CyberWalk : a web-based distributed virtual walkthrough environment

A distributed virtual walkthrough environment allows users connected to the geometry server to walk through a specific place of interest, without having to travel physically. This place of interest may be a virtual museum, virtual library or virtual university. There are two basic approaches to distribute the virtual environment from the geometry server to the clients, complete replication and on-demand transmission. Although the on-demand transmission approach saves waiting time and optimizes network usage, many technical issues need to be addressed in order for the system to be interactive. CyberWalk is a web-based distributed virtual walkthrough system developed based on the on-demand transmission approach. It achieves the necessary performance with a multiresolution caching mechanism. First, it reduces the model transmission and rendering times by employing a progressive multiresolution modeling technique. Second, it reduces the Internet response time by providing a caching and prefetching mechanism. Third, it allows a client to continue to operate, at least partially, when the Internet is disconnected. The caching mechanism of CyberWalk tries to maintain at least a minimum resolution of the object models in order to provide at least a coarse view of the objects to the viewer. All these features allow CyberWalk to provide sufficient interactivity to the user for virtual walkthrough over the Internet environment. In this paper, we demonstrate the design and implementation of CyberWalk. We investigate the effectiveness of the multiresolution caching mechanism of CyberWalk in supporting virtual walkthrough applications in the Internet environment through numerous experiments, both on the simulation system and on the prototype system

An interpretive investigation of trust and workflow in advertising communities

Adopting a socio–economic perspective and a multimethod field research approach this thesis investigates the correlation between trust and workflow in advertising communities of practice. Using a semiotic mode of analysis a comparative examination of offline and online communities will be conducted to inspect the practices of trust when multiple stakeholders follow the creative workflow process to fulfil creative briefs. The motivation to lead the research stems from a current lack of understanding of how trust is operationalized in online creative communities. Shortcomings from the literature 1) do not account for the significance of constructed workplace settings in the offline domain, 2) focus on providing generalisations through quantification, while fail to offer insights through qualitative methods and 3) overlook the weaknesses of trust in professional relationships. To address these shortcomings the thesis provides an extensive literature review to explicate the complexity of trust. The review forms the foundation of the thesis from which it makes original theoretical, analytical and empirical contributions. It 1) introduces a conceptual framework that correlates trust with workflow in offline and online advertising communities; 2) presents a novel thematic–narrative analytical method to interpret and map trust and workflow at the granular level; 3) reports from three sequential field studies that explores trust and workflow in professional relationships. These contributions highlight the operationalization of trust and that trust is an active determinant of workflow. The findings have implications to the study of trust and virtual workspaces in the digital economy that will influence their design, development and utilization. The first study examines trust and workflow in an offline advertising community. The findings indicate a positive correlation: trust is strongly aligned to workflow, inferred by strongly embedded situational and trust–warranting properties. The second and third studies examine trust and workflow in online advertising communities. The former indicates a negative correlation: trust is mediumly misaligned to workflow, inferred by weakly embedded situational properties. The findings of the latter also indicate a negative correlation: trust is strongly misaligned to workflow, inferred by weakly embedded situational and trust–warranting properties. In short, trust and workflow have a negative correlation online compared to the offline domain and is deficient in situational and trust–warranting properties. As a consequence the online domain does not perform to the same professional standard as the offline domain

An interpretive investigation of trust and workflow in advertising communities

Adopting a socio–economic perspective and a multimethod field research approach this thesis investigates the correlation between trust and workflow in advertising communities of practice. Using a semiotic mode of analysis a comparative examination of offline and online communities will be conducted to inspect the practices of trust when multiple stakeholders follow the creative workflow process to fulfil creative briefs. The motivation to lead the research stems from a current lack of understanding of how trust is operationalized in online creative communities. Shortcomings from the literature 1) do not account for the significance of constructed workplace settings in the offline domain, 2) focus on providing generalisations through quantification, while fail to offer insights through qualitative methods and 3) overlook the weaknesses of trust in professional relationships. To address these shortcomings the thesis provides an extensive literature review to explicate the complexity of trust. The review forms the foundation of the thesis from which it makes original theoretical, analytical and empirical contributions. It 1) introduces a conceptual framework that correlates trust with workflow in offline and online advertising communities; 2) presents a novel thematic–narrative analytical method to interpret and map trust and workflow at the granular level; 3) reports from three sequential field studies that explores trust and workflow in professional relationships. These contributions highlight the operationalization of trust and that trust is an active determinant of workflow. The findings have implications to the study of trust and virtual workspaces in the digital economy that will influence their design, development and utilization. The first study examines trust and workflow in an offline advertising community. The findings indicate a positive correlation: trust is strongly aligned to workflow, inferred by strongly embedded situational and trust–warranting properties. The second and third studies examine trust and workflow in online advertising communities. The former indicates a negative correlation: trust is mediumly misaligned to workflow, inferred by weakly embedded situational properties. The findings of the latter also indicate a negative correlation: trust is strongly misaligned to workflow, inferred by weakly embedded situational and trust–warranting properties. In short, trust and workflow have a negative correlation online compared to the offline domain and is deficient in situational and trust–warranting properties. As a consequence the online domain does not perform to the same professional standard as the offline domain

Prelamination of Neourethra with Uterine Mucosa in Radial Forearm Osteocutaneous Free Flap Phalloplasty in the Female-to-Male Transgender Patient

Radial forearm free flap phalloplasty is the most commonly performed flap for neophallus construction in the female-to-male (FtM) transgender patient. Urological complications, however, can arise quite frequently and can prevent the patient from urinating in the standing position, an important postsurgical goal for many. Using mucosa to construct the fixed urethra and to prelaminate the penile urethra has been successful in reducing urologic complications, particularly strictures and fistulas. Until now, only buccal, vaginal, colonic, and bladder sites have been described as sources for these mucosal grafts. We present the successful use of uterine mucosa for prelamination of the neourethra in an FtM patient who underwent hysterectomy and vaginectomy at the prelamination stage of a radial forearm phalloplasty. Three months postoperatively, the patient was able to void while standing and showed no evidence of stricture or fistula on retrograde cystogram. These results suggest that uterine mucosa may be used for prelamination of the penile neourethra in patients undergoing phalloplasty

Multi-Resolution Model Transmission in Distributed Virtual Environments

Distributed virtual environments allow users at different geographical locations to share and interact within a common virtual environment via a local network or through the Internet. To deliver a good performance for such applications, we need to address several issues in different research disciplines. First, we must be able to model virtual objects effectively. The recently developed multi-resolution techniques for object modeling are of great value here, since they are capable of simplifying the object models and therefore reducing the time to render them. This may greatly reduce the demand for rendering performance on the client machines. Second, with the constraint of the limited bandwidth of the Internet, we need to reduce the response time by reducing the amount of data requested over the network. Caching of suitable object models of high affinity will reduce the amount of data requested over the network for a faster response time. Prefetching object models by predicting those ..

Mitral valve infective endocarditis: benefit of early operation and aggressive use of repair.

BACKGROUND: In-hospital mortality rates for left-sided infective endocarditis (IE) exceed 20%. We investigated the outcomes of an aggressive approach to mitral valve IE that emphasizes early surgical intervention and preferential performance of mitral valve repair. METHODS: We reviewed 89 consecutive operations in 87 patients for native mitral valve IE at a single institution from 2002 to 2007. Operations occurred promptly after completion of preoperative studies. Independent risk factors for death were investigated using multivariable logistic regression. RESULTS: Mitral valve repair was accomplished in 56 of 89 patients (63%). Perioperative mortality was 4.4% (n = 4). Survival rates at 1 and 5 years were 89.9% (80 of 89) and 82.0% (73 of 90). There was a survival benefit for repair vs replacement at 1 (p = 0.03) and 5 years (p = 0.0017). Repair vs replacement (odds ratio [OR], 0.2; 95% confidence interval [CI], 0.06 to 0.72), diabetes (OR, 4.43; 95% CI, 1.18 to 16.66), and renal failure (OR, 3.65; 95% CI, 1.3 to 12.91) were independent risk factors for late mortality. Among 59 patients with active IE, preoperative head computed tomography (CT) showed 29 (49%) had abnormalities, including 12 (41%) with intracerebral hemorrhage. The median interval was 4 days from admission to operation. The rate of permanent postoperative stroke was 1.1% (1 of 89). CONCLUSIONS: These results support early surgical therapy for mitral valve IE. Head CT abnormalities do not warrant delay of operation. Mitral valve repair was associated with a long-term survival advantage compared with valve replacement

Relationships between Prenatal Distress and Infant Body Mass Index in the First Year of Life in a Lower-Middle Income Country

Prenatal stress affects body composition in childhood and later in life. However, few studies assess body composition in infancy. Furthermore, most are in high-income countries and do not consider interactive or curvilinear relationships. We assessed distress and diet during pregnancy via questionnaires among 310 women in Vanuatu, a lower-middle income country. We measured body mass index (BMI) among 54 infants at 4–12 months of age. We analyzed interactive relationships between prenatal distress and diet with BMI Z-scores, and curvilinear relationships between distress and BMI Z-scores. There were no direct linear or interactive relationships between prenatal distress or diet with BMI Z-scores. We observed curvilinear relationships between prenatal distress and BMI Z-scores (p = 0.008), explaining 13.3 percent of unique variance. Results highlight that relationships between prenatal stress and body composition are evident in infancy but might not be detected if only linear relationships are assessed. Analyses in more diverse samples might help to explain inconsistencies in past studies