Fiberkomposittpropeller. En ny æra for propulsjon?

I denne oppgaven har en litteraturstudie og en materialstudie blitt gjennomført. Litteraturstudiens hensikt har vært å sjekke hvor komposittpropeller står i det sivile markedet i dag. Våre funn er todelt. På den ene siden har vi inntrykk av at det er en vilje i propulsjonsindustrien til å utvikle komposittpropeller for markedet. Denne viljen er særlig drevet av marinefartøys søken etter et fortrinn innenfor propulsjon. På den andre siden er det en stor skepsis rundt bruken av komposittpropeller som et alternativ til det veletablerte NAB materialet. Denne skepsisen er trolig en følge av manglende kunnskap om anisotropien til fiberkompositter. Den gjennomførte material studien har gitt interessante resultater, som har bygd en grunnleggende forståelse for hvordan karbonfiber oppfører seg under bøying. Det faktum at fiberkompositter ikke må behandles som isotopiske materialer er her en viktig lærdom. Dette må i videre studier vektlegges i særlig grad, for bedre å forstå fiberkomposittets retningsbestemte egenskaper. Fiberkomposittpropeller innehar en rekke egenskaper, og noen av dem er dekket i denne studien. Produktet har etter vår mening få klare fordeler sammenliknet med konvensjonelle NAB propellere. Propellenes evne til self piching, kan redusere belastninger på maskineri og aksling, ved at propellbladet depitches under belastning. Dette kan gi en fordel i grov sjø. Videre kan propellvirkningsgraden kunne økes litt, fordi en større diameter kan oppnås. På alle skipspropeller er kavitasjon et problem. Fiberkompositter har generelt dårlig motstandsdyktighet mot kavitasjon, og dette gjør det mer aktuelt til fartøyer som kaviteter lite, slik som undervannsbåter. Produksjonen av fiberkompositt propeller kan ved riktig produksjonsteknikk være tidsmessig fordelaktig ovenfor produksjonen av en tilsvarende NAB propell. Fiberkompositt har egenskaper som er retningsbestemte. Hvilken bestanddel av materialet som svikter kan være svært vanskelig å bestemme. Dette gjør at styrkeberegning av komplekse konstruksjoner med mange lag i laminatet blir tidkrevende. Propeller er en slik konstruksjon. Fiberkompositt ser ut til å inneha gode dempningsegenskaper. Dette bør studeres videre, da gode dempningsegenskaper vil gi en lavere signatur. For undervannsbåter vil redusert signatur gi en stridsteknisk fordel. Siden fiberkomposittpropeller viser seg å ha et begrenset bruksområde, som følge av lav motstandsdyktighet mot kavitasjon, vil det ikke være særlig aktuelt for overflatefartøy. Vår anbefaling er at fiberkomposittpropeller vurderes som propulsor for undervannsbåter, hvor kavitasjonen er liten, og signatur er av stor betydning

Effect of female genital schistosomiasis and anti-schistosomal treatment on monocytes, CD4+ T-cells and CCR5 expression in the female genital tract

BACKGROUND: Schistosoma haematobium is a waterborne parasite that may cause female genital schistosomiasis (FGS), characterized by genital mucosal lesions. There is clinical and epidemiological evidence for a relationship between FGS and HIV. We investigated the impact of FGS on HIV target cell density and expression of the HIV co-receptor CCR5 in blood and cervical cytobrush samples. Furthermore we evaluated the effect of anti-schistosomal treatment on these cell populations. Design The study followed a case-control design with post treatment follow-up, nested in an on-going field study on FGS. METHODS: Blood and cervical cytobrush samples were collected from FGS negative and positive women for flow cytometry analyses. Urine samples were investigated for schistosome ova by microscopy and polymerase chain reaction (PCR). RESULTS: FGS was associated with a higher frequency of CD14 + cells (monocytes) in blood (11.5% in FGS+ vs. 2.2% in FGS-, p = 0.042). Frequencies of CD4 + cells expressing CCR5 were higher in blood samples from FGS+ than from FGS- women (4.7% vs. 1.5%, p = 0.018). The CD14 + cell population decreased significantly in both compartments after anti-schistosomal treatment (p = 0.043). Although the frequency of CD4+ cells did not change after treatment, frequencies of CCR5 expression by CD4+ cells decreased significantly in both compartments (from 3.4% to 0.5% in blood, p = 0.036; and from 42.4% to 5.6% in genital samples, p = 0.025). CONCLUSIONS: The results support the hypothesis that FGS may increase the risk of HIV acquisition, not only through damage of the mucosal epithelial barrier, but also by affecting HIV target cell populations, and that anti-schistosomal treatment can modify this

Deep Learning for Improved Precision and Reproducibility of Left Ventricular Strain in Echocardiography: A Test-Retest Study

Aims: Assessment of left ventricular (LV) function by echocardiography is hampered by modest test-retest reproducibility. A novel artificial intelligence (AI) method based on deep learning provides fully automated measurements of LV global longitudinal strain (GLS) and may improve the clinical utility of echocardiography by reducing user-related variability. The aim of this study was to assess within-patient test-retest reproducibility of LV GLS measured by the novel AI method in repeated echocardiograms recorded by different echocardiographers and to compare the results to manual measurements. Methods: Two test-retest data sets (n = 40 and n = 32) were obtained at separate centers. Repeated recordings were acquired in immediate succession by 2 different echocardiographers at each center. For each data set, 4 readers measured GLS in both recordings using a semiautomatic method to construct test-retest interreader and intrareader scenarios. Agreement, mean absolute difference, and minimal detectable change (MDC) were compared to analyses by AI. In a subset of 10 patients, beat-to-beat variability in 3 cardiac cycles was assessed by 2 readers and AI. Results: Test-retest variability was lower with AI compared with interreader scenarios (data set I: MDC = 3.7 vs 5.5, mean absolute difference = 1.4 vs 2.1, respectively; data set II: MDC = 3.9 vs 5.2, mean absolute difference = 1.6 vs 1.9, respectively; all P < .05). There was bias in GLS measurements in 13 of 24 test-retest interreader scenarios (largest bias, 3.2 strain units). In contrast, there was no bias in measurements by AI. Beat-to-beat MDCs were 1.5, 2.1, and 2.3 for AI and the 2 readers, respectively. Processing time for analyses of GLS by the AI method was 7.9 ± 2.8 seconds. Conclusion: A fast AI method for automated measurements of LV GLS reduced test-retest variability and removed bias between readers in both test-retest data sets. By improving the precision and reproducibility, AI may increase the clinical utility of echocardiography.publishedVersio

The Wireless Tram : Providing Wireless Trondheim/Wi-Fi coverage using mobile WiMAX as backhaul

In spring 2008, a pre-mobile WiMAX network is installed in Trondheim. Its purpose is to cover the tram line and provide wireless backhaul to a Wi-Fi hotspot inside the tram, thus providing Internet access to travelling passengers. Testing is carried out in order to investigate if WiMAX can be used in such scenario. Based on radio propagation modelling, two sectors are initially set up to cover the entire tram line. The WiMAX system operates in the 2.6 GHz band with a bandwidth of 5 MHz. Testing reveals that reception along the first half of the tram line, covered by the first sector, is mostly according to the Okumura-Hata models for open and sub-urban areas. Adequate signal quality for a high grade of service (-80 dBm) is achieved up to 1.5 km from the base station. The second half of the tram line, covered by the second sector, is mostly according to the Okumura-Hata models for sub-urban and urban areas. The coverage provided by the second site is only enough to provide adequate signal quality half a kilometre from the base station. It is concluded that two sectors are not adequate to cover the entire tram line from start to end. The impact of 2nd order diversity is also investigated with respect to signal quality and throughput. Separation in space and by polarisation are both tested. A noticeable increase in average throughput of 50% is measured when using diversity with separation in space. Separation by polarisation yields an average increase of 14% only. Improvements in coverage when using diversity is very small, measured to a few hundred meters. It is noted that the throughput achieved along the tram line varies with the speed of the tram. When standing still, maximum TCP throughput in the downlink is measured to just above 6 Mbps, which is only 70% of the theoretical maximum of 9 Mbps when using an UL/DL ratio of 50/50. While in motion, the TCP throughput seldom rises above 1 Mbps. It is expected that the low throughput in motion is caused by a combination of Doppler effects and the use of an omni-directional antenna on the tram

Global longitudinal strain is a more reproducible measure of left ventricular function than ejection fraction regardless of echocardiographic training

Background: Left ventricular ejection fraction (LVEF) is an established method for evaluation of left ventricular (LV)systolic function. Global longitudinal strain (GLS) by speckle tracking echocardiography seems to be an important additive method for evaluation of LV function with improved reproducibility compared with LVEF. Our aim was to compare reproducibility of GLS and LVEF between an expert and trainee both as echocardiographic examiner and analyst. Methods: Forty-seven patients with recent Acute Coronary Syndrome (ACS) underwent echocardiographic examination by both an expert echocardiographer and a trainee. Both echocardiographers, blinded for clinical data and each other’s findings, performed image analysis for evaluation of intra- and inter- observer variability. GLS was measured using speckle tracking echocardiography. LVEF was calculated by Simpson’s biplane method. Results: The trainee measured a GLS of−19.4% (±3.5%) and expert−18.7% (±3.2%) with an Intra class correlation coefficient (ICC) of 0.89 (0.74–0.95). LVEF by trainee was 50.3% (±8.2%) and by expert 53.6% (±8.6%), ICC coefficient was 0.63 (0.32–0.80). For GLS the systematic difference was 0.21% (−4.58–2.64) vs. 4.08% (−20.78–12.62) for LVEF. Conclusion: GLS is a more reproducible method for evaluation of LV function than LVEF regardless of echocardiographic training

Effect of Female Genital Schistosomiasis and Anti-Schistosomal Treatment on Monocytes, CD4+ T-Cells and CCR5 Expression in the Female Genital Tract

Background Schistosoma haematobium is a waterborne parasite that may cause female genital schistosomiasis (FGS), characterized by genital mucosal lesions. There is clinical and epidemiological evidence for a relationship between FGS and HIV. We investigated the impact of FGS on HIV target cell density and expression of the HIV co-receptor CCR5 in blood and cervical cytobrush samples. Furthermore we evaluated the effect of anti-schistosomal treatment on these cell populations. Design The study followed a case-control design with post treatment follow-up, nested in an on-going field study on FGS. Methods Blood and cervical cytobrush samples were collected from FGS negative and positive women for flow cytometry analyses. Urine samples were investigated for schistosome ova by microscopy and polymerase chain reaction (PCR). Results FGS was associated with a higher frequency of CD14+ cells (monocytes) in blood (11.5% in FGS+ vs. 2.2% in FGS-, p = 0.042). Frequencies of CD4+ cells expressing CCR5 were higher in blood samples from FGS+ than from FGS- women (4.7% vs. 1.5%, p = 0.018). The CD14+ cell population decreased significantly in both compartments after anti-schistosomal treatment (p = 0.043). Although the frequency of CD4+ cells did not change after treatment, frequencies of CCR5 expression by CD4+ cells decreased significantly in both compartments (from 3.4% to 0.5% in blood, p = 0.036; and from 42.4% to 5.6% in genital samples, p = 0.025). Conclusions The results support the hypothesis that FGS may increase the risk of HIV acquisition, not only through damage of the mucosal epithelial barrier, but also by affecting HIV target cell populations, and that anti-schistosomal treatment can modify this

Artificial Intelligence for Automatic Measurement of Left Ventricular Strain in Echocardiography

Objectives This study sought to examine if fully automated measurements of global longitudinal strain (GLS) using a novel motion estimation technology based on deep learning and artificial intelligence (AI) are feasible and comparable with a conventional speckle-tracking application. Background GLS is an important parameter when evaluating left ventricular function. However, analyses of GLS are time consuming and demand expertise, and thus are underused in clinical practice. Methods In this study, 200 patients with a wide range of left ventricle (LV) function were included. Three standard apical cine-loops were analyzed using the AI pipeline. The AI method measured GLS and was compared with a commercially available semiautomatic speckle-tracking software (EchoPAC v202, GE Healthcare. Results The AI method succeeded to both correctly classify all 3 standard apical views and perform timing of cardiac events in 89% of patients. Furthermore, the method successfully performed automatic segmentation, motion estimates, and measurements of GLS in all examinations, across different cardiac pathologies and throughout the spectrum of LV function. GLS was −12.0 ± 4.1% for the AI method and −13.5 ± 5.3% for the reference method. Bias was −1.4 ± 0.3% (95% limits of agreement: 2.3 to −5.1), which is comparable with intervendor studies. The AI method eliminated measurement variability and a complete GLS analysis was processed within 15 s. Conclusions Through the range of LV function this novel AI method succeeds, without any operator input, to automatically identify the 3 standard apical views, perform timing of cardiac events, trace the myocardium, perform motion estimation, and measure GLS. Fully automated measurements based on AI could facilitate the clinical implementation of GLS

Artificial Intelligence for Automatic Measurement of Left Ventricular Strain in Echocardiography

Objectives This study sought to examine if fully automated measurements of global longitudinal strain (GLS) using a novel motion estimation technology based on deep learning and artificial intelligence (AI) are feasible and comparable with a conventional speckle-tracking application. Background GLS is an important parameter when evaluating left ventricular function. However, analyses of GLS are time consuming and demand expertise, and thus are underused in clinical practice. Methods In this study, 200 patients with a wide range of left ventricle (LV) function were included. Three standard apical cine-loops were analyzed using the AI pipeline. The AI method measured GLS and was compared with a commercially available semiautomatic speckle-tracking software (EchoPAC v202, GE Healthcare. Results The AI method succeeded to both correctly classify all 3 standard apical views and perform timing of cardiac events in 89% of patients. Furthermore, the method successfully performed automatic segmentation, motion estimates, and measurements of GLS in all examinations, across different cardiac pathologies and throughout the spectrum of LV function. GLS was −12.0 ± 4.1% for the AI method and −13.5 ± 5.3% for the reference method. Bias was −1.4 ± 0.3% (95% limits of agreement: 2.3 to −5.1), which is comparable with intervendor studies. The AI method eliminated measurement variability and a complete GLS analysis was processed within 15 s. Conclusions Through the range of LV function this novel AI method succeeds, without any operator input, to automatically identify the 3 standard apical views, perform timing of cardiac events, trace the myocardium, perform motion estimation, and measure GLS. Fully automated measurements based on AI could facilitate the clinical implementation of GLS