Analysis of the Ordinary and Extraordinary Ionospheric Modes for NVIS Digital Communications Channels.

Sensor networks have become more popular in recent years, now featuring plenty of options and capabilities. Notwithstanding this, remote locations present many difficulties for their study and monitoring. High-frequency (HF) communications are presented as an alternative to satellite communications, being a low-cost and easy-to-deploy solution.

NVIS Multicarrier Modulations for Remote-Sensor Applications.

The number of Internet of Things (IoT) devices has experienced a large growth during the last decade, as well as the data volume gathered from remote sensors. Satellites are still a suitable communication method and may be preferable for a remote ubiquitous sensor network (USN), which sometimes are located in places without much communications infrastructure where coverage is the principal drawback. Alternatively, the proposed solution for this article aims at a near-vertical incidence skywave (NVIS) channel for high frequencies (HF) with a low-cost platform, allowing a low-power transmissions coverage area up to 250 km for USN.

An integrated view of data quality in Earth observation.

Data quality is a difficult notion to define precisely, and different communities have different views and understandings of the subject. This causes confusion, a lack of harmonization of data across communities and omission of vital quality information. For some existing data infrastructures, data quality standards cannot address the problem adequately and cannot fulfil all user needs or cover all concepts of data quality.

[Low flow cavernous sinus fistula. Treatment by highly selective embolization].

Carotid-cavernous sinus fistulae are anomalous communications between the carotid artery and the cavernous sinus. They are classified according to whether they are traumatic or spontaneous, but distinction in relation to the anatomical origin of the branches of the carotid artery which supplies them is more important. The anatomy of the regional vasculature is analysed in this article.

Application of pulse polarography with anodic stripping voltammetry to biological and toxicological analyses for lead and cadmium.

The development of polarographic techniques within the last thirty years has made possible exceptional increases in sensitivity ; thus the order of concentration studied has passed from 10-3 g ion/1. to 10-10 g ion/1. Pulse polarography with anodic stripping voltammetry is, therefore, particularly suitable for the determination of a large number of the so-called " biologically essential " and " highly toxic " metals, more often than not present in extremely low concentrations in biological samples which may be of limited volume (blood, for example).