Data transmission by frequency-hopped multilevel frequency shift keying

Spread spectrum systems make use of radio frequency bandwidths which far exceed the minimum bandwidth necessary to transmit the basic message information.These systems are designed to provide satisfactory communication of the message information under difficult transmission conditions. Frequency-hopped multilevel frequency shift keying (FH-MFSK) is one of the many techniques used in spread spectrum systems. It is a combination of frequency hopping and time hopping. In this system many users share a common frequency band using code division multiplexing. Each user is assigned an address and the message is modulated into the address. The receiver, knowing the address, decodes the received signal and extracts the message. This technique is suggested for digital mobile telephony. This thesis is concerned with an investigation of the possibility of utilising FH-MFSK for data transmission corrupted by additive white gaussian noise (A.W.G.N.). Work related to FH-MFSK has so far been mostly confined to its validity, and its performance in the presence of A.W.G.N. has not been reported before. An experimental system was therefore constructed which utilised combined hardware and software and operated under the supervision of a microprocessor system. The experimental system was used to develop an error-rate model for the system under investigation. The performance of FH-MFSK for data transmission was established in the presence of A.W.G.N. and with deleted and delayed sample effects. Its capability for multiuser applications was determined theoretically. The results show that FH-MFSK is a suitable technique for data transmission in the presence of A.W.G.N.

The impact of national cultures and interpersonal factors on managerial communication

This study was undertaken for two primary purposes. The first was to discover whether or not two of the four cultural dimensions depicted by Hof-stede (1980), namely Power Distance and Uncertainty Avoidance, could be repeated using samples from seven organizations operating in three distinct cultural settings. The second was to assess the degree to which these dimensions affect superior-subordinate communication across the culturally-different groups. Also, the impact of the three interpersonal factors: Trust in Superior, Upward Influence and Mobility Aspirations was investigated cross-culturally. Participants were 291 managers from seven organizations; four Sudanese, two white British and an organization in Britain run by a group of British citizens of Pakistani extraction. It was hypothesized that the Power Distance and Uncertainty Avoidance of the three groups would replicate Hof-stede's. Specific implications of these dimensions for organizational communication and in particular for superior-subordinate communication were also hypothesized. Multiple regression analyses were performed with items of the two cultural dimensions and the three interpersonal factors (each in turn) forming the independent variables, while the organizational communication aspects formed the dependent variables. T-tests between means were also used to compare and contrast issues such as directionality of information flow across organizations operating in these settings. Work-related values of each of the three cultural groups provided support for Hofstede's model. However, only tentative support was given to the hypothesized relationships between the cultural dimensions and organizational communication. Similarly, weak associations were found between the three interpersonal factors and superior-subordinate communication behaviour. Some practical and theoretical implications are offered. An evaluation of the study and recommendation for further research are also given.

The development of chemical exposure limits for the workplace

The thesis examines and explains the development of occupational exposure limits (OELs) as a means of preventing work related disease and ill health. The research focuses on the USA and UK and sets the work within a certain historical and social context. A subsidiary aim of the thesis is to identify any short comings in OELs and the methods by which they are set and suggest alternatives. The research framework uses Thomas Kuhn's idea of science progressing by means of paradigms which he describes at one point, `lq ... universally recognised scientific achievements that for a time provide model problems and solutions to a community of practitioners. KUHN (1970). Once learned individuals in the community, `lq ... are committed to the same rules and standards for scientific practice. Ibid. Kuhn's ideas are adapted by combining them with a view of industrial hygiene as an applied science-based profession having many of the qualities of non-scientific professions. The great advantage of this approach to OELs is that it keeps the analysis grounded in the behaviour and priorities of the groups which have forged, propounded, used, benefited from, and defended, them. The development and use of OELs on a larger scale is shown to be connected to the growth of a new profession in the USA; industrial hygiene, with the assistance of another new profession; industrial toxicology. The origins of these professions, particularly industrial hygiene, are traced. By examining the growth of the professions and the writings of key individuals it is possible to show how technical, economic and social factors became embedded in the OEL paradigm which industrial hygienists and toxicologists forged. The origin, mission and needs of these professions and their clients made such influences almost inevitable. The use of the OEL paradigm in practice is examined by an analysis of the process of the American Conference of Governmental Industrial Hygienists, Threshold Limit Value (ACGIH, TLV) Committee via the Minutes from 1962-1984. A similar approach is taken with the development of OELs in the UK. Although the form and definition of TLVs has encouraged the belief that they are health-based OELs the conclusion is that they, and most other OELs, are, and always have been, reasonably practicable limits: the degree of risk posed by a substance is weighed against the feasibility and cost of controlling exposure to that substance. The confusion over the status of TLVs and other OELs is seen to be a confusion at the heart of the OEL paradigm and the historical perspective explains why this should be. The paradigm has prevented the creation of truly health-based and, conversely, truly reasonably practicable OELs. In the final part of the thesis the analysis of the development of OELs is set in a contemporary context and a proposal for a two-stage, two-committee procedure for producing sets of OELs is put forward. This approach is set within an alternative OEL paradigm. The advantages, benefits and likely obstacles to these proposals are discussed.

β-amyloid (Aβ) deposition in cognitively normal brain, dementia with Lewy bodies, and Alzheimer's disease:a study using principal components analysis

The densities of diffuse, primitive, and classic ß-amyloid (Aß) deposits were studied in the temporal lobe in cognitively normal brain, dementia with Lewy bodies (DLB), familial Alzheimer’s disease (FAD), and sporadic AD (SAD). Principal components analysis (PCA) was used to determine whether there were distinct differences between groups or whether Aß pathology was more continuously distributed from group to group. Three principal components (PC) were extracted from the data accounting for 56% of the total variance. Plots of cases in relation to the PC did not result in distinct groups but suggested overlap in Aß deposition between the groups. In addition, there were linear correlations between the densities of Aß deposits and the distribution of the cases along the PC in specific brain regions suggesting continuous variation from group to group. PC1 was associated with the degree of maturation of Aß deposits, PC2 with differences between FAD and SAD, and PC3 with the degree of spread of Aß pathology into the hippocampus. Apolipoprotein E (APOE) genotype was not associated with variation in Aß deposition between cases. PCA may be a useful method of studying the pathological interface between closely related neurodegenerative disorders.

Measurement of implicit leadership theories and their effect on leadership processes and outcomes

The leadership categorisation theory suggests that followers rely on a hierarchical cognitive structure in perceiving leaders and the leadership process, which consists of three levels; superordinate, basic and subordinate. The predominant view is that followers rely on Implicit Leadership Theories (ILTs) at the basic level in making judgments about managers. The thesis examines whether this presumption is true by proposing and testing two competing conceptualisations; namely the congruence between the basic level ILTs (general leader) and actual manager perceptions, and subordinate level ILTs (job-specific leader) and actual manager. The conceptualisation at the job-specific level builds on context-related assertions of the ILT explanatory models: leadership categorisation, information processing and connectionist network theories. Further, the thesis addresses the effects of ILT congruence at the group level. The hypothesised model suggests that Leader-Member Exchange (LMX) will act as a mediator between ILT congruence and outcomes. Three studies examined the proposed model. The first was cross-sectional with 175 students reporting on work experience during a 1-year industrial placement. The second was longitudinal and had a sample of 343 students engaging in a business simulation in groups with formal leadership. The final study was a cross-sectional survey in several organisations with a sample of 178. A novel approach was taken to congruence analysis; the hypothesised models were tested using Latent Congruence Modelling (LCM), which accounts for measurement error and overcomes the majority of limitations of traditional approaches. The first two studies confirm the traditional theorised view that employees rely on basic-level ILTs in making judgments about their managers with important implications, and show that LMX mediates the relationship between ILT congruence and work-related outcomes (performance, job satisfaction, well-being, task satisfaction, intragroup conflict, group satisfaction, team realness, team-member exchange, group performance). The third study confirms this with conflict, well-being, self-rated performance and commitment as outcomes.

An investigation of the prevalence and measurement of teams in organisations:the development and validation of the real team scale

This thesis begins with a review of the literature on team-based working in organisations, highlighting the variations in research findings, and the need for greater precision in our measurement of teams. It continues with an illustration of the nature and prevalence of real and pseudo team-based working, by presenting results from a large sample of secondary data from the UK National Health Service. Results demonstrate that ‘real teams’ have an important and significant impact on the reduction of many work-related safety outcomes. Based on both theoretical and methodological limitations of existing approaches, the thesis moves on to provide a clarification and extension of the ‘real team’ construct, demarcating this from other (pseudo-like) team typologies on a sliding scale, rather than a simple dichotomy. A conceptual model for defining real teams is presented, providing a theoretical basis for the development of a scale on which teams can be measured for varying extents of ‘realness’. A new twelve-item scale is developed and tested with three samples of data comprising 53 undergraduate teams, 52 postgraduate teams, and 63 public sector teams from a large UK organisation. Evidence for the content, construct and criterion-related validity of the real team scale is examined over seven separate validation studies. Theoretical, methodological and practical implications of the real team scale are then discussed.

Do left and right asymmetries of hemispheric preference interact with attention to predict local and global performance in applied tasks?

Many cognitive neuroscience studies show that the ability to attend to and identify global or local information is lateralised between the two hemispheres in the human brain; the left hemisphere is biased towards the local level, whereas the right hemisphere is biased towards the global level. Results of two studies show attention-focused people with a right ear preference (biased towards the left hemisphere) are better at local tasks, whereas people with a left ear preference (biased towards the right hemisphere) are better at more global tasks. In a third study we determined if right hemisphere-biased followers who attend to global stimuli are likely to have a stronger relationship between attention and globally based supervisor ratings of performance. Results provide evidence in support of this hypothesis. Our research supports our model and suggests that the interaction between attention and lateral preference is an important and novel predictor of work-related outcomes. © 2012 Copyright Psychology Press Ltd.

Team reflexivity

With the increasing relevance of teamwork in organizations, the quest for the factors that enhance team effectiveness has grown exponentially. Team reflexivity is one of the factors that has been identified as a possible key variable in explaining the effectiveness of work teams. Team reflexivity can be defined as the extent to which team members collectively reflect on the team's objectives, strategies, and processes, as well as their wider organizations and environments, and adapt accordingly. The concept of team reflexivity was initially developed by Michael West, but other scholars, such as Michaela Schippers and Carsten de Dreu, have also contributed significantly to its understanding. It is conceptualized as a process involving three stages or components: reflection , planning , and action or adaptation. The three stages are of equal importance. The first stage, team reflection , refers to a team's joint exploration of work-related issues and includes behaviors such as ...

Advanced techniques for the improvement of optical transmission systems

This thesis presents the experimental investigation into two novel techniques which can be incorporated into current optical systems. These techniques have the capability to improve the performance of transmission and the recovery of the transmitted signal at the receiver. The experimental objectives are described and the results for each technique are presented in two sections: The first experimental section is on work related to Ultra-long Raman Fibre lasers (ULRFLs). The fibre lasers have become an important research topic in recent years due to the significant improvement they give over lumped Raman amplification and their potential use in the development of system with large bandwidths and very low losses. The experiments involved the use of ASK and DPSK modulation types over a distance of 240km and DPSK over a distance of 320km. These results are compared to the current state of-the-art and against other types of ultra-long transmission amplification techniques. The second technique investigated involves asymmetrical, or offset, filtering. This technique is important because it deals with the strong filtering regimes that are a part of optical systems and networks in modern high-speed communications. It allows the improvement of the received signal by offsetting the central frequency of a filter after the output of a Delay Line Interferometer (DLI), which induces significant improvement in BER and/or Qvalues at the receiver and therefore an increase in signal quality. The experimental results are then concluded against the objectives of the experimental work and potential future work discussed.

The importance of detecting and managing comorbidities in people with dementia?

Dementia is a debilitating condition characterised by global loss of cognitive and intellectual functioning, which gradually interferes with social and occupational performance. It is a common worldwide condition with a significant impact on society. There are currently 36 million people worldwide with Alzheimer's disease (AD) and other dementias [1]. This is expected to more than double by 2030 (65 million) and reach ∼115 million in 2050, unless a major breakthrough is made. The worldwide societal costs were estimated at USD 604 billion in 2010 and rising [2]. To date research on the specific physical healthcare needs of people with dementia has been neglected. Yet, physical comorbidities are reported as common in people with dementia [3] and have been shown to lead to increased disability and reduced quality of life for the affected person and their carer [4]. Dementia is most frequently associated with older people who often present with other medical conditions, known as co-morbidities. Such co-morbidities include diabetes, chronic obstructive pulmonary disorder, musculoskeletal disorders and chronic cardiac failure and are common, 61% of people with …

24-Karat or fool’s gold? Consequences of real team and co-acting group membership in healthcare organizations

Although theory on team membership is emerging, limited empirical attention has been paid to the effects of different types of team membership on outcomes. We propose that an important but overlooked distinction is that between membership of real teams and membership of co-acting groups, with the former being characterized by members who report that their teams have shared objectives, and structural interdependence and engage in team reflexivity. We hypothesize that real team membership will be associated with more positive individual- and organizational-level outcomes. These predictions were tested in the English National Health Service, using data from 62,733 respondents from 147 acute hospitals. The results revealed that individuals reporting the characteristics of real team membership, in comparison with those reporting the characteristics of co-acting group membership, witnessed fewer errors and incidents, experienced fewer work related injuries and illness, were less likely to be victims of violence and harassment, and were less likely to intend to leave their current employment. At the organizational level, hospitals with higher proportions of staff reporting the characteristics of real team membership had lower levels of patient mortality and sickness absence. The results suggest the need to clearly delineate real team membership in order to advance scientific understanding of the processes and outcomes of organizational teamwork.

Corticobasal degeneration and dementia

Corticobasal degeneration is a rare, progressive neurodegenerative disorder which significantly impairs movement. The most common initial symptom is asymmetric limb clumsiness with or without accompanying rigidity or tremor. Subsequently, the disease progresses to affect gait and there is a slow progression to influence ipsilateral arms and legs. Apraxia and dementia are the most common cortical signs. Clinical diagnosis of the disorder is difficult as the symptoms resemble those of related neurodegenerative disorders. Histopathologically, there is widespread neuronal and glial pathology including tau-immunoreactive neuronal cytoplasmic inclusions, neuropil threads, oligodendroglial inclusions, astrocytic plaques, together with abnormally enlarged ‘ballooned’ neurons. Corticobasal degeneration has affinities both with the parkinsonian syndromes including Parkinson’s disease, progressive supranuclear palsy, and multiple system atrophy and with the fronto-temporal dementias. Treatment of corticobasal degeneration involves managing and reducing the effect of symptoms.

Conceptualizing leadership perceptions as attitudes:using attitude theory to further the understanding of the relation between leadership and outcomes

Leadership is one of the most examined factors in relation to understanding employee wellbeing and performance. While there are disparate approaches to studying leadership, they share a common assumption that perceptions of a leader's behavior determine reactions to the leader. The concept of leadership perception is poorly understood in most theoretical approaches. To address this, we propose that there are many benefits from examining leadership perceptions as an attitude towards the leader. In this review, we show how research examining a number of aspects of attitudes (content, structure and function) can advance understanding of leadership perceptions and how these affect work-related outcomes. Such a perspective provides a more multi-faceted understanding of leadership perceptions than previously envisaged and this can provide a more detailed understanding of how such perceptions affect outcomes. In addition, we examine some of the main theoretical and methodological implications of viewing leadership perceptions as attitudes to the wider leadership area. The cross-fertilization of research from the attitudes literature to understanding leadership perceptions provides new insights into leadership processes and potential avenues for further research. (C) 2015 Elsevier Inc. All rights reserved

Pregnancy complications in hyperemesis-affected pregnancy:a large hospital database study

Objective: Vomiting in pregnancy is a common condition affecting 80% of pregnant women. Hyperemesis is at one end of the spectrum, seen in 0.5–2% of the pregnant population. Known factors such as nulliparity, younger age and high body mass indexare associated with an increased risk of this condition in the first trimester. Late pregnancy complications attributable to hyperemesis, the pathogenesis of which is poorly understood, have not been studied in large population-based studies in the United Kingdom. The objective of this study was to determine a plausible association between hyperemesis and pregnancy complications,such as pregnancy-related hypertension, gestational diabetes and liver problems in pregnancy, and the rates of elective (ElCS) and emergency caesarean section (EmCS). Methods: Using a database based on ICD-10 classification, anonymised data of admissions to a large multi-ethnic hospital in Manchester, UK between 2000 and 2012 were examined.Notwithstanding the obvious limitations with hospital database-based research, this large volume of datasets allows powerful studies of disease trends and complications.Results Between 2000 and 2012, 156 507 women aged 45 or under were admitted to hospital. Of these, 1111 women were coded for hyperemesis (0.4%). A greater proportion of women with hyperemesis than without hyperemesis were coded forhypertensive disorders in pregnancy such as pregnancy-induced hypertension, pre-eclampsia and eclampsia (2.7% vs 1.5%;P=0.001). The proportion of gestational diabetes and liver disorders in pregnancy was similar for both groups (diabetes:0.5% vs. 0.4%; P=0.945, liver disorders: 0.2% vs. 0.1%;P=0.662). Hyperemesis patients had a higher proportion of elective and emergency caesarean sections compared with the non-hyperemesis group (ElCS: 3.3% vs. 2%; P=0.002, EmCS: 5% vs.3%; P=0.00). Conclusions: There was a higher rate of emergency and elective caesarean section in women with hyperemesis, which could reflect the higher prevalence of pregnancy-related hypertensive disorders(but not diabetes or liver disorders) in this group. The factors contributing to the higher prevalence of hypertensive disorders arenot known, but these findings lead us to question whether there is a similar pathogenesis in the development of both the conditions and hence whether further study in this area is warranted.