Data transmission by pulse compression

Pulse compression techniques originated in radar.The present work is concerned with the utilization of these techniques in general, and the linear FM (LFM) technique in particular, for comnunications. It introduces these techniques from an optimum communications viewpoint and outlines their capabilities.It also considers the candidacy of the class of LFM signals for digital data transmission and the LFM spectrum. Work related to the utilization of LFM signals for digital data transmission has been mostly experimental and mainly concerned with employing two rectangular LFM pulses (or chirps) with reversed slopes to convey the bits 1 and 0 in an incoherent node.No systematic theory for LFM signal design and system performance has been available. Accordingly, the present work establishes such a theory taking into account coherent and noncoherent single-link and multiplex signalling modes. Some new results concerning the slope-reversal chirp pair are obtained. The LFM technique combines the typical capabilities of pulse compression with a relative ease of implementation. However, these merits are often hampered by the difficulty of handling the LFM spectrum which cannot generally be expressed closed-form. The common practice is to obtain a plot of this spectrum with a digital computer for every single set of LFM pulse parameters.Moreover, reported work has been Justly confined to the spectrum of an ideally rectangular chirp pulse with no rise or fall times.Accordingly, the present work comprises a systerratic study of the LFM spectrum which takes the rise and fall time of the chirp pulse into account and can accommodate any LFM pulse with any parameters.It· formulates rather simple and accurate prediction criteria concerning the behaviour of this spectrum in the different frequency regions. These criteria would facilitate the handling of the LFM technique in theory and practice.

How well does the theory of planned behaviour predict alcohol consumption? A systematic review and meta-analysis

This study aimed to quantify correlations between theory of planned behaviour (TPB) variables and (i) intentions to consume alcohol and (ii) alcohol consumption. Systematic literature searches identified 40 eligible studies that were meta-analysed. Three moderator analyses were conducted: pattern of consumption, gender of participants and age of participants. Across studies, intentions had the strongest relationship with attitudes (r+ = .62), followed by subjective norms (r+ = .47) and perceived behavioural control (PBC; r+ = .31). Self-efficacy (SE) had a stronger relationship with intentions (r+ = .48) compared with perceived control (PC; r+ = −.10). Intention had the strongest relationship with alcohol consumption (r+ = .54), followed by SE (r+ = .41). In contrast, PBC and PC had negative relationships with alcohol consumption (r+ = −.05 and −.13, respectively). All moderators affected TPB relationships. Patterns of consumption with clear definitions had stronger TPB relations, females reported stronger attitude–intention relations than males, and adults reported stronger attitude–intention and SE–intention relations than adolescents. Recommendations for future research include targeting attitudes and intentions in interventions to reduce alcohol consumption, using clear definitions of alcohol consumption in TPB items to improve prediction and assessing SE when investigating risk behaviours.

Advanced mean field methods:theory and practice

A major problem in modern probabilistic modeling is the huge computational complexity involved in typical calculations with multivariate probability distributions when the number of random variables is large. Because exact computations are infeasible in such cases and Monte Carlo sampling techniques may reach their limits, there is a need for methods that allow for efficient approximate computations. One of the simplest approximations is based on the mean field method, which has a long history in statistical physics. The method is widely used, particularly in the growing field of graphical models. Researchers from disciplines such as statistical physics, computer science, and mathematical statistics are studying ways to improve this and related methods and are exploring novel application areas. Leading approaches include the variational approach, which goes beyond factorizable distributions to achieve systematic improvements; the TAP (Thouless-Anderson-Palmer) approach, which incorporates correlations by including effective reaction terms in the mean field theory; and the more general methods of graphical models. Bringing together ideas and techniques from these diverse disciplines, this book covers the theoretical foundations of advanced mean field methods, explores the relation between the different approaches, examines the quality of the approximation obtained, and demonstrates their application to various areas of probabilistic modeling.

Using grounded theory for theory building in operations management research:a study on inter-firm relationship governance

Purpose – Qualitative theory building approaches, such as grounded theory method (GTM), are still not very widespread and rigorously applied in operations management (OM) research. Yet it is agreed that more systematic observation of current industrial phenomena is necessary to help managers deal with their problems. The purpose of this paper is to provide an example to help guide other researchers on using GTM for theory building in OM research. Design/methodology/approach – A GTM study in the German automotive industry consisting of 31 interviews is followed by a validation stage comprising a survey (110 responses) and a focus group. Findings – The result is an example of conducting GTM research in OM, illustrated by the development of the novel collaborative enterprise governance framework for inter-firm relationship governance in the German automotive industry. Research limitations/implications – GTM is appropriate for qualitative theory building research, but the resultant theories need further testing. Research is necessary to identify the transferability of the collaborative enterprise governance concept to other industries than automotive, to other organisational areas than R&D and to product and service settings that are less complex and innovative. Practical implications – The paper helps researchers make more informed use of GTM when engaging in qualitative theory building research in OM. Originality/value – There is a lack of explicit and well-informed use of GTM in OM research because of poor understanding. This paper addresses this deficiency. The collaborative enterprise governance framework is a significant contribution in an area of growing importance within OM.

How well do the theory of reasoned action and theory of planned behaviour predict intentions and attendance at screening programmes? A meta-analysis

Meta-analysis was used to quantify how well the Theories of Reasoned Action and Planned Behaviour have predicted intentions to attend screening programmes and actual attendance behaviour. Systematic literature searches identified 33 studies that were included in the review. Across the studies as a whole, attitudes had a large-sized relationship with intention, while subjective norms and perceived behavioural control (PBC) possessed medium-sized relationships with intention. Intention had a medium-sized relationship with attendance, whereas the PBC-attendance relationship was small sized. Due to heterogeneity in results between studies, moderator analyses were conducted. The moderator variables were (a) type of screening test, (b) location of recruitment, (c) screening cost and (d) invitation to screen. All moderators affected theory of planned behaviour relationships. Suggestions for future research emerging from these results include targeting attitudes to promote intention to screen, a greater use of implementation intentions in screening information and examining the credibility of different screening providers.

An information foraging theory based user study of an adaptive user interaction framework for content-based image retrieval

This paper presents the design and results of a task-based user study, based on Information Foraging Theory, on a novel user interaction framework - uInteract - for content-based image retrieval (CBIR). The framework includes a four-factor user interaction model and an interactive interface. The user study involves three focused evaluations, 12 simulated real life search tasks with different complexity levels, 12 comparative systems and 50 subjects. Information Foraging Theory is applied to the user study design and the quantitative data analysis. The systematic findings have not only shown how effective and easy to use the uInteract framework is, but also illustrate the value of Information Foraging Theory for interpreting user interaction with CBIR. © 2011 Springer-Verlag Berlin Heidelberg.

Applying Information Foraging Theory to understand user interaction with content-based image retrieval

The paper proposes an ISE (Information goal, Search strategy, Evaluation threshold) user classification model based on Information Foraging Theory for understanding user interaction with content-based image retrieval (CBIR). The proposed model is verified by a multiple linear regression analysis based on 50 users' interaction features collected from a task-based user study of interactive CBIR systems. To our best knowledge, this is the first principled user classification model in CBIR verified by a formal and systematic qualitative analysis of extensive user interaction data. Copyright 2010 ACM.

Systematic financial resources allocation processes:a model for critical resources mobilization and deployment for nigerian universities

Purpose – The purpose of this research is to study the perceived impact of some factors on the resources allocation processes of the Nigerian universities and to suggest a framework that will help practitioners and academics to understand and improve such processes. Design/methodology/approach – The study adopted the interpretive qualitative approach aimed at an ‘in-depth’ understanding of the resource allocation experiences of key university personnel and their perceived impact of the contextual factors affecting such processes. The analysis of individual narratives from each university established the conditions and factors impacting the resources allocation processes within each institution. Findings – The resources allocation process issues in the Nigerian universities may be categorised into people (core and peripheral units’ challenge, and politics and power); process (resources allocation processes); and resources (critical financial shortage and resources dependence response). The study also provides insight that resourcing efficiency in Nigerian universities appears strongly constrained by the rivalry among the resource managers. The efficient resources allocation process (ERAP) model is proposed to resolve the identified resourcing deficiencies. Research limitations/implications – The research is not focused to provide generalizable observations but ‘in-depth’ perceived factors and their impact on the resources allocation processes in Nigerian universities. The study is limited to the internal resources allocation issues within the universities and excludes the external funding factors. The resource managers’ responses to the identified factors may affect their internal resourcing efficiency. Further research using more empirical samples is required to obtain more widespread results and the implications for all universities. Originality/value – This study contributes a fresh literature framework to resources allocation processes focusing at ‘people’, ‘process’ and ‘resources’. Also a middle range theory triangulation is developed in relation to better understanding of resourcing process management. The study will be of interest to university managers and policy makers.

Patients’ perceptions and experiences of cardiovascular disease and diabetes prevention programmes:a systematic review and framework synthesis using the Theoretical Domains Framework

Background - This review provides a worked example of ‘best fit’ framework synthesis using the Theoretical Domains Framework (TDF) of health psychology theories as an a priori framework in the synthesis of qualitative evidence. Framework synthesis works best with ‘policy urgent’ questions. Objective - The review question selected was: what are patients’ experiences of prevention programmes for cardiovascular disease (CVD) and diabetes? The significance of these conditions is clear: CVD claims more deaths worldwide than any other; diabetes is a risk factor for CVD and leading cause of death. Method - A systematic review and framework synthesis were conducted. This novel method for synthesizing qualitative evidence aims to make health psychology theory accessible to implementation science and advance the application of qualitative research findings in evidence-based healthcare. Results - Findings from 14 original studies were coded deductively into the TDF and subsequently an inductive thematic analysis was conducted. Synthesized findings produced six themes relating to: knowledge, beliefs, cues to (in)action, social influences, role and identity, and context. A conceptual model was generated illustrating combinations of factors that produce cues to (in)action. This model demonstrated interrelationships between individual (beliefs and knowledge) and societal (social influences, role and identity, context) factors. Conclusion - Several intervention points were highlighted where factors could be manipulated to produce favourable cues to action. However, a lack of transparency of behavioural components of published interventions needs to be corrected and further evaluations of acceptability in relation to patient experience are required. Further work is needed to test the comprehensiveness of the TDF as an a priori framework for ‘policy urgent’ questions using ‘best fit’ framework synthesis.