Eculizumab Dosing Regimen in Atypical HUS: Possibilities for Individualized Treatment

Contains fulltext : 177003.pdf (publisher's version ) (Closed access) Contains fulltext : 177003pos.pdf (postprint version ) (Open Access)Recent studies indicate that eculizumab is often given in excess to atypical hemolytic uremic syndrome (aHUS) patients. Individualization of treatment is thus highly requested; however, data on the pharmacokinetics and pharmacodynamics of eculizumab remain limited. We analyzed 11 patients during induction (weekly), maintenance (2-weekly), and tapering (every 3-8 weeks) phases of treatment. The trough eculizumab levels increased with each additional dose during the induction phase (depending on body weight). During maintenance, high eculizumab concentrations of up to 772 mug/mL were observed. The levels decreased with each following dose during tapering (3- and 4-week intervals); however, three patients maintained target eculizumab levels over long time periods (30-48 weeks). At intervals of 6-8 weeks, target eculizumab levels were no longer attained. Serum samples with eculizumab concentrations >/=50 mug/mL showed adequate complement blockade. Our data provide essential insight for optimization of eculizumab dosing schemes and lessening of therapy burden for the patients and cost of the treatment

Spatial filtering approach for dymamic range reduction in cognitive radios

Cognitive radios (CRs) receive several users simultaneously. Therefore, the ADC of an CR requires a large dynamic range (DR) to guarantee adequate resolution per user. Thus far the ADC DR requirements have been prohibitive for the wide spread introduction of CR in the hand held market. The power consumption of an ADC reduces with an order of magnitude per decade. In the absence of disruptive new technologies, we expect this power trend to continue for the foreseeable future. Therefore, we propose an analog spatial filtering technique and present iterative methods to alleviate the ADC DR requirements and accelerate the overall power reduction of a CR. Simulation results indicate that for realistic scenarios the ADC resolution can be reduced by 4 bits per ADC, reducing the overall ADC power consumption with more than 90%

Theoretical model for maximum throughput of a radio receiver with limited battery power

Maximizing the battery life time of mobile devices and sensor nodes increasingly becomes a challenge. In many applications the energy consumed by the receiver is orders of magnitude larger than the energy consumed by the transmitter. We address the challenge of achieving the highest possible throughput per Watt of available receiver circuit power. Our closed form solution allows us to formalize the relation between adjacent channel interference power and achievable throughput for a given available receiver circuit power budget. We conclude that for a given adjacent channel interference level, there is an optimum receiver power that needs to be applied to operate the link at optimum efficiency in terms of bits per Joule. If the receiver has less power available than this optimum, it preferably applies a duty cycling scheme, switching between an off state and operation at the optimum power. This observation is contrast to commonly used capacity models where throughput is limited by transmit power

Full MIMO spatial filtering approach for dynamic range reduction in wideband cognitive radios

Wideband cognitive radios (CRs) receive signals from multiple transmitters simultaneously to increase spectrum utilization. Processing a wideband spectrum is challenging due to large dynamic range (DR) of the received signal and required high sampling speed of the ADC. The power consumption of high sampling speed/high-resolution ADCs have been prohibitive for handheld radios. However, in CR applications strong inband signals that pose large DR requirements can be filtered out, since CR needs to detect unused spectrum bands where no signal is present. Spatial domain filtering approaches through use of multiple antennas to reduce DR of the wideband signal are proposed. Algorithms and architectures are developed for vector beamforming (multiple antennas and a single ADC) and full multiple-input multiple-output (MIMO) (multiple antennas with an ADC per antenna) analog spatial filters for adaptive interference suppression. Simulation results indicate that for realistic indoor propagation environments the ADC resolution of an analog beamformer can be reduced by 4 bits when the receiver operates at 2 bits/s/Hz, reducing ADC power consumption by approximately 90%. Moreover, simulations indicate that full MIMO analog spatial filter can reduce ADC resolution with over 3 bits per ADC when the receiver operates at 5 bits/s/Hz, reducing ADC power consumption by approximately 85%

Power dissipation minimization in RF front ends

In mobile and portable wireless devices, it is important to have low power dissipation so as to maximize battery life. As the overall power dissipation of a device is dominated by the radio frequency (RF) front end rather than the digital circuit, low-power RF front end design has become a very hot topic in both research and implementation. In this paper, we propose a design method to minimize the power dissipation of a RF front end. Specifically, given the overall specifications of gain, linearity and noise figure of a front end, we derive the optimal specification for each building block of the RF front end such that the overall power dissipation is minimized. By using a specific example of a front end consisting of a couple of cascaded circuit blocks using 90nm CMOS technology, we demonstrate that significant reduction in power dissipation can be achieved using the proposed design method

Power dissipation minimization in RF front ends

In mobile and portable wireless devices, it is important to have low power dissipation so as to maximize battery life. As the overall power dissipation of a device is dominated by the radio frequency (RF) front end rather than the digital circuit, low-power RF front end design has become a very hot topic in both research and implementation. In this paper, we propose a design method to minimize the power dissipation of a RF front end. Specifically, given the overall specifications of gain, linearity and noise figure of a front end, we derive the optimal specification for each building block of the RF front end such that the overall power dissipation is minimized. By using a specific example of a front end consisting of a couple of cascaded circuit blocks using 90nm CMOS technology, we demonstrate that significant reduction in power dissipation can be achieved using the proposed design method

Front end power dissipation minimization and optimal transmission rate for wireless receivers

Most wireless battery-operated devices spend more energy receiving than transmitting. Hence, minimizing the power dissipation in the receiver front end, which, in many cases, is the prominent power consuming part of the receiver, is an important challenge. This paper addresses this challenge by solving two closely related optimization problems. Firstly, we optimize the overall power dissipation in an RF front end consisting of a chain of building blocks to satisfy required overall specifications in gain, linearity and noise figure. We extend this into a second optimization problem, namely to maximize the transmission rate that the receiver can accommodate for a given available receiver battery power budget. In fact, the ratio of this transmission rate vs the available receiver power budget serves as the figure-of-merit that allows a formal optimization where, in particular, the (adjacent channel) interference is a critical factor. Our results include closed-form analytical solutions for certain cases. For high signal power, where the noise is limited by interference, the largest bit/s/Hz per nJ drawn from receiver is reached for a transmission rate of 2.3 bits/s/Hz, irrespective of interference power. Numerical results using practical circuit blocks with 90 nm and 65 nm technologies are in close agreement with the analytical results

Measurement and analysis of UWB radio channel for indoor localization in a hospital environment

This paper focuses on accurate localization of patients in a hospital environment. To reduce power consumption and increase privacy, the localization of patients is only activated in case of an emergency. To evaluate the performance of 'single-shot' localization, ultra-wideband (UWB) radio channel measurements are performed in a modern hospital between a 'mobile agent' and 9 'anchors'. The anchors are placed at existing infrastructure, to allow for easy future integration. The agent is moved over a distance of 40 m at 460 points and spans several furnished rooms and a corridor. The channel is measured from 5 to 10 GHz with a link-budget of 120dB. Using post-processing, the impact of system parameters, like bandwidth and link-budget reduction, on the localization accuracy is evaluated. Our results show that a model based on the logistic distribution yields a higher accuracy, as it more resilient against outliers. The 'single-shot' localization has a mean error of 8.7 cm for a link budget of 110 dB, a bandwidth of 500 MHz, and a carrier frequency of 8.0 GHz. Results show that increasing the bandwidth does not improve the mean localization accuracy. However, reducing the link budget results in a considerably larger mean error

A 1.2 nJ/bit 2.4 GHz receiver with a sliding-IF phase-to-digital converter for wireless personal/body area networks

This paper presents an ultra-low power 2.4 GHz FSK/PSK RX for wireless personal/body area networks. A single-channel phase-tracking RX based on a sliding-IF phase-to-digital conversion (SIF-PDC) loop is proposed to directly demodulate and digitize the frequency/phase-modulated information. The sliding-IF frequency plan reduces the power consumption of the multi-phase LO generation. A phase rotator is adopted in SIF-PDC to guarantee frequency stability, i.e., avoid the frequency pulling by interference or frequency drift. It equivalently transforms the RF signal processing from the I/Q amplitude domain to a digital-phase domain, which saves up to nearly 40% on power consumption and relaxes the digital baseband complexity. A phase-domain linear model of the proposed SIF-PDC is presented to analyze the frequency response. Fabricated in a 90 nm CMOS technology, the presented RX consumes 2.4 mW at 2 Mbps data rate, i.e., 1.2 nJ/b efficiency, and achieves a sensitivity of -92 dBm