical mile(-2)). This pattern is associated with differences in behaviour and horizontal and vertical distributions between day and night: by day, the fish school near the seabed, and by night, they move into the pelagic zone and disperse into widespread scattering layers. More than 40% of the total backscatter by day originated from the bottom 10 m, but at night this proportion decreased to <10%. The findings demonstrate considerable influences of behaviour and aggregation dynamics on acoustic measurements. Possible implications for the estimates of acoustic abundance are discussed in the light of the differences.
    2010-07Journal article Open access Show more
  • Small bowel intussusception secondary to metastatic renal cell carcinoma: a case report
    Publication . Barros, Pedro; Oliveira, Bárbara; Pereira, Rute; Dores, Marco; Coutinho, Aníbal
    Bowel intussusception is rare in adults and is usually driven by an underlying pathological process affecting the bowel. Renal cell carcinoma (RCC) is the most common type of kidney cancer and its disease course, depending on the initial histology and disease stage, can metastasize to adrenal glands, lungs, bones, brains and contralateral kidney that can be challenging to follow. We present the case of a patient with a history of radical left nephrectomy for RCC that developed an acute bowel obstruction, secondary to an ileal metastasis of RCC. In previous surgeries, small bowel obstruction (SBO) is usually found due to adhesions, nonetheless in a patient with a history of high-grade disease at diagnosis, one must keep in mind the possibility of disease relapse in the setting of SBO.
    2023-08-31Journal article Open access Show more