1,101 research outputs found
Large-scale secondary circulations in a limited area model â the impact of lateral boundaries and resolution
Within their domain, regional climate and weather forecasting models deviate from the driving data. Small-scale deviations are a desired effect of adding regional details. There are, however, also deviations of the large-scale circulation, which can be caused by orographic effects and depend on the large-scale flow condition. These âsecondary circulationsâ (SCs) are confined to the model domain due to the prescribed boundary conditions. Here, the impact of different regional model configurations on the SC is analysed in a case study for the European region using an ensemble approach. It is shown that at 500âhPa, vortices of the SC have diameters on the order of several thousand kilometres and are related to wind speed anomalies of more than 5âm/s and geopotential height anomalies of more than 5 dam. The spatial structure and the amplitude of the SC strongly depend on the location of the lateral boundaries. The impact of the boundary location on the anomalies is on the same order of magnitude as the anomalies themselves. The resolution of the regional model, as well as the application of spectral nudging and a smoothed topography, affects mainly the amplitude of the SC, but not the spatial structure
A quantum repeater based on decoherence free subspaces
We study a quantum repeater which is based on decoherence free quantum gates
recently proposed by Klein et al. [Phys. Rev. A 73, 012332 (2006)]. A number of
operations on the decoherence free subspace in this scheme makes use of an
ancilla qubit, which undergoes dephasing and thus introduces decoherence to the
system. We examine how this decoherence affects entanglement swapping and
purification as well as the performance of a quantum repeater. We compare the
decoherence free quantum repeater with a quantum repeater based on qubits that
are subject to decoherence and show that it outperforms the latter when
decoherence due to long waiting times of conventional qubits becomes
significant. Thus, a quantum repeater based on decoherence free subspaces is a
possibility to greatly improve quantum communication over long or even
intercontinental distances.Comment: 22 pages, 18 figures, accepted for publication in Quantum Information
& Computatio
Intensivierte, peri-interventionelle Physiotherapie vor und nach transvaskulärer Aortenklappenimplantation - Einfluss der Patientenmotivation auf die Trainingsergebnisse
Einleitung: Pulmonale Komplikationen stellen die grĂśĂte Gruppe unter allen nicht-kardiovaskulären Komplikationen nach Transkatheter-Aortenklappenimplantation (TAVI) dar. Ziel der Studie war zu beweisen, dass ein spezielles präinterventionelles Atemtraining und eine forcierte periinterventionelle Physiotherapie der Patienten sowohl pulmonale Komplikationen verhindert als auch das GesamtĂźberleben verlängert. Hierbei untersuchten wir gesondert, ob Patienten mit einer hohen Motivation zum Training bessere Ergebnisse erreichen.Methode: 98 Patienten wurden 1:1 in eine Standardtherapiegruppe randomisiert, die kein präinterventionelles Atemtraining und nur eine einfache postinterventionelle Physiotherapie erhielt, und in eine Trainingsgruppe, die ein spezielles präinterventionelles Atem- und Bewegungstraining, und eine forcierte periinterventionelle Physiotherapie erhielt. Zur weiteren Untersuchung des Einflusses der Motivation erfolgte eine dichotome Teilung der Trainingsgruppe in eine Gruppe mit âguter Motivationâ gegen âschlechte Motivation durch eine subjektive Motivationsangabe der Patienten. Die Patienten wurden bis zum Zeitpunkt ihrer Entlassung beobachtet, Follow-Up´s erfolgten nach 30 Tagen und 3 Monaten.Ergebnisse: âGute gegen schlechte Motivationâ: Bei den primären Endpunkten (Tod, Re-Hospitalisation und Krankenhausverweildauer) erreichen die besser motivierten Patienten numerisch, aber nicht signifikant bessere Ergebnisse. In der Gruppe der âgut motiviertenâ Patienten starb nur ein Patient innerhalb der ersten 90 Tage nach Transkatheter-Aortenklappenimplantation, in der âschlecht motiviertenâ Gruppe vier Patienten innerhalb von 90 Tagen (4,3% vs. 18,2%, P=0,14). Die Rehospitalisierungsrate lag bei sechs Patienten innerhalb von 90 Tagen in der âgut motiviertenâ Gruppe gegen vier Patienten in der âschlecht motiviertenâ Gruppe (27% vs. 18%, P=0,52). Der Krankenhausaufenthalt war mit 11 Tagen bei den âgut motiviertenâ Patienten gleich hoch wie bei den âschlecht motivierten Patienten. BezĂźglich der sekundären Endpunkte bestehen signifikante Unterschiede beim Canadian-Cardiovascular-Society-Score (CCS) zum Einschlusszeitpunkt mit 0,652 in der âgut motiviertenâ Gruppe gegen 1,545 in der âschlecht motiviertenâ Gruppe (P = 0,045), beim 6-Minuten-Gehtest zum Zeitpunkt PostTAVI mit 218 m in der âgut motiviertenâ Gruppe gegen 133,5 m in der âschlecht motiviertenâ Gruppe (P = 0,048), als auch beim Mental component summary score (MCS) zum Einschluss- und PräTAVI-Zeitpunkt (55,1 âgut motivierteâ Gruppe gegen 50,6 âschlecht motivierteâ Gruppe zum Einschlusszeitpunkt (P = 0,033), 56,4 âgut motivierteâ Gruppe gegen 48,8 âschlecht motivierteâ Gruppe zum Zeitpunkt PräTAVI (P = 0,015)). Im wichtigen postoperative pulmonal complication Score (PPC) haben die âbesser motiviertenâ Patienten hĂśhere und damit schlechtere Werte zum Zeitpunkt PostTAVI und 30-Tages-Follow-up, die nicht signifikant sind. Zum 90-Tages-Follow-up hingegen erreichen die âbesser motiviertenâ Patienten signifikant bessere Werte (0,31 bei den âschlecht motiviertenâ Patienten gegen 0 bei den âgut motivierten Patientenâ, P = 0,04) âGute Motivation gegen Standardgruppeâ: Es gibt es keine signifikanten Unterschiede zwischen beiden Gruppen bei den primären Endpunkten. In der Standardgruppe verstarben fĂźnf Patienten (10%, P = 0,3) und es kam zu neun Rehospitalisierungen im Untersuchungszeitraum (22%, P = 0,71). Vor allem beim postoperative pulmonal complication Score (PPC) erreichten ab dem Zeitpunkt PostTAVI die Therapiepatienten mit âguter Motivationâ bessere, zum Zeitpunkt 90-Tages-Follow-up sogar signifikant bessere Ergebnisse (0,57 bei den Standardpatienten, 0 bei den Trainingspatienten (P = 0,016). Beim 6-Minuten-Gehtest erreichen die Trainingspatienten ebenfalls durchgehend bessere Ergebnisse, zum Zeitpunkt PostTAVI signifikant bessere (218 m in der Trainingsgruppe gegen 137 m in der Standardgruppe (P = 0,03). Schlussfolgerung: Besser motivierte Patienten erreichen in vielen primären und sekundären Endpunkten, numerisch bessere Ergebnisse als Patienten, die âschlechter motiviertâ sind. Signifikante Unterschiede bleiben jedoch häufig aus. Die besser motivierten Patienten trainieren signifikant mehr und sind mobiler. Durch eine gesteigerte Motivation und damit verbundene signifikant bessere Trainingsergebnisse lässt sich nicht die Pneumonierate oder das GesamtĂźberleben verlängern. Im Vergleich mit der Standardgruppe fallen die Unterschiede stärker aus, sind jedoch auch hier nicht signifikant. Diese Ergebnisse gelten fĂźr eine relativ geringe Probandenzahl
Dramatic reduction of mortality in pneumococcal meningitis
Background
Acute bacterial meningitis is still a life threatening disease.
Methods
We performed a retrospective observational study on the clinical characteristics of consecutively admitted patients with acute pneumococcal meningitis in a single tertiary care center in central Europe (from 2003 until 2015). Data were compared with a previously published historical group of 87 patients treated for pneumococcal meningitis at the same hospital (from 1984 until 2002).
Results
Fifty-five consecutive patients with microbiologically proven pneumococcal meningitis were included. Most striking, mortality was down to 5.5 %, which was significantly lower than in the historical group where 24.1 % of the patients did not survive. Intracranial complications during the course of the disease were common and affected half of the patients. Unlike in the historic group, most of the intracranial complications (except ischemic stroke) were no longer associated with a low Glasgow Outcome Score at discharge.
Conclusion
The drastic reduction of mortality proves there have been important advances in the treatment of pneumococcal meningitis. Nevertheless, the fact that only 44.2 % of survivors had a full recovery indicates that the search for new adjunctive treatment options must be ongoing
The Falciform Ligament for Mesenteric and Portal Vein Reconstruction in Local Advanced Pancreatic Tumor: A Surgical Guide and Single-Center Experience
Background. Since local tumor infiltration to the mesenteric-portal axis might represent a challenging assignment for curative intended resectability during pancreatic surgery, appropriate techniques for venous reconstruction are essential. In this study, we acknowledge the falciform ligament as a feasible and convenient substitute for mesenteric and portal vein reconstruction with high reliability and patency for local advanced pancreatic tumor. Methods. A retrospective single-center analysis. Between June 2017 and January 2018, a total of eleven consecutive patients underwent pancreatic resections with venous reconstruction using falciform ligament. Among them, venous resection was performed in nine cases by wedge and in two cases by full segment. Patency rates and perioperative details were reviewed. Results. Mean clamping time of the mesenteric-portal blood flow was 34 min, while perioperative mortality rate was 0%. By means of Duplex ultrasonography, nine patients were shown to be patent on the day of discharge, while two cases revealed an entire occlusion of the mesenteric-portal axis. Orthograde flow demonstrated a mean value of 34 cm/s. All patent grafts on discharge revealed persistent patencywithin various follow-up assessments. Conclusion. The falciform ligament appears to be a feasible and reliable autologous tissue for venous blood flow reconstruction with high postoperative patency. Especially the possibility of customizing graft dimensions to the individual needs based on local findings allows an optimal size matching of the conduit. The risk of stenosis and/or segmental occlusionmay thus be further reduced
Reduced spiral ganglion neuronal loss by adjunctive neurotrophin-3 in experimental pneumococcal meningitis
<p>Abstract</p> <p>Background</p> <p>Hearing loss is a frequent long-term complication of pneumococcal meningitis (PM). Its main pathological correlate is damage to the organ of Corti and loss of spiral ganglion neurons. The only current treatment option is cochlear implants which require surviving neurons. Here, we investigated the impact of systemically applied neurotrophin-3 (NT-3) on long-term hearing loss and the survival of neurons.</p> <p>Methods</p> <p>Eighteen hours after infection with <it>S. pneumoniae</it>, C57BL/6 mice were treated with a combination of ceftriaxone with NT-3 or dexamethasone or placebo. Hearing, cochlear damage, and brain damage were assessed by audiometry and histology.</p> <p>Results</p> <p>The main findings from immunohistochemical visualization of neurotrophins (NT-3, BDNF) and their receptors (TrkB, TrkC, and p75) in the cochlea were (i) enhanced staining for the cell survival-promoting receptor TrkB and (ii) increased NT-3 staining in NT-3 treated mice, showing that systemically applied NT-3 reaches the cochlea. The major effects of adjunctive NT-3 treatment were (i) a reduction of meningitis-induced hearing impairment and (ii) a reduction of spiral ganglion neuronal loss. The efficacy of NT-3 therapy was comparable to that of dexamethasone.</p> <p>Conclusion</p> <p>Systemically applied NT-3 might be an interesting candidate to improve hearing outcome after pneumococcal meningitis.</p
On the Observation of Vacuum Birefringence
We suggest an experiment to observe vacuum birefringence induced by intense
laser fields. A high-intensity laser pulse is focused to ultra-relativistic
intensity and polarizes the vacuum which then acts like a birefringent medium.
The latter is probed by a linearly polarized x-ray pulse. We calculate the
resulting ellipticity signal within strong-field QED assuming Gaussian beams.
The laser technology required for detecting the signal will be available within
the next three years.Comment: 4 pages, 4 figure
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