I/Q imbalance in AF dual-hop relaying: Performance analysis in Nakagami-m fading

We analyze the performance of amplify-and-forward dual-hop relaying systems in the presence of in-phase and quadrature-phase imbalance (IQI) at the relay node. In particular, an exact analytical expression for and tight lower bounds on the outage probability are derived over independent, non-identically distributed Nakagami-m fading channels. Moreover, tractable upper and lower bounds on the ergodic capacity are presented at arbitrary signal-to-noise ratios (SNRs). Some special cases of practical interest (e.g., Rayleigh and Nakagami-0.5 fading) are also studied. An asymptotic analysis is performed in the high SNR regime, where we observe that IQI results in a ceiling effect on the signal-to-interference-plus-noise ratio (SINR), which depends only on the level of I/Q impairments, i.e., the joint image rejection ratio. Finally, the optimal I/Q amplitude and phase mismatch parameters are provided for maximizing the SINR ceiling, thus improving the system performance. An interesting observation is that, under a fixed total phase mismatch constraint, it is optimal to have the same level of transmitter (TX) and receiver (RX) phase mismatch at the relay node, while the optimal values for the TX and RX amplitude mismatch should be inversely proportional to each other.

On the Ontological Quality and Logical Quality of Conceptual-Modeling Grammars: The Need for a Dual Perspective

A core activity in information systems development involves building a conceptual model of the domain that an information system is intended to support. Such models are created using a conceptual-modeling (CM) grammar. Just as high-quality conceptual models facilitate high-quality systems development, high-quality CM grammars facilitate high-quality conceptual modeling. This paper provides a new perspective on ways to improve the quality of the semantics of CM grammars. For many years, the leading approach to this topic has relied on ontological theory. We show, however, that the ontological approach captures only half the story. It needs to be coupled with a logical approach. We explain how the ontological quality and logical quality of CM grammars interrelate. Furthermore, we outline three contributions that a logical approach can make to evaluating the quality of CM grammars: a means of seeing some familiar conceptual-modeling problems in simpler ways; the illumination of new problems; and the ability to prove the benefit of modifying existing CM grammars in particular ways. We demonstrate these benefits in the context of the Entity-Relationship grammar. More generally, our paper opens up a new area of research with many opportunities for future research and practice.

Dual Classification Revisited: Rodney Needham and Vertical Asymmetry aboard Scottish Trawlers

Drawing on ethnographic data collected while working as a deckhand on two Scottish trawlers, this article analyses the spatialisation of social, religious and economic inequalities that marked relations between crew members while they hunted for prawns in the North Sea. Moreover, it explores these inequalities as a wider feature of life in Gamrie, Aberdeenshire, a Brethren and Presbyterian fishing village riven by disparities in wealth and religion. Inequalities identified by fishermen at sea mirrored those identified by residents onshore, resulting in fishing boats being experienced as small 'floating villages'. Drawing on the work of Rodney Needham, this article suggests that these asymmetries can be traced along a vertical axis, with greater to lesser wealth and religiosity moving from top/above to bottom/below. The article seeks to understand the presence and persistence of these hierarchies at sea and on land, by revisiting dual classification within anthropological theory.

An Evaluation of the Dual Diagnosis (substance use and mental health )Strategy in the South Eastern Trust Workers and Service Users Perceptions of Dual Diagnosis Issues

In the UK it is estimated that over 33% of psychiatric patients with enduring mental illness have a substance misuse problem, whilst over 50 % of clients currently accessing drug and alcohol services have a mental health problem. Between 2003 and 2013 in Northern Ireland, there were 741 recorded suicides by patients who were in contact with mental health services. Of this number, 68% (n=501) had a history of either alcohol or drug misuse or both, resulting in an average of 46 patient suicides per year associated with dual diagnosis (University of Manchester 2015).
The current evaluation examined staff attitudes towards working with dual diagnosis (co-existing difficulties) issues, staff confidence in working with clients with dual diagnosis, workers’ perceptions of the South Eastern dual diagnosis strategy and service user perspectives of dual diagnosis service provision.
The purpose of the evaluation was to provide evidence regarding the following in accordance with the current dual diagnosis strategy;
Staff understanding of the concept of dual diagnosis,
Staff attitudes towards working with dual diagnosis,
Staff confidence in working with individuals, who present with dual diagnosis,
Service users’ perspectives of SE Trust provision for dual diagnosis.
Staff views on the South Eastern Trust Dual Diagnosis Strategy.