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Critical Problems (critical + problem)
Selected AbstractsREDUCING THE RISK OF PERISTOMAL INFECTION AFTER PEG PLACEMENTDIGESTIVE ENDOSCOPY, Issue 4 2005Iruru Maetani Percutaneous endoscopic gastrostomy (PEG) was first described in 1980 as an effective means of enteral nutrition where oral intake is not possible. PEG placement is safe and has now replaced the nasogastric tube in patients who need long-term feeding. Although it is relatively safe with a very low associated mortality, minor complications, especially local and systemic infection, remain a problem. Of these, peristomal wound infections are the most common complication of PEG. In patients indicated for this procedure who are aged and/or frail, this complication may pose a critical problem. In the commonly used pull or push methods for PEG placement, the PEG tube is readily colonized by oropharyngeal bacteria. Infection of the PEG site is considered to be associated with contamination of the PEG catheter. There are important measures that should be taken to prevent peristomal infection. A number of rigorous studies have shown that prophylactic antibiotics are effective in reducing the risk of peristomal infection. As methicillin-resistant Staphylococcus aureus (MRSA) or other resistant organisms are emerging as a major pathogen in peristomal infection, however, currently recommended antibiotic prophylaxis regimens might be inappropriate. Alternative regimens and other approaches to prevent contamination of the PEG tube during the procedure are required. [source] A structural optimization method based on the level set method using a new geometry-based re-initialization schemeINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 12 2010Shintaro Yamasaki Abstract Structural optimization methods based on the level set method are a new type of structural optimization method where the outlines of target structures can be implicitly represented using the level set function, and updated by solving the so-called Hamilton,Jacobi equation based on a Eulerian coordinate system. These new methods can allow topological alterations, such as the number of holes, during the optimization process whereas the boundaries of the target structure are clearly defined. However, the re-initialization scheme used when updating the level set function is a critical problem when seeking to obtain appropriately updated outlines of target structures. In this paper, we propose a new structural optimization method based on the level set method using a new geometry-based re-initialization scheme where both the numerical analysis used when solving the equilibrium equations and the updating process of the level set function are performed using the Finite Element Method. The stiffness maximization, eigenfrequency maximization, and eigenfrequency matching problems are considered as optimization problems. Several design examples are presented to confirm the usefulness of the proposed method. Copyright © 2010 John Wiley & Sons, Ltd. [source] Influence of Radial Clearance and Rotor Motion to Hemolysis in a Journal Bearing of a Centrifugal Blood PumpARTIFICIAL ORGANS, Issue 11 2006Hiroyuki Kataoka Abstract:, Hemolysis due to narrow clearance of noncontact bearings is a critical problem for rotary blood pumps. We developed a centrifugal blood pump with a magnetic and hydrodynamic hybrid bearing, and found that the hemolysis in the narrow clearance depends not only on the clearance size, but also on the rotor stability. In this study, we quantified the relation between the hemolysis, radial clearance (c), and rotor stability through the measurement of the rotor motion and hemolysis. As a result, it was confirmed that the rotor of the current pump is stabilized within the oscillation of 20 ,m in blood, and the hemolysis decreases with increase in the c, which is the opposite in the unstable rotor motion with the previous pump. In order to theoretically discuss this hemolysis tendency, we implemented hemolysis estimation in the c according to hydrodynamics and hemodynamics. This estimation can represent the measured hemolysis tendency, and revealed that the flow rate has large influence on the hemolysis in the c. [source] Nanomaterials for Neural InterfacesADVANCED MATERIALS, Issue 40 2009Nicholas A. Kotov Abstract This review focuses on the application of nanomaterials for neural interfacing. The junction between nanotechnology and neural tissues can be particularly worthy of scientific attention for several reasons: (i) Neural cells are electroactive, and the electronic properties of nanostructures can be tailored to match the charge transport requirements of electrical cellular interfacing. (ii) The unique mechanical and chemical properties of nanomaterials are critical for integration with neural tissue as long-term implants. (iii) Solutions to many critical problems in neural biology/medicine are limited by the availability of specialized materials. (iv) Neuronal stimulation is needed for a variety of common and severe health problems. This confluence of need, accumulated expertise, and potential impact on the well-being of people suggests the potential of nanomaterials to revolutionize the field of neural interfacing. In this review, we begin with foundational topics, such as the current status of neural electrode (NE) technology, the key challenges facing the practical utilization of NEs, and the potential advantages of nanostructures as components of chronic implants. After that the detailed account of toxicology and biocompatibility of nanomaterials in respect to neural tissues is given. Next, we cover a variety of specific applications of nanoengineered devices, including drug delivery, imaging, topographic patterning, electrode design, nanoscale transistors for high-resolution neural interfacing, and photoactivated interfaces. We also critically evaluate the specific properties of particular nanomaterials,including nanoparticles, nanowires, and carbon nanotubes,that can be taken advantage of in neuroprosthetic devices. The most promising future areas of research and practical device engineering are discussed as a conclusion to the review. [source] Faecal screening of colorectal cancerINTERNATIONAL JOURNAL OF CLINICAL PRACTICE, Issue 3 2008A. Loganayagam Summary Aims:, Screening and prevention of colorectal cancer (CRC) is a public health priority. Recent progress in understanding the biology of CRC has lead to possible new approaches to screening. In particular, assay of faecal molecular markers represents a promising non-invasive approach to screening, with improved safety, accuracy and patient compliance. Methods:, MEDLINE/PubMed searches were used to identify key articles relating to faecal-based screening with secondary review of cited publications. Results:, Faecal markers of CRC can be broadly divided into DNA based and non-DNA based. Conclusions:, Faecal occult blood testing for CRC screening has been advocated for decades for its non-invasiveness and low cost. It has exhibited a 15,33% decrease in mortality, despite drawbacks with sensitivity and compliance. Other non-DNA markers have the adequate sensitivity for inflammatory lesions but do not have the required specificity for screening average-risk populations. Faecal DNA testing has the potential to enhance the performance characteristics of stool testing. Because of molecular heterogeneity of cancer, no single DNA marker has yielded adequate sensitivity. Analysis of several combinations of markers in studies have produced high detection rates of both CRC and advanced adenomas in selected patient groups. However, the currently available markers, both non-DNA and DNA, have not yet been validated in large-scale studies screening average -risk population nor have they so far shown the necessary sensitivity and specificity required for large-scale screening programmes. Another major drawback with the DNA-based markers is the cost-effectiveness. Issues regarding implementation and compliance remain unanswered. These critical problems have to be rectified before these techniques can be recommended for large-scale CRC screening. [source] Optimizing Patching-based multicast for video-on-demand in wireless mesh networksINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 9-10 2010Fei Xie Abstract In this work, we study the application of video-on-demand (VoD) in wireless mesh networks (WMN), a next generation edge technology to provide broadband data access in residential, business and even city-wise networks. We adopt a Patching-based multicast technique to better utilize the bandwidth resources in the mesh network. We optimize the Patching-based multicast by addressing two critical problems, namely, the Minimum Cost Multicast Tree (MCMT) problem and the Maximum Benefit Multicast Group (MBMG) problem. The MCMT problem is to find a MCMT in the network. We show that finding such a tree in the WMN can be formulated as a graph theory problem, which is to find the tree with minimum number of non-leaf nodes, and which spans all the nodes in the multicast group. We further prove the problem is NP-hard and propose a fast greedy algorithm to accommodate the real-time feature of the VoD application. We solve the MBMG problem by minimizing the communication of a Patching group in the entire network. A Markov model is proposed to capture the growth of the multicast group in the WMN. Simulation study results validate the proposed solutions of the two problems. Copyright © 2009 John Wiley & Sons, Ltd. [source] Religion, Belief and Action: The Case of Ngarrindjeri ,Women's Business' on Hindmarsh Island, South Australia, 1994,1996THE AUSTRALIAN JOURNAL OF ANTHROPOLOGY, Issue 1 2002James F. Weiner The question of what role beliefs play in the description of a culture or a religious system, and whether beliefs as such can be ,tested', arose during a dramatic State Royal Commission into an Aboriginal sacred site claim in South Australia in 1995 focused on the proposed Hindmarsh Island-Goolwa bridge. In this paper I examine some aspects of the legal and anthropological defence of the claim and suggest that insufficient distinction was made between belief as an interior subjective state, and as a gloss on a certain disposition to behave that is conventionally defined. Further, the issue of the social testing of belief statements was obscured by re-phrasing the Royal Commission as an attack on the Aboriginal claimants' right to religious belief. Appealing to Needham, Sperber and Quine, and utilising comparative analysis of a similar court case in North America, I suggest an anthropological approach to belief that side-steps some of the critical problems in the anthropology of religion created during the Hindmarsh Island Bridge Royal Commission. [source] How to be Bicameral: Reading William Connolly's Pluralism with Whitehead and DeleuzeBRITISH JOURNAL OF POLITICS & INTERNATIONAL RELATIONS, Issue 2 2008James Williams This article argues that the concept of bicameralism is central to William Connolly's pluralism. The concept is analysed in terms of its roots in political bicameralism, in the bicameral mind and in organic bicameralism in order to show its richness and its capacity to provide positive answers to a series of standard criticisms of pluralism. Two more persistent critical problems are presented in the problem of evil (can we afford to be open to other political positions if they are evil?) and in the problem of the generation of paradoxes (does pluralism depend on adopting perniciously paradoxical positions?). These questions are answered by drawing connections from Connolly's work to Alfred North Whitehead's definition of evil and to Gilles Deleuze's work on paradox. [source] | ||||||||||||||||