Common carotid intima-media thickness was measured by B-mode ultrasound imaging in 46 children (mean age, 7.4 years) with serum cholesterol 26.4 mmol/L (mean, 8.25 mmol/L) and in 48 children (mean age, 6.4 years) with serum cholesterol <6.4 mmol/L (mean, 4.60 mmol/L). Maximum thickness was significantly higher in hypercholesterolemic children than in control children (0.50 versus 0.47 mm, P=.007). Subgroup analysis showed that only in children >6.2 years old (the median of all the children's ages) was maximum thickness significantly higher in hypercholesterolemic children than in control children (0.51 versus 0.48 mm, P=.O14). The odds ratio (OR) of common carotid intima-media thickening T he relationship between hypercholesterolemia and coronary artery diseases (CAD) has been proved in adult CAD patients. 1 " 3 The significance of this relationship is more controversial in healthy subjects, particularly if their serum cholesterol is <6.4 mmol/L, 4 -6 Children form a special subgroup of healthy individuals.Population-based or "high-risk"-based screenings for serum cholesterol are usually recommended, 710 although others oppose this view on the basis of potential harm and of nonproven efficacy in the prevention of adult CAD. 1112Autopsy studies on arterial specimens of human subjects have shown that fatty streaks (nonraised lesions) can be found in the aortas even of 3-year-olds 13 and appear in the coronary arteries during the second decade of life.14 More advanced coronary atherosclerosis was seen in a majority of young adults in whom autopsies were performed during the Korean and Vietnam wars. -16 Aortic fatty streaks detected in subjects who had died between full-term birth and age 29 years appeared to be strongly related to antemortem levels of both total and low-density lipoprotein (LDL) cholesterol. 17 Raised lesions, like fibrous plaques, are related to clinical CAD, 18 but the progression of fatty streaks to fibrous plaques is uncertain. Arterial fibrous plaques have been found in autopsy specimens from children, Received October 5, 1993; revision accepted March 25, 1994. From the Institute of Internal Medicine and Metabolic Diseases and the Department of Pediatrics (R.S., A. Di C), Federico II University, Naples, Italy.Correspondence to Dr Paolo Pauciullo, Institute of Internal Medicine and Metabolic Diseases, Federico II University, Via Sergio Pansini, 5, 80131 Naples, Italy.© 1994 American Heart Association, Inc.(maximum thickness of the far wall higher than the 95th percentile of the control group, 0.51 mm) between patients and control subjects was statistically significant both in univariate analysis (OR, 6.39; 95% confidence interval, 1.19 to 32.3; f>=.025) and after age (OR, 5.96; 95% confidence interval, 1.09 to 32.4; P=.O39) and sex (OR, 7.54; 95% confidence interval, 1.38 to 41.2; P=.02O) were controlled for. Children >6 years old with serum cholesterol ^6.4 mmol/L show increased thickness of the common carotid intima-media.

Fractal geometries are appealing in all applications where miniaturization capabilities are required, ranging from antennas to frequency selective surfaces (FSS) design. Recently, some fractal patches configurations, giving low losses, reduced size, and quite good phase ranges, have been proposed for the design of reflectarray unit cells. This paper reviews existing fractal-based reflectarrays, highlighting their benefits and limitations. Furthermore, a comprehensive analysis of an innovative reflectarray unit cell, using a fractal-shaped fixed-size patch, is presented. The miniaturization capabilities of the Minkowski fractal shape are fully exploited to obtain a compact cell offering quite good phase agility, by leaving unchanged the patch size and acting only on the fractal scaling factor. Experimental validations are fully discussed on a realized 10 GHz0.3λ×0.3λcell. This is subsequently adopted to synthesize various reflectarray prototypes offering single or multiple-beam capabilities over a quite large angular region (up to 50 degrees). Finally, experimental validations on a realized15×15elements prototype are presented to demonstrate the wide angle beam-pointing capabilities as well as a quite large bandwidth of about 6%.

Abstract-Software Defined Radar is the latest trend in radar development.

The Universal Software Radio Peripheral USRP NI2920, a software defined transceiver so far mainly used in Software Defined Radio applications, is adopted in this work to design a high resolution L-Band Software Defined Radar system. The enhanced available bandwidth, due to the Gigabit Ethernet interface, is exploited to obtain a higher slant-range resolution with respect to the existing Software Defined Radar implementations. A specific LabVIEW application, performing radar operations, is discussed, and successful validations are presented to demonstrate the accurate target detection capability of the proposed software radar architecture. In particular, outdoor and indoor test are performed by adopting a metal plate as reference structure located at different distances from the designed radar system, and results obtained from the measured echo are successfully processed to accurately reveal the correct target position, with the predicted slant-range resolution equal to 6 m.

Visible Light Communication (VLC) paradigm allows the reusing of existing illuminating infrastructures in order to provide data communication. VLC can be considered a promising technology also for positioning in indoor environments, due to its potentially high accuracy and low costs. However, the main obstacle to the use of VLC for localization purposes is the high level of environmental noises, mainly due to sunlight. A novel approach, for easily measuring environmental noises and compensating their effects on localization results performed by an Indoor Positioning System (IPS) based on VLC, is proposed in this work. Frequency Division Multiplexing (FDM) is adopted to divide the total bandwidth into a series of non-overlapping frequency sub-bands corresponding to each signal, while an estimation of Signal to Noise Ratio (SNR), obtained through real time Power Spectral Density measurements in the proper frequency ranges, is exploited to compensate the error in positioning due to sunlight and other wideband external optical disturbing signals. The proposed approach has been validated through experimental tests, carried out using a simple deployment of low power lamps, low cost hardware and a software defined approach. In the region under test, receiver position has been experimentally detected with higher accuracy in comparison to classical FDM approach, confirming the correctness and effectiveness of our proposed technique. In order to further validate the proposed approach, an additive measurement campaign has been successfully carried out considering a scenario characterized by very low SNR levels.

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Visible light communication (VLC) builds on the dual use of lightening infrastructure for communication. Even though the advantages of VLC are well known, as emerging communication paradigm, some open issues still need to be addressed in order to rely on it as a robust communication system. First of all, external interference as an extremely varying signal impacting on the reliability of the VLC system needs to be analyzed. In this paper, we propose a system where the link conditions (in terms of signal-to-noise-ratio (SNR)) drive the modulation scheme and this procedure is managed through the use of an uplink/channel, to assure a feedback path. The receiver is in charge of choosing the modulation scheme matching the requirement in terms of error rate on the basis of the measured SNR after noise mitigation. The feasibility of the system and its effectiveness are evaluated by designing and implementing a complete bi-directional system. In particular, an uplink channel sending the information regarding the specific selected modulation technique has been implemented and the whole system is based on a fine synchronization approach in order to "track" in real time the most suitable modulation scheme. Experimental results show the effectiveness of a bi-directional system in order to implement an adaptive VLC system able to follow the environmental changes (in terms of interference and noise).