Attention-aided partial bidirectional RNN-based nonlinear equalizer in coherent optical systems.

We leverage the attention mechanism to investigate and comprehend the contribution of each input symbol of the input sequence and their hidden representations for predicting the received symbol in the bidirectional recurrent neural network (BRNN)-based nonlinear equalizer. In this paper, we propose an attention-aided novel design of a partial BRNN-based nonlinear equalizer, and evaluate with both LSTM and GRU units in a single-channel DP-64QAM 30Gbaud coherent optical communication systems of 20 × 50 km standard single-mode fiber (SSMF) spans. Our approach maintains the Q-factor performance of the baseline equalizer with a significant complexity reduction of ∼56.16% in the number of real multiplications required to equalize per symbol (RMpS). In comparison of the performance under similar complexity, our approach outperforms the baseline by ∼0.2dB to ∼0.25dB at the optimal transmit power, and ∼0.3dB to ∼0.45dB towards the more nonlinear region.

Impact of Lithium-Ion Battery State of Charge on In Situ QAM-Based Power Line Communication.

Power line communication within a lithium-ion battery allows for high fidelity sensor data to be transferred between sensor nodes of each instrumented cell within the battery pack to an external battery management system. In this paper, the changing characteristics of the lithium-ion cell at various states of charge are measured, analysed, and compared to understand their effectiveness on the communication channel of a power line communication system for carrier frequencies of 10 MHz to 6 GHz. Moreover, the use of quadrature amplitude modulation (QAM) is investigated to determine its effectiveness as a state-of-the-art modulation method for the same carrier frequency range. The overall results indicate that certain carrier frequencies and QAM orders may not be suitable for the in situ battery pack power line communication due to changes in battery impedance with certain lithium-ion cell states of charge, which cause an increase in error vector magnitude, bit error ratio, and symbol error ratio. Recommendations and trends on the impact of these changing characteristics based upon empirical results are also presented in this paper.

Hospital Volume as a Source of Variation for Major Complications and Early In-Hospital Mortality After Total Joint Arthroplasty.

Background: Although the effects of hospital volume on mortality have been studied in other procedures, data on total joint arthroplasty (TJA) are limited. Furthermore, mortality rate among surgical patients with early major complications has become an important patient safety indicator and has been shown to be an important driver of mortality in certain operations. Our objective was to examine the effect of hospital volume on early complications and in-hospital mortality rate after TJA. Material and methods: A total of 5,396,644 patients undergoing elective, unilateral TJA between 2002 and 2011 were identified using the Nationwide Inpatient Sample database. Hospitals were divided by annual volume into tertiles. Major complications associated with postoperative mortality were identified. Risk-adjusted mortality (RAM) was calculated to adjust for hospital case mix. Results: For THAs performed at high-volume centers, RAM was significantly lower (0.03% vs 0.41%, P < .05, high vs low volume) with lower prevalence of major complications (2.2% vs 3.3%, P < .05, high vs low volume). We observed similar results for TKA where RAM was lower (<0.01% vs 0.06%, P < .05, high vs low volume). Major complications, however, were not significant (1.4% vs 1.5%, P < .83). Pneumonia was the most prevalent complication for THA (1.5% vs 0.9%, P < .05, high vs low volume) and TKA (0.9% vs 0.5%, P < .05 high vs low volume). Conclusion: Hospital volume appears to drive a large proportion of the variation in early in-hospital mortality after TJA. This variation does not seem to be explained by hospital case mix and rather by the higher prevalence of major postoperative complications in lower volume institutions.

Nano-rectenna powered body-centric nano-networks in the terahertz band.

A wireless body-centric nano-network consists of various nano-sized sensors with the purpose of healthcare application. One of the main challenges in the network is caused by the very limited power that can be stored in nano-batteries in comparison with the power required to drive the device for communications. Recently, novel rectifying antennas (rectennas) based on carbon nanotubes (CNTs), metal and graphene have been proposed. At the same time, research on simultaneous wireless information and power transfer (SWIPT) schemes has progressed apace. Body-centric nano-networks can overcome their energy bottleneck using these mechanisms. In this Letter, a nano-rectenna energy harvesting model is developed. The energy harvesting is realised by a nano-antenna and an ultra-high-speed rectifying diode combined as a nano-rectenna. This device can be used to power nanosensors using part of the terahertz (THz) information signal without any other system external energy source. The broadband properties of nano-rectennas enable them to generate direct current (DC) electricity from inputs with THz to optical frequencies. The authors calculate the output power generated by the nano-rectenna and compare this with the power required for nanosensors to communicate in the THz band. The calculation and analysis suggest that the nano-rectenna can be a viable approach to provide power for nanosensors in body-centric nano-networks.

Super Obesity Is an Independent Risk Factor for Complications After Primary Total Hip Arthroplasty.

BACKGROUND: Recent studies have reported higher postoperative complication rates in obese and morbidly obese patients undergoing total hip arthroplasty (THA). Less data are available regarding super-obese (body mass index [BMI] >50 kg/m2) patients. This study aims to quantify the risk of complications after THA in super-obese patients on a national scale and to put these risks in context by comparing them to patients of other BMI classes as well as those undergoing revision THA. METHODS: Utilizing a national insurance database, complication rates after THA in super-obese patients (n = 3244) were compared to nonobese, obese, and morbidly obese patients undergoing primary THA and all patients undergoing revision THA. A logistic regression analysis controlling for demographic and comorbidity variables was utilized to determine the independent effect of super obesity on complication rates after THA. RESULTS: Super-obese patients had significantly higher rates of most complications than nonobese, obese, morbidly obese, and revision THA patients, including venous thromboembolism, infection, blood transfusion, medical complications, dislocation, readmission, and revision THA. CONCLUSION: Super-obese patients (BMI >50 kg/m2) have higher rates of postoperative complications after THA than nonobese, obese, morbidly obese, and revision THA patients. Super obesity is an independent risk factor for increased rates of most postoperative complications including the need for early revision THA.

The Effect of Two Receivers on Broadcast Molecular Communication Systems.

Molecular communication is a paradigm that utilizes molecules to exchange information between nano-machines. When considering such systems where multiple receivers are present, prior work has assumed for simplicity that they do not interfere with each other. This paper aims to address this issue and shows to what extent an interfering receiver, [Formula: see text], will have an impact on the target receiver, [Formula: see text], with respect to Bit Error Rate (BER) and capacity. Furthermore, approximations of the Binomial distribution are applied to reduce the complexity of calculations. Results show the sensitivity in communication performance due to the relative location of the interfering receiver. Critically, placing [Formula: see text] between the transmitter [Formula: see text] and [Formula: see text] causes a significant increase in BER or decrease in capacity.

Flexible quality of service model for wireless body area sensor networks.

Wireless body area sensor networks (WBASNs) are becoming an increasingly significant breakthrough technology for smart healthcare systems, enabling improved clinical decision-making in daily medical care. Recently, radio frequency ultra-wideband technology has developed substantially for physiological signal monitoring due to its advantages such as low-power consumption, high transmission data rate, and miniature antenna size. Applications of future ubiquitous healthcare systems offer the prospect of collecting human vital signs, early detection of abnormal medical conditions, real-time healthcare data transmission and remote telemedicine support. However, due to the technical constraints of sensor batteries, the supply of power is a major bottleneck for healthcare system design. Moreover, medium access control (MAC) needs to support reliable transmission links that allow sensors to transmit data safely and stably. In this Letter, the authors provide a flexible quality of service model for ad hoc networks that can support fast data transmission, adaptive schedule MAC control, and energy efficient ubiquitous WBASN networks. Results show that the proposed multi-hop communication ad hoc network model can balance information packet collisions and power consumption. Additionally, wireless communications link in WBASNs can effectively overcome multi-user interference and offer high transmission data rates for healthcare systems.