A novel phase retrieval technique based on propagation diversity via a dielectric slab.

This paper deals with a novel technique to determine the far field of an aperture starting from the knowledge of two near-field intensity data sets collected over the same measurement plane. The diversity between the two intensity data sets is achieved by ensuring different conditions of the near field propagation between the aperture and the measurement plane. In particular, one measurement is performed under free-space propagation condition while the second one is performed by exploiting a dielectric slab, with known properties, filling partly the space between the aperture and the measurement plane. A phase retrieval technique, that faces a non linear inverse problem, is solved by assuming as unknown the plane wave spectrum of the aperture field. The feasibility of the novel approach is presented also in comparison with the usual near field phase retrieval technique exploiting measurements of the near field intensity over two scanning planes. © 2007 Optical Society of America

Driving with no brakes: Molecular pathophysiology of Kv7 potassium channels

Kv7 potassium channels regulate excitability in neuronal, sensory, and muscular cells. Here, we describe their molecular architecture, physiological roles, and involvement in genetically determined channelopathies highlighting their relevance as targets for pharmacological treatment of several human disorders

Bathymetry Determination via X-Band Radar Data: A New Strategy and Numerical Results

This work deals with the question of sea state monitoring using marine X-band radar images and focuses its attention on the problem of sea depth estimation. We present and discuss a technique to estimate bathymetry by exploiting the dispersion relation for surface gravity waves. This estimation technique is based on the correlation between the measured and the theoretical sea wave spectra and a simple analysis of the approach is performed through test cases with synthetic data. More in detail, the reliability of the estimate technique is verified through simulated data sets that are concerned with different values of bathymetry and surface currents for two types of sea spectrum: JONSWAP and Pierson-Moskowitz. The results show how the estimated bathymetry is fairly accurate for low depth values, while the estimate is less accurate as the bathymetry increases, due to a less significant role of the bathymetry on the sea surface waves as the water depth increases

Imaging of Scarce Archaeological Remains Using Microwave Tomographic Depictions of Ground Penetrating Radar Data

The Romano-British site of Barcombe in East Sussex, England, has suffered heavy postdepositional attrition through reuse of the building materials for the effects of ploughing. A detailed GPR survey of the site was carried out in 2001, with results, achieved by usual radar data processing, published in 2002. The current paper reexamines the GPR data using microwave tomography approach, based on a linear inverse scattering model, and a 3D visualization that permits to improve the definition of the villa plan and reexamine the possibility of detecting earlier prehistoric remains

Monitoring the breath through mechanical movements of the chest using continuous wave bioradar system

In space missions, during the long isolation at extreme condition for human health is most important monitoring vital signs. One of these is the breathing detection. Indeed several factors can induce some breathing anomalies during the sleep, which may cause apnea episodes. In order to act timely with the right therapy, an early diagnosis is required. A new, innovative, way to perform this kind of measurement is continuous wave bioradar, shown in Figure 1, operating in the microwave frequency. This is effective contactless tool for monitoring the respiratory activity through the measurement of chest deformation due to inhalation and exhalation. This system emit a low power electromagnetic wave at a single frequency, which is reflected by the human chest. Through to measuring of the phases shift between the incident and reflected wave is possible discovering and monitoring the respiratory rate. In this paper, the continuous wave bioradar measurement technique and test campaign experimental results are presented. Furthermore, to this end, bioradar results are compared with data recorded by a spirometer, which is a standard and noted medical device that measures the air volume inhaled and exhaled by the subject. Finally, the measurement standard uncertainty of the bioradar system is defined, and the system performance is evaluated. Please click Additional Files below to see the full abstract

Measurements Performance of a Bioradar for Human Respiration Monitoring

Abstract Breathing pattern monitoring of humans is very important especially during long isolation in space missions. In particular, several factors can induce some breathing anomalies during the sleep, which may cause apnea episodes; an early diagnosis of such episodes is crucial for the application of an efficient therapy. Continuous wave bioradars operating in the microwave frequency range are effective contactless tools for monitoring the respiratory activity. These active systems emit a low power electromagnetic wave at a single frequency, which is reflected by the human chest. Based on the phase difference between the incident and reflected signals, it is possible to estimate and monitor the respiratory rate. In this paper, a metrological characterization of the bioradar methodology is presented. To this end, bioradar results are compared with the ground truth data recorded by a spirometer, which is a standard medical device that measures the air volume inhaled and exhaled by the subject

A Comprehensive Forward Model for Imaging under Irregular Terrain Using RF Tomography

Imaging of tunnel networks under irregular terrain using RF tomography is generalized to include the possibility of magnetic dipoles (i.e., electric loops) either as transmitting or receiving devices. Forward scattering models are presented, and a generalized method for computing numerical dyadic Green’s functions is detailed. Explicit formulas for fast numerical implementation are also presented. The paper is corroborated with numerical simulations aimed at validating formulas

3D Imaging of Buried Dielectric Targets with a Tomographic Microwave Approach Applied to GPR Synthetic Data

Effective diagnostics with ground penetrating radar (GPR) is strongly dependent on the amount and quality of available data as well as on the efficiency of the adopted imaging procedure. In this frame, the aim of the present work is to investigate the capability of a typical GPR system placed at a ground interface to derive three-dimensional (3D) information on the features of buried dielectric targets (location, dimension, and shape). The scatterers can have size comparable to the resolution limits and can be placed in the shallow subsurface in the antenna near field. Referring to canonical multimonostatic configurations, the forward scattering problem is analyzed first, obtaining a variety of synthetic GPR traces and radargrams by means of a customized implementation of an electromagnetic CAD tool. By employing these numerical data, a full 3D frequency-domain microwave tomographic approach, specifically designed for the inversion problem at hand, is applied to tackle the imaging process. The method is tested here by considering various scatterers, with different shapes and dielectric contrasts. The selected tomographic results illustrate the aptitude of the proposed approach to recover the fundamental features of the targets even with critical GPR settings

Radiometric Imaging for Monitoring and Surveillance Issues

This paper deals with the recent advances performed by State Research Center “Iceberg” (SRC) in the field of the passive imaging at millimeter wavelengths. In particular, first the paper describes the design and the realization of two systems working in 3 mm and 8 mm wave bands, respectively. Second, the measurements collected by the two systems are enhanced by means of simple data processing strategies developed by the Institute for Electromagnetic Sensing of the Environment (IREA-CNR)