35 research outputs found
Demographic and clinical characteristics of patients with sustained and switching treatments using biological and targeted synthetic disease-modifying antirheumatic drugs: A multicenter, observational cross-sectional study for rheumatoid arthritis
Introduction Rheumatoid arthritis is a chronic inflammatory disease with different disease activity grades. Several registries have been designed to determine the appropriate regimens of disease-modifying antirheumatic drugs to obtain sustained clinical remission. We examined epidemiological and clinical characteristics of rheumatoid arthritis patients using a clinical registry database (BioSTaR) and analyzed the differences in patients with sustained and switched therapies. Methods A multicenter, observational cross-sectional study for rheumatoid arthritis was performed between February 2019 and September 2020 using the BioStaR-RA registry. Demographic and clinical characteristics were prospectively recorded into a specifically designed electronic database. The patients were divided into three groups due to the heterogeneity of the study cohort. Patients were grouped as Group I (Initial; within the first 6 months of treatment with biological/targeted synthetic drugs), Group ST (Sustained Treatment; any first drug lasting for at least 6 months without any change), and Group S (Switch; any switching to another drug). Comparative analysis was performed between sustained treatment (Group ST) and drug switching (Group S) groups. Results The study included a total of 565 patients. The mean age was 53.7 +/- 12.8 years, and the majority were female (80.4%). There were 104, 267, and 194 patients in Groups I, ST, and S, respectively. Erosive arthritis and hematological extra-articular involvement were more frequently detected in Group S than Group ST (p = 0.009 and p = 0.001). The patients in Group S had significantly higher disease activity scores (DAS28-CRP, CDAI, and SDAI) (p = 0.025, p = 0.010, and p = 0.003). There were significantly more patients with moderate disease activity in Group S (p < 0.05). Conclusions The groups with sustained treatment and switching included patients with different disease activity status, although higher disease activity was determined in switchers. Overall, moderate disease activity and remission were the most common disease activity levels. Lower disease activity scores, lower hematologic manifestations, better functional status, and lesser radiographic damage are associated with sustained treatment.Turkish Medicine and Medical Devices Agency ; Ankara Numune Egitim ve Arastirma Hastanes
Pravděpodobnostní nelineární výpočtová mechanika pro predikci mechanické odezvy konstrukcí
The effect of inherent uncertainties in material properties on the global response of substandard reinforced concrete (RC) structural members was investigated by the stochastic study. An experimentally validated finite element model (FEM) was, therefore, combined with a suitable stochastic sampling technique (Latin Hypercube Sampling (LHS)). Then, the effect of inherent uncertainties on the material mechanical properties was studied by uncertainty analysis, while the uneven distribution of concrete mechanical properties over the specimen was accurately characterized by random fields theory. The partial correlation coefficient between material parameters and response variables was also evaluated to outline the parameters which mainly contribute to the global response (i.e., sensitivity analysis). Such an advanced modelling strategy was implemented on three different testing programs comprising RC members designed with structural details and material properties non-conforming to current codes and guidelines. The first testing program deals with experimental performance of an over-reinforced and shear critical beams together with stochastic assessments of beam members via computational stochastic mechanics. The effect of uncertainties on the response of shear critical and carbon fiber reinforced polymer (CFRP) retrofitted beam-column joints, which were selected from available testing programs in the literature, was also discussed. The stochastic-based numerical prediction of beam-type RILEM bond specimens characterized variability in the identical tests satisfactorily. Owing to the more realistic assessment capability of the stochastic-based nonlinear finite element (FE) analysis, the global response of the substandard RC members (over-reinforced and shear critical beams; shear critical and CFRP retrofitted beam-column joints; beam-type RILEM bond specimens) was accurately reproduced.Práce studuje vliv nejistot materiálových vlastností na mechanickou odezvu (poddimenzovaných) prvků železobetonových konstrukcí, který je vyšetřovaný pomocí stochastického přístupu s využitím experimentálně validovaných MKP modelů a vhodné simulační metody (LHS). Ve vybraných případech byl také aplikován koncept náhodných polí pro simulaci rozložení mechanických vlastností betonu ve studovaných konstrukčních prvcích. Součástí jednotlivých studií je také citlivostní analýza. Nastíněný přístup je aplikován na tři vybrané konstrukční železobetonové prvky, které nesplňují aktuální normové předpisy (nedostatečné vyztužení či nízké hodnoty materiálových vlastností užitých betonů), ovšem jejichž výskyt byl v hojné míře prokázán v mnoha zemích. Prvním příkladem je nosník s nedostatečnou smykovou výztuží. Zaznamenané chování/poškození nosníku je také porovnáno s dostatečně vyztuženým, resp. předimenzovaným nosníkem. Druhý případ představuje poddimenzovaný styk sloupu a průvlaku namáhaný cyklickým zatížením, přičemž jsou zkoumány i možnosti sanace pomocí externích polymerních lamel na bázi uhlíkových vláken. Třetí vyšetřovaný případ představuje soubor experimentů a numerických modelů zaměřených na stanovení soudržnosti výztuže a betonu dle postupu RILEM. Ve všech popsaných případech je výsledná odezva studována experimentálně i numericky, přičemž stochastický přístup dobře postihuje reálné chování vyšetřovaných prvků.Dopravní fakulta Jana PerneraDokončená práce s úspěšnou obhajobo
Měření vertikální kolové síly na kolejnici
The efficiency of the proposed method, which measures the wheel force by using strain gauges installed on the rail, is investigated. Five full-scale tests were conducted in the maintenance center of CZ LOKO, Česká Třebová, Czech Republic. Six strain gauges (three active, three dummy) in each rail were installed in the half Wheatstone bridge configuration so that the wheel force can be calculated by the measured strain. While one active strain gauge was placed in the middle of the bottom flange of rail, two of the active strain gauges were mounted symmetrically to each other on the edges of the bottom flange. The optimal places of the strain gauges were determined by finite element analysis. Besides, both force and lateral shift dependence of the presented method were investigated with an experimentally validated finite element model. Two parametric equations corresponding to the results of finite element method are proposed. Moreover, two more equations were derived by means of a conventional method, which is an experimental calibration method. These equations are used to predict the wheel vertical force regardless from any lateral effect. All the results obtained from the equations were matched quantitively well with the measured mass in the weighing device.Tato práce se zaměřuje na zjištění schopnosti navrhované metody měření kolové síly pomocí tenzometrů umístěných na kolejnici. Za tímto účelem bylo provedeno pět experimentů ve firmě CZ LOKO v České Třebové. Šest foliových tenzometrů na každé kolejnici (tři aktivní, tři kompenzační) bylo nainstalováno a zapojeno do polovičních Wheatstoneových můstků tak, aby bylo možné vypočítat kolovou sílu z měřených deformací. Vždy jeden aktivní tenzometr byl umístěn na spodní straně paty kolejnice uprostřed, zbývající dva tenzometry byly instalovány také na spodní straně paty kolejnice, avšak symetricky a blíže k hranám paty kolejnice. Nejvhodnější pozice pro umístění tenzometrů byly určeny pomocí metody konečných prvků (MKP). Kromě toho byl zkoumán vliv zatěžující síly a příčné polohy kola na kolejnici na výsledky navrhované metody s využitím validovaného konečně-prvkového modelu koleje. Výsledkem analýzy zatěžování kolejnic metodou konečných prvků byl návrh dvou parametrických rovnic. Navíc, další dvě rovnice byly odvozené za pomoci experimentální kalibrační metody. Tyto rovnice jsou použity k určení svislé kolové síly bez ohledu na jakýkoli efekt v příčném směru. Veškeré výsledky získané z těchto rovnic se kvantitativně dobře shodují směřenými kolovými silami na kolové váze.Katedra dopravních prostředků a diagnostikyStudent přednesl obhajobu své diplomové práce a vyčerpávajícím způsobem zodpověděl dotazy z oponentního posudku
Yüksek sıcaklıkta çalışan proton geçiren zarlı yakıt pilleri için asit yüklü polibenzimidazol zarlar.
Acid Doped Polybenzimidazole Membranes for High Temperature Proton Exchange Membrane Fuel Cells Author: Ahmet Özgür Yurdakul One of the most popular candidates for high temperature PEMFC’s is phosphoric acid doped polybenzimidazole (PBI) membrane due to its thermal and mechanical stability. In this study, high molecular weight PBI was synthesized by using PPA polymerization. The stirring rate of reaction solution was optimized to obtain high molecular weight. The inherent viscosity of polymer was measured at four points in 96 percent sulphuric acid solution at 30 degree centigrade by using an Ubbelohde viscometer. The highest average molecular weight was found as approximately 120,000 using the Mark-Houwink equation. The polymer was dissolved in N,N-dimethylacetamide at 70 degree centigrade with an ultrasonic stirrer. The membranes cast from this solution were doped with phosphoric acid solutions at different concentrations. The doping levels of the membranes were 6, 8, 10 and 11 moles phosphoric acid/PBI repeat unit. The mechanical strength of the acid doped membranes measured by tensile tests were found as 23, 16, 12 and 11 MPa, respectively. Conductivity measurements were made using the four probe technique. The membranes were placed in a conductivity cell and measurements were taken in humidity chamber with temperature and pressure control. The conductivity of membranes was measured at 110, 130 and 150 degree centigrade in both dry air and water vapor. The highest conductivity was 0.12 S/cm at 150 degree centigrade and 33 percent relative humidity for the membrane doped with 11 moles of H3PO4. The measurements showed that conductivity increased with increasing doping and humidity. Moreover, membranes had acceptable conductivity levels in dry air.M.S. - Master of Scienc
Strengthening of substandard reinforced concrete beam-column joints by external post-tension rods
The efficiency of the proposed strengthening method using externally applied post-tension rods in reinforced concrete external beam-column joints, which do not comply with any code requirements, is investigated. Five full-scale specimens were tested in the laboratory. They have specific deficiencies resulting from the lack of shear reinforcement in the joint and poor material properties including low strength concrete and the presence of plain round reinforcement bars. While all specimens were built with column and in plane beam, one of the tested specimens consists of a transverse beam to demonstrate the applicability of the presented retrofit technique. All specimens were subjected to a cyclic quasi-static loading up to 8% drift ratio to observe different levels of structural damage. Two post-tension rods, which were mounted diagonally at each side of the joint, are utilized as a local retrofit technique. The reference specimen displayed a brittle behavior with the concentration of shear cracks mostly in the joint while the rest of the RC components were almost in their elastic range. The ultimate lateral load capacity was increased considerably for all retrofitted specimens. However, a brittle type of failure mechanism was observed such as a joint shear failure or beam-joint failure in the three retrofitted specimens. A relatively ductile response was observed in the specimen with transverse beam, although the axial force in the post-tension rods was the same with the specimens without transverse beam. After testing all specimens, it is found that the lateral force capacities of the beam-column assemblies can be improved up to code requirements by the proposed retrofitting method.The efficiency of the proposed strengthening method using externally applied post-tension rods in reinforced concrete external beam-column joints, which do not comply with any code requirements, is investigated. Five full-scale specimens were tested in the laboratory. They have specific deficiencies resulting from the lack of shear reinforcement in the joint and poor material properties including low strength concrete and the presence of plain round reinforcement bars. While all specimens were built with column and in plane beam, one of the tested specimens consists of a transverse beam to demonstrate the applicability of the presented retrofit technique. All specimens were subjected to a cyclic quasi-static loading up to 8% drift ratio to observe different levels of structural damage. Two post-tension rods, which were mounted diagonally at each side of the joint, are utilized as a local retrofit technique. The reference specimen displayed a brittle behavior with the concentration of shear cracks mostly in the joint while the rest of the RC components were almost in their elastic range. The ultimate lateral load capacity was increased considerably for all retrofitted specimens. However, a brittle type of failure mechanism was observed such as a joint shear failure or beam-joint failure in the three retrofitted specimens. A relatively ductile response was observed in the specimen with transverse beam, although the axial force in the post-tension rods was the same with the specimens without transverse beam. After testing all specimens, it is found that the lateral force capacities of the beam-column assemblies can be improved up to code requirements by the proposed retrofitting method
Reliability analysis of a shear-critical beam
The response of a reinforced concrete beam constructed without transverse reinforcement to achieve shear failure was investigated by experimental and numerical methods. Due to inherent uncertainties in material constitutive models, a nonlinear finite element method (FEM) was combined with a suitable stochastic sampling technique to propose a more advanced model for estimating the response of a shear-critical beam. For this purpose, the specimen was first tested under monotonic loading up to shear failure by a four-point bending test. Then, the stochastic model was developed by using Latin Hypercube Sampling (LHS) including statistical correlation among the prominent material parameters. Random parameters of concrete and reinforcement steel were defined in accordance with the material test results and code recommendations. The constituent outcomes of the stochastic model including a set of load-displacement curves are presented. The results of the stochastic approach matched well with the behavior of the specimen observed during the experimental test. The probability density function for ultimate load was obtained. After that, the reliability of the member for the ultimate limit state was compared with the code requirements to ensure the safe loading range. The design load, which corresponds the failure probability related to ultimate limit state was computed. Moreover, a simplified ECOV (Estimation of Coefficient of Variation) method was carried out to estimate the design load. It is found that the load obtained from reliability analyses for design load was reasonably in good agreement with the code recommended value.The response of a reinforced concrete beam constructed without transverse reinforcement to achieve shear failure was investigated by experimental and numerical methods. Due to inherent uncertainties in material constitutive models, a nonlinear finite element method (FEM) was combined with a suitable stochastic sampling technique to propose a more advanced model for estimating the response of a shear-critical beam. For this purpose, the specimen was first tested under monotonic loading up to shear failure by a four-point bending test. Then, the stochastic model was developed by using Latin Hypercube Sampling (LHS) including statistical correlation among the prominent material parameters. Random parameters of concrete and reinforcement steel were defined in accordance with the material test results and code recommendations. The constituent outcomes of the stochastic model including a set of load-displacement curves are presented. The results of the stochastic approach matched well with the behavior of the specimen observed during the experimental test. The probability density function for ultimate load was obtained. After that, the reliability of the member for the ultimate limit state was compared with the code requirements to ensure the safe loading range. The design load, which corresponds the failure probability related to ultimate limit state was computed. Moreover, a simplified ECOV (Estimation of Coefficient of Variation) method was carried out to estimate the design load. It is found that the load obtained from reliability analyses for design load was reasonably in good agreement with the code recommended value
The ‘Arab Clans’ Discourse: Narrating Racialization, Kinship, and Crime in the German Media
In the last decade’s media discourse, particular Arab immigrant groups received the name ‘Arab clans’ and have been portrayed as criminal kinship networks irrespective of actual involvement in crime. We question how ‘Arab clans’ are categorized, criminalized, and racialized in the German media. To answer this question, we collected clan-related mainstream media articles published between 2010 and 2020. Our first-step quantitative topic modeling of ‘clan’ coverage (n = 23,893) shows that the discourse about ‘Arab clans’ is situated as the most racialized and criminalized vis-à-vis other ‘clan’ discourses and is channeled through three macro topics: law and order, family and kinship, and criminal groupness. Second, to explore the deeper meaning of the discourse about ‘Arab clans’ by juxtaposing corpus linguistics and novel narrative approaches to the discourse-historical approach, we qualitatively analyzed 97 text passages extracted with the keywords in context search (KWIC). Our analysis reveals three prevalent argumentative strategies (Arab clan immigration out of control, Arab clans as enclaves, policing Arab clans) embedded in a media narrative of ethnonational rebirth: a story of Germany’s present-day need (‘moral panic’) to police and repel the threats associated with ‘the Arab clan Other’ in order for a celebratory return to a nostalgically idealized pre-Arab-immigration social/moral order.Peer Reviewe
The ‘Arab Clans’ Discourse: Narrating Racialization, Kinship, and Crime in the German Media
In the last decade’s media discourse, particular Arab immigrant groups received the name ‘Arab clans’ and have been portrayed as criminal kinship networks irrespective of actual involvement in crime. We question how ‘Arab clans’ are categorized, criminalized, and racialized in the German media. To answer this question, we collected clan-related mainstream media articles published between 2010 and 2020. Our first-step quantitative topic modeling of ‘clan’ coverage (n = 23,893) shows that the discourse about ‘Arab clans’ is situated as the most racialized and criminalized vis-à-vis other ‘clan’ discourses and is channeled through three macro topics: law and order, family and kinship, and criminal groupness. Second, to explore the deeper meaning of the discourse about ‘Arab clans’ by juxtaposing corpus linguistics and novel narrative approaches to the discourse-historical approach, we qualitatively analyzed 97 text passages extracted with the keywords in context search (KWIC). Our analysis reveals three prevalent argumentative strategies (Arab clan immigration out of control, Arab clans as enclaves, policing Arab clans) embedded in a media narrative of ethnonational rebirth: a story of Germany’s present-day need (‘moral panic’) to police and repel the threats associated with ‘the Arab clan Other’ in order for a celebratory return to a nostalgically idealized pre-Arab-immigration social/moral order
Retrofit of non-seismically designed beam-column joints by post-tensioned superelastic shape memory alloy bars
A series of tests on three full-scale substandard exterior beam-column joints were performed to investigate the efficiency of the proposed retrofit configuration, which is the use of externally applied post-tensioned shape memory alloy (SMA) bars. A major group of structural deficiencies resulting from lack of shear reinforcement in the joint, use of low strength concrete and plain round bars were taken into account in the construction of test specimens. While the reference specimen represents the as-built subassembly, the other two were retrofitted by the post-tensioned SMA and steel bars to compare the contribution of superelastic and conventional material on the response. The specimens were exposed to quasi-static cyclic loading up to 8% drift ratio to simulate an intensive level of seismic hazard. The reference specimen underwent a brittle shear failure as excessive cracks mostly concentrated in the joint panel while there was almost no damage in the rest of the RC components. A joint failure with enhanced response quantities was observed in the specimen retrofitted by post-tensioned steel bars. The specimen incorporating the retrofit solution via post-tensioned SMA bars was capable of performing an adequate performance and promoting minimization of the damage in the joint panel, which results in more ductile behavior. The hysteretic response of the SMA retrofitted specimen was validated with a refined numerical model in ATENA Science software. Experimentally observed response was also verified by an analytical model based on fracture mechanics considering the nonlinear behavior of plain concrete under tension. Due to inherent uncertainties in material constitutive laws, the analytical model was evolved to a stochastic level to propose a more advanced model for estimating the capacity of the reference and retrofitted joint. It is found that the experimental results were within the prominent range of Probability Density Functions (i.e. mean +/- 1 SD) of the estimated joint tensile stress especially for the shear damaged specimens.A series of tests on three full-scale substandard exterior beam-column joints were performed to investigate the efficiency of the proposed retrofit configuration, which is the use of externally applied post-tensioned shape memory alloy (SMA) bars. A major group of structural deficiencies resulting from lack of shear reinforcement in the joint, use of low strength concrete and plain round bars were taken into account in the construction of test specimens. While the reference specimen represents the as-built subassembly, the other two were retrofitted by the post-tensioned SMA and steel bars to compare the contribution of superelastic and conventional material on the response. The specimens were exposed to quasi-static cyclic loading up to 8% drift ratio to simulate an intensive level of seismic hazard. The reference specimen underwent a brittle shear failure as excessive cracks mostly concentrated in the joint panel while there was almost no damage in the rest of the RC components. A joint failure with enhanced response quantities was observed in the specimen retrofitted by post-tensioned steel bars. The specimen incorporating the retrofit solution via post-tensioned SMA bars was capable of performing an adequate performance and promoting minimization of the damage in the joint panel, which results in more ductile behavior. The hysteretic response of the SMA retrofitted specimen was validated with a refined numerical model in ATENA Science software. Experimentally observed response was also verified by an analytical model based on fracture mechanics considering the nonlinear behavior of plain concrete under tension. Due to inherent uncertainties in material constitutive laws, the analytical model was evolved to a stochastic level to propose a more advanced model for estimating the capacity of the reference and retrofitted joint. It is found that the experimental results were within the prominent range of Probability Density Functions (i.e. mean +/- 1 SD) of the estimated joint tensile stress especially for the shear damaged specimens
Stochastic assessment of concrete core strength in fire exposed specimens simulating non-engineered RC structures in Turkey
The spatial variability of concrete compressive strength over the specific region is simulated by the stochastic approach. The compressive strength of cores taken from fire-exposed beams simulating non-engineered structures in Turkey is obtained. Therefore, improper mix-design and low strength concrete are targeted. Then, the uneven distribution of the concrete compressive strength along the fire exposed specimens is handled by the random fields approach. Thus, the adverse effect of the fire is not only established by the compressive test results but also the scatter in the core results is estimated by the stochastic method. The stochastic model accounting for the scatter in the core results is generated from the given distribution and mean cylindrical compressive strength values. The concrete compressive strength is not distributed evenly but established stronger and weaker regions over the specimen in the stochastic models. The statistical samples are generated by the Monte Carlo-type stratified sampling method, which is Latin Hypercube Sampling (LHS). A total of 500 random samples closely predicts the scatter in the compressive strength at each temperature level with a range of 25 & ndash;700 degrees C. The variability at different geometrical positions on the fire-exposed beam specimens with low strength concrete is characterized as well. Overall, the experimentally observed uncertainties arising from uneven distribution of concrete compressive strength over the fire-exposed beams simulating non-engineered structures in Turkey are accurately reproduced by the random fields approach. (c) 2021 Elsevier Ltd. All rights reserved.The spatial variability of concrete compressive strength over the specific region is simulated by the stochastic approach. The compressive strength of cores taken from fire-exposed beams simulating non-engineered structures in Turkey is obtained. Therefore, improper mix-design and low strength concrete are targeted. Then, the uneven distribution of the concrete compressive strength along the fire exposed specimens is handled by the random fields approach. Thus, the adverse effect of the fire is not only established by the compressive test results but also the scatter in the core results is estimated by the stochastic method. The stochastic model accounting for the scatter in the core results is generated from the given distribution and mean cylindrical compressive strength values. The concrete compressive strength is not distributed evenly but established stronger and weaker regions over the specimen in the stochastic models. The statistical samples are generated by the Monte Carlo-type stratified sampling method, which is Latin Hypercube Sampling (LHS). A total of 500 random samples closely predicts the scatter in the compressive strength at each temperature level with a range of 25 & ndash;700 degrees C. The variability at different geometrical positions on the fire-exposed beam specimens with low strength concrete is characterized as well. Overall, the experimentally observed uncertainties arising from uneven distribution of concrete compressive strength over the fire-exposed beams simulating non-engineered structures in Turkey are accurately reproduced by the random fields approach. (c) 2021 Elsevier Ltd. All rights reserved