Reverberation Reduction in Capacitive Micromachined Ultrasonic Transducers (CMUTs) by Front-face Reflectivity Minimization

Front-face acoustic reflectivity of ultrasonic imaging transducers, due to acoustic impedance mismatch with the propagation medium, may cause reverberation phenomena during wideband pulse-echo operation. Front-face reflectivity may be reduced by promoting the transmission of the echoes, received from the medium, to the transducer backing, and by maximizing the mechanical-to-electrical energy conversion and dissipation by tuning the electrical load impedance connected to the transducer. In Capacitive Micromachined Ultrasonic Transducers (CMUTs), the energy transfer from the medium to the backing is very low due to the large impedance mismatch between the medium and the transducer substrate, typically made of silicon. Reverse Fabrication Process (RFP) makes it possible providing CMUTs with custom substrate materials, thus eliminating the original silicon microfabrication support. In this paper, we propose two methods for the front-face reflectivity reduction in RFP-CMUTs: the first one is based on the use of low-impedance, highly attenuating backing materials, and the second one is based on the maximization of the mechanoelectrical energy conversion and dissipation. We analyze the methods by finite element simulations and experimentally validate the obtained results by fabricating and characterizing single-element RFP-CMUTs provided with different backing materials and electrical loads

Implementing a test to assess reaction, attention and inhibition capacity in elderly

SB'20, 45eme Congrès de la Société de Biomécanique, Metz, France, 26-/10/2020 - 28/10/2020Therefore, the aim of this work was to complement the CSRT with additional tasks to better assess in elderly people perception and response execution, attention and inhibition capacity. For this purpose, a test with different tasks is proposed. It was tested in two different samples, young and elderly, in order to determinate differences between them and anticipate relevant conclusions

Acoustic reflectivity minimization in Capacitive Micromachined Ultrasonic Transducers (CMUTs)

When Capacitive Micromachined Ultrasonic Transducers (CMUTs) are coupled with water, they show high front-face acoustic reflectivity, due to the impedance mismatch between the transducer substrate material, typically based on silicon, and the propagation medium. During pulse-echo operation, surface reflectivity is responsible for multiple reflections of the received acoustic signals, which result in a set of unwanted echoes. In ultrasound imaging applications, this signal reverberation creates artifacts and reduces the image contrast. In this paper, a method to reduce front-face reflectivity is proposed, and a Reverberation Level (RL) index is introduced in order to quantify the unwanted reverberation of the signal returned to the transducer surface. The proposed method combines the increase of the bias voltage, the application of an optimized resistive load and the addition of a low-impedance acoustic backing to CMUTs realized by Reverse Fabrication Process (RFP). In this way, the mechanical energy conversion and transmission to the backing, as well as the electrical energy dissipation, are improved, thus reducing the energy reflection into the medium. The proposed method is analyzed by means of Finite Element simulations and is experimentally validated by characterizing single-element RFP-CMUTs, provided with different backing materials and electrical loads. In the analyzed prototypes, a RL reduction of 8.6 dB is obtained

Reverberation reduction in capacitive micromachined ultrasonic transducers (CMUTs) by front-face reflectivity minimization

Front-face acoustic reflectivity of ultrasonic imaging transducers, due to acoustic impedance mismatch with the propagation medium, may cause reverberation phenomena during wideband pulse-echo operation. Front-face reflectivity may be reduced by promoting the transmission of the echoes, received from the medium, to the transducer backing, and by maximizing the mechanical-to-electrical energy conversion and dissipation by tuning the electrical load impedance connected to the transducer. In Capacitive Micromachined Ultrasonic Transducers (CMUTs), the energy transfer from the medium to the backing is very low due to the large impedance mismatch between the medium and the transducer substrate, typically made of silicon. Reverse Fabrication Process (RFP) makes it possible providing CMUTs with custom substrate materials, thus eliminating the original silicon microfabrication support. In this paper, we propose two methods for the front-face reflectivity reduction in RFP-CMUTs: the first one is based on the use of low-impedance, highly attenuating backing materials, and the second one is based on the maximization of the mechanoelectrical energy conversion and dissipation. We analyze the methods by finite element simulations and experimentally validate the obtained results by fabricating and characterizing single-element RFP-CMUTs provided with different backing materials and electrical loads

Anthelmintic efficacy of an oral formulation of moxidectin against gastro-intestinal strongyles in sheep flocks from Central Italy

Introduction - Gastrointestinal strongyle (GI) infections are the most important parasitoses threatening sheep production, as they may be responsible for significant economic lost. The control of these infections is still largely based on the massive use of broad-spectrum anthelmintics, which, however, favored the onset of the anthelmintic resistance. The anthelmintic resistance is a widespread problem of increasing concern in several countries, and regarding mainly BZ (fenbendazole), IMD (levamisole) and LM (ivermectin). At present, there are no reported cases of resistance to moxidectin in Italy, but severs international studies have shown the presence of strongyle populations resistent to moxidectin that represents the molecule of choice for the treatment of GI strongylosis in small ruminants.Aim - The aim of the present study was to evaluate the efficacy of an oral formulation containing moxidectin for the treatment of sheep GI strongylosis raised in central Italy, in order to acquire more information regarding its preserved efficacy at national level.Materials and methods - The study was carried out in two dairy sheep farms located in Umbria regions (A1 and A2); the farms were found positive for GI strongyles at a screening copromicroscopic investigations conducted at the time T-7. Thirty-five sheep from A1 and 37 animals from A2 were selected for the field trial and treated orally with a commercially available product containing moxidectin. The efficacy of the treatment was calculated on the basis of the faecal reduction egg count (FECR) of the time T-14 in comparison with time T-0, according with the indications provided by the W.A.A.V.P.Result and conclusions - The results obtained showed that moxidectin has an excellent and preserved efficacy against GI strongyle infections, with a FECR value of 100%. The monitoring, the effectiveness of treatment regimens through FECR test, is extremely important as it allows to recognize the anthelmintic resistance phenomenon in the phases early, when a correct management of the molecule can still maintain the efficacy value at high levels

Advancing One human-animal-environment Health for global health security: what does the evidence say?

In this Series paper, we review the contributions of One Health approaches (ie, at the human-animal-environment interface) to improve global health security across a range of health hazards and we summarise contemporary evidence of incremental benefits of a One Health approach. We assessed how One Health approaches were reported to the Food and Agricultural Organization of the UN, the World Organisation for Animal Health (WOAH, formerly OIE), and WHO, within the monitoring and assessment frameworks, including WHO International Health Regulations (2005) and WOAH Performance of Veterinary Services. We reviewed One Health theoretical foundations, methods, and case studies. Examples from joint health services and infrastructure, surveillance-response systems, surveillance of antimicrobial resistance, food safety and security, environmental hazards, water and sanitation, and zoonoses control clearly show incremental benefits of One Health approaches. One Health approaches appear to be most effective and sustainable in the prevention, preparedness, and early detection and investigation of evolving risks and hazards; the evidence base for their application is strongest in the control of endemic and neglected tropical diseases. For benefits to be maximised and extended, improved One Health operationalisation is needed by strengthening multisectoral coordination mechanisms at national, regional, and global levels