An analysis on decentralized adaptive MAC protocols for Cognitive Radio networks

The scarcity of bandwidth in the radio spectrum has become more vital since the demand for more and more wireless applications has increased. Most of the spectrum bands have been allocated although many studies have shown that these bands are significantly underutilized most of the time. The problem of unavailability of spectrum and inefficiency in its utilization has been smartly addressed by the Cognitive Radio (CR) Technology which is an opportunistic network that senses the environment, observes the network changes, and then using knowledge gained from the prior interaction with the network, makes intelligent decisions by dynamically adapting their transmission characteristics. In this paper some of the decentralized adaptive MAC protocols for CR networks have been critically analyzed and a novel adaptive MAC protocol for CR networks, DNG-MAC which is decentralized and non-global in nature, has been proposed. The results show the DNG-MAC out performs other CR MAC protocols in terms of time and energy efficiency

Impediments to eye transplantation: Ocular viability following optic-nerve transection or enucleation

Maintenance of ocular viability is one of the major impediments to successful whole-eye transplantation. This review provides a comprehensive understanding of the current literature to help guide future studies in order to overcome this hurdle. A systematic multistage review of published literature was performed. Three specific questions were addressed: (1) Is recovery of visual function following eye transplantation greater in cold-blooded vertebrates when compared with mammals? (2) Is outer retina function following enucleation and reperfusion improved compared with enucleation alone? (3) Following optic-nerve transection, is there a correlation between retinal ganglion cell (RGC) survival and either time after transection or proximity of the transection to the globe? In a majority of the studies performed in the literature, recovery of visual function can occur after whole-eye transplantation in cold-blooded vertebrates. Following enucleation (and reperfusion), outer retinal function is maintained from 4 to 9 h. RGC survival following optic-nerve transection is inversely related to both the time since transection and the proximity of transection to the globe. Lastly, neurotrophins can increase RGC survival following optic-nerve transection. This review of the literature suggests that the use of a donor eye is feasible for whole-eye transplantation.published_or_final_versio

Discovery of Molecular Markers to Discriminate Corneal Endothelial Cells in the Human Body

The corneal endothelium is a monolayer of hexagonal corneal endothelial cells (CECs) on the inner surface of the cornea. CECs are critical in maintaining corneal transparency through their barrier and pump functions. CECs in vivo have a limited capacity in proliferation, and loss of a significant number of CECs results in corneal edema called bullous keratopathy which can lead to severe visual loss. Corneal transplantation is the most effective method to treat corneal endothelial dysfunction, where it suffers from donor shortage. Therefore, regeneration of CECs from other cell types attracts increasing interests, and specific markers of CECs are crucial to identify actual CECs. However, the currently used markers are far from satisfactory because of their non-specific expression in other cell types. Here, we explored molecular markers to discriminate CECs from other cell types in the human body by integrating the published RNA-seq data of CECs and the FANTOM5 atlas representing diverse range of cell types based on expression patterns. We identified five genes, CLRN1, MRGPRX3, HTR1D, GRIP1 and ZP4 as novel markers of CECs, and the specificities of these genes were successfully confirmed by independent experiments at both the RNA and protein levels. Notably none of them have been documented in the context of CEC function. These markers could be useful for the purification of actual CECs, and also available for the evaluation of the products derived from other cell types. Our results demonstrate an effective approach to identify molecular markers for CECs and open the door for the regeneration of CECs in vitro

Diabetic retinopathy: current and future methods for early screening from a retinal hemodynamic and geometric approach

Diabetic retinopathy (DR) is a major disease and is the number one cause of blindness in the UK. In England alone, 4200 new cases appear every year and 1280 lead to blindness. DR is a result of diabetes mellitus, which affects the retina of the eye and specifically the vessel structure. Elevated levels of glucose cause a malfunction in the cell structure, which affects the vessel wall and, in severe conditions, leads to their breakage. Much research has been carried out on detecting the different stages of DR but not enough versatile research has been carried out on the detection of early DR before the appearance of any lesions. In this review, the authors approach the topic from the functional side of the human eye and how hemodynamic factors that are impaired by diabetes affect the vascular structur

A pilot study of performance among hospitalised elderly patients on a novel test of visuospatial cognition: the letter and shape drawing (LSD) test.

peer-reviewedObjectives. Conventional bedside tests of visuospatial function such as the clock drawing (CDT) and intersecting pentagons tests (IPT) are subject to considerable inconsistency in their delivery and interpretation. We compared performance on a novel test – the letter and shape drawing (LSD) test –with these conventional tests in hospitalised elderly patients. Methods. The LSD, IPT, CDT and the Montreal Cognitive Assessment (MoCA) were performed in 40 acute elderly medical inpatients at University Hospital Limerick The correlation between these tests was examined as well as the accuracy of the visuospatial tests to identify significant cognitive impairment on the MoCA. Results. The patients (mean age 81.0±7.71; 21 female) had a median MoCA score of 15.5 (range = 1–29). There was a strong, positive correlation between the LSD and both the CDT (r = 0.56) and IPT (r = 0.71). The correlation between the LSD and MoCA (r = 0.91) was greater than for the CDT and IPT (both 0.67). The LSD correlated highly with all MoCA domains (ranging from 0.54 to 0.86) and especially for the domains of orientation (r = 0.86), attention (0.81) and visuospatial function (r = 0.73). Two or more errors on the LSD identified 90% (26/29) of those patients with MoCA scores of ⩽20, which was substantially higher than for the CDT (59%) and IPT (55%). Conclusion. The LSD is a novel test of visuospatial function that is brief, readily administered and easily interpreted. Performance correlates strongly with other tests of visuospatial ability, with favourable ability to identify patients with significant impairment of general cognition.PUBLISHEDpeer-reviewe