Efficient decision support framework and swift occupation of the available licensed spectrum slot by secondary users (SUs) are the challenging issues in cognitive radio networks. An SU has to sense multiple target frequency spectrum slots in the shortest possible time before deciding to select and occupy the best idle slot for its transmission. A spectrum decision framework for the SUs in cognitive radio networks based on fuzzy logic is proposed. The activity time, possession, and quality of service of the spectrum slot lead to the decision of occupying the available spectrum slot(s). The proposed decision framework ensures that the SU's transmission in the particular spectrum slot does not cause any interference with the licensed user of the slot. The proposed method yields enhanced throughput as compared with the existing channel assignment schemes.
RF Spectrum Decision in Cognitive Radio enables unlicensed users of wireless communication systems to occupy the vacant spectrum slots as a solution to scarce spectrum. Internet of Things (IoT) is a wide-reaching network of unified entities. IoT capable things will be interconnected through wireless communication technologies offering cost-effectiveness and accessibility to remote users making quality life style. IoT implementation suffers from challenges of vulnerabilities to dynamic environmental conditions, ease of access, bandwidth allocation and utilization, and cost to purchase RF spectrum. As RF spectrum is a precious commodity and there is a dearth of RF spectrum, hence IoT connections are drifting towards Cognitive Radio Networks (CRNs). Permeating things with cognitive abilities will be able to make RF spectrum decisions to achieve interference-free and wireless connectivity as per their QoS requirements. The wireless systems are rapidly advancing. The leap from packet switching along with circuit switching with 144 kbps data rate (2G and 2.5G) to Long Term Evolution Advanced (LTE-A), i.e., 4G occurred in one decade time frame. As the current wireless connectivity is aimed at higher capacity, higher data rate, low end-to-end latency, massive device connectivity, reduced cost and consistent Quality of Experience (QoE) provision, therefore, 4G is being replaced with 5G. Presently the Radio Frequency (RF) spectrum band is fully sold out and allocated to various wireless operators and applications. On the other hand, new wireless applications are emerging and there is a serious dearth of frequency spectrum to be allocated to emerging wireless services. The efficient utilization of assigned RF spectrum which is otherwise underutilized due to the typical usage by the licensed users known as Primary Users (PUs) is the one of the best possible way to implement IoT in 5G. Thus the Spectrum Decision by unlicensed users of CR holds a significance in CR-based IoT in 5G and beyond network. This chapter describes a scientific supported spectrum decision support framework for CR Network. The main goal of this chapter is to discuss how CR technology can be helpful for the IoT paradigm.
Acute Mesenteric Ischemia is a rare condition with an incidence of 5/100,000. Occlusive subtype has the better outcome if early presentation and urgent surgical intervention is made.
The study was conducted at Lahore General Hospital, Lahore from Jan, 2016 to Jan, 2018. During this time period 12 patients were enrolled in the study fulfilling the inclusion and exclusion criteria.
Mean age was 58 years and all were male (range 45 - 75 years). All 12 patients were symptomatic at presentation with severe abdominal pain (94.3%), abdominal distension (63.6%) and vomiting (40.4%) alone or in combination. 7 patients (58.3%) presented within 24 hours from the onset of symptoms whereas 5 patients (41.6%) presented late. All patients who presented within 24 hours of onset of symptoms survived whereas all patients who presented after 24 hours from the onset of symptoms could not survive. The mortality rate for early presenters was zero % while for late presenters it was 100 %. On whole the mortality rate for our 12 patients with Acute Mesenteric Ischemia was 41.7 %.
Conclusion
Acute mesenteric ischemia patient presentation within 24 hours from the onset of symptoms with early diagnosis and surgical intervention had much better outcome.
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