Chronic or sustained hyperglycemia associated to diabetes mellitus leads to many medical complications, thus, it is necessary to track the evolution of patients for providing the adequate management of the disease that is required for the restoration of the carbohydrate metabolism to a normal state. In this paper, a novel monitoring approach based on mm-wave spectroscopy is comprehensively described and experimentally validated using living animal models as target. The measurement method has proved the possibility of non-invasive, in-vivo, detection of hyperglycemia-associated conditions in different mouse models, making possible to clearly differentiate between several hyperglycemic states.
properties of propagating electromagnetic waves, such as wave front, polarization, intensity, or spectrum, in ways unachievable by bulk materials of the same subwavelength thickness. [1][2][3] The constituent elements of a metasurface can be either metallic or dielectric and they are usually patterned on a low-loss, dielectric substrate. All-dielectric metasurfaces, in particular, which are composed of elements made of a high-refractive index dielectric material, have been lately attracting more attention, as they show a very high diversity of exploitable properties, while being free from ohmic losses associated with the presence of metals. [4] The potential of dielectric metasurfaces as a platform for low-loss, compact, functional components has been extensively demonstrated in numerous applications, such as reflection/refraction control and wave-front shaping, [5][6][7][8] lensing, [9] control of light emission [10,11] or photoluminescence, [12,13] polarization control [14,15] and polarimetry, [16] generation of vortex beams, [17] highly selective filtering, [18,19] or enhancement of nonlinear processes. [20,21] In addition to offering novel solutions in practical applications, metasurfaces can also provide insight in theoretical physics, optics, and the investigation of phenomena based on particular light-matter interaction conditions. One such case is that of toroidal modes, which have been under intense investigation, thanks to their unusual electromagnetic properties. The toroidal dipole, the simplest toroidal mode, is generated by a current flowing in a solenoid, which is bent into a torus. Under certain conditions, the excitation of the toroidal dipole can interfere destructively with the electric dipole mode and cancel the far-field scattering radiation of dielectric particles, in the so-called "anapole" state. [22] Since decades ago, toroidal modes were employed in physics, for instance, to explain the parity violation of the weak interactions in atomic nuclei, [23] to propose models of stable atoms, [24] or to describe dark matter. [25] In recent years, though, the interest on electromagnetic toroidal moments is rapidly increasing as, apart from the fundamental physical insight, they can be harnessed in numerous applications. [26,27] Toroidal modes in individual dielectric particles or small clusters have been theoretically proposed for the excitation of toroidal response, [28] cloaking, [29] enhanced absorption, [30] and nanolasing [31] or experimentally demonstrated as nonradiating sources [32] and for the enhancement of nonlinear effects. [33,34] Moreover, it A single-layer, all-dielectric metasurface exhibiting a strong toroidal resonance in the low-atmospheric loss radio window of the subterahertz W-band is theoretically proposed and experimentally demonstrated. The metasurface is fabricated on a high-resistivity floating-zone silicon wafer by means of a singleprocess, wet anisotropic etching technique. The properties of the toroidal mode of both the constituent dielectric elements and the metasur...
In this article, we discuss the use of advanced statistical techniques (functional data analysis) in millimeter-wave (mm-wave) spectroscopy for biomedical applications. We employ a W-band transmit-receive unit with reference channel to acquire the spectral data. The choice of the W-band is based on a trade-off between penetration through the skin providing an upper bound for the frequencies and spectral content across the band. The data obtained are processed using Functional Principal Component Logit Regression (FPCLoR), which enables to obtain a predictive model for sustained hyperglycemia, typically associated with diabetes. The predictions are based on the transmission data from non-invasive mm-wave spectrometer at W-band. We show that there exists a frequency range most suitable for identification, classification, and prediction of sustained hyperglycemia when evaluating the functional parameter of the FPCLoR model (β). This allows for the optimization of the spectroscopic instrument in the aim to obtain a compact and potential low-cost non-invasive instrument for hyperglycemia assessment. Furthermore, we also demonstrate that the statistical tools alleviate the problem of calibration, which is a serious obstacle in similar measurements at terahertz and IR frequencies.
<p>We will present the preliminary results of the CarbonSurvey project (Towards the Next Generation of Sensors for Surveying the Atmospheric Carbon Cycle). As outlined by the European Commission green report in the framework of the Operational Anthropogenic CO2 Emissions Monitoring and Verification Support (MVS) capacity, the existing ground-based networks currently do not meet all the operational requirements for the Copernicus CO2 MVS capacity due to the lack of in situ measurement data from urban areas and other emission hot spots. The main expected contribution of this project is to address this weakness through the development of a new generation of instruments to enable unprecedented CO2 monitoring capabilities, the biggest GHG contributor to human-caused global warming. The necessary scientific and technical contributions required to reach the main goal of the project involve two complementary developments: (i) firstly, a gas analyzer capable of obtaining the vertical profile (with resolution in altitude) of CO2 concentration. The system, which is based on the Laser Heterodyne Radiometry (LHR) technique, will operate from the Earth's surface analyzing the effect in the spectrum of the received sunlight of the atmospheric components to accurately find the distribution of the concentration of CO2 in the atmospheric column. Thus, this instrument will provide a characterization of the CO2 in the atmospheric volume located above the measurement site. Secondly, (ii) the project aims to develop Photacoustic Spectroscopy (PAS) cost-competitive photonic solution for in situ urban GHG measurements. As a main difference with today&#8217;s commercially available instrumentation, the system proposed, based on a compact photoacoustic sensing cell, will combine small-size, high sensitivity, and a straightforward field deployment capacity. This directly enables the possibility of providing an accurate, and potentially gap-free, map of the concentration of gases at ground level. These two sets of instruments provide indeed complementary information for a full reconstruction of the map of CO2 around the areas of interest. It is important to remark that both instrument designs will be equipped as well with an important additional feature: the ability to determine the isotopic fingerprint of CO2 in order to discern between natural and anthropogenic CO2 sources, such as fossil fuel combustion or biogenic respiration.</p><p>The CarbonSurvey project is funded by the Spanish State Research Agency, it started December 2022 and last until November 2024. We will present the sensors design and the preliminary laboratory results. By the end of the project, we will have both sensor prototypes fully operational and calibrated at the Iza&#241;a Atmospheric center. Moreover, the sensing systems will be specifically designed for a straightforward in situ deployment in different areas of interest, providing full coverage of the most important blind spots existing today. This new generation of sensors could establish the necessary basis to guide decision-making policies in the green transition process ahead.</p>
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