71 research outputs found

    Stochastic Properties of Confidence Ellipsoids after Least Squares Adjustment, Derived from GUM Analysis and Monte Carlo Simulations

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    In this paper stochastic properties are discussed for the final results of the application of an innovative approach for uncertainty assessment for network computations, which can be characterized as two-step approach: As the first step, raw measuring data and all possible influencing factors were analyzed, applying uncertainty modeling in accordance with GUM (Guide to the Expression of Uncertainty in Measurement). As the second step, Monte Carlo (MC) simulations were set up for the complete processing chain, i.e., for simulating all input data and performing adjustment computations. The input datasets were generated by pseudo random numbers and pre-set probability distribution functions were considered for all these variables. The main extensions here are related to an analysis of the stochastic properties of the final results, which are point clouds for station coordinates. According to Cramer’s central limit theorem and Hagen’s elementary error theory, there are some justifications for why these coordinate variations follow a normal distribution. The applied statistical tests on the normal distribution confirmed this assumption. This result allows us to derive confidence ellipsoids out of these point clouds and to continue with our quality assessment and more detailed analysis of the results, similar to the procedures well-known in classical network theory. This approach and the check on normal distribution is applied to the local tie network of Metsähovi, Finland, where terrestrial geodetic observations are combined with Global Navigation Satellite System (GNSS) data

    Engineering Geodesy - Definition and Core Competencies

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    This article summarises discussions concerning the definition of "engineering geodesy" within the German Geodetic Commission. It is noted that engineering geodesy by means of its tasks, methods and characteristics is an application-oriented science whose research questions often arise from observed phenomena or from unsolved practical problems. In particular it is characterised by the professional handling of geometry-related problems in a cost-effective manner that includes comprehensive quality assessment at all phases of the problem solution - from planning through measurement to data processing and interpretation. The current methodical developments are primarily characterised by the increasing integration of the measurement and analysis into challenging construction, production and monitoring processes as well as by the transition to spatially continuous methods. A modern definition of engineering geodesy is proposed at the end of this articl

    Lohnpolitik auf neuen Wegen?

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    Survey Configuration for Terrestrial Laser Scanning : Aufnahmekonfiguration fĂĽr Terrestrisches Laserscanning

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    Despite the enormous popularity of terrestrial laser scanners in the field of geodesy and related sciences the vital task of viewpoint planning is mostly considered intuitively. In contrast to established acquisition techniques, such as tacheometry and classical photogrammetry, optimisation of the acquisition configuration cannot be conducted based on assumed object coordinates, as these would change in dependence to the chosen viewpoint. Hence, this article discusses on how laser scans can be simulated based on predefined viewpoints and a given 3D model. Afterwards the task of viewpoint planning is observed from two perspectives namely regarding the achievable precision in the field as well as from an economic point of view in the context of data acquisition.Trotz der enormen Popularität von terrestrischen Laserscannern in der Geodäsie und benachbarten Fachdisziplinen wird die grundlegende Aufgabe der Standpunktplanung zumeist intuitiv gelöst. Im Gegensatz zum Vorgehen bei etablierten Erfassungsmethoden wie Tachymetrie und klassische Photogrammetrie, kann die Optimierung der Aufnahmekonfiguration nicht anhand fest vorgegebener Objektkoordinaten erfolgen, da sich die Punktverteilung beim Laserscanning in Abhängigkeit vom gewählten Aufnahmestandpunkt ändert. Daher wird in diesem Beitrag zunächst aufgezeigt, wie Laserscans unter Verwendung eines 3D-Modells des zu erfassenden Objekts sowie vorgegebener Standpunkte simuliert werden können. Danach wird die Aufgabe der Standpunktplanung von zwei Seiten betrachtet, nämlich in Bezug auf die erreichbare Genauigkeit sowie unter ökonomischen Gesichtspunkten im Zusammenhang mit der Datenerfassung

    Neuronal Plasticity and the Cholinergic System Are Affected in Atopic Dermatitis and in Response to Acute Experimental Mental Stress in a Randomized Controlled Pilot Study

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    Rationale In mouse models for atopic dermatitis (AD) hypothalamus pituitary adrenal axis (HPA) dysfunction and neuropeptide-dependent neurogenic inflammation explain stress-aggravated flares to some extent. Lately, cholinergic signaling has emerged as a link between innate and adaptive immunity as well as stress responses in chronic inflammatory diseases. Here we aim to determine in humans the impact of acute stress on neuro-immune interaction as well as on the non-neuronal cholinergic system (NNCS). Methods Skin biopsies were obtained from 22 individuals (AD patients and matched healthy control subjects) before and after the Trier social stress test (TSST). To assess neuro-immune interaction, nerve fiber (NF)-density, NF-mast cell contacts and mast cell activation were determined by immunohistomorphometry. To evaluate NNCS effects, expression of secreted mammal Ly-6/urokinase-type plasminogen activator receptor-related protein (SLURP) 1 and 2 (endogenous nicotinic acetylcholine receptor ligands) and their main corresponding receptors were assessed by quantitative RT-PCR. Results With respect to neuro-immune interaction we found higher numbers of NGF+ dermal NF in lesional compared to non-lesional AD but lower numbers of Gap43+ growing NF at baseline. Mast cell-NF contacts correlated with SCORAD and itch in lesional skin. With respect to the NNCS, nicotinic acetylcholine receptor α7 (α7nAChR) mRNA was significantly lower in lesional AD skin at baseline. After TSST, PGP 9.5+ NF numbers dropped in lesional AD as did their contacts with mast cells. NGF+ NF now correlated with SCORAD and mast cell-NF contacts with itch in non-lesional skin. At the same time, SLURP-2 levels increased in lesional AD skin. Conclusions In humans chronic inflammatory and highly acute psycho-emotional stress interact to modulate cutaneous neuro- immune communication and NNCS marker expression. These findings may have consequences for understanding and treatment of chronic inflammatory diseases in the future

    calibration of finite element models of concrete arch gravity dams using dynamical measures the case of ridracoli

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    Abstract Accurate and reliable predictions of the dynamic behaviour of dams is essential to ensure their correct management and the safety of the downstream population. In this context, structural monitoring and testing procedures for their dynamic characterization are essential tools for the calibration of numerical models of dams. This paper presents some results of an ongoing research program aimed at an accurate definition of the geometric and structural properties of a large arch-gravity dam: the Ridracoli dam in the Emilia-Romagna region, Italy. In the first part of the research, a detailed survey carried out by an Unmanned Aerial Vehicle has allowed the detailed reconstruction of the three-dimensional geometry of the structure. The dense point cloud, as provided by the aerial survey, has been the base for the definition of a high-fidelity finite element model, including the dam, the surrounding rock mass, with a detailed reconstruction of the site topography, and the reservoir water, whose dynamic interaction with the structure is modelled by means of acoustic elements. A large program of structural monitoring, including a number of vibration tests, has been performed on the Ridracoli dam during the last thirty years. The dynamic monitoring system includes accelerometers, located in the structure and in the foundation rock mass, strain gauges and hydrodynamic pressure cells. The forced vibration tests were carried out in correspondence to the maximum water level, in order to identify the dynamic characteristics of the dam. The mechanical properties of the dam material and of the foundation rock are calibrated by comparing model predictions with the results obtained from vibration tests and from acceleration recordings acquired under recent seismic events, considering the actual water levels registered during the tests. The finite element model obtained will allow the simulation of the seismic performance of the dam under different design earthquakes. The assessment of the effects of the reservoir level and of the vertical joints on the dynamic response of the structure will be analysed

    General synovitis score and immunologic synovitis score reflect clinical disease activity in patients with advanced stage rheumatoid arthritis

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    The purpose of this study was to investigate the relationship between clinical disease activity in patients with advanced stage rheumatoid arthritis (RA) on treatment with Disease Modifying Antirheumatic Drugs (DMARDs) and histopathological scores of synovial inflammation. To this end, synovial biopsies of 62 RA patients who underwent surgery for either synovectomy or total joint arthroplasty were assessed by a general synovitis score (GSS) and an immunologic synovitis score (IMSYC). The clinical disease activity index (CDAI) was significantly correlated with both the GSS and the IMSYC (r = 0.65, p = <0.001, r = 0.68, p = <0.001). Compared to patients with moderate and high disease activity, there was a significantly lower expression of T cell (CD3), B cell (CD20) and neutrophil (CD15) markers in synovial tissue of patients with low activity, but similar expression of the macrophage marker CD68. Subgroup analyses revealed no differences between small and large joints, seropositive and seronegative RA and patients with or without prednisolone treatment. However, we found a significantly stronger correlation of CDAI with IMSYC in patients undergoing arthroplasty (r = 0.82) than in patients undergoing synovectomy (r = 0.55). In addition, there was a stronger correlation of CDAI with GSS in patients treated with methotrexate (r = 0.86) than in patients with TNFα blockade (r = 0.55). In summary, the present study demonstrates that the histopathological scores GSS and IMSYC in general reflect clinical disease activity in patients with advanced stage rheumatoid arthritis, but that there is some heterogeneity between subgroups of patients within the cohort. In the future, molecular characterization of synovial inflammatory cell populations, including plasma cell infiltrates, will help to further defined clinically important subtypes of RA and treatment response
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