1,310 research outputs found
Selbstkontrolle und Sensation Seeking: Protektive Faktoren in Stresssituationen?
Leistungssportler stehen einer ganzen Bandbreite von Stressoren gegenĂŒber, die sie mit Hilfe individueller FĂ€higkeiten und Fertigkeiten zu meistern versuchen. Hierbei wird insbesondere die FĂ€higkeit zur Selbstkontrolle mit funktionaler StressbewĂ€ltigung in Verbindung gesetzt. Auch das Persönlichkeitsmerkmal Sensation Seeking steht mit effektiver Stressregulation in Zusammenhang. GemÀà der zentralen Annahme der vorliegenden Forschungsarbeit wird von einem Stress reduzierenden Einfluss der Selbstkontrolle sowie des Sensation Seeking in akuten Anforderungssituationen ausgegangen. Um dies zu ĂŒberprĂŒfen, wurden zwei Studien durchgefĂŒhrt, innerhalb derer insgesamt 120 Probanden hinsichtlich ihrer Stressreaktion auf ein sportspezifisches Kletterparadigma getestet wurden. Die Reaktionen der Probanden wurden mittels psychologischer, physiologischer sowie verhaltensbezogener MaĂe untersucht. In beiden Studien zeigten sich Interaktionseffekte mit spezifischen physiologischen und psychologischen Parametern. Die Befunde bekrĂ€ftigen, dass sowohl Selbstkontrolle als auch die AusprĂ€gung in Sensation Seeking von groĂer Relevanz fĂŒr das Stresserleben und Wohlergehen von Athleten/-innen sind
Transition from time-variant to static networks: timescale separation in NIMFA SIS epidemics
We extend the N-intertwined mean-field approximation (NIMFA) for the
Susceptible-Infectious-Susceptible (SIS) epidemiological process to
time-varying networks. Processes on time-varying networks are often analysed
under the assumption that the process and network evolution happen on different
timescales. This approximation is called timescale separation. We investigate
timescale separation between disease spreading and topology updates of the
network. We introduce the transition times and
as the boundaries between the intermediate regime
and the annealed (fast changing network) and quenched (static network) regimes,
respectively. By analysing the convergence of static NIMFA processes, we
analytically derive upper and lower bounds for . Our
results provide insights/bounds on the time of convergence to the steady state
of the static NIMFA SIS process. We show that, under our assumptions, the upper
transition time is almost entirely determined by the
basic reproduction number of the network. The value of the upper
transition time around the epidemic threshold is
large, which agrees with the current understanding that some real-world
epidemics cannot be approximated with the aforementioned timescale separation.Comment: 30 pages, 13 figure
Improving efficiency and robustness of enhanced assumed strain elements for nonlinear problems
The enhanced assumed strain (EAS) method is one of the most frequently used methods to avoid locking in solid and structural finite elements. One issue of EAS elements in the context of geometrically nonlinear analyses is their lack of robustness in the NewtonâRaphson scheme, which is characterized by the necessity of small load increments and large number of iterations. In the present work we extend the recently proposed mixed integration point (MIP) method to EAS elements in order to overcome this drawback in numerous applications. Furthermore, the MIP method is generalized to generic material models, which makes this simple method easily applicable for a broad class of problems. In the numerical simulations in this work, we compare standard strainâbased EAS elements and their MIP improved versions to elements based on the assumed stress method in order to explain when and why the MIP method allows to improve robustness. A further novelty in the present work is an inverse stressâstrain relation for a NeoâHookean material model
Independent Promotion of Young Talents in Satellite Development on the Full-Scale Satellite Mission SOURCE
The SOURCE mission is the first student satellite developed at the University of Stuttgart. This unique opportunity for undergraduate and graduate students is made possible by the cooperation between the Institute of Space Systems (IRS) and the Small Satellite Student Society (KSat e.V.
HF-Eigenschaften von Wellenkontaktierungen in AbhÀngigkeit zur Drehzahl
Innerhalb von Elektromotoren fĂŒr automobile HV-Anwendungen wird der Bedarf an EMV-MaĂnahmen in und um den Elektromotor immer wichtiger. Ein möglicher Ausbreitungspfad fĂŒr EMV-Störungen auf Systemebene ist hierbei die rotierende Motorwelle [1]. Transientes Schaltverhalten aus dem angeschlossenen Wechselrichter wird hierbei ĂŒber die Statorwicklungen kapazitiv auf die Motorwelle ĂŒbertragen und kann sich im schlimmsten Fall unkontrolliert im System ausbreiten (Bild 1). Eine mögliche MaĂnahme zur UnterdrĂŒckung dieser Störausbreitung ist eine Kontaktierung der rotierenden Motorwelle gegenĂŒber dem MotorgehĂ€use. Zur Wellenkontaktierung sind Lösungen von unterschiedlichen Herstellern verfĂŒgbar
Stroke with unknown time of symptom onset: baseline clinical and magnetic resonance imaging data of the first thousand patients in WAKE-UP (efficacy and safety of mri-based thrombolysis in wake-up stroke: a randomized, doubleblind, placebo-controlled trial)
Background and PurposeâWe describe clinical and magnetic resonance imaging (MRI) characteristics of stroke patients with unknown time of symptom onset potentially eligible for thrombolysis from a large prospective cohort.
MethodsâWe analyzed baseline data from WAKE-UP (Efficacy and Safety of MRI-Based Thrombolysis in Wake-Up Stroke: A Randomized, Doubleblind, Placebo-Controlled Trial), an investigator-initiated, randomized, placebo-controlled trial of MRI-based thrombolysis in stroke patients with unknown time of symptom onset. MRI judgment included assessment of the mismatch between visibility of the acute ischemic lesion on diffusion-weighted imaging and fluid-attenuated inversion recovery.
ResultsâOf 1005 patients included, diffusion-weighted imaging and fluid-attenuated inversion recovery mismatch was present in 479 patients (48.0%). Patients with daytime-unwitnessed stroke (n=138, 13.7%) had a shorter delay between symptom recognition and hospital arrival (1.5 versus 1.8 hours; P=0.002), a higher National Institutes of Stroke Scale score on admission (8 versus 6; P<0.001), and more often aphasia (72.5% versus 34.0%; P<0.001) when compared with stroke patients waking up from nighttime sleep. Frequency of diffusion-weighted imaging and fluid-attenuated inversion recovery mismatch was comparable between both groups (43.7% versus 48.7%; P=0.30).
ConclusionsâAlmost half of the patients with unknown time of symptom onset stroke otherwise eligible for thrombolysis had MRI findings making them likely to be within a time window for safe and effective thrombolysis. Patients with daytime onset unwitnessed stroke differ from wake-up stroke patients with regards to clinical characteristics but are comparable in terms of MRI characteristics of lesion age.
Clinical Trial RegistrationâURL: http://www.clinicaltrials.gov. Unique identifier: NCT01525290. URL: https://www.clinicaltrialsregister.eu. Unique identifier: 2011-005906-32
Clinical characteristics of unknown symptom onset stroke patients with and without diffusion-weighted imaging and fluid-attenuated inversion recovery mismatch
Background:
Diffusion-weighted imaging (DWI) and fluid-attenuated inversion recovery (FLAIR) mismatch was suggested to identify stroke patients with unknown time of symptom onset likely to be within the time window for thrombolysis.
Aims:
We aimed to study clinical characteristics associated with DWI-FLAIR mismatch in patients with unknown onset stroke.
Methods:
We analyzed baseline MRI and clinical data from patients with acute ischemic stroke proven by DWI from WAKE-UP, an investigator-initiated, randomized, placebo-controlled trial of MRI-based thrombolysis in stroke patients with unknown time of symptom onset. Clinical characteristics were compared between patients with and without DWI-FLAIR mismatch.
Results:
Of 699 patients included, 418 (59.8%) presented with DWI-FLAIR mismatch. A shorter delay between last seen well and symptom recognition (pâ=â0.0063), a shorter delay between symptom recognition and arrival at hospital (pâ=â0.0025), and history of atrial fibrillation (pâ=â0.19) were predictors of DWI-FLAIR mismatch in multivariate analysis. All other characteristics were comparable between groups.
Conclusions:
There are only minor differences in measured clinical characteristics between unknown symptom onset stroke patients with and without DWI-FLAIR mismatch. DWI-FLAIR mismatch as an indicator of stroke onset within 4.5âh shows no relevant association with commonly collected clinical characteristics of stroke patients
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