Selected topics on distributed video coding

Distributed Video Coding (DVC) is a new paradigm for video compression based on the information theoretical results of Slepian and Wolf (SW), and Wyner and Ziv (WZ). While conventional coding has a rigid complexity allocation as most of the complex tasks are performed at the encoder side, DVC enables a flexible complexity allocation between the encoder and the decoder. The most novel and interesting case is low complexity encoding and complex decoding, which is the opposite of conventional coding. While the latter is suitable for applications where the cost of the decoder is more critical than the encoder's one, DVC opens the door for a new range of applications where low complexity encoding is required and the decoder's complexity is not critical. This is interesting with the deployment of small and battery-powered multimedia mobile devices all around in our daily life. Further, since DVC operates as a reversed-complexity scheme when compared to conventional coding, DVC also enables the interesting scenario of low complexity encoding and decoding between two ends by transcoding between DVC and conventional coding. More specifically, low complexity encoding is possible by DVC at one end. Then, the resulting stream is decoded and conventionally re-encoded to enable low complexity decoding at the other end. Multiview video is attractive for a wide range of applications such as free viewpoint television, which is a system that allows viewing the scene from a viewpoint chosen by the viewer. Moreover, multiview can be beneficial for monitoring purposes in video surveillance. The increased use of multiview video systems is mainly due to the improvements in video technology and the reduced cost of cameras. While a multiview conventional codec will try to exploit the correlation among the different cameras at the encoder side, DVC allows for separate encoding of correlated video sources. Therefore, DVC requires no communication between the cameras in a multiview scenario. This is an advantage since communication is time consuming (i.e. more delay) and requires complex networking. Another appealing feature of DVC is the fact that it is based on a statistical framework. Moreover, DVC behaves as a natural joint source-channel coding solution. This results in an improved error resilience performance when compared to conventional coding. Further, DVC-based scalable codecs do not require a deterministic knowledge of the lower layers. In other words, the enhancement layers are completely independent from the base layer codec. This is called the codec-independent scalability feature, which offers a high flexibility in the way the various layers are distributed in a network. This thesis addresses the following topics: First, the theoretical foundations of DVC as well as the practical DVC scheme used in this research are presented. The potential applications for DVC are also outlined. DVC-based schemes use conventional coding to compress parts of the data, while the rest is compressed in a distributed fashion. Thus, different conventional codecs are studied in this research as they are compared in terms of compression efficiency for a rich set of sequences. This includes fine tuning the compression parameters such that the best performance is achieved for each codec. Further, DVC tools for improved Side Information (SI) and Error Concealment (EC) are introduced for monoview DVC using a partially decoded frame. The improved SI results in a significant gain in reconstruction quality for video with high activity and motion. This is done by re-estimating the erroneous motion vectors using the partially decoded frame to improve the SI quality. The latter is then used to enhance the reconstruction of the finally decoded frame. Further, the introduced spatio-temporal EC improves the quality of decoded video in the case of erroneously received packets, outperforming both spatial and temporal EC. Moreover, it also outperforms error-concealed conventional coding in different modes. Then, multiview DVC is studied in terms of SI generation, which differentiates it from the monoview case. More specifically, different multiview prediction techniques for SI generation are described and compared in terms of prediction quality, complexity and compression efficiency. Further, a technique for iterative multiview SI is introduced, where the final SI is used in an enhanced reconstruction process. The iterative SI outperforms the other SI generation techniques, especially for high motion video content. Finally, fusion techniques of temporal and inter-view side informations are introduced as well, which improves the performance of multiview DVC over monoview coding. DVC is also used to enable scalability for image and video coding. Since DVC is based on a statistical framework, the base and enhancement layers are completely independent, which is an interesting property called codec-independent scalability. Moreover, the introduced DVC scalable schemes show a good robustness to errors as the quality of decoded video steadily decreases with error rate increase. On the other hand, conventional coding exhibits a cliff effect as the performance drops dramatically after a certain error rate value. Further, the issue of privacy protection is addressed for DVC by transform domain scrambling, which is used to alter regions of interest in video such that the scene is still understood and privacy is preserved as well. The proposed scrambling techniques are shown to provide a good level of security without impairing the performance of the DVC scheme when compared to the one without scrambling. This is particularly attractive for video surveillance scenarios, which is one of the most promising applications for DVC. Finally, a practical DVC demonstrator built during this research is described, where the main requirements as well as the observed limitations are presented. Furthermore, it is defined in a setup being as close as possible to a complete real application scenario. This shows that it is actually possible to implement a complete end-to-end practical DVC system relying only on realistic assumptions. Even though DVC is inferior in terms of compression efficiency to the state of the art conventional coding for the moment, strengths of DVC reside in its good error resilience properties and the codec-independent scalability feature. Therefore, DVC offers promising possibilities for video compression with transmission over error-prone environments requirement as it significantly outperforms conventional coding in this case

Transvaginal natural orifice transluminal endoscopic surgery (vNOTES) adnexectomy for benign pathology compared with laparoscopic excision (NOTABLE) : A protocol for a randomised controlled trial

M1 - 018059 Acknowledgments We thank the vNOTES investigators’ team for taking care of the study participants. We also thank Amanda McPhail for language correction and editing of the manuscript.Peer reviewedPublisher PD

A Textbook of Advanced Oral and Maxillofacial Surgery

The scope of OMF surgery has expanded; encompassing treatment of diseases, disorders, defects and injuries of the head, face, jaws and oral cavity. This internationally-recognized specialty is evolving with advancements in technology and instrumentation. Specialists of this discipline treat patients with impacted teeth, facial pain, misaligned jaws, facial trauma, oral cancer, cysts and tumors; they also perform facial cosmetic surgery and place dental implants. The contents of this volume essentially complements the volume 1; with chapters that cover both basic and advanced concepts on complex topics in oral and maxillofacial surgery

Patterns of injury and violence in Yaoundé Cameroon: an analysis of hospital data.

BackgroundInjuries are quickly becoming a leading cause of death globally, disproportionately affecting sub-Saharan Africa, where reports on the epidemiology of injuries are extremely limited. Reports on the patterns and frequency of injuries are available from Cameroon are also scarce. This study explores the patterns of trauma seen at the emergency ward of the busiest trauma center in Cameroon's capital city.Materials and methodsAdministrative records from January 1, 2007, through December 31, 2007, were retrospectively reviewed; information on age, gender, mechanism of injury, and outcome was abstracted for all trauma patients presenting to the emergency ward. Univariate analysis was performed to assess patterns of injuries in terms of mechanism, date, age, and gender. Bivariate analysis was used to explore potential relationships between demographic variables and mechanism of injury.ResultsA total of 6,234 injured people were seen at the Central Hospital of Yaoundé's emergency ward during the year 2007. Males comprised 71% of those injured, and the mean age of injured patients was 29 years (SD = 14.9). Nearly 60% of the injuries were due to road traffic accidents, 46% of which involved a pedestrian. Intentional injuries were the second most common mechanism of injury (22.5%), 55% of which involved unarmed assault. Patients injured in falls were more likely to be admitted to the hospital (p < 0.001), whereas patients suffering intentional injuries and bites were less likely to be hospitalized (p < 0.001). Males were significantly more likely to be admitted than females (p < 0.001)DiscussionPatterns in terms of age, gender, and mechanism of injury are similar to reports from other countries from the same geographic region, but the magnitude of cases reported is high for a single institution in an African city the size of Yaoundé. As the burden of disease is predicted to increase dramatically in sub-Saharan Africa, immediate efforts in prevention and treatment in Cameroon are strongly warranted

The potential role of statins in the treatment and prevention of oesophageal adenocarcinoma

Oesophageal adenocarcinoma (OAC) is an aggressive malignancy with a very poor prognosis overall. Barrett’s oesophagus (BO) is the only known precursor lesion. Emerging preclinical evidence indicates statins, medications commonly used in the primary and secondary prevention of cardiovascular disease, inhibit proliferation, promote apoptosis and limit invasiveness of OAC. Inhibition of the mevalonate pathway depletes downstream products involved in candidate growth-signalling cascades. This research aimed to determine: (1) associations between statin use after diagnosis of oesophageal carcinoma (OC) and mortality outcomes; (2) the feasibility of assessing adjuvant statin therapy in patients with operable OAC in a future phase III randomised controlled trial; and (3) associations between statin use and malignant progression to high-grade dysplasia (HGD)/OAC in BO populations. In a cohort of 4445 patients with OC in a large primary care dataset, the General Practice Research Database, post-diagnostic statin use was associated with significant reductions in OC-specific and all-cause mortality. Significant associations were demonstrated in patients with OAC but not in oesophageal squamous cell carcinoma. A multi-centre, double-blind, parallel group, randomised, placebo-controlled feasibility trial of adjuvant statin therapy recruited patients with operable OAC. In total, 32 patients were randomised (1:1) to simvastatin (40mg) or matched placebo. Treatment started from the date of discharge following surgery and continued for up to one year. The trial estimated recruitment, retention, drug absorption, adherence, safety, quality of life, generalisability, and mortality outcomes. The feasibility of a future phase III trial was demonstrated; and derived feasibility estimates inform its design and conduct. A nested case-control analysis of a cohort with BO registered with the United Kingdom National Barrett’s Oesophagus Registry (UKBOR) demonstrated no significant associations between statin use and malignant progression. Significant dose and duration-response relationships were not demonstrated

PRELIMINARY FINDINGS OF A POTENZIATED PIEZOSURGERGICAL DEVICE AT THE RABBIT SKULL

The number of available ultrasonic osteotomes has remarkably increased. In vitro and in vivo studies have revealed differences between conventional osteotomes, such as rotating or sawing devices, and ultrasound-supported osteotomes (Piezosurgery®) regarding the micromorphology and roughness values of osteotomized bone surfaces. Objective: the present study compares the micro-morphologies and roughness values of osteotomized bone surfaces after the application of rotating and sawing devices, Piezosurgery Medical® and Piezosurgery Medical New Generation Powerful Handpiece. Methods: Fresh, standard-sized bony samples were taken from a rabbit skull using the following osteotomes: rotating and sawing devices, Piezosurgery Medical® and a Piezosurgery Medical New Generation Powerful Handpiece. The required duration of time for each osteotomy was recorded. Micromorphologies and roughness values to characterize the bone surfaces following the different osteotomy methods were described. The prepared surfaces were examined via light microscopy, environmental surface electron microscopy (ESEM), transmission electron microscopy (TEM), confocal laser scanning microscopy (CLSM) and atomic force microscopy. The selective cutting of mineralized tissues while preserving adjacent soft tissue (dura mater and nervous tissue) was studied. Bone necrosis of the osteotomy sites and the vitality of the osteocytes near the sectional plane were investigated, as well as the proportion of apoptosis or cell degeneration. Results and Conclusions: The potential positive effects on bone healing and reossification associated with different devices were evaluated and the comparative analysis among the different devices used was performed, in order to determine the best osteotomes to be employed during cranio-facial surgery

Outcomes after acute intracerebral haemorrhage

Primary Intracerebral haemorrhage is a severe form of stroke with poor prognosis attributed to haematoma characteristics. High blood pressure is present during the acute phase of intracerebral haemorrhage and associated with poor outcome in part through expansion of haematoma. Data from the ‘Efficacy of Nitric Oxide in Stroke trial’ (ENOS) was used to analyse the performance characteristics of qualitative and quantitative descriptors of intracerebral haematoma. The results showed that formal measurement of haemorrhage characteristics and visual estimates are reproducible. Intracerebral haemorrhage volumes measured using the modified ABC/2 formula were significantly lower compared to standard ABC/2 and computer assisted semi-automatic segmentation. In 629 patients with intracerebral haemorrhage presenting within 48 hours, the effect of blood pressure lowering with transdermal glyceryl trinitrate was assessed. Glyceryl trinitrate lowered blood pressure, was safe but did not improve functional outcome. In a small group of patients treated within 6 hours, glyceryl trinitrate improved functional outcome. Analysis of 246 patients with acute intracerebral haemorrhage from ENOS was undertaken to assess whether there were any differences in functional outcome among those who continued prior antihypertensive drugs during the immediate stroke period compared to those assigned to stop temporarily for 7 days. The results were neutral indicating that there was no benefit in those who continued treatment. Data of 1,011 patients with intracerebral haemorrhage in hyperacute trials from the VISTA collaboration showed differences in baseline characteristics and functional outcomes among patients from various ethnic backgrounds. A systematic review was updated to assess the effect of 26 randomised controlled trials that aimed to alter blood pressure within one week of acute stroke. The results showed that blood pressure reduction did not improve functional outcome irrespective of stroke type. When examined by time, treatment within 6 hours appeared to benefit but the number of patients were small and more studies are needed. The analysis also showed that continuing prestroke antihypertensive drugs in the immediate period after stroke did not benefit and might be harmful. In summary, this thesis provides new information on parameters used to estimate intracerebral haematoma, relationship between management of blood pressure and outcomes after haemorrhagic stroke. The work supports testing of whether very early blood pressure lowering after ictus is beneficial as is being undertaken in ongoing randomised controlled trials. Adjusting for ethnic differences may further identify patients in whom treatment may confer measurable advantage

Landscaping the subject: Virtuality, embodiment, and the discourse of the interface

This thesis examines the linear perspective interface as a key technology in the staging of Western subjectivity, and the body and 'nature' as critical terms in the description of the subject and its environment. It examines three historical moments in the discourse of the interface - Brunelleschi's perspective demonstration, eighteenth century landscape gardening, and the present-day virtual reality interface - and shows how, in each case, the discourse of the interface insists on a distance between the subject and its perceived environment. In this visualist paradigm, the body and nature are framed as excessive - uninvolved in the constitution of subjectivity. This is also the framework assumed by Lacan in his description of the subject. Though this distinction may work in theory, in practice it is impossible to sustain - a fact that is made explicit in the eighteenth-century landscape garden. Focusing not only on the landscape view, but on the enclosed sections of the garden between the views, this thesis investigates the complex involvement of representation and the carnal body in the construction of the subject and (its) nature. Here, the relation of the subject to the anamorphic image becomes important. Against the distance and disembodiment implied in the perspectival view, the anamorphic relation is one of embodiment and proximity - suggesting that phenomenology, rather than psychoanalysis, is the most effective approach to the discourse of the interface and its subject. This hypothesis is developed through an examination of the virtual reality interface. The latter both assumes and exceeds a/the actively viewing subject, foregrounding the ontological complexity of subjectivity and the failure of theory to fully describe or prescribe it. Psychoanalytic models in particular fail to address interfaced being as embodied being. The notion of 'anamorphic subjectivity' - interfaced being as a multistable condition of technological embodiment - is put forward as a possible alternative to perspectival models