Design Space Exploration on High-Order QAM Demodulation Circuits: Algorithms, Arithmetic and Approximation Techniques

Every new generation of wireless communication standard aims to improve the overall performance and quality of service (QoS), compared to the previous generations. Increased data rates, numbers and capabilities of connected devices, new applications, and higher data volume transfers are some of the key parameters that are of interest. To satisfy these increased requirements, the synergy between wireless technologies and optical transport will dominate the 5G network topologies. This work focuses on a fundamental digital function in an orthogonal frequency-division multiplexing (OFDM) baseband transceiver architecture and aims at improving the throughput and circuit complexity of this function. Specifically, we consider the high-order QAM demodulation and apply approximation techniques to achieve our goals. We adopt approximate computing as a design strategy to exploit the error resiliency of the QAM function and deliver significant gains in terms of critical performance metrics. Particularly, we take into consideration and explore four demodulation algorithms and develop accurate floating- and fixed-point circuits in VHDL. In addition, we further explore the effects of introducing approximate arithmetic components. For our test case, we consider 64-QAM demodulators, and the results suggest that the most promising design provides bit error rates (BER) ranging from 10−1 to 10−4 for SNR 0–14 dB in terms of accuracy. Targeting a Xilinx Zynq Ultrascale+ ZCU106 (XCZU7EV) FPGA device, the approximate circuits achieve up to 98% reduction in LUT utilization, compared to the accurate floating-point model of the same algorithm, and up to a 122% increase in operating frequency. In terms of power consumption, our most efficient circuit configurations consume 0.6–1.1 W when operating at their maximum clock frequency. Our results show that if the objective is to achieve high accuracy in terms of BER, the prevailing solution is the approximate LLR algorithm configured with fixed-point arithmetic and 8-bit truncation, providing 81% decrease in LUTs and 13% increase in frequency and sustains a throughput of 323 Msamples/s

Low-dose clozapine monotherapy for recurring episodes of depression, hypersomnia and behavioural disturbances: a case report

Case Report: We present a 27-year-old woman who manifested recurrent episodes of hypersomnia, compulsive hyperphagia, hypersexuality, impulsive behaviours, irritability and depressive mood since the age of 13 after a viral febrile infection. She had 3-4 episodes/year lasting from a few days to 2-3 weeks which were managed with various psychotropics. During her last episode, she was admitted because of persistent behavioural disturbances. Brain 99m-Tc-ethyl cysteinate dimer single-photon emission computed tomography scans showed bilateral mesiotemporal and thalamic hypoperfusion, more significant in the right hemisphere. While hospitalised, she developed neuroleptic malignant syndrome following haloperidol administration. She was discharged on clozapine 100 mg/day. Over the following 30 months, she remained symptom free on clozapine 50-100 mg/day. Discussion: Differential diagnosis included either an atypical recurrent mood disorder with hypersomnia and behavioural disturbances or Kleine-Levin syndrome. Conclusion: Low-dose clozapine monotherapy may worth being further investigated for the management of recurring episodes of depression, hypersomnia and behavioural disturbances

The Education and training of clinical medical physicists in 25 European, 2 North American and 2 Australasian countries: Similarities and differences

Purpose: The clinical medical physicist is part of a team responsible for safe and competent provision of radiation-based diagnostic examinations and therapeutic practices. To ensure that the physicist can provide an adequate service, sufficient education and training is indispensable. The aim of this study is to provide a structured description of the present status of the clinical medical physicist education and training framework in 25 European, 2 North American and 2 Australasian countries. Methods: For this study, data collection was based on a questionnaire prepared by the European Federation of Organizations in Medical Physics (EFOMP) and filled-in either by the corresponding scientific societies-organizations or by the authors. Results: In the majority of cases, a qualified medical physicist should have an MSc in medical physics and 1–3 years of clinical experience. Education and training takes place in both universities and hospitals and the total duration of the programs ranges from 2.5 to 9 years. In 56% of all European countries, it is mandatory to hold a diploma or license to work as a medical physicist, the situation being similar in Australasian and 4 states of USA. Generally, there are national registers of medical physicists with inclusion on the register being voluntary. There are renewal mechanisms in the registers usually based on a Continuing Professional Development (CPD) system. Conclusions: In conclusion, a common policy is followed in general, on topics concerning education and training as well as the practice of the medical physicist profession, notwithstanding the presence of a few differences

The international context of education, training and certification for medical physicists in Europe, North America and Australasia

A common international education, training and certification framework for medical physicists is not available. Because of this an agreed uniform level of skills and knowledge, which is considered as a prerequisite for the free movement of professionals, does not exist. The aim of this study is to provide a description of the present status of the medical physicist education, training and certification framework in 25 European, 2 North American and 2 Australasian countries and compare this with an international certification model. We find that a common policy is generally followed on education, training and certification as well as on professional practice, notwithstanding a few national differences. Attempts to formulate general guidelines are already in progress based on common features and differences between countries which could be used to inform the development of a truly international certification process for medical physicists