42 resultados para Conceptual-systemic model
em BORIS: Bern Open Repository and Information System - Berna - Suiça
Resumo:
We present a conceptual prototype model of a focal plane array unit for the STEAMR instrument, highlighting the challenges presented by the required high relative beam proximity of the instrument and focus on how edge-diffraction effects contribute to the array's performance. The analysis was carried out as a comparative process using both PO & PTD and MoM techniques. We first highlight general differences between these computational techniques, with the discussion focusing on diffractive edge effects for near-field imaging reflectors with high truncation. We then present the results of in-depth modeling analyses of the STEAMR focal plane array followed by near-field antenna measurements of a breadboard model of the array. The results of these near-field measurements agree well with both simulation techniques although MoM shows slightly higher complex beam coupling to the measurements than PO & PTD.
Resumo:
Despite promising cost saving potential, many offshore software projects fail to realize the expected benefits. A frequent source of failure lies in the insufficient transfer of knowledge during the transition phase. Former literature has reported cases where some domains of knowledge were successfully transferred to vendor personnel whereas others were not. There is further evidence that the actual knowledge transfer processes often vary from case to case. This raises the question whether there is a systematic relationship between the chosen knowledge transfer process and know-ledge transfer success. This paper introduces a dynamic perspective that distinguishes different types of knowledge transfer processes explaining under which circumstances which type is deemed most appropriate to successfully transfer knowledge. Our paper draws on knowledge transfer literature, the Model of Work-Based Learning and theories from cognitive psychology to show how characteristics of know-ledge and the absorptive capacity of knowledge recipients fit particular knowledge transfer processes. The knowledge transfer processes are conceptualized as combinations of generic knowledge transfer activities. This results in six gestalts of know-ledge transfer processes, each representing a fit between the characteristics of the knowledge process and the characteristics of the knowledge to be transferred and the absorptive capacity of the knowledge recipient.
Resumo:
Spinal muscular atrophy (SMA) is a childhood fatal motor neuron disease caused by mutations in the Survival Motor Neuron 1 (SMN1) gene, currently without effective treatment. One possible therapeutic approach is the use of antisense oligonucleotides (ASOs) to redirect the splicing of a paralogous gene, SMN2, to increase the production of functional SMN protein. A range of ASOs with different chemical properties is suitable for these applications, including a morpholino (MO) variant, which has a particularly excellent safety, and efficacy profile. We used a 25- nt MO oligomer sequence against the ISS-N1 region of SMN2 (HSMN2Ex7D(-10-34)) with superior efficacy to previously described sequences also in transgenic SMA Δ7 mice. The combined local and systemic administration of MO (bare or conjugated to octa-guanidine) is necessary to increase full-length SMN expression, leading to robust neuropathological features improvement and survival rescue. Additionally, several snRNA levels that are dysregulated in SMA mice could be restored by MO treatment. These results demonstrate that MO therapy is efficacious and can result in phenotypic rescue. These data provide important insights for the development of therapeutic strategies in SMA patients.
Resumo:
This chapter introduces a conceptual model to combine creativity techniques with fuzzy cognitive maps (FCMs) and aims to support knowledge management methods by improving expert knowledge acquisition and aggregation. The aim of the conceptual model is to represent acquired knowledge in a manner that is as computer-understandable as possible with the intention of developing automated reasoning in the future as part of intelligent information systems. The formal represented knowledge thus may provide businesses with intelligent information integration. To this end, we introduce and evaluate various creativity techniques with a list of attributes to define the most suitable to combine with FCMs. This proposed combination enables enhanced knowledge management through the acquisition and representation of expert knowledge with FCMs. Our evaluation indicates that the creativity technique known as mind mapping is the most suitable technique in our set. Finally, a scenario from stakeholder management demonstrates the combination of mind mapping with FCMs as an integrated system.
Resumo:
BACKGROUND: Spinal muscular atrophy (SMA) is a fatal motor neuron disease of childhood that is caused by mutations in the SMN1 gene. Currently, no effective treatment is available. One possible therapeutic approach is the use of antisense oligos (ASOs) to redirect the splicing of the paralogous gene SMN2, thus increasing functional SMN protein production. Various ASOs with different chemical properties are suitable for these applications, including a morpholino oligomer (MO) variant with a particularly excellent safety and efficacy profile. OBJECTIVE: We investigated a 25-nt MO sequence targeting the negative intronic splicing silencer (ISS-N1) 10 to 34 region. METHODS: We administered a 25-nt MO sequence against the ISS-N1 region of SMN2 (HSMN2Ex7D[-10-34]) in the SMAΔ7 mouse model and evaluated the effect and neuropathologic phenotype. We tested different concentrations (from 2 to 24 nM) and delivery protocols (intracerebroventricular injection, systemic injection, or both). We evaluated the treatment efficacy regarding SMN levels, survival, neuromuscular phenotype, and neuropathologic features. RESULTS: We found that a 25-nt MO sequence against the ISS-N1 region of SMN2 (HSMN2Ex7D[-10-34]) exhibited superior efficacy in transgenic SMAΔ7 mice compared with previously described sequences. In our experiments, the combination of local and systemic administration of MO (bare or conjugated to octaguanidine) was the most effective approach for increasing full-length SMN expression, leading to robust improvement in neuropathologic features and survival. Moreover, we found that several small nuclear RNAs were deregulated in SMA mice and that their levels were restored by MO treatment. CONCLUSION: These results indicate that MO-mediated SMA therapy is efficacious and can result in phenotypic rescue, providing important insights for further development of ASO-based therapeutic strategies in SMA patients.
Resumo:
Lumbar spinal instability (LSI) is a common spinal disorder and can be associated with substantial disability. The concept of defining clinically relevant classifications of disease or 'target condition' is used in diagnostic research. Applying this concept to LSI we hypothesize that a set of clinical and radiological criteria can be developed to identify patients with this target condition who are at high risk of 'irreversible' decompensated LSI for whom surgery becomes the treatment of choice. In LSI, structural deterioration of the lumbar disc initiates a degenerative cascade of segmental instability. Over time, radiographic signs become visible: traction spurs, facet joint degeneration, misalignment, stenosis, olisthesis and de novo scoliosis. Ligaments, joint capsules, local and distant musculature are the functional elements of the lumbar motion segment. Influenced by non-functional factors, these functional elements allow a compensation of degeneration of the motion segment. Compensation may happen on each step of the degenerative cascade but cannot reverse it. However, compensation of LSI may lead to an alleviation or resolution of clinical symptoms. In return, the target condition of decompensation of LSI may cause the new occurrence of symptoms and pain. Functional compensation and decompensation are subject to numerous factors that can change which makes estimation of an individual's long-term prognosis difficult. Compensation and decompensation may influence radiographic signs of degeneration, e.g. the degree of misalignment and segmental angulation caused by LSI is influenced by the tonus of the local musculature. This conceptual model of compensation/decompensation may help solve the debate on functional and psychosocial factors that influence low back pain and to establish a new definition of non-specific low back pain. Individual differences of identical structural disorders could be explained by compensated or decompensated LSI leading to changes in clinical symptoms and pain. Future spine surgery will have to carefully define and measure functional aspects of LSI, e.g. to identify a point of no return where multidisciplinary interventions do not allow a re-compensation and surgery becomes the treatment of choice.
Resumo:
Waddlia chondrophila is a known bovine abortigenic Chlamydia-related bacterium that has been associated with adverse pregnancy outcomes in human. However, there is a lack of knowledge regarding how W. chondrophila infection spreads, its ability to elicit an immune response and induce pathology. A murine model of genital infection was developed to investigate the pathogenicity and immune response associated with a W. chondrophila infection. Genital inoculation of the bacterial agent resulted in a dose-dependent infection that spread to lumbar lymph nodes and successively to spleen and liver. Bacterial-induced pathology peaked on day 14, characterized by leukocyte infiltration (uterine horn, liver, and spleen), necrosis (liver) and extramedullary hematopoiesis (spleen). Immunohistochemistry demonstrated the presence of a large number of W. chondrophila in the spleen on day 14. Robust IgG titers were detected by day 14 and remained high until day 52. IgG isotypes consisted of high IgG2a, moderate IgG3 and no detectable IgG1, indicating a Th1-associated immune response. This study provides the first evidence that W. chondrophila genital infection is capable of inducing a systemic infection that spreads to major organs, induces uterus, spleen, and liver pathology and elicits a Th1-skewed humoral response. This new animal model will help our understanding of the mechanisms related to intracellular bacteria-induced miscarriages, the most frequent complication of pregnancy that affects one in four women.
Resumo:
Regional citrate anticoagulation (RCA) during hemodialysis (HD) has several advantages over heparin anticoagulation, but calcium (Ca) derangements are a major concern necessitating repeated monitoring of systemic ionized Ca (Ca(2+)). We developed a mathematical model of Ca and citrate (Ci) kinetics during RCA.
Resumo:
Delayed cerebral vasospasm after aneurysmal subarachnoid hemorrhage (SAH) is a major cause of high morbidity and mortality. The reduced availability of nitric oxide (NO) in blood and cerebrospinal fluid (CSF) is well established as a key mechanism of vasospasm. Systemic administration of glyceryl trinitrate (GTN), an NO donor also known as nitroglycerin, has failed to be established in clinical settings to prevent vasospasm because of its adverse effects, particularly hypotension. The purpose of this study was to analyze the effect of intrathecally administered GTN on vasospasm after experimental SAH in the rabbit basilar artery.
Resumo:
Dahl salt-sensitive (DS) and salt-resistant (DR) inbred rat strains represent a well established animal model for cardiovascular research. Upon prolonged administration of high-salt-containing diet, DS rats develop systemic hypertension, and as a consequence they develop left ventricular hypertrophy, followed by heart failure. The aim of this work was to explore whether this animal model is suitable to identify biomarkers that characterize defined stages of cardiac pathophysiological conditions. The work had to be performed in two stages: in the first part proteomic differences that are attributable to the two separate rat lines (DS and DR) had to be established, and in the second part the process of development of heart failure due to feeding the rats with high-salt-containing diet has to be monitored. This work describes the results of the first stage, with the outcome of protein expression profiles of left ventricular tissues of DS and DR rats kept under low salt diet. Substantial extent of quantitative and qualitative expression differences between both strains of Dahl rats in heart tissue was detected. Using Principal Component Analysis, Linear Discriminant Analysis and other statistical means we have established sets of differentially expressed proteins, candidates for further molecular analysis of the heart failure mechanisms.
Resumo:
Salmonella enterica serovar Typhimurium has long been recognised as a zoonotic pathogen of economic significance in animals and humans. Attempts to protect humans and livestock may be based on immunization with vaccines aimed to induce a protective response. We recently demonstrated that the oral administration of a Salmonella enterica serovar Typhimurium strain unable to synthesize the zinc transporter ZnuABC is able to protect mice against systemic salmonellosis induced by a virulent homologous challenge. This finding suggested that this mutant strain could represent an interesting candidate vaccine for mucosal delivery. In this study, the protective effect of this Salmonella strain was tested in a streptomycin-pretreated mouse model of salmonellosis that is distinguished by the capability of evoking typhlitis and colitis. The here reported results demonstrate that mice immunized with Salmonella enterica serovar Typhimurium (S. Typhimurium) SA186 survive to the intestinal challenge and, compared to control mice, show a reduced number of virulent bacteria in the gut, with milder signs of inflammation. This study demonstrates that the oral administration a of S. Typhimurium strain lacking ZnuABC is able to elicit an effective immune response which protects mice against intestinal S. Typhimurium infection. These results, collectively, suggest that the streptomycin-pretreated mouse model of S. typhimurium infection can represent a valuable tool to screen S. typhimurium attenuated mutant strains and potentially help to assess their protective efficacy as potential live vaccines.
Resumo:
The pre-treatment of tumour neovessels by low-level photodynamic therapy (PDT) improves the distribution of concomitantly administered systemic chemotherapy. The mechanism by which PDT permeabilizes the tumour vessel wall is only partially known. We have recently shown that leukocyte-endothelial cell interaction is essential for photodynamic drug delivery to normal tissue. The present study investigates whether PDT enhances drug delivery in malignant mesothelioma and whether it involves comparable mechanisms of actions.