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A hybrid methodology for the assessment of liquid rocket engines' thermoacoustic stability is analyzed and approaches to resolve deficiencies are studied, including revised calculation procedures for the mean flow and the flame dynamics. Radial flow stratification significantly impacts the damping rate predictions as does the flame response modeling. Due to the high uncertainties in these components a sound validation cannot be based on the stability behavior alone but requires additional data., Eine hybride Methode zur Vorhersage der thermoakustischen Stabilität von Flüssigraketentriebwerken wird analysiert und Lösungsansätze für Defizite werden untersucht. Dies umfasst überarbeitete Berechnungsmethoden für Grundströmung und Flammendynamik. Radiale Strömungsstratifizierung und Modellierung der Flammenantwort wirken sich deutlich auf die Stabilitätsvorhersage aus. Unsicherheiten in diesen Komponenten machen neben dem Stabilitätsverhalten weitere Daten für eine Validierung erforderlich.

Physical characteristics: Original contains color illustrations, 形態: カラー図版あり, Accepted: 2017-10-25

BACKGROUND: Atrial fibrillation (AF) ablation improves patient-reported outcomes, irrespective of mode of intermittent rhythm monitoring. We evaluated the use of an AF-specific and a generic patient-reported outcomes instrument during continuous rhythm monitoring 2 years after AF ablation. METHODS AND RESULTS: Fifty-four patients completed the generic 36-Item Short-Form Health Survey and the AF-specific AF6 questionnaires before and 6, 12, and 24 months after AF ablation. All patients underwent continuous ECG monitoring via an implantable loop recorder. The generic patient-reported outcomes scores were compared with those of a Swedish age- and sex-matched population. After ablation, both summary scores reached normative levels at 24 months, while role-physical and vitality remained lower than norms. Responders to ablation (AF burden <0.5%) reached the norms in all individual 36-Item Short-Form Health Survey domains, while nonresponders (AF burden >0.5%) reached norms only in social functioning and mental component summary. All AF6 items and the sum score showed moderate to large improvement in both responders and nonresponders, although responders showed significantly greater improvement in all items except item 1 from before to 24 months after ablation. Higher AF burden was independently associated with poorer physical component summary and AF6 sum score. CONCLUSIONS: The AF-specific AF6 questionnaire was more sensitive to changes related to AF burden than the generic 36-Item Short-Form Health Survey. Patients improved as documented by both instruments, but a higher AF burden after ablation was associated with poorer AF-specific patient-reported outcomes and poorer generic physical but not mental health. Our results support the use of an AF-specific instrument, alone or in combination with a generic instrument, to assess the effect of ablation. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT00697359., Funding Agencies:Örebro Heart Foundation Research Committee of Örebro University Hospital, Örebro, Sweden

Objective: To evaluate rhythm control up to two years after AF ablation and its relation to reported symptoms. Background: The implantable loop recorder (ILR) continuously records the ECG, has an automatic AF detection algorithm and a possibility for patients to activate an ECG recording during symptoms. Methods: Fifty-seven patients (mean age 57±9 years, 60% male, 88% paroxysmal AF) underwent AF ablation following ILR implantation. Device data were downloaded at the ablation and three, six, 12, 18 and 24 months after ablation. Results: Fifty-four patients completed the two-year follow-up. Thirteen (24%) patients had no AF episodes detected by ILR during follow-up. Ten of 41 patients (24%) with AF recurrence were only detected by ILR and AF recurrences were detected earlier by ILR (P<0.001). The median AF burden in patients with AF recurrence was 5.7% (IQR 0.4-14.4) and was even lower in patients with AF only detected by ILR (P = 0.001). Forty-eight % of the patients indicated symptoms via the patient activator but 33% of those recordings were not due to AF. Early AF recurrence (within 3 months) was highly associated with later AF recurrence (P<0.001). AF burden >0.5% and longest >6h before the ablation were independent predictors of AF recurrence during intermittent but not continuous monitoring. Conclusions: After AF ablation, the AF burden was low throughout the 24 months follow-up. Nevertheless, symptoms were commonly indicated but one third of patient activated recordings did not show AF. Continuous monitoring was superior to intermittent follow-up in detecting AF episodes and assessing the AF burden. Clinical trial registration: URL: http://clinicaltrials.gov. Unique Identifier: NCT00697359., Funding Agencies:MedtronicÖrebro heart foundationResearch Committee of Örebro University Hospital, Örebro, Sweden