173 research outputs found

    A split questionnaire survey design applied to German media and consumer surveys

    Get PDF
    On the basis of real data sets it is shown that splitting a questionnaire survey according to technical rather than qualitative criteria can reduce costs and respondent burden remarkably. Household interview surveys about media and consuming behavior are analyzed and splitted into components. Following the matrix sampling approach, respondents are asked only the varying subsets of the components inducing missing data by design. These missing data are imputed afterwards to create a complete data set. In an iterative algorithm every variable with missing values is regressed on all other variables which either are originally complete or contain actual imputations. The imputation procedure itself is based on the socalled predictive mean matching. In this contribution the validity of split and imputation is discussed based on the preservation of empirical distributions, bivariate associations, conditional associations and on regression inference. Finally, we find that many empirical distributions of the complete data are reproduced well in the imputed data sets. Concerning these long media and consumer questionnaires we like to conclude that nearly the same inference can be achieved by means of such a split design with reduced costs and minor respondent burden --

    NaturdĂŒnger fĂŒr Sportrasen

    Get PDF
    Die StĂ€dte Basel, Luzern und ZĂŒrich prĂŒften, ob der Rasen von Sport- und Parkanlagen mit BiodĂŒnger und Kompost gepflegt werden kann. Der Wunsch, den stadteigenen Kompost wiederzuverwerten, gab dazu den Ausschlag. Die Tests erwiesen sich als vielversprechend

    Femtosekunden-Infrarot-Spektroskopie an PropionsÀure-Dimeren und an photochromen Fulgiden und Fulgimiden

    Get PDF
    Experimente mit hohen Struktur- und Zeitauflösungen sind Voraussetzungen, um ein detailliertes VerstĂ€ndnis grundlegender Prozesse auf molekularer Ebene zu erlangen. Zeitauflösungen im Bereich von Femtosekunden kann die Anreg-Abtast-Laserspektroskopie erreichen. Mit Abtastimpulsen im infraroten Spektralbereich lassen sich zudem die nötigen strukturellen Informationen gewinnen. Im Rahmen dieser Arbeit wurde ein transientes Femtosekunden-Infrarotspektrometer fĂŒr verschiedene Anwendungen auf dem Gebiet der MolekĂŒlphysik weiterentwickelt. Dieses betraf zum Einen eine Erzeugung fĂŒr abstimmbare Ultraviolett-Anregungsimpulse, zum Anderen eine mehrstufige, optisch parametrische Frequenzkonversion zur Generierung spektral schmalbandiger, abstimmbarer Pumpimpulse im Mittelinfraroten. An PropionsĂ€ure-Dimeren, einem Modellsystem fĂŒr die biologisch relevanten WasserstoffbrĂŒckenbindungen, wurden Infrarot-Anreg-Infrarot-Abtast-Experimente durchgefĂŒhrt. Die Anregung erfolgte dabei im Bereich der OH-Streckschwingungen, wĂ€hrend die CO-Streck- und CH-/OH-Biegeschwingungen abgetastet wurden. Es konnte gezeigt werden, dass diese Schwingungen stark aneinander koppeln. Die genaue WellenlĂ€nge der Infrarot-Pumpimpulse hat Einfluss auf die Relaxation der Schwingungsenergie. Intramolekulare Energieumverteilung findet mit Zeitkonstanten von 0,5 ps und 1,5 ps statt; eine weitere intramolekulare Relaxation, vornehmlich aus mitangeregten CH-Streckschwingungen, sowie das KĂŒhlen zum Lösungsmittel, geschehen mit Zeiten von 12 ps. DarĂŒber hinaus wurde das transiente Brechen nur einer der beiden WasserstoffbrĂŒckenbindungen der PropionsĂ€ure-Dimere nach der Infrarot-Anregung beobachtet. Neben umfangreichen Experimenten mittels Ultraviolett-/Sichtbar-Anreg-Infrarot-Abtastspektroskopie wurde an photochromen Fulgiden und Fulgimiden eine Zuordnung von Schwingungsbanden mit Hilfe von Dichtefunktionaltheorie-Rechnungen durchgefĂŒhrt. Lichtinduzierte, ultraschnelle und reversibel schaltbare Ringschluss- sowie Ringöffnungsreaktionen zwischen den thermisch stabilen Konformeren wurden untersucht. Mit dem Zerfall eines elektronisch angeregten Zustands, dessen Lebensdauer auf der Zeitskala weniger Pikosekunden anzusiedeln ist, wird das entsprechende Photoprodukt gebildet. Alle Photoreaktionen sind nach 50 ps abgeschlossen. Durch spektral sehr breitbandiges Abtasten konnten auch Infrarotspektren des elektronisch angeregten Zustandes gewonnen und dessen Absorptionsbanden teilweise auch Normalschwingungen zugeordnet werden. Die potentielle Eignung von Fulgiden als ultraschneller, optischer Speicher wurde in einem Schreib-Lösch-Zyklus demonstriert. Mit einem ersten Ultraviolett-Impuls wurde die Ringschluss-, mit einem weiteren Impuls im Sichtbaren nach nur 4 ps die Ringöffnungsreaktion induziert, entsprechend einer möglichen Schalttaktrate von 250 GHz. Die Absorptionsunterschiede aufgrund der KonformationsĂ€nderungen konnten im Infraroten ausgelesen werden, ohne die jeweilige Konformation der MolekĂŒle zu verĂ€ndern

    Analyse unvollstÀndiger Befragungsdaten - Multiple Imputation mittels Bayesian Bootstrap Predictive Mean Matching

    Get PDF
    Multiple Imputation (MI) is a general purpose approach to impute partially incomplete data. The proposed method - Bayesian Bootstrap Predictive Mean Matching - is a variant that incorporates the robustifying properties of a nearest neighbour technique (Predictive Mean Matching) into MI.Multiple Imputation (MI) ist ein allgemeiner Ansatz zur ErgÀnzung fehlender Daten. Die vorgestellte Methode - Bayesian Bootstrap Predictive Mean Matching - ist eine MI-Variante, welche die robustifizierenden Eigenschaften eines Nearest-Neighbour-Verfahrens (Predictive Mean Matching) integriert

    The Tinnitus Research Initiative (TRI) database: A new approach for delineation of tinnitus subtypes and generation of predictors for treatment outcome

    Get PDF
    Tinnitus, the phantom perception of sound, is a frequent disorder that causes significant morbidity and treatment is elusive. A large variety of different treatment options have been proposed and from most of them some patients benefit. However, a particular treatment that helps one patient may fail for others. This suggests that there are different forms of tinnitus which differ in their pathophysiology and their response to specific treatments. Therefore, it is a major challenge for tinnitus treatment to identify the most promising therapy for a specific patient

    Distributional effects of carbon taxation in passenger transport with lump-sum offset: how low income households, retirees and families would benefit in Germany

    Get PDF
    Background: The introduction of a carbon tax on passenger transport is currently being discussed in Germany. Various stakeholders favour a consumption-based, revenue-neutral carbon tax with a uniform lump-sum offset for private households and a tax rate of 40 € per ton of CO2. Objective: In this study, we examine the distributional effects of carbon taxation for the German passenger transport sector under the assumption of the proposed tax model. We discuss as to what extent which socioeconomic groups would be burdened and who might even benefit from carbon taxation. To answer these questions we use a uniquely modelled data set that encompasses all forms of passenger transport (i.e. in Germany and abroad) of the German resident population over 1 year. The national household travel survey Mobility in Germany 2017 is the basis of the microscopic data set. We derive annual CO2 emissions and carbon tax burdens for various population groups using the data on passenger transport, as well as specific emission factors. Results: Results show that low income households, retirees, single parents and family households with two or more children would benefit from the proposed carbon taxation scheme due to below-average emissions per person; in contrast, working age households without children and car owners with heavy car use would be burdened. Our results are of particular relevance to transport researchers, transport politicians and decision makers as a basis for designing, developing and introducing a carbon taxation schem

    Incidence of Anaplastic Large Cell Lymphoma and Breast-Implant-Associated Lymphoma—An Analysis of a Certified Tumor Registry over 17 Years

    Get PDF
    Background: Breast-implant-associated anaplastic large cell lymphoma (BI-ALCL) and primary breast ALCL are rare extranodal manifestations of non-Hodgkin lymphoma. The rarity of both diseases, along with unreleased sales data on breast implants and constant updates of classification systems impede the calculation of an exact incidence. Methods: The database of the Tumor Center Regensburg in Bavaria was searched for patients with CD30-positive and ALK-negative anaplastic large cell lymphoma between 2002 and 2018. These lymphomas were identified by the ICD-O-3 morphology code "97023" and were cross-checked by searching the diagnosis by name the and ICD-10 code C84.7. Furthermore, we tried to calculate the incidence rates and corresponding 95% confidence intervals, standardized to 1,000,000 implant years of breast-implant-associated anaplastic large cell lymphoma and primary breast anaplastic large cell lymphoma. Results: Twelve ALK-negative and CD30-positive anaplastic large cell lymphomas were identified out of 170,405 malignancies. No case was found within the breast tissue and none of the patients had a previous history of breast implant placement. In five cases, lymph node involvement in close proximity to the breast was observed. Conclusion: We found a low incidence of anaplastic large cell lymphoma and no association to breast implants in these patients. A review of the current literature revealed inconsistent use of classification systems for anaplastic large cell lymphomas and potential overestimation of cases

    Classical blood biomarkers identify patients with higher risk for relapse 6 months after alcohol withdrawal treatment

    Get PDF
    This naturalistic study among patients with alcohol dependence examined whether routine blood biomarkers could help to identify patients with high risk for relapse after withdrawal treatment. In a longitudinal study with 6-month follow-up among 133 patients with alcohol dependence who received inpatient alcohol withdrawal treatment, we investigated the usefulness of routine blood biomarkers and clinical and sociodemographic factors for potential outcome prediction and risk stratification. Baseline routine blood biomarkers (gamma-glutamyl transferase GGT, alanine aminotransferase ALT/GPT, aspartate aminotransferase AST/GOT, mean cell volume of erythrocytes MCV), and clinical and sociodemographic characteristics were recorded at admission. Standardized 6~months' follow-up assessed outcome variables continuous abstinence, days of continuous abstinence, daily alcohol consumption and current abstinence. The combined threshold criterion of an AST:ALT ratio > 1.00 and MCV > 90.0 fl helped to identify high-risk patients. They had lower abstinence rates (P = 0.001), higher rates of daily alcohol consumption (P < 0.001) and shorter periods of continuous abstinence (P = 0.027) compared with low-risk patients who did not meet the threshold criterion. Regression analysis confirmed our hypothesis that the combination criterion is an individual baseline variable that significantly predicted parts of the respective outcome variances. Routinely assessed indirect alcohol biomarkers help to identify patients with high risk for relapse after alcohol withdrawal treatment. Clinical decision algorithms to identify patients with high risk for relapse after alcohol withdrawal treatment could include classical blood biomarkers in addition to clinical and sociodemographic items
    • 

    corecore