No abstract

Underground mining is an industry that preserves the miners' safety and efficiency in their work using wireless communication systems as a tool. In addition to communication links characterized by radio frequency signals, optical links in the visible light spectrum are under intense research for underground mining applications due to their high transmission rates and immunity to electromagnetic interference. However, the design of a robust visible-light communication (VLC) system for underground mining is a challenging task due to the harsh propagation conditions encountered in mining tunnels. To assist researchers in the design of such VLC systems, we present in this paper a novel channel model that incorporates important factors that influence the quality of the VLC link in underground mines. Features such as an arbitrary positioning and orientation of the optical transmitter and receiver, tunnels with irregular walls, shadowing by large machinery, and scattering by dust clouds are considered. These factors are integrated into a single modeling framework that lends itself for the derivation of compact mathematical expressions for the overall DC gain, the impulse response, the root mean square delay spread, and the received power of the proposed VLC channel model. Our analytical results are validated by computer simulations. These results show that the rotation and tilt of the transmitter and receiver, as well as the tunnels' irregular walls have a notorious influence on the magnitude and temporal dispersion of the VLC channel's line of sight (LoS) and non-LoS components. Furthermore, results show that shadowing reduces the LoS component's magnitude significantly. Our findings also show that scattering by dust particles contributes slightly to the total VLC channel gain, although it generates a large temporal dispersion of the received optical signal. INDEX TERMS Channel impulse response, channel modeling, scattering, shadowing, underground mining, visible light communication.

Transbronchial biopsy using forceps (TBB) is the first diagnostic technique performed on patients with interstitial lung disease (ILD). However, the small size of the samples and the presence of artefacts in the tissue obtained make the yield variable.Our objectives were 1) to attempt to reproduce transbronchial cryobiopsy under the same conditions with which we performed conventional TBB, that is, in the bronchoscopy unit without intubating the patient and without fluoroscopy or general anaesthesia; 2) to describe the method used for its execution; and 3) to analyse the diagnostic yield and its complications.We carried out a prospective study that included 106 patients with clinical and radiological features suggestive of ILD who underwent cryo-transbronchial lung biopsy (cryo-TBB) under moderate sedation without endotracheal intubation, general anaesthesia or use of fluoroscopy. We performed the procedure using two flexible bronchoscopes connected to two video processors, which we alternated until obtaining the number of desired samples.A definitive diagnosis was obtained in 91 patients (86%). As for complications, there were five pneumothoraces (4.7%) and in no case was there severe haemorrhage or exacerbation of the underlying interstitial disease. Cryo-TBB following our method is a minimally invasive, rapid, safe and economic technique that can be performed in a bronchoscopy suite under moderate sedation without the need for intubating the patient or using fluoroscopy and without requiring general anaesthesia.

In this paper, we study the performance of telecommand space links affected by pulsed, continuous wave and pseudo-noise jamming. Countermeasures include coding, interleaving, and direct sequence spread spectrum. Binary and non-binary low-density parity-check codes, parallel turbo codes, and soft-decision decoded BCH codes are considered. We investigate the impact of different decoding algorithms, also taking into account the role of jamming state information, spreading processing gain and interleaving. The results show that significant gains (up to more than 10 dB) can be achieved in a number of interesting scenarios.During the active time, the jamming signal has a power spectral density that is constant over the W ss band, with two-side value J 0P 2 , where J 0P D J P W ss . For proper comparison, it is also useful to introduce an equivalent (with the same energy) Gaussian continuous jamming signal. Because the same energy is transmitted over T instead of B, it has a power J D J P . Also, this equivalent jamming signal has a power spectral density constant over the W ss band, with two-side value J 0 2 , where J 0 D J W ss D J 0P . The error rate performance can be expressed in terms of the ratio E b J 0 between the energy per bit and the equivalent one-side jamming spectral density.

Ultrasound-guided axillary vein cannulation using a wireless transducer for the implantation of CIEDs is a feasible, fast, and safe method.