James Paul Gee, How to Do Discourse Analysis: A Toolkit, New York: Routledge, 2011; ix + 206 pp., €25.00/US$33.00 (pbk)

Book reviews

Oxygen radical induced alterations in polyclonal IgG

In the sera and synovial fluid of patients with rheumatoid arthritis, part of the IgG fraction is found in an aggregated and fluorescent form. Oxygen-free radicals have been implicated in this denaturation, although the precise radical species responsible is unknown. In this work, oxygen-free radicals generated radiolytically were allowed to attack polyclonal IgG in solution. OH radicals induced aggregation of the monomer and a new fluorescence appeared in the visible region (Ex 360 nm, Em 454 nm). The superoxide radical anion was found to be inert in both these respects, whilst peroxy radicals induced autofluorescence without concomitant aggregation. The results suggest that OH.and/or peroxy radical attack may be an in vivo mechanism for IgG denaturation.

Transducer diffraction theory and development of an ultrasonic tomogram

The work described in this thesis is the development of an ultrasonic tomogram to provide outlines of cross-sections of the ulna in vivo. This instrument, used in conjunction with X-ray densitometry previously developed in this department, would provide actual bone mineral density to a high resolution. It was hoped that the accuracy of the plot obtained from the tomogram would exceed that of existing ultrasonic techniques by about five times. Repeat measurements with these instruments to follow bone mineral changes would involve very low X-ray doses. A theoretical study has been made of acoustic diffraction, using a geometrical transform applicable to the integration of three different Green's functions, for axisymmetric systems. This has involved the derivation of one of these in a form amenable to computation. It is considered that this function fits the boundary conditions occurring in medical ultrasonography more closely than those used previously. A three dimensional plot of the pressure field using this function has been made for a ring transducer, in addition to that for disc transducers using all three functions. It has been shown how the theory may be extended to investigate the nature and magnitude of the particle velocity, at any point in the field, for the three functions mentioned. From this study. a concept of diffraction fronts has been developed, which has made it possible to determine energy flow also in a diffracting system. Intensity has been displayed in a manner similar to that used for pressure. Plots have been made of diffraction fronts and energy flow direction lines.

Investigation on probing schemes in probe-based multicast admission control

Multicast is an efficient approach to save network bandwidth for multimedia streaming services. To provide Quality of Services (QoS) for the multimedia services while maintain the advantage of multicast in bandwidth efficiency, admission control for multicast sessions are expected. Probe-based multicast admission control (PBMAC) schemes are of a sort of scalable and simple admission control for multicast. Probing scheme is the essence of PBMAC. In this paper, after a detailed survey on three existing probing schemes, we evaluate these schemes using simulation and analysis approaches in two aspects: admission correctness and group scalability. Admission correctness of the schemes is compared by simulation investigation. Analytical models for group scalability are derived, and validated by simulation results. The evaluation results illustrate the advantages and weaknesses of each scheme, which are helpful for people to choose proper probing scheme for network.

Congestion pricing by priority auction

This paper analyzes a communication network facing users with a continuous distribution of delay cost per unit time. Priority queueing is often used as a way to provide differential services for users with different delay sensitivities. Delay is a key dimension of network service quality, so priority is a valuable resource which is limited and should to be optimally allocated. We investigate the allocation of priority in queues via a simple bidding mechanism. In our mechanism, arriving users can decide not to enter the network at all or submit an announced delay sensitive value. User entering the network obtains priority over all users who make lower bids, and is charged by a payment function which is designed following an exclusion compensation principle. The payment function is proved to be incentive compatible, so the equilibrium bidding behavior leads to the implementation of "cµ-rule". Social warfare or revenue maximizing by appropriately setting the reserve payment is also analyzed.

An adaptive scheduling scheme for fair bandwidth allocation

Class-based service differentiation is provided in DiffServ networks. However, this differentiation will be disordered under dynamic traffic loads due to the fixed weighted scheduling. An adaptive weighted scheduling scheme is proposed in this paper to achieve fair bandwidth allocation among different service classes. In this scheme, the number of active flows and the subscribed bandwidth are estimated based on the measurement of local queue metrics, then the scheduling weights of each service class are adjusted for the per-flow fairness of excess bandwidth allocation. This adaptive scheme can be combined with any weighted scheduling algorithm. Simulation results show that, comparing with fixed weighted scheduling, it effectively improve the fairness of excess bandwidth allocation.

Editorial

Welcome to the latest issue of Contact Lens and Anterior Eye. In this issue, Kuldeep Razaida provides a fascinating look at fitting prosthetic lenses to patients in India. I had the good fortune of visiting his clinic in August 2006 at the LV Prasad Eye Institute in Hyderabad, India and was humbled by the vast expertise within the one building. The institute started in 1987 and is the brainchild of the infamous Professor Rao. I think there are few such places in the world where the clinicians work so passionately in treating such interesting patients (for details regarding the LV Prasad Eye Institute see www.lvpei.org). I was in Hyderabad courtesy of IACLE (see issue 29:5 for an editorial by Judith Morris and Sonja Cronje about IACLE) and was able to share ideas with contact lens educators from across the world (for more information on IACLE see www.iacle.org). The issue contains some regular contact lens type papers too; with our aging population readers will be particularly interested in a paper by Mike Freeman and Neil Charman looking at modified monovision with diffractive bifocal lenses. There is an article looking at visual problems with video display terminal use and a study looking at the effects of surface treatment of silicone hydrogel contact lenses. There is an interesting piece from Dr Aisling Mann of Aston University looking at tear protein analysis; this article contains one CET point too for readers who complete the attached multiple choice questions before the relevant deadline. Also, congratulations to the BCLA members who successfully undertook the Fellowship of the BCLA at this year's BCLA conference in Manchester. If you are interested in undertaking the Fellowship please look at the details on the BCLA web page (http://www.bcla.org.uk/fellowship.asp). Amongst the case reports in this issue of CLAE you will notice one from Andrew Elder-Smith, this particular case report was presented as part of his successful Fellowship submission in 2006 and was thought to be of particular good quality by the examiners who asked Andrew to kindly submit it for publication to Contact Lens and Anterior Eye as an example for potential candidates. Finally, it is my sad duty to report the death of Howard Gee earlier this year, a past council member of the BCLA. Our thoughts and prayers are with his family and friends.

Influence of birth cohort on age of onset cluster analysis in bipolar I disorder

PURPOSE: Two common approaches to identify subgroups of patients with bipolar disorder are clustering methodology (mixture analysis) based on the age of onset, and a birth cohort analysis. This study investigates if a birth cohort effect will influence the results of clustering on the age of onset, using a large, international database. METHODS: The database includes 4037 patients with a diagnosis of bipolar I disorder, previously collected at 36 collection sites in 23 countries. Generalized estimating equations (GEE) were used to adjust the data for country median age, and in some models, birth cohort. Model-based clustering (mixture analysis) was then performed on the age of onset data using the residuals. Clinical variables in subgroups were compared. RESULTS: There was a strong birth cohort effect. Without adjusting for the birth cohort, three subgroups were found by clustering. After adjusting for the birth cohort or when considering only those born after 1959, two subgroups were found. With results of either two or three subgroups, the youngest subgroup was more likely to have a family history of mood disorders and a first episode with depressed polarity. However, without adjusting for birth cohort (three subgroups), family history and polarity of the first episode could not be distinguished between the middle and oldest subgroups. CONCLUSION: These results using international data confirm prior findings using single country data, that there are subgroups of bipolar I disorder based on the age of onset, and that there is a birth cohort effect. Including the birth cohort adjustment altered the number and characteristics of subgroups detected when clustering by age of onset. Further investigation is needed to determine if combining both approaches will identify subgroups that are more useful for research.

Investigating the prevalence of Salmonella in dogs within the Midlands region of the United Kingdom

Background - The intimate relationship between dogs and their owners has the potential to increase the risk of human exposure to bacterial pathogens. Over the past 40 years, there have been several reports on transmission of salmonellae from dogs to humans. This study therefore aimed to determine the prevalence of Salmonella in the faeces of dogs from the Midlands region of the United Kingdom to assess exposure risk and potential for zoonotic transmission. Results - A total of 436 apparently healthy dogs without diarrhoea from households (n = 126), rescue centres (n = 96), boarding kennels (n = 43), retired greyhound kennels (n = 39) and a pet nutrition facility (n = 132) were investigated for Salmonella shedding. Faecal samples were processed by an enrichment culture based method. The faeces from one dog (0.23 %; 95 % confidence limit 0.006 %, 1.27 %) was positive for Salmonella. The species was S. enterica subspecies arizonae. Conclusion - This study showed that the prevalence of Salmonella from faeces from apparently healthy dogs from a variety of housing conditions is low; however, Salmonella shedding was still identified.

Solution to reduce nonlinearity in LTE RoF system for an efficient das topology:a brief review

In this paper, a review on radio-over-fiber (RoF) technology is conducted to support the exploding growth of mobile broadband. An RoF system will provide a platform for distributed antenna system (DAS) as a fronthaul of long term evolution (LTE) technology. A higher splitting ratio from a macrocell is required to support large DAS topology, hence higher optical launch power (OLP) is the right approach. However, high OLP generates undesired nonlinearities, namely the stimulated Brillouin scattering (SBS). Three different aspects of solving the SBS process are covered in this paper, where the solutions ultimately provided an additional 4 dB link budget.