129 research outputs found

    Stepwise drying of Lake Turkana at the end of the African Humid Period: a forced regression modulated by solar activity variations?

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    Although the timing of the termination of the African Humid Period (AHP) is now relatively well estab- lished, the modes and controlling factors of this drying are still debated. Here, through a geomorphological approach, we characterize the regression of Lake Turkana at the end of the AHP. We show that lake level fall during this period was not continuous but rather stepwise and consisted of five episodes of rapid lake level fall separated by episodes marked by slower rates of lake level fall. Whereas the overall regres- sive trend reflects a decrease in regional precipitations linked to the gradual reduction in Northern Hemisphere summer in- solation, itself controlled by orbital precession, we focus dis- cussion on the origin of the five periods of accelerated lake level fall. We propose that these periods are due to temporary reductions in rainfall across the Lake Turkana area associ- ated with repeated westward displacement of the Congo Air Boundary (CAB) during solar activity minima

    Who Opts Out? The Customisation of Marriage in the German Matrimonial Property Regime

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    This study examines the prevalence of marital contracts across marriage cohorts (1990–2019) in Germany. We further investigate the characteristics of spouses who signed a marital contract. Using cross-sectional data from the German Family Panel (pairfam, 2018/19), we employ complementary log–log and multinomial logistic regression models to predict the prevalence and the type of marital contracts. The results show that 5% of all married couples opt out of the default matrimonial property regime by signing a contract in Germany. Differentiating between contract types, most couples either specify a separation of property (40%) or modify the default community of accrued gains (31%). We find an increase in the prevalence of marital contracts across marriage cohorts. The decision to opt out of the default is strongly positively associated with self-employment that often requires the customisation of asset ownership structures within marriage. Married individuals with prior divorce experiences are more likely to opt for the separation of property, indicating that the awareness of the economic consequences of divorce promotes the individualisation of marriage. Our results are in line with the cross-national trend towards customised marriages, although the trend in Germany is less pronounced than in other countries

    My Wealth, (Y)Our Life Satisfaction? Sole and Joint Wealth Ownership and Life Satisfaction in Marriage

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    This study examines the money-subjective well-being nexus by studying the link between changes in jointly and solely (i.e. respondents’ own and their partner’s own) held gross wealth and changes in married individuals’ subjective well-being. Joint assets reflect norms of sharing responsibilities and resources. Solely held assets, in contrast, offer individual economic independence. Using wealth data from the German Socio-Economic Panel Study (SOEP; 2002, 2007, 2012, 2017), we estimate individual fixed effects regressions. Although coefficients for all three wealth measures are positive, our results highlight that only increases in jointly held wealth are associated with statistically significant increases in spouses’ life satisfaction in Germany. Despite expectations about a stronger relevance of joint wealth for men compared to women in line with men’s role as a financial provider for the family, we do not find substantial gender differences in the positive association between increases in joint wealth and life satisfaction. In light of the individualisation of marriages, our results highlight that the personal benefits associated with marital sharing of wealth seem to trump those of economic independence and financial autonomy

    Power Utility Maximization in Discrete-Time and Continuous-Time Exponential Levy Models

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    Consider power utility maximization of terminal wealth in a 1-dimensional continuous-time exponential Levy model with finite time horizon. We discretize the model by restricting portfolio adjustments to an equidistant discrete time grid. Under minimal assumptions we prove convergence of the optimal discrete-time strategies to the continuous-time counterpart. In addition, we provide and compare qualitative properties of the discrete-time and continuous-time optimizers.Comment: 18 pages, to appear in Mathematical Methods of Operations Research. The final publication is available at springerlink.co

    Synthesis and substrate-controlled reactions of 2,2′-Unsaturated biquinazolinones

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    A series of BiQuinazolinones bearing either double or triple bonds in their lateral chains have been synthesized. These compounds were then subjected to substrate-controlled reactions such as Diels-Alder, epoxidation and Pauson-Khand reactions. The stereoselective outcome observed in these transformations is very promising for the future application of BiQuinazolinones as chiral auxiliaries

    On the monotone stability approach to BSDEs with jumps: Extensions, concrete criteria and examples

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    We show a concise extension of the monotone stability approach to backward stochastic differential equations (BSDEs) that are jointly driven by a Brownian motion and a random measure for jumps, which could be of infinite activity with a non-deterministic and time inhomogeneous compensator. The BSDE generator function can be non convex and needs not to satisfy global Lipschitz conditions in the jump integrand. We contribute concrete criteria, that are easy to verify, for results on existence and uniqueness of bounded solutions to BSDEs with jumps, and on comparison and a-priori LL^{\infty}-bounds. Several examples and counter examples are discussed to shed light on the scope and applicability of different assumptions, and we provide an overview of major applications in finance and optimal control.Comment: 28 pages. Added DOI https://link.springer.com/chapter/10.1007%2F978-3-030-22285-7_1 for final publication, corrected typo (missing gamma) in example 4.1

    Quantum modulation of a coherent state wavepacket with a single electron spin

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    The interaction of quantum objects lies at the heart of fundamental quantum physics and is key to a wide range of quantum information technologies. Photon-quantum-emitter interactions are among the most widely studied. Two-qubit interactions are generally simplified into two quantum objects in static well-defined states . In this work we explore a fundamentally new dynamic type of spin-photon interaction. We demonstrate modulation of a coherent narrowband wavepacket with another truly quantum object, a quantum dot with ground state spin degree of freedom. What results is a quantum modulation of the wavepacket phase (either 0 or {\pi} but no values in between), a new quantum state of light that cannot be described classically.Comment: Supplementary Information available on reques

    Efficient Interpolation for the Theory of Arrays

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    Existing techniques for Craig interpolation for the quantifier-free fragment of the theory of arrays are inefficient for computing sequence and tree interpolants: the solver needs to run for every partitioning (A,B)(A, B) of the interpolation problem to avoid creating ABAB-mixed terms. We present a new approach using Proof Tree Preserving Interpolation and an array solver based on Weak Equivalence on Arrays. We give an interpolation algorithm for the lemmas produced by the array solver. The computed interpolants have worst-case exponential size for extensionality lemmas and worst-case quadratic size otherwise. We show that these bounds are strict in the sense that there are lemmas with no smaller interpolants. We implemented the algorithm and show that the produced interpolants are useful to prove memory safety for C programs.Comment: long version of the paper at IJCAR 201

    Determination of the LOQ in real-time PCR by receiver operating characteristic curve analysis: application to qPCR assays for Fusarium verticillioides and F. proliferatum

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    Real-time PCR (qPCR) is the principal technique for the quantification of pathogen biomass in host tissue, yet no generic methods exist for the determination of the limit of quantification (LOQ) and the limit of detection (LOD) in qPCR. We suggest using the Youden index in the context of the receiver operating characteristic (ROC) curve analysis for this purpose. The LOQ was defined as the amount of target DNA that maximizes the sum of sensitivity and specificity. The LOD was defined as the lowest amount of target DNA that was amplified with a false-negative rate below a given threshold. We applied this concept to qPCR assays for Fusarium verticillioides and Fusarium proliferatum DNA in maize kernels. Spiked matrix and field samples characterized by melting curve analysis of PCR products were used as the source of true positives and true negatives. On the basis of the analysis of sensitivity and specificity of the assays, we estimated the LOQ values as 0.11 pg of DNA for spiked matrix and 0.62 pg of DNA for field samples for F. verticillioides. The LOQ values for F. proliferatum were 0.03 pg for spiked matrix and 0.24 pg for field samples. The mean LOQ values correspond to approximately eight genomes for F. verticillioides and three genomes for F. proliferatum. We demonstrated that the ROC analysis concept, developed for qualitative diagnostics, can be used for the determination of performance parameters of quantitative PCR
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