Non-reciprocity in doubly periodic strip arrays on ferrite-dielectric substrate

Doubly periodic arrays of strip conductors printed on a composite ferrite-dielectric substrate have been investigated at oblique incidence of linear polarized plane waves. The simulation results revealed strong non-reciprocity of wave reflectance and transmittance at positive and negative angles of incidence. It is also shown that the non-reciprocity is further enhanced by the strip conductor pattern. 

An effective key generation system using improved channel reciprocity

In physical layer security systems there is a clear need to exploit the radio link characteristics to automatically generate an encryption key between two end points. The success of the key generation depends on the channel reciprocity, which is impacted by the non-simultaneous measurements and the white nature of the noise. In this paper, an OFDM subcarriers' channel responses based key generation system with enhanced channel reciprocity is proposed. By theoretically modelling the OFDM subcarriers' channel responses, the channel reciprocity is modelled and analyzed. A low pass filter is accordingly designed to improve the channel reciprocity by suppressing the noise. This feature is essential in low SNR environments in order to reduce the risk of the failure of the information reconciliation phase during key generation. The simulation results show that the low pass filter improves the channel reciprocity, decreases the key disagreement, and effectively increases the success of the key generation.

Experimental Study on Channel Reciprocity in Wireless Key Generation

Key generation from wireless channels is a promising alternative to public key cryptography for the establishment of cryptographic keys. It is the first paper to experimentally study the channel reciprocity principle of key generation, through investigating and quantifying channel measurements' cross-correlation relationship affected by noise and non-simultaneous measurements. Channel measurements, both received signal strength and channel state information, are collected from a real experimental platform using the wireless open access research platform (WARP) in a multipath office room. We found that in a slow fading channel (e.g., with a coherence time of about 50~ms), the channel cross-correlation is impacted greatly by noise but little by non-simultaneous measurements with a small sampling time difference (e.g., 0.06 ms). The resolution of the sampling time difference can be satisfied by wireless systems such as IEEE 802.11 to maintain an acceptable cross-correlation coefficient without affecting the bandwidth and communication efficiency.

Integrating Ballymun? Flawed progress in Ireland's largest estate regeneration scheme

Urban regeneration in the Republic of Ireland takes place in the context of the rapid, ‘Celtic Tiger’ economic growth of the 1990s. The boom transformed Irish society and led to greater affluence for many people, along with continuing and arguably worsening inequality for those excluded from its opportunities. In particular, Ireland’s small social rented sector has become the focus of the country’s most concentrated poverty and social exclusion. The Ballymun regeneration programme in North Dublin aims to facilitate physical, social and economic change in order to integrate the area more closely with the
more affluent surrounding suburbs. This article reviews the issues involved in restructuring such a large area of social exclusion within a rapidly changing European capital city, using a framework that disaggregates the concept of integration into three elements: market, citizenship and reciprocity. With just over half the physical refurbishment complete, progress has been made but some fundamental issues remain. The article concludes that although substantial advancement has been made with physical regeneration, progress with wider economic and social integration has been uneven and in some cases flawed.

Sub-Wavelength Profile 2-D Leaky-Wave Antennas With Two Periodic Layers

A fast and accurate analysis and synthesis technique for high-gain sub-wavelength 2-D Fabry-Perot leaky-wave antennas (LWA) consisting of two periodic metallodielectric arrays over a ground plane is presented. Full-wave method of moments (MoM) together with reciprocity is employed for the estimation of the near fields upon plane wave illumination and the extraction of the radiation patterns of the LWA. This yields a fast and rigorous tool for the characterisation of this type of antennas. A thorough convergence study for different antenna designs is presented and the operation principles of these antennas as well as the radiation characteristics are discussed. Moreover, design guidelines to tailor the antenna profile, the dimensions of the arrays as well as the antenna directivity and bandwidth are provided. A study on the radiation efficiency for antennas with different profiles is also presented and the trade off between directivity and radiation bandwidth is discussed. Numerical examples are given throughout to demonstrate the technique. A finite size antenna model is simulated using commercial software (CST Microstripes 2009) which validates the technique.

Democratic Participation, Engagement, and Freedom

It is commonly supposed that democracies should encourage greater political participation and civic engagement. This article identifies two distinct perspectives on political participation and civic engagement: a ‘freedom-centred’ model and an ‘ethical’ model. The ‘freedom-centred’ model defended here draws on the republican concept of freedom as non-domination, together with the political liberal notion of fair deliberative proceduralism, while the ethical model draws on Aristotelian, perfectionist, sources. It is argued that the ‘ethical’ model is overly concerned with the ‘moral renewal’ of modern social life, and is insensitive to problems of domination posed by its account of civic reciprocity and trust. By contrast, the ‘freedom-centred’ model developed offers a systematic account of personal and political freedom, which provides qualified support for deliberative modes of participation and engagement.

Social Exchange at Work and Emotional Exhaustion: The Role of Personality

Unbalanced social-exchange processes at work have been linked to emotional exhaustion. In addition to organizational factors, individual differences are important determinants of reciprocity perceptions. This study explored whether broad and narrow personality traits were associated with perceived lack of reciprocity (organizational and interpersonal levels), and whether personality moderated the relationship between reciprocity and emotional exhaustion, in a sample of 322 civil servants. Extraversion, agreeableness, emotional stability, internal locus of control, and Type A behavior predicted reciprocity. The relationship between perceived lack of reciprocity with the organization and emotional exhaustion was stronger for individuals reporting lower negative affect or higher extraversion. These findings highlight the importance of personality for understanding perceived reciprocity at work and its impact on emotional exhaustion.

Prospective study of workplace social capital and depression: are vertical and horizontal components equally important?

Background Recent studies have emphasised the multidimensional nature of the social capital concept, but it is not known whether the health effects of social capital vary by dimension. The objective of this study was to examine the vertical component (ie, respectful and trusting relationships across power differentials at work) and the horizontal component of workplace social capital (trust and reciprocity between employees at the same hierarchical level) as risk factors for subsequent depression.

Workplace social capital and risk of chronic and severe hypertension: a cohort study

Objective: The association between workplace factors and the development of hypertension remains uncertain. We examined the risk of hypertension as a function of workplace social capital, that is, social cohesion, trust and reciprocity in the workplace.

Reciprocal value propositions in practice: Constraints in digital markets

The value proposition concept, while forming a central foundational premise of service-dominant (S-D) logic, has nevertheless been treated somewhat ambiguously. Recent work in attempting to address this has focused through a S-D logic lens on the reciprocal nature of value propositions. Important to this work has been a focus on communicative interactions and resource integration between network suppliers and customers. Overall, value proposition thinking has not studied in detail their adoption and use in practice. Considering the compelling notion of reciprocity, there have been recent calls for research to consider reciprocal value propositions in practice. The overall aim of this paper, therefore, was to explore how reciprocal value propositions are developed (or not) in practice at the network level. The study was set in the mobile television (TV) sector, which, as an internet-driven sector, is viewed as particularly pertinent. To conduct the study an S-D logic and Industrial Marketing and Purchasing (IMP) Group framework are integrated for the first time. A key finding is that while the reciprocal value proposition concept is theoretically intuitive, it is by no means inevitable in practice. Reciprocal value propositions were found to be simultaneously constrained, and, potentially enabled by these constraints in practice. At an overall level this paper contributes to the ongoing collaborative process, which aims to move S-D logic from a framework to a theory. More specifically, we provide new insights into the development of reciprocal value propositions in practice.

Women (Re)Negotiating Care across Family Generations: Intersections of Gender and Socioeconomic Status

Changing Generations, a study of intergenerational relations in Ireland undertaken between 2011 and 2013 by the Social Policy and Ageing Research Centre (SPARC), Trinity College, Dublin, and the Irish Centre for Social Gerontology (ICSG), NUI Galway, used the Constructivist Grounded Theory method to interrogate support and care provision between generations. This article draws on interviews with 52 women ages 18 to 102, allowing for simultaneous analysis of older and younger women’s perspectives. The intersectionality of gender and class emerged as central to the analysis. Socioeconomic positions shape contrasting forms of interdependency among family generations, ranging from “enmeshed” lives among lower socioeconomic groups to “freed” lives among higher socioeconomic groups. Women are initiating changes in how care and support flow across generations. Older women in higher socioeconomic groups are attuned to how emotional capital women expend across family generations can constrain (young) women’s lives. In an expression of solidarity, older women are renegotiating the place of care labor in their own lives and in the lives of younger women. A new reciprocity emerges that amounts to women “undoing gender.” This process is, however, deeply classed as it is women in higher socioeconomic groups whose resources best place them to renegotiate care.

England, Neo-Latin, and the Continental Journey: Linguistic and Textual Itineraries

This chapter examines the ramifications of continental travel and associated epistolary communication for English poets of the period. It argues that recourse to neo-Latin, the universal language of diplomacy, served not only to establish a sense of shared space—linguistic, cultural, generic—between England and the continent, but also to signal self-conscious differences (climatic, geographical, historical, political) between England and her continental peers. Through an investigation of a range of ‘performances’ on stages that were ‘academic’, poetic, autobiographical, and epistolographic, it assesses the central role of neo-Latin as a language that underwent a series of textual itineraries. These ‘itineraries’ manifest themselves in a number of ways. Neo-Latin as a shared linguistic medium can facilitate, and quite uniquely so, intertextual engagement with the classics, but now ancient Rome, its language, its mythology, its hierarchy of genres, are viewed through a seventeenth-century lens and appropriated by poets in both England and Italy to describe contemporary events, whether personal, or political. Close examination of the neo-Latin poetry of Milton and Marvell reveals, it is argued, a self-fashioning coloured by such textual itineraries and interchanges. The absorption and replication of continental literary and linguistic methodologies (the academic debate; the etymological play of Marinism; the hybridity of neo-Latin and Italian voices) reveal in short a linguistic and textual reciprocity that gave birth to something very new.

Effects of peer network interactions on adolescent cannabis use

Purpose
This study capitalises on three waves of longitudinal data from a cohort of 4351 secondary school pupils to examine the effects on individuals’ cannabis use uptake of both peer cannabis use and position within a peer network.

Design/methodology/approach
Both cross-sectional and individual fixed effects models are used to estimate the effect on cannabis use of nominated friends’ cannabis use, of reciprocity and transitivity of nominations across the friendship cluster, and of interactions between these nominated friends. Post hoc analyses parsed the behaviour of reciprocating and non-reciprocating friends.

Findings
Cannabis use varied depending on the stability of friendship network and the degree of reciprocity and interconnectedness within the group. Behavioural influence was strong, but interaction effects were observed between the prevalence of cannabis use among friends, the structure of the friendship group and ego’s proximity to group members. These interactions demonstrate that behavioural influence is more salient in more cohesive groups. When reciprocating and non-reciprocating friends’ mean cannabis use were separated, influence from reciprocating friends was estimated at twice the magnitude of other friends.

Originality/value
While preventing any one individual from using cannabis is likely to have a multiplier effect on classmates, the bonds and interactions between classmates will determine which classmates are affected by this multiplier and the salience of that effect.

Simultaneous Measurements of the Channel Response for Multiple Eavesdroppers Operating in the Vicinity of a Body Area Network at 2.45 GHz

Channel randomness can be exploited to generate secret keys. However, to ensure secrecy, it is necessary that the channel response of any eavesdropping party remain sufficiently de-correlated with that of the legitimate users'. In this paper, we investigate whether such de-correlation occurs for a body area network (BAN) operating in an indoor environment at 2.45 GHz. The hypothetical BAN configuration consisted of two legitimate transceivers, one situated on the user's left wrist and the other on the user's waist. The eavesdroppers were positioned in either a co-located or distributed manner in the area surrounding the BAN user. Using the simultaneous channel response measured at the legitimate BAN nodes and the eavesdropper positions for stationary and mobile scenarios, we analyze the localized correlation coefficient. This allows us to determine if it is possible to generate secret keys in the presence of multiple eavesdroppers in an indoor environment. Our experimental results show that although channel reciprocity was observed for both the stationary and the mobile scenarios, a higher de-correlation between the legitimate users' channels was observed for the stationary case. This indicates that mobile scenarios are better suited for secret key generation.