Experimental OFDM transmission performance analysis in a SOA - fiber cavity laser.

In this article, we present an experimental study of OFDM transmission using a specific bi-directional fiber cavity laser based on a semiconductor optical amplifier. We show that in the presence of sinusoidal modulation, its frequency response presents resonances relative to the optical cavity modes. We investigate first the performance of the system in terms of Error Vector Magnitude (EVM) for different configurations relative to the frequency position of the OFDM sub-carriers with respect to the frequency interval of the resonant modes. The obtained results show a significant improvement in the OFDM transmission EVM by increasing the OFDM subcarriers per frequency interval. We then analyze the impact of inter-symbol interference and inter-frame interference on the system's performance due to the round-trip echo and propose a pre-compensation method that added a small percentage of the previous symbol inversed before transmitting it inside the cavity where a decrease in the EVM is obtained respectively from 21.4% to 9.6% and from 26.8% to 13.2% for 4-QAM and 16-QAM data transmission.

Effects of preexisting stroke on acute hospital outcomes for older adults admitted with neurotrauma and orthopedic injury.

OBJECTIVE: We aimed to examine acute trauma outcomes, specifically among those with neurotrauma (NT), in patients with preexisting cerebrovascular accident (CVA). METHODS: We identified patients treated for neurotrauma or orthopedic trauma at hospitals in Pennsylvania with and without an identified history of stroke with residual deficits, aged 50-99 across four groups of N = 11,648 each. We assessed mortality, craniotomy, and total hospital, ICU, step-down, and ventilator days, functional status at discharge (FSD), and discharge destination. RESULTS: Stroke history did not influence mortality but was predictive of patients undergoing craniotomy (OR = 1.25, p = 0.008). There was a moderate group effect on total ICU days, with the CVA+NT group in the ICU the longest (η2 = 0.10, p < 0.001). Patients with stroke history were less likely to be discharged to home (OR = 0.65, p < 0.001) and had poorer FSD scores across the various domains assessed. CONCLUSIONS: Trauma patients with preexisting CVA were found to have poorer outcomes on a number of different metrics when compared to those without stroke history. While it is possible that functional differences pre-injury influenced FSD and discharge destination, given these results, clinicians should assess for possible comorbidities that may influence treatment.

Two cascaded SOAs used as intensity modulators for adaptively modulated optical OFDM signals in optical access networks.

Detailed theoretical and numerical investigations of the transmission performance of adaptively modulated optical orthogonal frequency division multiplexed (AMOOFDM) signals are undertaken, for the first time, in optical amplification and chromatic dispersion (CD) compensation free single mode fiber (SMF) intensity-modulated and direct-detection (IMDD) systems using two cascaded semiconductor optical amplifiers in a counterpropagating configuration as an intensity modulator (TC-SOA-CC-IM). A theoretical model describing the characteristics of this configuration is developed. Extensive performance comparisons are also made between the TC-SOA-CC and the single SOA intensity modulators. It is shown that, the TC-SOA-CC reaches its strongly saturated region using a lower input optical power much faster than the single SOA resulting in significantly reduced effective carrier lifetime and thus wide TC-SOA-CC bandwidths. It is shown that at low input optical power, we can increase the signal line rate almost 115% which will be more than twice the transmission performance offered by single SOA. In addition, the TC-SOA-CC-IM is capable of supporting signal line rates higher than corresponding to the SOA-IM by using 10dB lower input optical powers. For long transmission distance, the TC-SOA-CC-IM has much stronger CD compensation capability compared to the SOA-IM. In addition the use of TC-SOA-CC-IM is more effective regarding the capability to benefit from the CD compensation for shorter distances starting at 60km SMF, whilst for the SOA-IM starting at 90km.

The 21st Century Cures Act: Inpatient Clinician Perceptions of Changes to Information Sharing at an Academic Medical Center.

Introduction To comply with the Information Blocking Rule in the 21st Century Cures Act, many hospitals began to release inpatient electronic health information such as clinical notes and results to patients immediately, starting in April 2021. We sought to understand the perceptions of hospital-based clinicians regarding the impact of these changes in information sharing on clinicians and patients. Materials and methods We developed and distributed an electronic survey to 122 inpatient attending physicians, resident physicians, and physician assistants within the internal medicine and family medicine departments at an academic medical center. The survey asked clinicians to rate their comfort with information-sharing protocols and describe their perceptions of the impact of immediate information sharing on their documentation habits and patient interactions following the implementation of the Cures Act. Results The survey response rate was 37.7% (46/122). Of the respondents, 56.5% felt comfortable with the note-sharing process, 84.8% reported omitting specific information from their notes to prevent patients from reading it, and 39.1% of clinicians agreed that patients have found clinical notes "more confusing than helpful." Conclusions Immediate sharing of electronic health information has the potential to be a powerful tool for communicating with hospitalized patients. However, our results show many hospital-based clinicians report limited comfort with the note-sharing process and perceive it to be confusing to patients. Efforts are needed to educate clinicians regarding information sharing, understand patient and family perspectives, and develop best practices to enhance communication through electronic notes.