On the structure of nonarchimedean analytic curves

Let K be an algebraically closed, complete nonarchimedean field and let X be a smooth K-curve. In this paper we elaborate on several aspects of the structure of the Berkovich analytic space X^an. We define semistable vertex sets of X^an and their associated skeleta, which are essentially finite metric graphs embedded in X^an. We prove a folklore theorem which states that semistable vertex sets of X are in natural bijective correspondence with semistable models of X, thus showing that our notion of skeleton coincides with the standard definition of Berkovich. We use the skeletal theory to define a canonical metric on H(X^an) := X^an - X(K), and we give a proof of Thuillier's nonarchimedean Poincar\'e-Lelong formula in this language using results of Bosch and L\"utkebohmert.Comment: 23 pages. This an expanded version of section 5 of arXiv:1104.0320 which appears in the conference proceedings "Tropical and Non-Archimedean Geometry

Assessment and comparison of total RF-EMF exposure in femtocell and macrocell base station scenarios

The indoor coverage of a mobile service can be drastically improved by deployment of an indoor femtocell base station (FBS). However, the impact of its proximity on the total exposure of the human body to radio-frequency (RF) electromagnetic fields (EMFs) is unknown. Using a framework designed for the combination of near-field and far-field exposure, the authors assessed and compared the RF-EMF exposure of a mobile-phone (MP) user that is either connected to an FBS or a conventional macrocell base station while in an office environment. It is found that, in average macrocell coverage and MP use-time conditions and for Universal Mobile Telecommunications System technology, the total exposure can be reduced by a factor of 20-40 by using an FBS, mostly due to the significant decrease in the output power of the MP. In general, the framework presented in this study can be used for any exposure scenario, featuring any number of technologies, base stations and/or access points, users and duration

Measurement-based modeling of RF-EMF exposure in urban environments using artificial intelligence techniques

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Comparison of uplink SAR values in train environment for different wireless technologies

A comparison of uplink Specific Absorption Rate (SAR) values in a train environment for different wireless technologies using macrocells or femtocells is presented. The comparison is based on both simulations and real-life experiments. Compared to a typical GSM900 macrocell scenario, the largest SAR reduction is observed when using a UMTS femtocell base station, which leads to uplink SAR reductions by a factor 358,820

Novel wearable antenna systems for high datarate mobile communication in healthcare

In critical healthcare applications, there is a need for reliable wideband mobile communication links, implemented by portable units with sufficient autonomy. We present the latest generation wearable antenna systems for invisible and comfortable integration in patients' or caregivers' garments. These active textile modules boast excellent performance and reliability, thanks to innovative antenna topologies, leveraged by the application of substrate integrated waveguide technology, pervasive integration of electronics and energy harvesters, and the application of multi-antenna processing techniques. Applications range from mobile communication links between caregivers and a coordination centre during interventions, over wireless sensor systems for patient monitoring, to relaying videos streams between a wireless endoscopy capsule and a remote control station

Prediction and comparison of downlink electric-field and uplink localised SAR values for realistic indoor wireless planning

In this paper, for the first time a heuristic network calculator for both whole-body exposure due to indoor base station antennas or access points (downlink exposure) and localised exposure due to the mobile device (uplink exposure) in indoor wireless networks is presented. As an application, three phone call scenarios are investigated (Universal Mobile Telecommunications System (UMTS) macrocell, UMTS femtocell andWiFi voice-over-IP) and compared with respect to the electric-field strength and localised specific absorption rate (SAR) distribution. Prediction models are created and successfully validated with an accuracy of 3 dB. The benefits of the UMTS power control mechanisms are demonstrated. However, dependent on the macrocell connection quality and on the user's average phone call connection time, also the macrocell solution might be preferential from an exposure point of view for the considered scenario

Mobile phones: a trade-off between speech intelligibility and exposure to noise levels and to radio-frequency electromagnetic fields

When making phone calls, cellphone and smartphone users are exposed to radio-frequency (RF) electromagnetic fields (EMFs) and sound pressure simultaneously. Speech intelligibility during mobile phone calls is related to the sound pressure level of speech relative to potential background sounds and also to the RF-EMF exposure, since the signal quality is correlated with the RF-EMF strength. Additionally, speech intelligibility, sound pressure level, and exposure to RF-EMFs are dependent on how the call is made (on speaker, held at the ear, or with headsets). The relationship between speech intelligibility, sound exposure, and exposure to RF-EMFs is determined in this study. To this aim, the transmitted RF-EMF power was recorded during phone calls made by 53 subjects in three different, controlled exposure scenarios: calling with the phone at the ear, calling in speaker mode, and calling with a headset. This emitted power is directly proportional to the exposure to RF EMFs and is translated into specific absorption rate using numerical simulations. Simultaneously, sound pressure levels have been recorded and speech intelligibility has been assessed during each phone call. The results show that exposure to RF-EMFs, quantified as the specific absorption in the head, will be reduced when speaker-mode or a headset is used, in comparison to calling next to the ear. Additionally, personal exposure to sound pressure is also found to be highest in the condition where the phone is held next to the ear. On the other hand, speech perception is found to be the best when calling with a phone next to the ear in comparison to the other studied conditions, when background noise is present

In situ measurement of absorption in high-power interferometers by using beam diameter measurements

We present a simple technique to make in situ measurements of the absorption in the optics of high-power laser interferometers. The measurement is particularly useful to those commissioning large-scale high power optical systems