Stream bundle management layer for optimum management of co-existing telemedicine traffic streams under varying channel conditions in heterogeneous networks.

Heterogeneous networks facilitate easy and cost-effective penetration of medical advice in both rural and urban areas. However, disparate characteristics of different wireless networks lead to noticeable variations in network conditions when users roam among them e.g. during vertical handovers. Telemedicine traffic consists of a variety of real-time and non real-time traffic streams, each with a different set of Quality of Service requirements. This paper discusses the challenges and issues involved in the successful adaptation of heterogeneous networks by wireless telemedicine applications. We propose the development of a Smart Bundle Management (SBM) Layer for optimally managing co-existing traffic streams under varying channel conditions in a heterogeneous network. The SBM Layer acts as an interface between the applications and the underlying layers for maintaining a fair sharing of channel resources. Internal priority management algorithms are explained using Coloured Petri nets. This paper lays the foundation for the development of strategies for efficient management of co-existing traffic streams across varying channel conditions

Proactive policy management for heterogeneous networks

Context-awareness is a vital requirement of heterogeneous devices which allows them to predict future network conditions with sufficient accuracy. In this paper we present a proactive modelling-based approach for policy management which allows the mobile node to calculate Time Before Vertical Handover for open and closed environments. The paper explains how the knowledge of this component can improve the manner in which multi-class traffic streams are allocated to available network channels. Simulation results confirm the feasibility of the concept

Client-based SBM layer for predictive management of traffic flows in heterogeneous networks

In a heterogeneous networking environment, the knowledge of the time before a vertical handover (TBVH) for any network is vital in correctly assigning connections to available channels. In this paper, we introduce a predictive mathematical model for calculating the estimated TBVH component from available network parameters and discuss the different scenarios that arise based on a mobile host’s trajectory. We then introduce the concept of an intelligent Stream Bundle Management Layer (SBM) which consists of a set of policies for scheduling and mapping prioritised traffic streams on to available channels based on their priority, device mobility pattern and prevailing channel conditions. The layer is also responsible for the maintenance of connections during vertical handovers to avoid their forced termination

Proactive policy management using TBVH mechanism in heterogeneous networks.

In order to achieve seamless interoperability in heterogeneous networking, it is vital to improve the context-awareness of the mobile node (MN) so that it is able to predict future network conditions with sufficient accuracy. In this paper, we introduce a predictive mathematical model for calculating the estimated Time Before Vertical Handover (TBVH) component from available network parameters. The model is practically implemented in OPNET and our simulation results confirm the validity of the concept. We then demonstrate how the knowledge of TBVH along with other network parameters can be applied by downward Quality of Service management policies which bundle multi-class traffic streams on to available network channels based on application QoS, device mobility patterns and prevailing channel conditions

Vestibulo-cerebellar disease impairs the central representation of self-orientation

Transformation of head-fixed otolith signals into a space-fixed frame of reference is essential for perception of self-orientation and ocular motor control. In monkeys the nodulus and ventral uvula of the vestibulo-cerebellum facilitate this transformation by computing an internal estimate of direction of gravity. These experimental findings motivated the hypothesis that degeneration of the vestibulo-cerebellum in humans alter perceptual and ocular motor functions that rely on accurate estimates of gravity, such as subjective visual vertical (SVV), static ocular counterroll (OCR), and gravity-dependent modulation of vertical ocular drifts. We assessed the SVV, OCR, and spontaneous vertical ocular drifts in 12 patients with chronic vestibulo-cerebellar disease and in 10 controls. Substantially increased variability in estimated SVV was noted in the patients. Furthermore, gravity-dependent modulation of spontaneous vertical ocular drifts along the pitch plane was significantly (p < 0.05) larger in the patients. However, the gain and variability of static OCR and errors in SVV were not significantly different. In conclusion, in chronic vestibulo-cerebellar disease SVV and OCR remain intact except for an abnormal variability in the perception of verticality and impaired stabilization of gaze mediated by the otoliths. These findings suggest that OCR and perceived vertical are relatively independent from the cerebellum unless there is a cerebellar imbalance like an acute unilateral cerebellar stroke. The increased trial-to-trial SVV variability may be a general feature of cerebellar disease since a function of the cerebellum may be to compensate for such. SVV variability might be useful to monitor disease progression and treatment response in patients

Determinants of Outcome in Non-Septic Critically Ill Patients with Acute Kidney Injury on Continuous Venovenous Hemofiltration

Background/Aims: In view of ongoing controversy, we wished to study whether patient characteristics and/or continuous venovenous hemofiltration (CVVH) characteristics contribute to the outcome of non-septic critically ill patients with acute kidney injury (AKI). Methods: We retrospectively studied 102 consecutive patients in the intensive care unit (ICU) with non-septic AKI needing CVVH. Patient and CVVH characteristics were evaluated. Primary outcome was mortality up to day 28 after CVVH initiation. Results: Forty-four patients (43%) died during the 28-day period after the start of CVVH. In univariate analyses, non-survivors had more often a cardiovascular reason for ICU admission, greater disease acuity/severity and organ failure, lower initial creatinine levels, less use of heparin and more use of bicarbonate-based substitution fluid. The latter two can be attributed to high lactate levels and bleeding tendency in non-survivors necessitating withholding lactate-buffered fluid and heparin, respectively, according to our clinical protocol. In multivariate analyses, mortality was predicted by disease severity, use of bicarbonate-based fluids and lack of heparin, while initial creatinine and CVVH dose did not contribute. Conclusion: The outcome of non-septic AKI in need of CVVH is more likely to be determined by underlying or concurrent, acute and severe disease rather than by CVVH characteristics, including timing and dose

A survey of network coverage prediction mechanisms in 4G heterogeneous wireless networks.

Seamless connectivity in 4G wireless networks requires the development of intelligent proactive mechanisms for efficiently predicting vertical handovers. Random device mobility patterns further increase the complexity of the handover process. Geographical topologies such as indoor and outdoor environments also exert additional constraints on network coverage and device mobility. The ability of a device to acquire refined knowledge about surrounding network coverage can significantly affect the performance of vertical handover prediction and QoS management mechanisms. This paper presents a comprehensive survey of research work conducted in the area of 4G wireless network coverage prediction for the optimisation of vertical handovers. It discusses different coverage prediction approaches and analyses their ability to accurately predict network coverage