428 research outputs found

    LITERATURE REVIEW ON ORGANIC MATERIALS FOR THIRD HARMONIC OPTICAL AND PHOTONIC APPLICATIONS

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    The third harmonic optical applications such as optical phase conjugation, image processing, optical switching, and optical limiting in Photonics requires efficient nonlinear optical materials to be used with low power laser beams. During the last three decades, organic molecules have attracted the attention of many researchers due to their high nonlinear optical susceptibility and the possibility of tailoring their properties suitable to be used to protect optical detection components and devices such as human eyes and optical sensors, by controlling the output energy on the image plane below the desired level. Extensive studies have been performed and reported for the case of single crystals of organic molecules, organic molecules in liquid solutions, and organics and organometallics doped in various solid substances. One of the major benefits of organic optical materials is that they are usually much less costly and easier to process in device form than their inorganic materials. In this paper, an extensive literature survey on nonlinear optical materials is depicted. This includes review of organic nonlinear material research, materials for reverse saturation absorption, molecules for two-photon and multi-photon absorption, experimental techniques for nonlinear refraction, nonlinear absorption, optical limiting, and optical phase conjugation. Finally, the review includes the materials used in photonic devices, materials used for optical phase conjugation like nonresonant media and resonant media including absorbing liquid and solid materials, lasing gain media, metal vapors, and photorefractive materials

    Neuro-Fuzzy Based Hybrid Model for Web Usage Mining

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    AbstractWeb Usage mining consists of three main steps: Pre-processing, Knowledge Discovery and Pattern Analysis. The information gained from the analysis can then be used by the website administrators for efficient administration and personalization of their websites and thus the specific needs of specific communities of users can be fulfilled and profit can be increased. Also, Web Usage Mining uncovers the hidden patterns underlying the Web Log Data. These patterns represent user browsing behaviours which can be employed in detecting deviations in user browsing behaviour in web based banking and other applications where data privacy and security is of utmost importance. Proposed work pre-process, discovers and analyses the Web Log Data of Dr. T.M.A.PAI polytechnic website. A neuro-fuzzy based hybrid model is employed for Knowledge Discovery from web logs

    Utility of palliative EUS-guided biliary drainage using lumen-apposing metal stents: a prospective multicenter feasibility study (with video)

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    BACKGROUND AND AIMS: Biliary drainage with ERCP is successful in only 80% to 90% of extrahepatic cholangiocarcinoma and pancreatic cancer. We present the results of a multicenter prospective study assessing the safety, feasibility, and quality of life of patients after EUS-guided biliary drainage (EUS-BD) with lumen-apposing metal stents (LAMSs), after failed ERCP. METHODS: All consecutive adults with a dilated common bile duct (CBD) ≄14 mm secondary to inoperable malignant distal common bile duct (CBD) stricture and failed ERCP biliary drainage were screened and recruited from 3 tertiary U.K. centers. Technical success of EUS-BD using LAMSs was the primary endpoint. Improvement in serum bilirubin, 30-day mortality, procedure-related adverse events, and quality of life were secondary endpoints. The quality of life improvement was measured using a validated questionnaire (EORTC QLQ-BIL21). RESULTS: Twenty patients were included in analysis. EUS-BD was technically successful in all patients and the clinical success was 95% (19/20) at day 7 (>50% reduction in bilirubin) and 92.3% (12/13) at day 30 (bilirubin <50 ÎŒmol/L). There were significant improvements in overall quality of life score (49 vs 42, p=0.03) at day 30. All cause 30-day mortality was 20% and the moderate adverse event rate was 10% (1 cholangitis and 1 stent migration). CONCLUSION: EUS-BD has acceptable technical success and safety as a second line palliative treatment for inoperable malignant distal CBD strictures. Randomized controlled studies comparing EUS-BD with percutaneous transhepatic biliary drainage (PTBD) are needed to determine their effectiveness in clinical practice

    Performance of an electrical distribution network with soft open point during a grid side AC fault

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    Soft Open Point (SOP) is a power electronic device installed in place of normally open points in electrical distribution networks. This paper investigates the dynamic performance of a medium voltage (MV) distribution network with a connected SOP, under grid side AC faults. Use of sequence networks was extended to include SOP, such that conventional fault analysis technique can be used on a distribution network with SOP. A Fault-Index was defined using symmetrical components of voltages measured at the grid connection point of the SOP. The network performance was investigated under a line-to-ground, a line-to-line and a three-phase fault. The behaviour of the network was analysed under different control schemes and various operating scenarios of the SOP. Furthermore, the dependence of the sequence voltages and currents on the SOP set points was investigated. Simulations were carried out on an 11 kV generic UK distribution network model developed in PSCAD/EMTDC. Results show that the convectional fault analysis technique is applicable on a network with SOP, regardless of the SOP control mode. The Fault-Index, defined based on the local voltage measurements, was effective in detecting the presence of an AC fault in the MV distribution network. In addition, the need for a non-current based detection method is illustrated

    How mobile technologies support business models: Case study-based empirical analysis

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    [Otros] Les technologies mobiles ont poussĂ© la connectivitĂ© des systĂšmes informatiques Ă  la limite, permettant aux personnes et aux objets de se connecter les uns aux autres Ă  tout moment. La quantitĂ© d'informations dont disposent les entreprises a augmentĂ© de façon exponentielle, en grande partie grĂące Ă  la gĂ©olocalisation et Ă  la vaste gamme de capteurs intĂ©grĂ©s dans les appareils mobiles. Ces informations peuvent ĂȘtre utilisĂ©es pour amĂ©liorer les activitĂ©s et les processus mĂ©tier, mais Ă©galement pour crĂ©er de nouveaux modĂšles d'affaires. En nous concentrant sur les modĂšles d'affaires, nous analysons les technologies mobiles comme catalyseurs des changements d'activitĂ©. Nous examinons les caractĂ©ristiques distinctives des technologies mobiles et examinons comment cellesÂżci peuvent supporter diffĂ©rentes fonctions de l'entreprise. Une Ă©tude basĂ©e sur une analyse qualitative comparĂ©e d'ensemble floue (fsQCA) de 30 cas, de diffĂ©rents secteurs, a permis d'identifier les facteurs de succĂšs de la technologie mobile pour diffĂ©rentes activitĂ©s du cƓur de mĂ©tier des firmes. Les rĂ©sultats montrent que plusieurs combinaisons de technologie mobile procurent un avantage concurrentiel lorsqu'elles correspondent au modĂšle d'affaire.[EN] Mobile technologies have pushed the connectivity of IT systems to the limit, enabling people and things to connect to one another at all times. The amount of information companies have at their disposal has increased exponentially, thanks largely to geolocation and to the vast array of sensors that have been integrated into mobile devices. This information can be used to enhance business activities and processes, but it can also be used to create new business models. Focusing on business models, we analyze mobile technologies as enablers of activity changes. We consider the differentiating characteristics of mobile technologies and examine how these can support different business functions. A study based on fuzzy-set qualitative comparative analysis (fsQCA) of 30 cases across different industries allows us to identify mobile technology success factors for different core activities. The results show that several combinations of mobile technology initiatives provide a competitive advantage when these initiatives match the business model.Peris-Ortiz, M.; Devece Carañana, CA.; Hikkerova, L. (2020). How mobile technologies support business models: Case study-based empirical analysis. Canadian Journal of Administrative Sciences / Revue Canadienne des Sciences de l Administration. 37(1):95-105. https://doi.org/10.1002/cjas.1550S95105371Al-Debei, M. M., & Avison, D. (2010). Developing a unified framework of the business model concept. 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Information Technology and Management, 9(3), 215-232. doi:10.1007/s10799-008-0040-3Liang, T., Huang, C., Yeh, Y., & Lin, B. (2007). Adoption of mobile technology in business: a fit‐viability model. Industrial Management & Data Systems, 107(8), 1154-1169. doi:10.1108/02635570710822796Martinez-Simarro, D., Devece, C., & Llopis-Albert, C. (2015). How information systems strategy moderates the relationship between business strategy and performance. Journal of Business Research, 68(7), 1592-1594. doi:10.1016/j.jbusres.2015.01.057Mello P.A.(2012).A critical review of applications in QCA and fuzzy‐set analysis and a ‘toolbox' of proven solutions to frequently encountered problems APSA Annual Meeting Paper. Retrieved fromhttps://ssrn.com/abstract=2105539Melville, Kraemer, & Gurbaxani. (2004). Review: Information Technology and Organizational Performance: An Integrative Model of IT Business Value. MIS Quarterly, 28(2), 283. doi:10.2307/25148636Ngai, E. W. T., & Gunasekaran, A. (2007). Mobile commerce: Strategies, technologies, and applications. Decision Support Systems, 43(1), 1-2. doi:10.1016/j.dss.2005.05.002Palattella, M. R., Dohler, M., Grieco, A., Rizzo, G., Torsner, J., Engel, T., & Ladid, L. (2016). Internet of Things in the 5G Era: Enablers, Architecture, and Business Models. IEEE Journal on Selected Areas in Communications, 34(3), 510-527. doi:10.1109/jsac.2016.2525418Pateli, A. G., & Giaglis, G. M. (2005). Technology innovation‐induced business model change: a contingency approach. Journal of Organizational Change Management, 18(2), 167-183. doi:10.1108/09534810510589589Piccoli, & Ives. (2005). Review: IT-Dependent Strategic Initiatives and Sustained Competitive Advantage: A Review and Synthesis of the Literature. MIS Quarterly, 29(4), 747. doi:10.2307/25148708Porter M. E.(2001).Strategy and the Internet. Harvard Business Review March 63–78.Ragin C. C.(2008).User's Guide to Fuzzy‐Set/Qualitative Comparative Analysis. Working Paper University of Arizona Arizona.Ray, G., Barney, J. B., & Muhanna, W. A. (2003). Capabilities, business processes, and competitive advantage: choosing the dependent variable in empirical tests of the resource-based view. Strategic Management Journal, 25(1), 23-37. doi:10.1002/smj.366Richter, C., Kraus, S., & SyrjĂ€, P. (2015). The shareconomy as a precursor for digital entrepreneurship business models. International Journal of Entrepreneurship and Small Business, 25(1), 18. doi:10.1504/ijesb.2015.068773Schneider, M. R., Schulze-Bentrop, C., & Paunescu, M. (2009). Mapping the institutional capital of high-tech firms: A fuzzy-set analysis of capitalist variety and export performance. Journal of International Business Studies, 41(2), 246-266. doi:10.1057/jibs.2009.36Sheng, H., Nah, F. F.-H., & Siau, K. (2005). Strategic implications of mobile technology: A case study using Value-Focused Thinking. The Journal of Strategic Information Systems, 14(3), 269-290. doi:10.1016/j.jsis.2005.07.004Sorescu, A. (2017). Data-Driven Business Model Innovation. Journal of Product Innovation Management, 34(5), 691-696. doi:10.1111/jpim.12398Tallon, P. P. (2007). A Process-Oriented Perspective on the Alignment of Information Technology and Business Strategy. Journal of Management Information Systems, 24(3), 227-268. doi:10.2753/mis0742-1222240308Tjaden, G. S. (1996). Measuring the information age business. Technology Analysis & Strategic Management, 8(3), 233-246. doi:10.1080/09537329608524248Vilmos A. Kovacs K. &Kutor L. (2007).NFC applications and business model of the ecosystem(pp.1469–1473) 16th IST Mobile and Wireless Communications Summit Budapest Hungary. doi:https://doi.org/10.1109/ISTMWC.2007.4299324.Wirtz, B. W., Schilke, O., & Ullrich, S. (2010). Strategic Development of Business Models. 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    Health-related Quality of Life in Patients With Nonalcoholic Fatty Liver Disease: A Prospective Multi-center UK Study

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    BACKGROUND & AIMS: It is unclear whether health-related quality of life (HRQoL) is impaired in patients with nonalcoholic fatty liver disease (NAFLD) without advanced fibrosis and how this compares with the general population. We aimed to assess HRQoL in patients with NAFLD in comparison to the general population and any associations of fibrosis severity and metabolic comorbidities with impairments in HRQoL. METHODS: We prospectively enrolled 513 consecutive patients with NAFLD who completed the EuroQol 5-dimensional questionnaire (EQ-5D) and Chronic Liver Disease Questionnaires (CLDQ). Demographic and clinical information, liver biopsy results, and/or liver stiffness (LS) by transient elastography were recorded. A general population sub-cohort of the Health Survey for England 2018 was used as a comparator (n = 5483), and a 1:1 propensity-score (PS) matching was performed, according to age, sex, body mass index, and type 2 diabetes mellitus (T2DM). RESULTS: EQ-5D-5L utility was significantly lower in 466 PS-matched patients with NAFLD compared with PS-matched controls (0.77 ± 0.27 vs 0.84 ± 0.19; P < .001), even in those without advanced fibrosis (F ≀2 or LS <8kPa) (0.80 ± 0.24 vs 0.84 ± 0.19; P = .024). HRQoL measures (EQ-5D-5L, EQ-VAS, CLDQ) did not differ between patients with NAFLD with and without advanced fibrosis. LS was independently associated with lower EQ-5D-5L in all patients with NAFLD but not in those without advanced fibrosis. In the latter, lower EQ-5D-5L was associated with female sex, T2DM, and depression. CONCLUSIONS: Patients with NAFLD, even those without advanced fibrosis, have worse HRQoL compared with the general population. In patients with NAFLD without advanced fibrosis, HRQoL is independently associated with non-liver comorbidities but not LS. Multi-disciplinary management is therefore required in NAFLD, irrespective of fibrosis severity

    Classifying the unclassifiable – A Delphi study to reach consensus on the fibrotic nature of diseases

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    Background Traditionally, clinical research has focused on individual fibrotic diseases or fibrosis in a particular organ. However, it is possible for people to have multiple fibrotic diseases. While multi-organ fibrosis may suggest shared pathogenic mechanisms, yet there is no consensus on what constitutes a fibrotic disease and therefore fibrotic multimorbidity. Aim A Delphi study was performed to reach consensus on which diseases may be described as fibrotic. Methods Participants were asked to rate a list of diseases, sub-grouped according to eight body regions, as ‘fibrotic manifestation always present’, ‘can develop fibrotic manifestations’, ‘associated with fibrotic manifestations’ or ‘not fibrotic nor associated’. Classifications of ‘fibrotic manifestation always present’ and ‘can develop fibrotic manifestations’ were merged and termed ‘fibrotic’. Clinical consensus was defined according to the interquartile range, having met a minimum number of responses. Clinical agreement was used for classification where diseases did not meet the minimum number of responses (required for consensus measure), were only classified if there was 100% consensus on disease classification. Results After consulting experts, searching the literature and coding dictionaries, a total of 323 non-overlapping diseases which might be considered fibrotic were identified; 92 clinical specialists responded to the first round of the survey. Over three survey rounds, 240 diseases were categorized as fibrotic via clinical consensus and 25 additional diseases through clinical agreement. Conclusion Using a robust methodology, an extensive list of diseases was classified. The findings lay the foundations for studies estimating the burden of fibrotic multimorbidity, as well as investigating shared mechanisms and therapies

    Economic evaluation of covered stents for transjugular intrahepatic portosystemic stent shunt in patients with variceal bleeding and refractory ascites secondary to cirrhosis

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    Objectives: Transjugular intrahepatic portosystemic stent shunt (TIPSS) is clinically effective in variceal bleeding and refractory ascites; however, the cost-effectiveness of TIPSS has yet to be evaluated in the UK. This study aimed to establish the cost-effectiveness of (i) pre-emptive TIPSS versus endoscopic band ligation (EBL) in populations with variceal bleeding and (ii) TIPSS versus large volume paracentesis (LVP) in refractory ascites. Methods: A cost-utility analysis was conducted with the perspective including healthcare costs and quality-adjusted life years (QALYs). A Markov model was constructed with a 2-year time horizon, health states for mortality and survival and probabilities for the development of variceal bleeding, ascites and hepatic encephalopathy. A survival analysis was conducted to extrapolate 12-month to 24-month mortality for the refractory ascites indication. Uncertainty was analysed in deterministic and probabilistic sensitivity analyses. Results: TIPSS was cost-effective (dominant) and cost saving for both indications. For variceal bleeding, pre-emptive TIPSS resulted in 0.209 additional QALYs, and saved £600 per patient compared with EBL. TIPSS had a very high probability of being cost-effective (95%) but was not cost saving in scenario analyses driven by rates of variceal rebleeding. For refractory ascites, TIPSS resulted in 0.526 additional QALYs and saved £17 983 per patient and had a 100% probability of being cost-effective and cost saving when compared with LVP. Conclusions: TIPSS is a cost-effective intervention for variceal bleeding and refractory ascites. TIPSS is highly cost-saving for refractory ascites. Robust randomised trial data are required to confirm whether pre-emptive TIPSS is cost saving for variceal bleeding

    Multicenter experience from the UK and Ireland of use of lumen-apposing metal stent for transluminal drainage of pancreatic fluid collections

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    Background and study aims: Pancreatic fluid collection (PFC) is a common complication of pancreatitis for which endoscopic ultrasound-guided drainage is first-line treatment. A new single-device, lumen-apposing, covered self-expanding metal stent (LAMS) has been licensed for PFC drainage. We therefore present our multicenter experience with the LAMS for PFC drainage in a multicenter prospective case series to assess success and complication rates. Patients and methods: All adult patients from 11 tertiary centers who had LAMS placement for PFC from July 2015 to July 2016 were included. Data including indications, technical success, clinical success, collection resolution, stent removal, early and late adverse events (AEs), mortality and recurrence at 6 months were collected. Results: 116 patients, median age 52.5 years (range 16 – 80) and 67 % male, were treated with a single LAMS in each case. The indication was walled off necrosis (WON) in 70 and pseudocyst in 46. Median size of the PFC was 11 cm (5 – 21 cm) and the estimated median necrotic volume in WON was 30 % (5 % – 90 %). Stent insertion was technically successful in 115 (99.1 %) and clinically successful in 109 (94 %). Early serious AEs (SAEs): n = 7 sepsis, n = 1 stent blockage with food, n = 1 stent migration requiring laparotomy, n = 1 stent dislodgement and n = 1 bleeding requiring emboliZation. Late AEs: n = 1 buried stent and n = 1 esophageal fistula. Non-procedure-related deaths: n = 3 (2.5 %). Conclusion: This multicenter case series demonstrates that use of the new LAMS is feasible, effective and relatively safe in draining PFC with a technical success rate of 99 % and cumulative SAE rate of 11.2 %

    What is the incidence of methotrexate or leflunomide discontinuation related to cytopenia, liver enzyme elevation or kidney function decline?

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    OBJECTIVES: To examine incidence of treatment changes due to abnormal blood-test results and, to explore rates of treatment changes due to liver, kidney and haematological blood-test abnormalities in autoimmune rheumatic diseases (AIRD) treated with low-dose methotrexate or leflunomide. METHODS: Data for people with AIRDs prescribed methotrexate or leflunomide were extracted from the Clinical Practice Research Datalink. Participants were followed-up from first prescription of methotrexate or leflunomide in primary-care. Primary outcome of interest was drug discontinuation, defined as a prescription gap of ≄ 90 days following an abnormal (or severely abnormal) blood-test result. Dose reduction was examined between consecutive prescriptions. Incidence rates per 1,000 person-years were calculated. RESULTS: 15,670 and 2,689 participants contributing 46,571 and 4,558 person-years follow-up were included in methotrexate and leflunomide cohorts respectively. The incidence of methotrexate and leflunomide discontinuation with abnormal (severely abnormal) blood-test was 42.24(6.16) and 106.53(9.42)/1,000 person-years in year-1, and 22.44(2.84) and 31.69(4.40)/1,000 person-years respectively thereafter. The cumulative incidence of methotrexate and leflunomide discontinuation with abnormal (severely abnormal) blood-tests was 1 in 24(1 in 169), 1 in 9(1 in 106) at 1-year; and 1 in 45(1 in 352), 1 in 32(1 in 227) per-year respectively thereafter. Raised liver enzymes were the commonest abnormality associated with drug discontinuation. Methotrexate and leflunomide dose reduction incidence were comparable in year-1, however, thereafter methotrexate dose was reduced more often than leflunomide (16.60(95% CI; 13.05-21.13) vs. 8.10(95% CI; 4.97-13.20)/1,000 person-years). CONCLUSION: Methotrexate and leflunomide were discontinued for blood-test abnormalities after year-1 of treatment, however, discontinuations for severely abnormal results were uncommon
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