Sea trout adapt their migratory behaviour in response to high salmon lice concentrations.

Sea trout face growth-mortality trade-offs when entering the sea to feed. Salmon lice epizootics resulting from aquaculture have shifted these trade-offs, as salmon lice might both increase mortality and reduce growth of sea trout. We studied mortality and behavioural adaptations of wild sea trout in a large-scale experiment with acoustic telemetry in an aquaculture intensive area that was fallowed (emptied of fish) synchronically biannually, creating large variations in salmon lice concentrations. We tagged 310 wild sea trout during 3 years, and gave half of the individuals a prophylaxis against further salmon lice infestation. There was no difference in survival among years or between treatments. In years of high infestation pressure, however, sea trout remained closer to the river outlet, used freshwater (FW) habitats for longer periods and returned earlier to the river than in the low infestation year. This indicates that sea trout adapt their migratory behaviour by actively choosing FW refuges from salmon lice to escape from immediate mortality risk. Nevertheless, simulations show that these adaptations can lead to lost growth opportunities. Reduced growth can increase long-term mortality of sea trout due to prolonged exposure to size-dependent predation risk, lead to lower fecundity and, ultimately, reduce the likelihood of sea migration.

A fixed point algorithm for extracting the atrial activity in the frequency domain.

In this work we present a fixed point algorithm to extract the atrial rhythm in atrial tachyarrhythmias from the surface electrocardiogram (ECG). In the frequency domain the atrial signal is characterized by a concentration of power around a main peak in the bandwidth 3-10Hz. The proposed algorithm exploits this discriminative property of the atrial component in combination with the decoupling of the atrial and other components superposed in the ECG. It recovers only the interesting atrial rhythm in a simple, fast and reliable way using the information contained in all the leads and reducing the average computational time from 0.902s (FastICA) to 0.023s (the proposed method). The algorithm is applied successfully to synthetic and real data. In simulated ECGs, the correlation index obtained was 0.792. In real ECGs, the accuracy of the results was validated using spectral and temporal parameters. The average peak frequency and spectral concentration obtained were 5.354Hz and 59.4%, respectively, and the kurtosis was 0.065.

Constrained temporal extraction of the atrial rhythm in Atrial Fibrillation episodes.

The extraction of the Atrial Activity from the Ventricular Activity in Atrial Fibrillation episodes is a must for clinical analysis. We follow the semi Blind Source Extraction S-BSE approach to solve the problem. The proposed algorithm modifies the BSE contrast function to satisfy the prior knowledge about the spectral content of the atrial signal. The introduction of this prior allows obtaining a new algorithm with the following advantages: it allows the extraction of only the atrial component and it improves the quality of the recovered atrial signal in terms of spectral concentration as we show in the results.

[Prevalence of chronic hidden infections in a cohort of patients in substitutive treatment with methadone]. / Prevalencia de infecciones crónicas ocultas en una cohorte de pacientes en tratamiento sustitutivo con metadona.

BACKGROUND: To analyse prevalence of hidden hepatitis B infection (HBV), hepatitis C virus (HCV), human immunodeficiency virus (HIV), and tuberculosis infection in drug users (DU) in a maintenance programme with methadone (MPM). PATIENTS AND METHOD: 189 DU were tested for HBV, HCV, HIV and tuberculin test. Drug addition history and route of administration were evaluated. RESULTS: Prevalence of HIV, HCV, and tuberculous infection was 29.2%, 75.9% and 59.3% respectively. Intravenous route, early use of heroin and delay to enter in MPM were significatively associated with HIV and HCV infections. CONCLUSIONS: There is a high prevalence of tuberculous and HCV infections in DU. Early access to MPM could decrease prevalence of those infections.

The maternal-infant center in the control of hepatitis B.

A seroepidemiologic survey of HBV infection was carried out in four population groups served by the Maternity Hospital of Majorca, an island in the Mediterranean. The prevalence of HBV markers (HBsAg, anti-HBs, anti-HBc), determined by enzyme-immunoassay, reached 17.2% among 864 parturients, 17.2% in 783 hospital personnel, 2.7% and 19.2% among the 186 children and 73 husbands of parturients with no HBV markers, 22.8% and 43.8%, respectively, among the 44 children and 48 husbands of HBsAg chronic carrier parturients. The prevalences of HBsAg in the same groups reached 0.9%, 1.5%, 0% and 0%, 11.4% and 2.1%, respectively. The carrier state represents 50% of all infection cases among children and 4.8% among husbands of carrier women. The prevalence of markers, which was especially high among personnel working in maintenance services (39.1%), on surgical wards (35.3%), among midwives (27.6%) and in cleaning and laundry services (27.1%), and laboratories (21.4%), is used as an indicator in defining priorities for the vaccination of people at risk. Sixty-seven newborn babies of HBsAg carrier mothers were administered one dose of HBIG and three doses of hepatitis B vaccine; at 12 months of age, the seroconversion rate was 98.5%, whereas 1 child (1.5%) became a chronic carrier. Maternity hospitals represent the ideal centers in which to carry out the detection of HBsAg in pregnant women prior to parturition, to ensure that all newborns of chronic carrier women receive passive-active immunization, and to screen their family contacts and vaccinate those who are found susceptible to the infection.