Use of SDWBA predictions for acoustic volume backscattering and the Self-Organizing Map to discern frequencies identifying Meganyctiphanes norvegica from mesopelagic fish species

To acoustically assess the biomass of multiple species or taxa within a survey region, the volume backscatter data should be apportioned to the constituent sound scatterers. Typically, measured backscatter is attributed to certain species using predictions at different frequencies, mostly based on the difference in scattering at the frequencies of 38 and 120 kHz ('dual frequency method'). We used the full version of the stochastic distorted wave Born approximation model (SDWBA) to predict backscatter spectra for Meganyctiphanes norvegica and to explore the sensitivities of ΔMVBS to the model parameters, e.g. acoustic frequency and incidence angle, and animal density and sound speed contrast, length, and shape. The orientation is almost the unique parameter responsible for variation, with fatness affecting longer lengths. We present a summary of ΔMVBS that can serve as the basis for identification algorithms. Next, we simulate the scenario encountered in the Balearic Sea (western Mediterranean) where Northern krill are mixed with mesopelagic fish species (bristlemouths and lanternfishes), which are modeled with a prolate spheroid model. Simulated numerical data are employed to emulate the discrimination process with the most common identification techniques and typical survey frequencies. The importance of using density-independent techniques for acoustic classification is highlighted. Finally, an unsupervised neural network, the Self-Organizing Map (SOM), is used to cluster these theoretical data and identify the frequencies that provide, in this case, the most classification potential. The simulation results confirm that pairs of frequencies spanning the Rayleigh and geometric scattering regimes of the targets are the most useful for clustering; a minimum of four frequencies are necessary to separate the three species, while three frequencies are able to differentiate krill from mesopelagic fish species.En prensa2,421

Perspectives from Italy during the COVID-19 pandemic: nationwide survey-based focus on minimally invasive HPB surgery

The safety of minimally invasive procedures during COVID pandemic remains hotly debated, especially in a country, like Italy, where minimally invasive techniques have progressively and pervasively entered clinical practice, in both the hepatobiliary and pancreatic community. A nationwide snapshot of the management of HPB minimally invasive surgery activity during COVID-19 pandemic is provided: a survey was developed and conducted within AICEP (Italian Association of HepatoBilioPancreatic Surgeons) with the final aim of conveying the experience, knowledge, and opinions into a unitary report enabling more efficient crisis management. Results from the survey (81 respondents) show that, in Italian hospitals, minimally invasive surgery maintains its role despite the COVID-19 pandemic, with the registered reduction of cases being proportional to the overall reduction of the HPB surgical activity. Respondents agree that the switch from minimally invasive to open technique can be considered as a valid option for cases with a high technical complexity. Several issues merit specific attention: screening for virus positivity should be universally performed; only expert surgical teams should operate on positive patients and specific technical measures to lower the biological risk of contamination during surgery must be followed. Future studies specifically designed to establish the true risks in minimally invasive surgery are suggested. Furthermore, a standard and univocal process of prioritization of patients from Regional Healthcare Systems is advisable

Perspectives from Italy during the COVID-19 pandemic: nationwide survey-based focus on minimally invasive HPB surgery

The safety of minimally invasive procedures during COVID pandemic remains hotly debated, especially in a country, like Italy, where minimally invasive techniques have progressively and pervasively entered clinical practice, in both the hepatobiliary and pancreatic community. A nationwide snapshot of the management of HPB minimally invasive surgery activity during COVID-19 pandemic is provided: a survey was developed and conducted within AICEP (Italian Association of HepatoBilioPancreatic Surgeons) with the final aim of conveying the experience, knowledge, and opinions into a unitary report enabling more efficient crisis management. Results from the survey (81 respondents) show that, in Italian hospitals, minimally invasive surgery maintains its role despite the COVID-19 pandemic, with the registered reduction of cases being proportional to the overall reduction of the HPB surgical activity. Respondents agree that the switch from minimally invasive to open technique can be considered as a valid option for cases with a high technical complexity. Several issues merit specific attention: screening for virus positivity should be universally performed; only expert surgical teams should operate on positive patients and specific technical measures to lower the biological risk of contamination during surgery must be followed. Future studies specifically designed to establish the true risks in minimally invasive surgery are suggested. Furthermore, a standard and univocal process of prioritization of patients from Regional Healthcare Systems is advisable