Avocado firmness monitoring with values obtained by means of laser doppler vibrometry

Avocado (Persea americana Mill.) ripeness is usually evaluated by destructive firmness assessment, yet quality is notorious for being heterogeneous within a consignment. This problem, which is especially true for imported avocado fruit, lends itself to searching for non-destructive methods for firmness evaluation. Firmness of objects can be analysed by impulse-response. This technique utilizes recording of a vibration signature and interpretation of the resonant frequency. In this study a laser Doppler vibrometer (LDV) was used for non-contact recording. The aim of this study was to show the feasibility of using a LDV to monitor avocado firmness. In order to create avocado batches of different homogeneity, three groups were treated with and without ethylene, inside or outside a box. After day 0 a third of the fruit were transferred into boxes (325 L) to be treated with ethylene for 24 h. A third was kept in boxes untreated and another third was kept on open trays. Avocado fruit cultivar ‘Hass’ were ripened at 18°C and measured on days 0, 2, 3, 4 and 6. Individual fruit were impacted once and two LDV measurements were taken simultaneously at the stem-end and seed-end. This was repeated twice around the fruit. Force-deformation measurements in compression mode were performed by means of uniaxial testing (Instron model 5542) on two opposite sides (day 0 n=8, then n=24 i.e., 8 per treatment/d). Significant differences were found between firmness of avocados over time and across treatments. Firmness decreased exponentially as expected (304.1 to 2.1 N) over six days. The LDV results showed significant differences between days, treatments and laser-location. The resonant frequency of the fruit decreased linearly until day 4 and then decreased more slowly (1671 to 476 Hz). On average, the frequency found at the seed-end of the fruit was higher than the resonant frequency at the stem-end. This is thought to be due to the seed itself, which could influence the vibration pattern. Resonant frequencies showed good correlation to the logarithm of firmness (r=0.87) and therefore were shown capable of monitoring avocado firmness

The timing of exogenous ethylene supplementation differentially affects stored sweetpotato roots

The effects of continuous supplemental ethylene (10 μL L−1) timing on the physiology and biochemistry of sweetpotato roots during storage at 25 °C were examined. Alongside continuous ethylene or air treatments, a subset of the roots were transferred at dormancy break, from those previously stored in ethylene into air and vice-versa. The study showed distinctive ethylene-induced effects on the metabolism of individual sugars, phenolic compounds and phytohormones (abscisic acid and zeatin riboside) across the spatial gradient of the root flesh and skin tissues. Although ethylene flushing doubled root respiration, sprout growth was significantly suppressed. Supplementation of roots with ethylene after dormancy break effectively inhibited sprout growth as much as continuous ethylene alone. On the other hand, truncating ethylene application after dormancy release promoted vigorous sprout growth. After prolonged storage, ethylene treatment was associated with increased weight loss and incidence of proximal rots. Supplemental ethylene also accelerated the catabolism of monosaccharides, and promoted accumulation of phenolic compounds in the proximal root sections

Design and construction of a flexible laboratory-scale mixing apparatus for continuous ethylene supplementation of fresh produce

The design and construction of a laboratory-scale apparatus for generating variable concentrations and flow rates of exogenous ethylene for fresh produce supplementation during storage trials is described. A stock of compressed ethylene in nitrogen (5000 μl l−1) was blended into a continuous flow stream of air and diluted to the desired concentrations. The ethylene and air flow rates were controlled with calibrated mass flow control valves. An empirical mathematical model was derived for real-time variation of both the mixed concentration and flow rate during continuous flow. Validation of the model was performed using fresh sweet potato as a case study where a steady continuous ethylene concentration of 10 μl l−1 was achieved for three months. The bespoke system offers easy-to-manage ethylene supplementation for research

Does early detection of suspected atherosclerotic renovascular hypertension change outcomes

We found no evidence for changed outcomes from early detection of renal artery stenosis (RAS). Treatment of RAS in refractory hypertension modestly improves blood pressure control. There was a trend toward improved clinical outcomes but studies were underpowered to demonstrate this (strength of recommendation [SOR]: A, based on systematic review of RCTs)

Book Discussion

Book discussion of Persepolis: The Story of a Childhood by Marjane Satrapi. Faculty panelists include Sandra Gandy, JoAnne Smith, and Jason Zingsheim with Provost Terry Allison as moderator

Data Augmentation of Wearable Sensor Data for Parkinson's Disease Monitoring using Convolutional Neural Networks

While convolutional neural networks (CNNs) have been successfully applied to many challenging classification applications, they typically require large datasets for training. When the availability of labeled data is limited, data augmentation is a critical preprocessing step for CNNs. However, data augmentation for wearable sensor data has not been deeply investigated yet. In this paper, various data augmentation methods for wearable sensor data are proposed. The proposed methods and CNNs are applied to the classification of the motor state of Parkinson's Disease patients, which is challenging due to small dataset size, noisy labels, and large intra-class variability. Appropriate augmentation improves the classification performance from 77.54\% to 86.88\%.Comment: ICMI2017 (oral session