2,716 research outputs found

    Broke, Ill, and Obese: The Effect of Household Debt on Health

    Get PDF
    We analyze the effect of household indebtedness on different health outcomes using data from the German Socio-Economic Panel from 1999–2009. To establish a causal effect, we rely on (a) fixed-eff ects methods, (b) a subsample of constantly employed individuals, and (c) lagged debt variables to rule out problems of reverse causality. We apply different measures of household indebtedness, such as the percentage shares of household income spent on consumer credit and home loan repayments (which indicate the severity of household indebtedness) and a binary variable of relative overindebtedness (which indicates a precarious debt situation). We find all debt measures to be strongly correlated with health satisfaction, mental health, and obesity. Controlling for unobserved heterogeneity and reversed causality we find evidence that household debt also causally deteriorates physical and mental health. However, there is no causal effect on being obese.Debt; health satisfaction; mental health; obesity; fixed-effects

    Broke, Ill, and Obese: The Effect of Household Debt on Health

    Get PDF
    We analyze the effect of household indebtedness on different health outcomes using data from the German Socio-Economic Panel from 1999-2009. To establish a causal effect, we rely on (a) fixed-effects methods, (b) a subsample of constantly employed individuals, and (c) lagged debt variables to rule out problems of reverse causality. We apply different measures of household indebtedness, such as the percentage shares of household income spent on consumer credit and home loan repayments (which indicate the severity of household indebtedness) and a binary variable of relative overindebtedness (which indicates a precarious debt situation). We find all debt measures to be strongly correlated with health satisfaction, mental health, and obesity. Controlling for unobserved heterogeneity and reversed causality we find evidence that household debt also causally deteriorates physical and mental health. However, there is no causal effect on being obese.Debt, health satisfaction, mental health, obesity, fixed-effects

    Minimal failure probability for ceramic design via shape control

    Full text link
    We consider the probability of failure for components made of brittle mate- rials under one time application of a load as introduced by Weibull and Batdorf - Crosse and more recently studied by NASA and the STAU cooperation as an objective functional in shape optimization and prove the existence of optimal shapes in the class of shapes with a uniform cone property. The corresponding integrand of the objective functional has convexity properties that allow to derive lower-semicontinuity according to Fujii (Opt. Th. Appl. 1988). These properties require less restrictive regularity assumptions for the boundaries and state functions compared to [arXiv:1210.4954]. Thereby, the weak formulation of linear elasticity can be kept for the abstract setting for shape optimization as presented in the book by Haslinger and Maekinen

    Horizontal vs. vertical tectonics: analysis of large-scale structures related to the deformation history of the Archean Barberton Greenstone Belt

    Get PDF
    One of the major unresolved questions in Precambrian geology is the nature of tectonic processes during Earth’s early history and the timing of the transition to modern-style plate tectonics. The Barberton Greenstone Belt (BGB) of South Africa and Eswatini features prominently in this discussion because it represents, along with the Pilbara region of Australia, the prime geological archive of the late Paleoarchean (ca. 3.5-3.2 Ga). This time period may mark the transition from a pre-plate tectonic setting to Phanerozoic-style plate tectonics. The cuspate-lobate geometry of the BGB, together with its general structural make-up (defined by folding style, stratigraphic fill and strain distribution) appears to represent a non-actualistic Archean tectonic style characterized by vertical rather than horizontal displacements, as known from modern plate tectonics. A compilation of geological data from the entire greenstone belt demonstrates its heterogeneity and complex deformation history is compared with own investigations in this work. A critical comparison of suggested tectonic settings to recent observations shows that no pure plate-tectonic scenarios are applicable. The temporal and spatial heterogeneity of deformation, the relative greenstone-down sense of shear along many of its contacts to the adjacent plutons, and the overall synclinal structure of the BGB emphasize a non-plate-tectonic setting dominated by vertical movements. Local subsidence due to folding, tilting and sagging of thick, dense greenstone regions into an incompetent granitoid middle crust during partial convective overturn plausibly explains the rotation of the enormous Onverwacht Anticline, the characteristic folding pattern and the temporally and spatially heterogeneous deformation history of the BGB

    Arteriogenesis versus angiogenesis: similarities and differences

    Get PDF
    Cardiovascular diseases account for more than half of total mortality before the age of 75 in industrialized countries. To develop therapies promoting the compensatory growth of blood vessels could be superior to palliative surgical surgical interventions. Therefore, much effort has been put into investigating underlying mechanisms. Depending on the initial trigger, growth of blood vessels in adult organisms proceeds via two major processes, angiogenesis and arteriogenesis. While angiogenesis is induced by hypoxia and results in new capillaries, arteriogenesis is induced by physical forces, most importantly fluid shear stress. Consequently, chronically elevated fluid shear stress was found to be the strongest trigger under experimental conditions. Arteriogenesis describes the remodelling of pre-existing arterio-arteriolar anastomoses to completely developed and functional arteries. In both growth processes, enlargement of vascular wall structures was proposed to be covered by proliferation of existing wall cells. Recently, increasing evidence emerges, implicating a pivotal role for circulating cells, above all blood monocytes, in vascular growth processes. Since it has been shown that monocytes/macrophage release a cocktail of chemokines, growth factors and proteases involved in vascular growth, their contribution seems to be of a paracrine fashion. A similar role is currently discussed for various populations of bone-marrow derived stem cells and endothelial progenitors. In contrast, the initial hypothesis that these cells -after undergoing a (trans-)differentiation- contribute by a structural integration into the growing vessel wall, is increasingly challenged

    Cosmic-ray exposure ages of fossil micrometeorites from mid-Ordovician sediments at Lynna River, Russia

    Full text link
    We measured the He and Ne concentrations of 50 individual extraterrestrial chromite grains recovered from mid-Ordovician (lower Darriwilian) sediments from the Lynna River section near St. Petersburg, Russia. High concentrations of solar wind-like He and Ne found in most grains indicate that they were delivered to Earth as micrometeoritic dust, while their abundance, stratigraphic position and major element composition indicate an origin related to the L chondrite parent body (LCPB) break-up event, 470 Ma ago. Compared to sediment-dispersed extraterrestrial chromite (SEC) grains extracted from coeval sediments at other localities, the grains from Lynna River are both highly concentrated and well preserved. As in previous work, in most grains from Lynna River, high concentrations of solar wind-derived He and Ne impede a clear quantification of cosmic-ray produced He and Ne. However, we have found several SEC grains poor in solar wind Ne, showing a resolvable contribution of cosmogenic 21Ne. This makes it possible, for the first time, to determine robust cosmic-ray exposure (CRE) ages in these fossil micrometeorites, on the order of a few hundred-thousand years. These ages are similar to the CRE ages measured in chromite grains from cm-sized fossil meteorites recovered from coeval sediments in Sweden. As the CRE ages are shorter than the orbital decay time of grains of this size by Poynting-Robertson drag, this suggests that the grains were delivered to Earth through direct injection into an orbital resonance. We demonstrate how CRE ages of fossil micrometeorites can be used, in principle, to determine sedimentation rates, and to correlate the sediments at Lynna River with the fossil meteorite-bearing sediment layers in Sweden.Comment: 25 pages, 4 figures, 2 table

    Dense fluidized granular media in microgravity

    Get PDF
    Handling and transport of granular media are inevitably governed by the settling of particles. Settling into a dense state is one of the defining characteristics of granular media, among dissipation and absence of thermal agitation. Hence, settling complicates the adaptation of microscopic theories from atomic, molecular, or colloidal media to granular media. It is desirable to provide experiments in which selectively one of the granular characteristics is tuned to test suitable adaptation of a theory. Here we show that gas fluidization of granular media in microgravity is a suitable approach to achieve steady states closer to thermally agitated systems free of settling. We use diffusing-wave spectroscopy to compare the spatial homogeneity and the microscopic dynamics of gas-fluidized granular media on the ground and in drop tower flights with increasing packing densities up to full arrest. The gas fluidization on the ground leads to inhomogeneous states as known from fluidized beds, and partial arrest occurs at packing fractions lower than the full arrested packing. The granular medium in microgravity in contrast attains a homogeneous state with complete mobilization even close to full arrest. Fluidized granular media thus can be studied in microgravity with dynamics and packing fractions not achievable on the ground

    Conceptual Aircraft Design Methodology for Disaster Relief Operations with a Variable Fidelity Interface

    Get PDF
    The target of the thesis is to develop conceptual design capabilities for cargo aircraft in humanitarian areas of operation. The work is based on DLR's inhouse aircraft design tool openAD. The software has to be modified from commercial passenger to cargo transport purposes, and make the cargo dimensions and masses driving the parametrized conceptual aircraft design. Therefore, a reference aircraft is redesigned and calibrated on the geometrical, mass and performance level. The implemented methods are validated by a suitable design of experiment

    Neue Entwicklungen in der Besamung beim Rind

    Get PDF

    Entwicklung, Anwendung und Vergleich von Methoden zur Berechnung von Infrarotspektren einzelner Moleküle in polaren Lösungsmitteln

    Get PDF
    Die Absorptionsspektroskopie im mittleren infraroten (MIR, etwa 500-4000 cm-1) Spektralbereich ist ein wichtiges Hilfsmittel in der biomolekularen Forschung. Mit ihrer Hilfe können z.B. strukturelle Eigenschaften von Proteinen und enzymatisch katalysierte Reaktionen sichtbar gemacht werden. Zur Interpretation solcher Spektren benötigt man jedoch Rechenmethoden, vermittels derer MIR Spektren mit hoher Genauigkeit vorhergesagt werden können. Im ersten Teil dieser Arbeit betrachte ich Cyclopyrimindimere (CPD), die durch ultraviolette Strahlung in dem Erbgutmolekül DNS entstehen und potentiell mutagene oder lethale Folgen für die Zelle haben. Um zukünftige Experimente zu leiten, welche die licht-induzierte Reparaturreaktion dieser Defekte durch das Enzym Photolyase mit zeitaufgelöster Spektroskopie verfolgen wollen, habe ich mit Hilfe der Dichtefunktionaltheorie (DFT) die MIR Spektren von Modellstrukturen einzelner Intermediate der CPD Reparatur berechnet. Die Ergebnisse zeigen, dass die Intermediate der CPD Reparatur anhand der spezifischen MIR Absorption ihrer Carbonylmoden identifiziert werden können und dass der Weg der Spaltung eines CPD in native DNS Basen auf diese Weise aufgeschlüsselt werden kann. Im zweiten Teil dieser Arbeit untersuche ich jene Methoden, die in der Literatur zur Berechnung von MIR Spektren aus Molekulardyamik (MD) Simulationen, bei denen eine DFT Beschreibung eines Moleküls mit einer molekülmechanischen (MM) Beschreibung der Umgebung kombiniert wird, vorgeschlagen worden sind. Dazu leite ich die Vorschriften der verschiedenen Methoden für den Fall eines einzelnen Moleküls in einem polaren Lösungsmittel aus der linearen, quantenmechanischen Störungstheorie her. Anhand dieser Herleitung und der Ergebnisse einer exemplarischen Anwendung der Methoden auf eine DFT/MM-MD Simulation eines Formaldehydmoleküls in Wasser diskutiere ich die den jeweiligen Methoden zugrundeliegenden Annahmen und Näherungen sowie mögliche neue Verfahren zur Korrektur der durch die Näherungen induzierten Fehler bei der Berechnung von MIR Spektren. Ferner entwickle ich aus dieser Analyse ein neues Verfahren zur Berechnung von MIR Spektren kleiner Moleküle in polaren Lösungsmitteln, mit dessen Hilfe sich die Frequenzfluktuationen des gelösten Moleküls, die durch die Wechselwirkung mit der fluktuierenden Lösungsmittelumgebung entstehen, mit einer Auflösung von etwa 10-30 fs berechnen lassen. Anhand einer exemplarischen Anwendung zeige ich, dass es diese Methode erlaubt, die Ursachen der Frequenzfluktuationen im Detail zu untersuchen und deren Beiträge zu MIR Linienbreiten zu ermitteln
    corecore