Weak-lensing shear estimates with general adaptive moments, and studies of bias by pixellation, PSF distortions, and noise

In weak gravitational lensing, weighted quadrupole moments of the brightness profile in galaxy images are a common way to estimate gravitational shear. We employ general adaptive moments (GLAM) to study causes of shear bias on a fundamental level and for a practical definition of an image ellipticity. The GLAM ellipticity has useful properties for any chosen weight profile: the weighted ellipticity is identical to that of isophotes of elliptical images, and in absence of noise and pixellation it is always an unbiased estimator of reduced shear. We show that moment-based techniques, adaptive or unweighted, are similar to a model-based approach in the sense that they can be seen as imperfect fit of an elliptical profile to the image. Due to residuals in the fit, moment-based estimates of ellipticities are prone to underfitting bias when inferred from observed images. The estimation is fundamentally limited mainly by pixellation which destroys information on the original, pre-seeing image. We give an optimized estimator for the pre-seeing GLAM ellipticity and quantify its bias for noise-free images. To deal with pixel noise, we consider a Bayesian approach where the posterior of the GLAM ellipticity can be inconsistent with the true ellipticity if we do not properly account for our ignorance about fit residuals. This underfitting bias is S/N-independent but changes with the pre-seeing brightness profile and the correlation or heterogeneity of pixel noise over the post-seeing image. Furthermore, when inferring a constant ellipticity or, more relevantly, constant shear from a source sample with a distribution of intrinsic properties (sizes, centroid positions, intrinsic shapes), an additional, now noise-dependent bias arises towards low S/N if incorrect priors for the intrinsic properties are used. We discuss the origin of this prior bias.Comment: 18 pages; 5 figures; accepted by A&A after major revision, especially of Sect. 3.3 that corrects the previous discussion on the bias by marginalizatio

Confronting semi-analytic galaxy models with galaxy-matter correlations observed by CFHTLenS

Testing predictions of semi-analytic models of galaxy evolution against observations help to understand the complex processes that shape galaxies. We compare predictions from the Garching and Durham models implemented on the Millennium Run with observations of galaxy-galaxy lensing (GGL) and galaxy-galaxy-galaxy lensing (G3L) for various galaxy samples with stellar masses in the range 0.5 < (M_* / 10^10 M_Sun) < 32 and photometric redshift range 0.2 < z < 0.6 in the Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS). We find that the predicted GGL and G3L signals are in qualitative agreement with CFHTLenS data. Quantitatively, the models succeed in reproducing the observed signals in the highest stellar mass bin (16 < ( M_* / 10^10 M_Sun) < 32) but show different degrees of tension for the other stellar mass samples. The Durham models are strongly excluded at the 95% confidence level by the observations as they largely over-predict the amplitudes of the GGL and G3L signals, probably because they predict too many satellite galaxies in massive halos.Comment: 9 pages, 8 figures, submitted to A&A. Comments welcom

Optimal annuity demand in behavioral decision models

The aim of this dissertation is to design and analyze behavioral decision models for the retirement phase of the life-cycle. The proposed decision models combine expected utility theory with the behavioral apects hyperbolic discounting, loss aversion and reference dependence. A thorough optimization is conducted within the models to find the optimal insurance endowments, investment and consumption plans and bequest sizes

On the mathematical justification of the consistent-approximation approach and the derivation of a shear-correction-factor free refined beam theory

The consistent approximation technique is a method for the derivation of analytical theories for thin structures from the settled three-dimensional theory of elasticity. The method was successfully applied for the derivation of refined plate theories for isotropic and anisotropic plates. The approach relies on computing the Euler-Lagrange equations of a truncated series expansion of the potential energy. In this thesis we extend the approach given in Kienzler (2002) towards the simultaneous truncation of a series expansion of the dual energy. The computation of the Euler-Lagrange equations of the truncated series expansion of the dual energy ensures a rigorous derivation of compatible boundary conditions. The series expansions of both energies are gained by Taylor-series expansions of the displacement field. We show that the decaying behavior of the energy summands is initially dominated by characteristic parameters that describe the relative thinness of the structure. Consequently, the energy series are truncated with respect to the power of the characteristic parameters. For the case of a homogeneous, one-dimensional structural member with rectangular cross-section we proof an a-priori error estimate that provides the mathematical justification for this method. The estimate implies the convergence of the solution of the truncated one-dimensional problem towards the exact solution of three-dimensional elasticity as the thickness goes to zero. Furthermore, the error of the Nth-order one-dimensional theory solution decreases like the (N 1)th-power of the characteristic parameter, so that a considerable gain of accuracy could be expected for higher-order theories, if the structure under consideration is sufficiently thin. The untruncated one-dimensional problem is equivalent to the three-dimensional problem of linear elasticity. We prove that the problem decouples into four independent subproblems for isotropic material: a rod-, a shaft- and two orthogonal beam-problems. A unique decomposition of any three-dimensional load case with respect to the direction and the symmetries of the load is introduced. It allows us to identify each part of the decomposition as a driving force for one of the four (exact) one-dimensional subproblems. Furthermore, we show how the coupling behavior of the four subproblems can be derived directly from the sparsity scheme of the stiffness tensor for general anisotropic materials. Since all propositions are proved for the exact one-dimensional problem, they also hold for any approximative Nth-order theory. The approach is applied to derive a new second-order beam theory for isotropic material free of a-priori assumptions, which in particular does not require a shear-correction. The theory is in general incompatible with the Timoshenko beam theory, since it contains three in general independent load resultants, whereas Timoshenko's theory only contains one. Furthermore, Timoshenko's theory ignores any effects in width direction. However, the assumption of a simple load case allows for a vis-a-vis comparison of both differential equations and in turn, two shear-correction factors for the use in Timoshenko's theory can be derived

Development of the Nuclear-Electronic Orbital Method for Applications to Molecular Electrocatalyst Systems

Studies of molecular electrocatalysts often involve input from quantum chemical computations in the pursuit of catalyst design targeting several desirable features. To this end, conventional density functional theory (DFT) calculations have proven to be a good match with a reasonable balance between computational accuracy and cost. However, a multicomponent method that treats select nuclei on the same quantum mechanical level as electrons would be useful for a more proper treatment of nuclear quantum effects. Such a multicomponent DFT method has been developed in recent years within the nuclear-electronic orbital (NEO) framework. However, for the multicomponent method to be practically applied to large, chemically interesting systems, several functionalities were necessary. The NEO diagonal Born-Oppenheimer correction was calculated and shown to be small enough to validate the underlying Born-Oppenheimer-like separation between light and heavy nuclei. Analytical NEO Hessian expressions were derived and implemented, and they were utilized to identify transition states and generate multicomponent minimum energy paths. Lastly, the calculation of infrared spectra in the NEO framework was formulated and shown to produce accurate values compared to experiment. These developments have each been significant steps in preparing NEO-DFT for utilization in modeling molecular electrocatalysts

Data semantic enrichment for complex event processing over IoT Data Streams

This thesis generalizes techniques for processing IoT data streams, semantically enrich data with contextual information, as well as complex event processing in IoT applications. A case study for ECG anomaly detection and signal classification was conducted to validate the knowledge foundation

Accuracy of Pedometers and their use in a 10,000 Steps Per Day Intervention Study

This dissertation was designed to assess pedometer accuracy under both controlled and free-living conditions and to assess the efficacy and feasibility of the 10,000 steps per day exercise prescription in sedentary, overweight men vs. women. The specific aims were to 1) assess the accuracy of 10 electronic pedometers over the course of a 400-m walk; 2) compare the step values of multiple brands of pedometers over a 24-hour period; 3) compare the effects on body composition, cardiovascular risk factors and adherence in response to a 10,000 steps per day exercise prescription in overweight men vs. women. First, the accuracy and reliability of 10 electronic pedometers was assessed over the course of a 400-m walk. Ten males and 10 females ranging in body mass index (BMI) from 19.8 to 33.6 kg∙m-2 walked 400-m around an outdoor track while wearing two pedometers of the same model (one on the right and left sides of the body) for each of ten models. Four pedometers of each model were assessed in this fashion. The Kenz Lifecorder (KZ), New Lifestyles NL-2000 (NL), and the Yamax Digi-Walker SW-701 (DW) were the most accurate in counting steps, displaying values that were within ±3% of the actual steps taken, 95% of the time. The Sportline 330 (SL330) and the Omron HJ-105 (OM) were the least accurate, displaying values that were within ±37% of the actual steps, 95% of the time. The reliability within a single model (Chronbach’s alpha) was \u3e0.80 for all pedometers with the exception of the SL330. The intra-model reliability was exceptionally high (\u3e0.99) in the KZ, OM, NL, and the DW. Second, a comparison of 13 pedometer models was made over a 24-hour period. Ten males and ten females ranging in BMI from 19.8 to 35.4 kg∙m-2 wore two pedometers for a 24-hour period. The criterion pedometer Yamax Digi-Walker SW-200 (YX200) was worn on the left side of the body and a comparison pedometer was worn on the right. Steps counted by each device were recorded at the end of the day for each of the thirteen pedometers. Subjects took an average of 9,244 steps∙d-1. The KZ, YX200, NL, Yamax Digi-Walker SW-701 (YX701), and SL330 yielded mean values that were not significantly different from the criterion. The Freestyle Pacer Pro (FR), Accusplit Alliance 1510 (AC) Yamax Skeletone EM-180 (SK), Colorado on the Move (CO), and Sportline 345 (SL345) significantly underestimated steps (P\u3c0.05) and the Walk4Life LS 2525 (WL), OM, and Oregon Scientific PE316CA (OR) significantly overestimated steps (P\u3c0.05) when compared to the criterion. In addition, some pedometers underestimated by 25% while others overestimated by 45%. Third, a comparison of the effects on body composition, cardiovascular risk factors and adherence was made in response to a 10,000 steps per day exercise prescription in sedentary, overweight males vs. females. Fifteen men (46 ± 7 yrs) (mean ± SD) and twenty-four women (48 ± 5 yrs) who were overweight or obese participated in a 10,000 steps per day intervention for 36 weeks. Body weight, BMI, percent body fat, fat mass, fat-free mass, waist circumference, hip circumference, systolic blood pressure, diastolic blood pressure, and heart rate were determined at baseline, after 20 weeks and again after 36 weeks. A blood lipid profile was assessed at baseline and after 36 weeks. Men and women given a 10,000 steps per day exercise prescription experienced similarly significant improvements in body weight, BMI, percent body fat, fat mass, waist and hip circumferences, and HDL-C. When men and women were combined to explore the effect of adherence to the exercise prescription, the adherers significantly reduced body weight, BMI, percent body fat, fat mass, waist circumference, and hip circumference after 36 weeks while the non-adherers experienced little or no change in these variables. Thus, the 10,000 steps per day exercise prescription was effective at increasing daily walking volume which resulted in significant improvements in body weight and body composition in overweight, sedentary, middle-aged men and women

Aplicación de un nuevo método para la evaluación censal de la ictiofauna de embalses : hidroacústica digital con haz vertical y horizontal

Se valoran nuevas posibilidades de censado de peces en embalses mediante el uso de la última tecnología hidroacústica (ecosonda de haz partido) realizando ecosondeos dinámicos -con orientación del haz tanto en vertical como en horizontal-, apoyados en un sistema de posicionamiento simultáneo con DGPS. Además, se plantea un procedimiento coherente de estratificación de los muestreos directos y de elaboración de cartografía temática digital. Los resultados han permitido identificar fuentes de errores notables en los métodos al uso, entre los que destacan la sobreestimación debida a las burbujas y a larvas emergentes de insectos. Se recomienda una actualización tecnológica en este campo, dado el indudable interés que tiene disponer de estimaciones realistas de abundancia y biomasa de peces en este tipo de sistemas, tanto para los estudios como para la gestión limnológica.New possibilities for evaluating fish abundance in reservoirs through latest hydroacoustic technology (split beam echosounder), combining echosoundings with vertical and horizontal beaming and using simultaneous positioning with DGPS are discussed. Additionally, a coherent procedure for stratifying the direct sampling and the elaboration of digital thematic maps is proposed. The results have led to the identification of important sources of error in the methods currently in use, particularly the overestimation of fish abundance due to bubbles and emerging insect larvae. A technological actualisation in this field is recommended, given the unquestionable interest in disposing of realistic estimations of fish abundance and biomass in this system, both for studies and for limnological management purposes as well