917 research outputs found

    On Fermionic Shadow Wave Functions for strongly-correlated multi-reference systems based on a single Slater determinant

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    We demonstrate that extending the Shadow Wave Function to fermionic systems facilitates to accurately calculate strongly-correlated multi-reference systems such as the stretched H2 molecule. This development considerably extends the scope of electronic structure calculations and enables to efficiently recover the static correlation energy using just a single Slater determinant.Comment: 6 pages, 2 figure

    Idiopathische thrombozytopenische Purpura im Kindesalter

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    Zusammenfassung: Die idiopathische thrombozytopenische Purpura (ITP) ist eine Blutungskrankheit, die durch eine verkürzte Lebensdauer der Thrombozyten charakterisiert ist. Sie ist heterogen ausgeprägt und wird durch endogene und erworbene Faktoren beeinflusst. Sie ist eine Ausschlussdiagnose, deren Differenzialdiagnose stets bedacht werden muss. Die Unkenntnis der Ätiologie und der Mangel an klinischen Daten aus kontrollierten prospektiven Studien haben Kontroversen hinsichtlich Diagnose und Behandlung zur Folge. Die bisherigen prospektiven Therapiestudien haben die Beschleunigung des Thrombozytenanstiegs zum Ziel. Diese Zielsetzung wird oft in den klinischen Alltag übertragen, ohne dass bisher gezeigt werden konnte, dass ein rascher Thrombozytenanstieg von klinischem Wert ist. Bei der Behandlung des Patienten mit ITP ist meist eine Vorbeugung vor fatalen Blutungen beabsichtigt. Diese sind aber im Kindesalter sehr selten. Die Therapieziele im klinischen Alltag, aber auch in klinischen Studien müssen überdacht werden. Andere wichtige Gesichtspunkte sind Blutungen, die Lebensqualität des Patienten und seiner Angehörigen, Nebenwirkungen von Medikamenten und ökonomische Aspekt

    Cavity-enhanced optical Hall effect in two-dimensional free charge carrier gases detected at terahertz frequencies

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    The effect of a tunable, externally coupled Fabry-P\'{e}rot cavity to resonantly enhance the optical Hall effect signatures at terahertz frequencies produced by a traditional Drude-like two-dimensional electron gas is shown and discussed in this communication. As a result, the detection of optical Hall effect signatures at conveniently obtainable magnetic fields, for example by neodymium permanent magnets, is demonstrated. An AlInN/GaN-based high electron mobility transistor structure grown on a sapphire substrate is used for the experiment. The optical Hall effect signatures and their dispersions, which are governed by the frequency and the reflectance minima and maxima of the externally coupled Fabry-P\'{e}rot cavity, are presented and discussed. Tuning the externally coupled Fabry-P\'{e}rot cavity strongly modifies the optical Hall effect signatures, which provides a new degree of freedom for optical Hall effect experiments in addition to frequency, angle of incidence and magnetic field direction and strength

    Electron effective mass in Al0.72_{0.72}Ga0.28_{0.28}N alloys determined by mid-infrared optical Hall effect

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    The effective electron mass parameter in Si-doped Al0.72_{0.72}Ga0.28_{0.28}N is determined to be m∗=(0.336±0.020) m0m^\ast=(0.336\pm0.020)\,m_0 from mid-infrared optical Hall effect measurements. No significant anisotropy of the effective electron mass parameter is found supporting theoretical predictions. Assuming a linear change of the effective electron mass with the Al content in AlGaN alloys and m∗=0.232 m0m^\ast=0.232\,m_0 for GaN, an average effective electron mass of m∗=0.376 m0m^\ast=0.376\,m_0 can be extrapolated for AlN. The analysis of mid-infrared spectroscopic ellipsometry measurements further confirms the two phonon mode behavior of the E1_1(TO) and one phonon mode behavior of the A1_1(LO) phonon mode in high-Al-content AlGaN alloys as seen in previous Raman scattering studies

    Characterization and financial impact of implantable cardioverter-defibrillator patients without interventions 5 years after implantation

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    Background: Implantable cardioverter defibrillators (ICD's) are increasingly used for primary and secondary prevention of sudden cardiac death. However, data on how many ICD patients indeed receive appropriate ICD therapy during long-term follow-up is scarce. Aim: The aim of our study was to determine the number of patients without appropriate ICD therapy 5 years after ICD implantation, to identify predicting factors, to assess the occurrence of late first ICD therapy and to quantify the financial impact of ICD therapy in a real-world setting. Design: Prospective observational study. Methods: We prospectively enrolled 322 consecutive ICD patients. Baseline data were collected at implantation and patients were followed for a median of 7.3 years (IQR 5.8-9.2 years). Time to first appropriate ICD therapy (either antitachycardia pacing or cardioversion) was documented. Results: Five years after implantation, 139 patients (43%) had not received appropriate ICD therapy. In multivariable analysis, a primary prevention indication and negative electrophysiological studies prior to ICD implantation were independent predictors of freedom from ICD therapy. Of the patients without ICD therapy, 5 years after implantation, 25% had experienced inappropriate ICD shocks. Two hundred and seven devices (1.5 devices per patient) were needed for the 139 patients without ICD intervention within 5 years, accounting for €31 784 per patient. During an additional follow-up of 3 years, 12% of the patients with unused ICD received a late first appropriate ICD therapy. Conclusions: About half of the ICD patients receive appropriate ICD therapy within 5 years after implantation. Furthermore, there is a significant proportion of patients receiving late first shocks after five initially uneventful year
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