Minimal information for studies of extracellular vesicles 2018 (MISEV2018): a position statement of the International Society for Extracellular Vesicles and update of the MISEV2014 guidelines

The last decade has seen a sharp increase in the number of scientific publications describing physiological and pathological functions of extracellular vesicles (EVs), a collective term covering various subtypes of cell-released, membranous structures, called exosomes, microvesicles, microparticles, ectosomes, oncosomes, apoptotic bodies, and many other names. However, specific issues arise when working with these entities, whose size and amount often make them difficult to obtain as relatively pure preparations, and to characterize properly. The International Society for Extracellular Vesicles (ISEV) proposed Minimal Information for Studies of Extracellular Vesicles (“MISEV”) guidelines for the field in 2014. We now update these “MISEV2014” guidelines based on evolution of the collective knowledge in the last four years. An important point to consider is that ascribing a specific function to EVs in general, or to subtypes of EVs, requires reporting of specific information beyond mere description of function in a crude, potentially contaminated, and heterogeneous preparation. For example, claims that exosomes are endowed with exquisite and specific activities remain difficult to support experimentally, given our still limited knowledge of their specific molecular machineries of biogenesis and release, as compared with other biophysically similar EVs. The MISEV2018 guidelines include tables and outlines of suggested protocols and steps to follow to document specific EV-associated functional activities. Finally, a checklist is provided with summaries of key points

Aeroacoustic model for the prediction of turbulent free jets noise using scanning laser doppler vibrometry

none3nononeCastellini P.; Martarelli M.; Tomasini E.P.Castellini, P.; Martarelli, M.; Tomasini, E. P

Envelope Cepstrum Based Method for Rolling Bearing Diagnostics

The task of identifying a faulty roller element bearing has been so far faced through the use of envelope analysis. As it is well known the main issue linked to such approach is related to the definition of the optimal band-pass filter which can enhance the defect characteristics when the vibration signal is affected by severe noise. The Kurtogram has overcome this limit by letting the optimal band-pass filter be selected in a semi-automatic way, that is by exploiting the potentials of the Spectral Kurtosis. This paper aims at presenting an alternative algorithm which is able to cope with faults characterised by an impulsive-periodic nature. It is well known that faults characterised by periodic-impulsive nature are identifiable by means of cepstral analysis while damages inducing modulation effects are usually assessed via envelope processing. The presented algorithm combine two instruments, since it is based on the Fourier spectrum of the cepstrum squared envelope. Such spectrum allows to isolate the modulation effect by centring the modulating frequency around the DC component. In this paper the algorithm is applied to both synthesized data reproducing typical damaged rolling bearing signals and experimental data. Results achieved by exploiting the proposed algorithm are compared to the ones obtained by applying conventional envelope analysis based on Spectral Kurtosis

Evaluation of Heart Rate Variability by means of Laser Doppler Vibrometry measurements

Heart Rate Variability (HRV) analysis aims to study the physiological variability of the Heart Rate (HR), which is related to the health conditions of the subject. HRV is assessed measuring heart periods (HP) on a time window of >5 minutes (1)-(2). HPs are determined from signals of different nature: electrocardiogram (ECG), photoplethysmogram (PPG), phonocardiogram (PCG) or vibrocardiogram (VCG) (3)-(4)-(5). The fundamental aspect is the identification of a feature in each heartbeat that allows to accurately compute cardiac periods (such as R peaks in ECG), in order to make possible the measurement of all the typical HRV evaluations on those intervals. VCG is a non-contact technique (4), very favourable in medicine, which detects the vibrations on the skin surface (e.g. on the carotid artery) resulting from vascular blood motion consequent to electrical signal (ECG). In this paper, we propose the use of VCG for the measurement of a signal related to HRV and the use of a novel algorithm based on signal geometry (7) to detect signal peaks, in order to accurately determine cardiac periods and the Poincare plot (9)-(10). The results reported are comparable to the ones reached with the gold standard (ECG) and in literature (3)-(5). We report mean values of HP of 832±54 ms and 832±55 ms by means of ECG and VCG, respectively. Moreover, this algorithm allow us to identify particular features of ECG and VCG signals, so that in the future we will be able to evaluate specific correlations between the two

Vibro-acoustic characterization of flexible hose in CO 2 car air conditioning systems

Following the EU directive 2006/40/EC proscribing from 2011 that refrigerant fluids must have a global warming potential not higher than 150, it will not be allowed anymore to employ the current R134a on car air conditioning systems. Maflow s.p.a (automotive hose maker) is developing products for each possible new refrigerant. This paper is focused on hoses for CO2 refrigerants operating in the worst conditions because of the high pressures and temperatures at which they are working (with R134a the high pressure is 18 bar and low pressure is 3 bar; with CO2 the high pressure is 100 bar and low pressure is 35 bar). Therefore the noise emission control of the CO2 air conditioning systems is very important. The aim of this study is to develop a standard measurement method for the vibro - acoustic characterization of High Pressure (HP - Shark F4) and Low Pressure (LP - ULEV) hoses to reduce noise emission and raise car passenger comfort; in particular deep research on high pressure hose. The method is based on the measurement of the vibration level of the hoses in a standard test bench by means of a Laser Doppler Vibrometer (LDV) and its acoustic emission by a sound intensity probe

The non-contact measure of the heart rate variability by laser Doppler vibrometry: Comparison with electrocardiography

The assessment of the heart rate variability (HRV) is of utmost importance, being one of the most promising markers of the activity of the autonomic nervous system and associated to cardiovascular mortality. Different signals can be used to perform HRV, primarily electrocardiography (ECG), photoplethysmography (PPG), phonocardiography (PCG) or vibrocardiography (VCG), since the fundamental aspect is the individuation of a periodic feature strictly correlated with cardiac activity (i.e. R-peak in ECG or the first sound in PCG). In this work, the authors demonstrate that the VCG performances in HRV analysis are sufficiently accurate if compared to the ones measured by ECG (i.e. standard methodology); moreover, the authors want to prove the feasibility of such measurement in correspondence of different measurement points (i.e. carotid artery—which is the typical VCG measurement point—and the radial artery on the wrist)1. Results show that VCG has a mean deviation of <1 bpm with respect to ECG in heart rate (HR) measurement; carotid artery is the most accurate site for the assessment, but also the radial artery is a valid site, even if with a reduced SNR. With regards to HRV parameters, the mean percentage deviation is <10% in correspondence of carotid artery, and ≈16% for the radial artery. So, VCG allows for non-contact monitoring of the cardiac activity