An HMM-based spectrum occupancy predictor for energy efficient cognitive radio

Spectrum sensing is the cornerstone of cognitive radio technology and refers to the process of obtaining awareness of the radio spectrum usage in order to detect the presence of other users. Spectrum sensing algorithms consume considerable energy and time. Prediction methods for inferring the channel occupancy of future time instants have been proposed as a means of improving performance in terms of energy and time consumption. This paper studies the performance of a hidden Markov model (HMM) spectrum occupancy predictor as well as the improvement in sensing energy and time consumption based on real occupancy data obtained in the 2.4GHz ISM band. Experimental results show that the HMM-based occupancy predictor outperforms a kth order Markov and a 1-nearest neighbour (1NN) predictor. Our study also suggests that by employing such a predictive scheme in spectrum sensing, an improvement of up to 66% can be achieved in the required sensing energy and time.

Physical rehabilitation interventions for adult patients during critical illness: an overview of systematic reviews

Background Physical rehabilitation interventions aim to ameliorate the effects of critical illness-associated muscle dysfunction in survivors. We conducted an overview of systematic reviews (SR) evaluating the effect of these interventions across the continuum of recovery.

Methods Six electronic databases (Cochrane Library, CENTRAL, DARE, Medline, Embase, and Cinahl) were searched. Two review authors independently screened articles for eligibility and conducted data extraction and quality appraisal. Reporting quality was assessed and the Grading of Recommendations Assessment, Development and Evaluation approach applied to summarise overall quality of evidence.

Results Five eligible SR were included in this overview, of which three included meta-analyses. Reporting quality of the reviews was judged as medium to high. Two reviews reported moderate-to-high quality evidence of the beneficial effects of physical therapy commencing during intensive care unit (ICU) admission in improving critical illness polyneuropathy/myopathy, quality of life, mortality and healthcare utilisation. These interventions included early mobilisation, cycle ergometry and electrical muscle stimulation. Two reviews reported very low to low quality evidence of the beneficial effects of electrical muscle stimulation delivered in the ICU for improving muscle strength, muscle structure and critical illness polyneuropathy/myopathy. One review reported that due to a lack of good quality randomised controlled trials and inconsistency in measuring outcomes, there was insufficient evidence to support beneficial effects from physical rehabilitation delivered post-ICU discharge.

Conclusions Patients derive short-term benefits from physical rehabilitation delivered during ICU admission. Further robust trials of electrical muscle stimulation in the ICU and rehabilitation delivered following ICU discharge are needed to determine the long-term impact on patient care. This overview provides recommendations for design of future interventional trials and SR.

Investigating Fractured Flow from Orthopaedics to Rehabilitation

Patients often spend time as inpatients in hospitals outside their home area because of the need to access specialist services. If there is a need for ongoing care after the need for specialist care has passed, patients are transferred (or ‘repatriated’) back to the inpatient care of a hospital in their local Health and Social Care Trust. The need for bed space in specialist units means that there is pressure for this transition to occur in a timely way. We investigated the flow of patients through a trauma and orthopaedics unit using the 6M Design® framework and Vitals Charts® in order to investigate concerns about delayed repatriation. We found that repatriation was part of a complex system that had interdependent components. There was considerable variation in the number of discharges (to any destination) by day of week, with a reduction on Saturdays and Sundays. Understanding that the pressure for quicker repatriation was really due to high work-in-progress led us to model the effects of strategies to address the high work-in-progress. We found that, because only a small proportion of patients require repatriation, expediting the repatriation process by one day for each patient would only reduce WIP by an average of 1.6 patients. Reducing the average length of stay for all trauma and orthopaedics inpatients by one day would reduce the WIP by 10 patients, which would make a much greater impact on the problem of high bed occupancy. Though the smooth and timely repatriation of patients to rehabilitation units is desirable, it is unlikely that efforts to achieve this will have a substantial impact on the problem of high WIP, so other strategies will be required. We will model the effects of strategies to reduce variation in daily discharges by the day of week in a future essay.