Anticipatory Buffer Control and Quality Selection for Wireless Video Streaming

Video streaming is in high demand by mobile users, as recent studies indicate. In cellular networks, however, the unreliable wireless channel leads to two major problems. Poor channel states degrade video quality and interrupt the playback when a user cannot sufficiently fill its local playout buffer: buffer underruns occur. In contrast to that, good channel conditions cause common greedy buffering schemes to pile up very long buffers. Such over-buffering wastes expensive wireless channel capacity. To keep buffering in balance, we employ a novel approach. Assuming that we can predict data rates, we plan the quality and download time of the video segments ahead. This anticipatory scheduling avoids buffer underruns by downloading a large number of segments before a channel outage occurs, without wasting wireless capacity by excessive buffering. We formalize this approach as an optimization problem and derive practical heuristics for segmented video streaming protocols (e.g., HLS or MPEG DASH). Simulation results and testbed measurements show that our solution essentially eliminates playback interruptions without significantly decreasing video quality

Muusikainstrumentide valik ja kasutamine põhikooli I kooliastme muusikatundides Pärnu linna koolide näitel

Käesoleva uurimistöö eesmärgiks oli välja selgitada tegurid, mille alusel valitakse ja kasutatakse muusikainstrumente Pärnu linna üldhariduskooli I kooliastme muusikatundides.http://tartu.ester.ee/record=b2655043~S1*es

Evaluierung und Optimierung eines neuartigen Bioreaktorsystems mit Ultraschallzerstäubung

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Therapeutika des neuropathischen Schmerzes blockieren den TTX-resistenten Natriumkanal des peripheren nozizeptiven Systems

Systemisch applizierte Natriumkanalblocker können die Schmerzsymptomatik bei bestimmten Schmerzformen verbessern, der hier zugrunde liegende Mechanismus ist jedoch unverstanden. Pathophysiologisch spielen TTX-resistente Natriumkanäle eine entscheidende Bedeutung für die Entstehung von ektopen Impulsen, die letztendlich zu neuropathischen Schmerzsyndromen führen. In der vorliegenden Arbeit wurden Ströme durch oben erwähnte Ionenkanäle mit Hilfe der Patch-clamp Methode in whole-cell Konfiguration an enzymatisch dissoziierten DRG-Zellen erwachsener Ratten aufgezeichnet. Hier wurde die Wirkung verschiedener klinisch eingesetzter Natriumkanalblocker an den Natriumkanälen ausgetestet. Dabei wurde besonderen Wert auf die Auswirkung von Membranpotentialänderungen auf die halbmaximale Blockierungskonzentration (IC50) gelegt. IC50-Werte wurden durch Konzentrations-Blockierungs-Kurven bei Haltepotentialen von -90-70 und -60 mV bestimmt. Lidocain, Mexiletin und Amitriptylin blockierten den TTX-resistenten Natriumkanal konzentrationsabhängig und use-dependent. Die Medikamente Carbamazepin und Memantin blockierten nicht use-dependent, Gabapentin zeigte keinen Effekt bis zu einer Konzentration von 3 mmol/l. Weiterhin reduziert sich der TTX-resistente Natriumstrom bei Depolarisation des Membranpotentials ohne blockierende Substanzen nur geringfügig. Daraus läßt sich folgern, daß ein weniger negatives Membranpotential und repetitive Aktivität die Sensitivität des TTX-resistenten Natriumkanales für die Medikamente Lidocain, Mexiletin und Amitriptylin erhöhen, so daß die in der klinischen Therapie erreichten systemischen Konzentrationen die Kanalfunktion beeinflussen. Diese Kanaleigenschaft kann eine Verringerung des Schmerzempfindens durch reduzierte Aktivität der ektopen Zentren ohne Beeinflussung von zentralen oder kardialen Erregungen erklären

T-Zellen, Monozyten-Untergruppen und Entzündungs-Moleküle im Kontext von Abstoßung und Hämodynamik in der Frühphase nach Herztransplantation

In der Frühphase nach Herztransplantation ist die Differentialdiagnose zwischen Transplantatversagen durch Abstossung, Infektion oder anderer Ursachen wichtig aber schwierig. Bei 22 Patienten wurden in den ersten drei Monaten nach Herztransplantation an 8 Zeitpunkten Messungen von Interleukin-6, T-Zell- und Monozyten-Untergruppen sowie anderer Immunparameter und Rechtsherzkatheter-Messungen mit Herzmuskelbiopsien und Echokardiographien durchgeführt. Wir fanden, dass eine Erhöhung von Interleukin-6, CRP, Fibrinogen, Neutrophilen Granulozyten, CD71-Monozyten, HLADR/CD14 und IgM und eine Erniedrigung von CD3-, CD4-, CD8-, CD3/CD25-, CD4/CD45R0- T-Lymphozyten und NK-Zellen verbunden ist mit einer verschlechterten Transplantatfunktion und einer ungünstigen Prognose in der postoperativen Frühphase. Die Kenntnis des Aktivierungsmusters von Immunparametern könnte möglicherweise prognostisch und therapeutisch - hinsichtlich der Feinregulierung der immunsuppressiven und antimikrobiellen Therapie in der Frühphase nach Herztransplantation verwertbar sein

Cryo-EM structure of the respiratory I + III2 supercomplex from Arabidopsis thaliana at 2 Å resolution

Protein complexes of the mitochondrial respiratory chain assemble into respiratory supercomplexes. Here we present the high-resolution electron cryo-microscopy structure of the Arabidopsis respiratory supercomplex consisting of complex I and a complex III dimer, with a total of 68 protein subunits and numerous bound cofactors. A complex I-ferredoxin, subunit B14.7 and P9, a newly defined subunit of plant complex I, mediate supercomplex formation. The component complexes stabilize one another, enabling new detailed insights into their structure. We describe (1) an interrupted aqueous passage for proton translocation in the membrane arm of complex I; (2) a new coenzyme A within the carbonic anhydrase module of plant complex I defining a second catalytic centre; and (3) the water structure at the proton exit pathway of complex III2 with a co-purified ubiquinone in the QO site. We propose that the main role of the plant supercomplex is to stabilize its components in the membrane

Improving aqueous biphasic hydroformylation of unsaturated oleochemicals using a jet-loop-reactor

In two case studies, the reaction performance of the aqueous biphasic hydroformylation of two industrially relevant oleochemicals, namely methyl 10-undecenoate (case 1) and methyl oleate (case 2), is significantly improved by the use of a Jet-Loop Reactor concept. Based on previously reported studies, only the two green and benign co-solvents, 1-butanol and isopropanol are applied, respectively, in the absence of any additional auxiliary. Both reactions benefit highly from using this special piece of equipment, specifically designed for improving gas–liquid–liquid mixing to create large interfacial areas with no moving internals. In case 1, the loading of the co-solvent 1-butanol is successfully reduced. For the first time significant yields (>40% after 1 h) are obtained in the absence of any co-solvent, which is very beneficial, since aldehyde products and substrate form a pure product phase enabling straightforward separation. In case 2, the loading of the substrate methyl oleate is successfully increased from 6 to 30 wt% still showing satisfying productivity. At 15 wt%, the yield of the desired internal aldehydes in the jet-loop reactor is increased by a factor of five compared to a stirred tank reactor after 3 h

Improvement of productivity for aqueous biphasic hydroformylation of methyl 10-undecenoate

The overall productivity of the aqueous biphasic hydroformylation of the castor oil-derived methyl 10-undecenoate is increased. To increase the reaction rate, the miscibility of water and the fatty compound is increased by addition of the green solvent 1-butanol as co-solvent. For the first time, the concentration of solvents, substrate, and product within the reaction process is experimentally examined in a biphasic system under 20 bar pressure of synthesis gas and 140 °C. A reactor to get samples of both phases is developed to determine the quarternary mixture of the reaction system presented in a four-dimensional tetrahedron diagram. With the knowledge gained about the reaction and its drivers, it is possible to increase the efficiency of the reaction process reported so far. With simultaneously high reaction rates (turn over frequency = >5000 h−1), the space–time yield of the reaction reaches values of >120 g L−1h−1 and can be improved significantly without negatively affecting catalyst leaching

Destructive per continuitatem spondylodiscitis after endovascular abdominal or thoracic aneurysm repair (EVAR/TEVAR): rare and untreatable?

Introduction Very few publications have previously described spondylodiscitis as a potential complication of endovascular aortic procedures (EVAR/TEVAR). We present to our knowledge the first case series of spondylodiscitis following EVAR/TEVAR based on our data base. Particular focus was laid on the complexity of disease treatment and grave outcome perspectives from a spine surgeon’s point of view in this seriously affected patient group. Materials and methods A retrospective analysis and chart review was performed for 11 out of 284 consecutive spondylodiscitis patients who underwent EVAR/TEVAR procedure and developed destructive per continuitatem spondylodiscitis. Results All 11 patients had single or more level destructive spondylodiscitis adjacent to the thoracic/lumbar stent graft. In mean, four surgeries were performed per patient to treat this rare complication. Six out of eleven patients (55%) died within 6 months of first identification of per continuitatem spondylodiscitis. In four patients due to persisting infection of the graft and recurrence of the abscess formation, a persisting fistula from anterior approach to the skin was applied. Conclusions Destructive per continuitatem spondylodiscitis is a rare and severe complication post-EVAR/TEVAR. Clinical and imaging features of anterior paravertebral disease and anterior vertebral body involvement suggest direct continuous spread of the graft infection to the adjacent vertebral column. The mortality rate of these severe infections is extremely high and treatment with a permanent fistula may be one salvage procedure