Search

Chestnut crops are threatened by fungal pathogens such as Gnomoniopsis castaneae , which cause significant degradation of quality. Early detection of such infections is crucial to maintain the quality of chestnuts in the food industry. This study explores the application of Terahertz Time-Domain Hyperspectral Imaging (THz-TDHIS) combined with unsupervised learning techniques to identify fungal infections in chestnuts. Unlike conventional methods that rely on light attenuation, this approach leverages the unique spectral signatures of infected tissues. By employing Principal Component Analysis, K-Means Clustering, and Agglomerative Clustering, we effectively differentiate between healthy and infected portions of chestnuts. Our findings indicate that spectral features, rather than just intensity variations, provide more reliable markers for infection. In addition, we demonstrate that these methods enable the quantification of the degree of infection in chestnuts. The robustness of these unsupervised learning methods in handling large and heterogeneous data sets further underscores their potential in agricultural applications. This integrated THz-TDHIS and machine learning approach presents a promising solution to ensure chestnut quality and safety. [Display omitted] • THz Spectroscopy and Imaging combined with unsupervised machine learning technique enables a correct classification of the quality of chestnut; • A quantitative assessment of the percentage of healthy chestnut portions is demonstrated; • Our experiment is a proof-of-concept for a non-invasive and real-time monitoring of chestnut quality. [ABSTRACT FROM AUTHOR]

We report on a precision spectroscopic study of room-temperature H 12 C 13 CH in the 6463–6520 cm − 1 range, using a continuous-wave diode laser phase-locked to a near-infrared optical frequency comb synthesizer stabilized, in turn, against a GPS-disciplined rubidium clock. By tuning the comb repetition frequency, several ro-vibrational transitions in the P and R branches of the 2 ν 3 overtone band are recorded. Accuracy levels as low as 100 kHz, 5 · 10 − 10 in fractional terms, are obtained in the determination of absolute line-center frequencies. In addition, line intensities are measured for the first time, with a best fractional uncertainty of 1%, and used to retrieve the purely vibrational transition dipole moment in conjunction with the first-order Herman–Wallis factor. Finally, the pressure broadening coefficients γ self are also derived for the studied transitions. [ABSTRACT FROM AUTHOR]

This study aimed to investigate self-representations within the family and their effects on the development of adaptive skills in terms of personal and social autonomy. The target was a group of teenagers and young adults with Down Syndrome (DS), compared with a group of nondisabled individuals. The purposes of this study were: 1) to show a relationship between the development of autonomy during adolescence and the perceptions of feelings and attitudes experienced within the family; 2) to identify a link between a) family relationships which are more oriented towards recognizing the maturation processes with the goal of the autonomy of adolescents with DS, and b) the building of adequate self-representations with positive effects on personal and social adaptation. The study sample was composed of 170 adolescents and young adults, 85 of whom have DS. The instruments employed were the Vineland Adaptive Behavior Scale - Survey Form (VABS), which measures the level of Adaptive Behavior by three domains (Communication, Daily Living and Socialization), and the Family Relations Test: Children's Version (FRTC), which assesses the feelings that the subject expresses and receives within the family. The data analysis showed that while all family members influence the level of autonomy in typically developing persons, individuals with DS are significantly influenced by their mothers. The results are discussed taking into account other relevant research, and the possible implications for implementing prevention programs, as well as parenting and development support strategies. [ABSTRACT FROM AUTHOR]

We review the recent developments in precision ro-vibrational spectroscopy of buffer-gas-cooled neutral molecules, obtained using infrared frequency combs either as direct probe sources or as ultra-accurate optical rulers. In particular, we show how coherent broadband spectroscopy of complex molecules especially benefits from drastic simplification of the spectra brought about by cooling of internal temperatures. Moreover, cooling the translational motion allows longer light-molecule interaction times and hence reduced transit-time broadening effects, crucial for high-precision spectroscopy on simple molecules. In this respect, we report on the progress of absolute frequency metrology experiments with buffer-gas-cooled molecules, focusing on the advanced technologies that led to record measurements with acetylene. Finally, we briefly discuss the prospects for further improving the ultimate accuracy of the spectroscopic frequency measurement. [ABSTRACT FROM AUTHOR]

Thanks to the recent development of innovative instruments and software with high accuracy and resolution, 3D modelling provides useful insights in several sectors (from industrial metrology to cultural heritage). Moreover, the 3D reconstruction of objects of artistic interest is becoming mandatory, not only because of the risks to which works of art are increasingly exposed (e.g., wars and climatic disasters) but also because of the leading role that the virtual fruition of art is taking. In this work, we compared the performance of four 3D instruments based on different working principles and techniques (laser micro-profilometry, structured-light topography and the phase-shifting method) by measuring four samples of different sizes, dimensions and surface characteristics. We aimed to assess the capabilities and limitations of these instruments to verify their accuracy and the technical specifications given in the suppliers' data sheets. To this end, we calculated the point densities and extracted several profiles from the models to evaluate both their lateral (XY) and axial (Z) resolution. A comparison between the nominal resolution values and those calculated on samples representative of cultural artefacts was used to predict the performance of the instruments in real case studies. Overall, the purpose of this comparison is to provide a quantitative assessment of the performance of the instruments that allows for their correct application to works of art according to their specific characteristics. [ABSTRACT FROM AUTHOR]

We report on rovibrational fine structure spectroscopy of room-temperature trifluoromethane with a saturated absorption method, using a quantum cascade laser at around 8.6 µm phase-locked to a self-referenced mid-infrared frequency comb synthesizer. The absolute line-center frequencies of 36 lines have been measured by means of the wavelength modulation method with a best fractional uncertainty of ∼ 3 × 10 − 9 in a single acquisition scan from 34.7426 to 34.7443 THz. In addition, an extensive investigation of the measured Lamb-dip profiles using both direct pump-probe spectroscopy method and wavelength modulation technique has been performed for two selected lines, r R 40 (64) and r R 36 (38), belonging to the υ 5 vibrational band, as a function of either the gas pressure or the pump beam power. This approach allowed the measurement of the main spectroscopic parameters, such as saturation intensity, transition electric dipole moment, as well as self-pressure broadening coefficient. [ABSTRACT FROM AUTHOR]

Quantum cascade lasers (QCLs) are becoming a key tool in several advanced experiments in the field of precision molecular spectroscopy and absolute frequency metrology. In view of this, a thorough control of their emission properties must be achieved, including a narrow linewidth as well as a high frequency-stability combined with referencing to a primary standard. Here, we give a review on recent developments and next perspectives in this scope, with particular regard to the use of QCLs in fundamental physics spectroscopic searches. [ABSTRACT FROM AUTHOR]