561 research outputs found

    Die Musikkritik - ein schulpÀdagogisches Aufgabenfeld? Bemerkungen zum Umgang mit Musikkritik im Unterricht der Sekundarstufe I und II

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    Im BedingungsgefĂŒge der musikalischen Produktion, Interpretation, Rezeption (bezogen sowohl auf das musikalische Ereignis selbst als auch auf die Aufnahme der musikkritischen Reflexion) und Distribution wirkt die Musikkritik regulierend und stimulierend auf den Kunstprozeß in seiner vielschichtigen sozialen Bestimmung und personellen Bestimmtheit. Die sich hieraus ergebende Wirkungsabsicht der Musikkritik bezĂŒglich einer spezifischen Art der Leser- bzw. Hörerbeeinflussung und -formierung wird von verschiedenen Autoren musikkritischer Darstellungen berechtigt als pĂ€dagogische Seite des musikkritischen Schrifttums angesehen. Diesen allgemeinen pĂ€dagogischen Ansatzpunkt gilt es weiterzufĂŒhren, indem von der Überlegung ausgegangen wird, das musikalische Schrifttum auch fĂŒr eine beziehungsreiche und effektive Gestaltung von Lernprozessen im Musikunterricht und in der außerunterrichtlichen musikerzieherischen Arbeit an allgemein bildenden Schulen nutzen. (DIPF/Orig.

    Microfluidically prepared sensor particles for determination of chloride by fluorescence quenching of matrix-embedded lucigenin

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    Polyacrylamide sensor particles have been synthesized by using a microfluidic arrangement for generation of microdroplets containing a reaction mixture for forming gel microparticles. The droplets are formed in an inert carrier liquid immiscible with the reaction mixture based on aqueous solutions. Gel particles are formed in situ by photochemical initiation of polymerization inside droplets using an UV-sensitive photoinitiator. In result, water-swellable spheres with submillimetre size are obtained. Those spheres were loaded with N,Nâ€Č-dimethyl-9,9â€Č-biacridinium dinitrate (lucigenin) as ion selective fluorescence probe for chloride. The particles can be dried, stored and re-swollen. Upon exposure of dried particles to sodium chloride solutions they showed dynamic fluorescence quenching obeying the linear plot of Stern–Volmer-equation between 0 and 130 mM Cl−. Thus, chloride concentrations up to 50 mM could be measured with appropriate accuracy. The particles allow a fast optical determination of chloride in tiny analyte volumes down to below ten microliters

    Micro flow photochemical synthesis of ca‐sensitive fluorescent sensor particles

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    Fluorescence probes have widely been used for detecting and imaging Ca 2+ ‐enriched parts of cells but more rarely for quantitative determination of concentrations. In this study we show how this can be achieved by a novel approach using hydrogel particles. In a microfluidic co‐flow arrangement spherical droplets were generated from an aqueous solution of acrylamide, N,N '‐methylenebisacrylamide crosslinker and photoinitiator and subsequently photo‐cured in situ yielding gel particles in a sub millimeter range. These particles were separated, dried under reduced pressure and re‐swollen in water containing Rhod‐5N tri potassium salt as calcium ion selective fluorescence probe. After that the particles were dried again and stored for further investigations. Upon exposure of dried particles to calcium chloride solutions they swell and take up Ca 2+ ‐ions forming a strong fluorescing complex with Rhod‐5N. Thus, fluorescence intensity increases with calcium ion concentration. Up to ca. 0.50 mM the enhancement effect is strong and then becomes considerably weaker. The intensity‐concentration‐dependence is well described by an equation derived from the equilibrium of the formation of a 1:1 Ca 2+ :Rhod‐5N complex. The particles allow for a fast optical determination of Ca 2+ ‐concentrations up to 0.50 mM in analyte volumes down to below 10 ÎŒL

    Comparison of a standard CO2 pressure pneumoperitoneum insufflator versus AirSealℱ: study protocol of a randomized controlled trial

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    BACKGROUND: AirSealℱ is a novel class of valve-free insufflation system that enables a stable pneumoperitoneum with continuous smoke evacuation and carbon dioxide (CO(2)) recirculation during laparoscopic surgery. Comparison data to standard CO(2) pressure pneumoperitoneum insufflators is scarce. The aim of this study is to evaluate the potential advantages of AirSealℱ compared to a standard CO(2) insufflator. METHODS/DESIGN: This is a single center randomized controlled trial comparing elective laparoscopic cholecystectomy, colorectal surgery and hernia repair with AirSealℱ (group A) versus a standard CO(2) pressure insufflator (group S). Patients are randomized using a web-based central randomization and registration system. Primary outcome measures will be operative time and level of postoperative shoulder pain by using the visual analog score (VAS). Secondary outcomes include the evaluation of immunological values through blood tests, anesthesiological parameters, surgical side effects and length of hospital stay. Taking into account an expected dropout rate of 5%, the total number of patients is 182 (n = 91 per group). All tests will be two-sided with a confidence level of 95% (P <0.05). DISCUSSION: The duration of an operation is an important factor in reducing the patient’s exposure to CO(2) pneumoperitoneum and its adverse consequences. This trial will help to evaluate if the announced advantages of AirSealℱ, such as clear sight of the operative site and an exceptionally stable working environment, will facilitate the course of selected procedures and influence operation time and patients clinical outcome. TRIAL REGISTRATION: ClinicalTrials.gov NCT01740011, registered 23 November 2012

    Salt-dependent regulation of a CNG channel subfamily in Arabidopsis

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    <p>Abstract</p> <p>Background</p> <p>In <it>Arabidopsis thaliana</it>, the family of cyclic nucleotide-gated channels (CNGCs) is composed of 20 members. Previous studies indicate that plant CNGCs are involved in the control of growth processes and responses to abiotic and biotic stresses. According to their proposed function as cation entry pathways these channels contribute to cellular cation homeostasis, including calcium and sodium, as well as to stress-related signal transduction. Here, we studied the expression patterns and regulation of <it>CNGC19 </it>and <it>CNGC20</it>, which constitute one of the five CNGC subfamilies.</p> <p>Results</p> <p>GUS, GFP and luciferase reporter assays were used to study the expression of <it>CNGC19 </it>and <it>CNGC20 </it>genes from <it>Arabidopsis thaliana </it>in response to developmental cues and salt stress. <it>CNGC19 </it>and <it>CNGC20 </it>were differentially expressed in roots and shoots. The <it>CNGC19 </it>gene was predominantly active in roots already at early growth stages. Major expression was observed in the phloem. <it>CNGC20 </it>showed highest promoter activity in mesophyll cells surrounding the veins. Its expression increased during development and was maximal in mature and senescent leaves. Both genes were upregulated in the shoot in response to elevated NaCl but not mannitol concentrations. While in the root, <it>CNGC19 </it>did not respond to changes in the salt concentration, in the shoot it was strongly upregulated in the observed time frame (6-72 hours). Salt-induction of <it>CNGC20 </it>was also observed in the shoot, starting already one hour after stress treatment. It occurred with similar kinetics, irrespective of whether NaCl was applied to roots of intact plants or to the petiole of detached leaves. No differences in K and Na contents of the shoots were measured in homozygous T-DNA insertion lines for <it>CNGC19 </it>and <it>CNGC20</it>, respectively, which developed a growth phenotype in the presence of up to 75 mM NaCl similar to that of the wild type.</p> <p>Conclusion</p> <p>Together, the results strongly suggest that both channels are involved in the salinity response of different cell types in the shoot. Upon salinity both genes are upregulated within hours. <it>CNGC19 </it>and <it>CNGC20 </it>could assist the plant to cope with toxic effects caused by salt stress, probably by contributing to a re-allocation of sodium within the plant.</p

    Textured and hierarchically constructed polymer micro- and nanoparticles

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    Microfluidic techniques allow for the tailored construction of specific microparticles, which are becoming increasingly interesting and relevant. Here, using a microfluidic hole-plate-device and thermal-initiated free radical polymerization, submicrometer polymer particles with a highly textured surface were synthesized. Two types of monomers were applied: (1) methylmethacrylate (MMA) combined with crosslinkers and (2) divinylbenzene (DVB). Surface texture and morphology can be influenced by a series of parameters such as the monomer–crosslinker–solvent composition, surfactants, and additives. Generally, the most structured surfaces with the simultaneously most uniform particles were obtained in the DVB–toluene–nonionic-tensides system. In a second approach, poly-MMA (PMMA) particles were used to build aggregates with bigger polymer particles. For this purpose, tripropyleneglycolediacrylate (TPGDA) particles were synthesized in a microfluidic co-flow arrangement and polymerized by light- irradiation. Then, PMMA particles were assembled at their surface. In a third step, these composites were dispersed in an aqueous acrylamide–methylenebisacrylamide solution, which again was run through a co-flow-device and photopolymerized. As such, entities consisting of particles of three different size ranges—typically 0.7/30/600 ”m—were obtained. The particles synthesized by both approaches are potentially suitable for loading with or incorporation of analytic probes or catalysts such as dyes or metals

    Geometry and Distortion Prediction of Multiple Layers for Wire Arc Additive Manufacturing with Artificial Neural Networks

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    Wire arc additive manufacturing (WAAM) is a direct energy deposition (DED) process with high deposition rates, but deformation and distortion can occur due to the high energy input and resulting strains. Despite great efforts, the prediction of distortion and resulting geometry in additive manufacturing processes using WAAM remains challenging. In this work, an artificial neural network (ANN) is established to predict welding distortion and geometric accuracy for multilayer WAAM structures. For demonstration purposes, the ANN creation process is presented on a smaller scale for multilayer beads on plate welds on a thin substrate sheet. Multiple concepts for the creation of ANNs and the handling of outliers are developed, implemented, and compared. Good results have been achieved by applying an enhanced ANN using deformation and geometry from the previously deposited layer. With further adaptions to this method, a prediction of additive welded structures, geometries, and shapes in defined segments is conceivable, which would enable a multitude of applications for ANNs in the WAAM-Process, especially for applications closer to industrial use cases. It would be feasible to use them as preparatory measures for multi-segmented structures as well as an application during the welding process to continuously adapt parameters for a higher resulting component quality
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