A Vision-Based Technique for Lay Length Measurement of Metallic Wire Ropes

The lay length of metallic wire ropes is an important dimensional quantity whose analysis is useful to highlight rope deformations due to distributed damages. This paper describes a measurement system that is based on a video camera and on an offline processing algorithm. The camera acquires an image sequence of the running rope; then, an image processing algorithm extracts the rope contour and measures both the distance among rope strands and the whole distance covered by the rope during the test. A mathematical model of the rope contour has been developed and employed to test the proposed algorithm with simulated data. Field tests have been carried out with the proposed system on a working aerial cableway using a general-purpose camer

Intima-Media Thickness: Setting a Standard for a Completely Automated Method of Ultrasound Measurement

The intima - media thickness (IMT) of the common carotid artery is a widely used clinical marker of severe cardiovascular diseases. IMT is usually manually measured on longitudinal B-Mode ultrasound images. Many computer-based techniques for IMT measurement have been proposed to overcome the limits of manual segmentation. Most of these, however, require a certain degree of user interaction. In this paper we describe a new completely automated layers extraction (CALEXia) technique for the segmentation and IMT measurement of carotid wall in ultrasound images. CALEXia is based on an integrated approach consisting of feature extraction, line fitting, and classification that enables the automated tracing of the carotid adventitial walls. IMT is then measured by relying on a fuzzy K-means classifier. We tested CALEXia on a database of 200 images. We compared CALEXia performances to those of a previously developed methodology that was based on signal analysis (CULEXsa). Three trained operators manually segmented the images and the average profiles were considered as the ground truth. The average error from CALEXia for lumen - intima (LI) and media - adventitia (MA) interface tracings were 1.46 ± 1.51 pixel (0.091 ± 0.093 mm) and 0.40 ± 0.87 pixel (0.025 ± 0.055 mm), respectively. The corresponding errors for CULEXsa were 0.55 ± 0.51 pixels (0.035 ± 0.032 mm) and 0.59 ± 0.46 pixels (0.037 ± 0.029 mm). The IMT measurement error was equal to 0.87 ± 0.56 pixel (0.054 ± 0.035 mm) for CALEXia and 0.12 ± 0.14 pixel (0.01 ± 0.01 mm) for CULEXsa. Thus, CALEXia showed limited performance in segmenting the LI interface, but outperformed CULEXsa in the MA interface and in the number of images correctly processed (10 for CALEXia and 16 for CULEXsa). Based on two complementary strategies, we anticipate fusing them for further IMT improvement

Rough Set Based Approach for IMT Automatic Estimation

Carotid artery (CA) intima-media thickness (IMT) is commonly deemed as one of the risk marker for cardiovascular diseases. The automatic estimation of the IMT on ultrasound images is based on the correct identification of the lumen-intima (LI) and media-adventitia (MA) interfaces. This task is complicated by noise, vessel morphology and pathology of the carotid artery. In a previous study we applied four non-linear methods for feature selection on a set of variables extracted from ultrasound carotid images. The main aim was to select those parameters containing the highest amount of information useful to classify the image pixels in the carotid regions they belong to. In this study we present a pixel classifier based on the selected features. Once the pixels classification was correctly performed, the IMT was evaluated and compared with two sets of manual-traced profiles. The results showed that the automatic IMTs are not statistically different from the manual one

Motion Artifact Reduction in Breast Dynamic Infrared Imaging

Dynamic infrared imaging is a promising technique in breast oncology. In this study a QWIP infrared camera is used to acquire a sequence of consecutive thermal images of the patient's breast for 10 s. Information on the local blood perfusion is obtained from the spectral analysis of the time series at each image pixel. Due to respiratory and motion artifacts, the direct comparison of the temperature values that a pixel assumes along the sequence becomes difficult. In fact, the small temperature changes due to blood perfusion, of the order of 10-50 mK, which constitute the signal of interest in the time domain, are superimposed onto large temperature fluctuations due to the subject's motion, which represent noise. To improve the time series signal-to-noise ratio, and, as a consequence, enhance the specificity and sensitivity of the dynamic infrared examination, it is important to realign the thermal images of the acquisition sequence thus reducing motion artifacts. In a previous study we demonstrated that a registration algorithm based on fiducial points is suitable to both clinical applications and research, when associated with a proper set of skin markers. In this paper, we quantitatively evaluate the performance of different marker sets by means of a model that allows for estimating the signal-to-noise ratio increment due to registration, and we conclude that a 12-marker set is a good compromise between motion artifact reduction and the time required to prepare the patien

Electron-hole localization in coupled quantum dots

We theoretically investigate correlated electron-hole states in vertically coupled quantum dots. Employing a prototypical double-dot confinement and a configuration-interaction description for the electron-hole states, it is shown that the few-particle ground state undergoes transitions between different quantum states as a function of the interdot distance, resulting in unexpected spatial correlations among carriers and in electron-hole localization. Such transitions provide a direct manifestations of inter- and intradot correlations, which can be directly monitored in experiments.Comment: 11 pages, 3 figures (eps), LaTeX 2e. To appear in PRB (Rapid Communication

Produzione di composti ad alto valore aggiunto da sottoprodotti rinnovabili mediante un sistema multienzimatico a cascata

The efficient valorization of the lignocellulosic biomass components, and in particular the lignin fraction, could serve as a starting point for the establishment of a circular bioeconomy model aimed at the recycling and reutilization of industrial by-products over the exploitation of virgin feedstock. From lignocellulosic biomass both fermentable carbohydrate and aromatics can be obtained, which can be used for the production of biofuels and bioplastics thus reducing the dependence on petroleum-based feedstocks. The present Ph.D. thesis focuses on the development of novel biotechnological processes aimed at the extraction of aromatics from lignocellulosic by-products and their conversion to value-added products using whole-cell biocatalytic approaches. Firstly, I developed an efficient and green process to produce ccMA from renewable feedstocks (i.e. kraft lignin and wheat bran) based on: a) the optimization of the extraction procedures of vanillin from lignin and of ferulic acid from wheat bran; b) the genetic engineering of an E. coli strain to modulate the expression of up to seven recombinant enzymes. In detail, vanillin was recovered from kraft lignin (4.5 mg vanillin/g kraft lignin) by an enzymatic treatment using the recombinant Bacillus licheniformis laccase, and ferulic acid from wheat bran (3.0 mg ferulic acid/g wheat bran) by a thermo-enzymatic method using the Ultraflo®XL commercial enzyme. The whole-cell biocatalyst used to convert vanillin into ccMA expresses the dehydrogenase LigV, the demethylase VanAB, the decarboxylase AroY and the dioxygenase C12O; meanwhile the whole-cell biocatalyst to convert ferulic acid to ccMA expresses all the above-mentioned enzymes plus the decarboxylase Fdc and the dioxygenase Ado. The engineered strains converted >95% of lignin-derived vanillin in 30 minutes, obtaining the production of 4.2 mg ccMA/g of kraft lignin. Starting from the wheat bran-derived ferulic acid, ccMA was produced with a >95% conversion yield in 10 hours, corresponding to 0.73 g ccMA/g ferulic acid, and 2.2 mg ccMA/g wheat bran biomass. To further evaluate the capabilities of the whole-cell biocatlyst, the scaled-up production of ccMA from vanillin using the engineered E. coli growing cells was studied. The bioconversion reaction was carried out in a fermenter, providing improved control of the reaction conditions such as pH, dissolved oxygen and substrate pulse-feed rate, streamlining the biocatalytic process and enhancing scalability. The optimized growth medium composition (0.5 g/L glucose and 2 g/L lactose) and substrate addition strategy (1 mmol/h pulse-feed) enabled the engineered strain to produce 5.2 ± 0.36 g/L of ccMA in 48 hours, corresponding to 0.86 g ccMA/g vanillin. The purification of the produced ccMA from the fermentation broth was achieved through crystallization, yielding 2.58 ± 0.07 g per liter of broth, corresponding to a ≈50% purification yield. Lastly, a preliminary analysis of a one-pot process for the production of 4-vinylguaiacol from wheat bran was conducted. The process involves the extraction of ferulic acid from the wheat bran using the three-step thermo-enzymatic protocol utilized previously and the simultaneous conversion of ferulic acid into 4-vinylguaicol using an engineered E. coli strain expressing the decarboxylase Fdc. The novelty of this process arises from the employment of the wheat bran crude extract as an auto-inducing growth medium, based on the presence of several fermentable carbohydrates and the utilization of a hybrid phenol-inducible promoter for the induction of Fdc expression, making the wheat bran-derived ferulic acid both the inducer and the substrate of the enzyme. The unoptimized process produced 1.8 mg 4-vinylguaiacol per gram of wheat bran, which correspond to the conversion of ≈75% of the ferulic acid extracted using the thermo-enzymatic method and ≈64% of the alkaline extractable ferulic acid present in the wheat bran

Evaluation of time-series registration methods in dynamic area telethermometry for breast cancer detection

Automated motion reduction in 3D dynamic infrared imaging is on demand in many applications. Few methods for registering time-series dynamic infrared frames have been proposed. Almost all such methods are feature based algorithms requiring manual intervention. We apply different automated registration methods based on spatial displacement to 11 datasets of Breast Dynamic Infrared Imaging (DIRI) and evaluate the results in terms of both the image similarity and anatomical consistency of the transformation. The aim is to optimize the registration strategy for breast DIRI in order to improve the spectral analysis of temperature modulation; thus facilitating the acquisition procedure in a Dynamic Area Telethermometry framework. The results show that symmetric diffeomorphic demons registration outperforms both warped frames similarity and smoothness of deformation fields; hence proving effective for time-series dynamic infrared registratio

Field-controlled suppression of phonon-induced transitions in coupled quantum dots

We calculate the longitudinal-acoustic phonon scattering rate for a vertical double quantum dot system with weak lateral confinement and show that a strong modulation of the single-electron excited states lifetime can be induced by an external magnetic or electric field. The results are obtained for typical realistic devices using a Fermi golden rule approach and a three-dimensional description of the electronic quantum states.Comment: REVTex4 class, 6 pages, 3 figures, to be published in Applied Physics Letter