102 research outputs found
Scale space consistency of piecewise constant least squares estimators : another look at the Regressogram
No full textWe study the asymptotic behavior of piecewise constant least squares regression estimates, when the number of partitions of the estimate is penalized. We show that the estimator is consistent in the relevant metric if the signal is in L2([0, 1]), the space of c`adl`ag functions equipped with the Skorokhod metric or C([0, 1]) equipped with the supremum metric. Moreover, we consider the family of estimates under a varying smoothing parameter, also called scale space. We prove convergence of the empirical scale space towards its deterministic target
Consistencies and Rates of Convergence of Jump-Penalized Least Squares Estimators
No full textWe study the asymptotics for jump-penalized least squares regression aiming at approximating a regression function by piecewise constant functions. Besides conventional consistency and convergence rates of the estimates in L 2 ([0,1)) our results cover other metrics like Skorokhod metric on the space of càdlàg functions and uniform metrics on C([0,1]) as well as convergence of the scale spaces, the family of estimates under varying smoothing parameter. We will show that the estimates used are in an adaptive sense rate optimal over the class of functions of bounded variation, (piecewise) Hölder continuous functions of order 1 ≥ α> 0 and the class of step functions. In the latter setting, we will also deduce the rates known from changepoint analysis for detecting the jumps.
Rhythmic Foot Embrocation According to Wegman/Hauschka for Alleviating Symptoms of Chemotherapy-Induced Peripheral Neuropathy: A Randomized Controlled Trial
No full textBackground: Chemotherapy-induced peripheral neuropathy (CIPN) in patients treated with platinum-, taxane- or vinca alkaloid-based chemotherapy may cause symptoms such as tingling, numbness, pain, and paresthesia, particularly in patients’ hands and feet. This study aimed to evaluate rhythmic embrocation (RE) of the feet according to Wegman/Hauschka in addition to an exercise program (EP) as a complementary treatment for CIPN symptoms. Methods: This study was a prospective, randomized controlled, 2-center trial. A total of 57 patients with CIPN symptoms were randomly allocated into 2 groups, with 52 patients analyzed: the intervention group (n = 26) and the control group (n = 26). While the intervention group received 3 RE according to Wegman/Hauska and EP within 14 days, the control group performed only EP. CIPN symptoms ( tingling, numbness, pain and cramps ) were evaluated with the Numeric Rating Scale (NRS), and quality of life related to peripheral neuropathy was assessed with the EORTC QLQ-CIPN20 questionnaire. Results: The mean NRS scores for total CIPN symptoms (tingling, numbness, pain, and cramps) decreased from baseline to 24 hours after the third intervention in both groups. However, the intervention group maintained lower scores 2 weeks later, whereas the scores in the control group returned to baseline levels. A significant time effect was observed for NRS scores with a medium effect size ( P .05). Similarly, significant time effects were observed in the sensory and motor subgroups of the EORTC QLQ-CIPN20 ( P .05). While the intervention group showed greater improvements, particularly at 2 weeks post-intervention, a statistically significant difference between the groups was not reached. Conclusion: According to our study results, RE combined with exercise, particularly after 3 interventions, was more effective in reducing CIPN symptoms in the short-term than was exercise alone; however, symptoms increased again in the absence of interventions (standard care) by the end of the fourth week.Rut und Klaus Bahlsen Stiftun
Mineral Solubilities in CO2-Saturated NaCl Brine Systems
No full textAbstractExperiments on CO2-brine-mineral interactions were designed to provide kinetic data for individual rock-forming minerals. Samples of an illite-smectite mixed layer mineral and a labradorite separate were stored in flexible Ti-cells together with 2M NaCl brine and pure CO2 at 80°C and 20MPa for two and three weeks, respectively. The empirical formulae K0.5-0.7(Mg0.1-0.2Al1.8-1.9)(Al0.4-0.6Si3.4-3.6)O10(OH)2 and Na0.5-0.6Ca0.4-0.5Al1.3-1.6Si2.4-2.6O8 were calculated for illite and labradorite. X-ray diffraction data with Rietveld refinements reveal a pure labradorite separate. The illite separate is composed of 73.5±1.3 wt% illite, 10.8±1.3 wt% Ca-smectite, 11.9±0.4 wt% orthoclase, and 3.9±0.2 wt% quartz. Based on the acquired geochemical data, the experiments on monomineralic separates indicate (i) preferred dissolution of the Ca-smectite component out of the illite-smectite mixed layer mineral, and (ii) dissolution of labradorite
Dissolution Kinetics of Iron Carbonate, Illite and Labradorite – CO2-Saline Fluid-mineral Experiments within the GaMin’11 Inter-laboratory Comparison Exercise
No full textAbstractExperiments to investigate individual CO2-brine-mineral interactions were designed to provide dissolution kinetics for rock-forming minerals. Separates of an iron carbonate, a clay mineral and a feldspar mineral were stored in flexible Titanium Grade-2 cells together with 2M NaCl brine and pure CO2 at 80°C and 20 (30) MPa for one (iron carbonate), two (clay) and three (feldspar) weeks, respectively. The carbonate separate consists of 96.3±3.2 wt% iron carbonate and 3.7±0.8 wt% quartz with the iron carbonate phase being composed of 72.3±1.4 wt% siderite and 27.7±1.2 wt% ankerite. During the experiments, siderite abundance increased to 83.3±1.5 wt%, while that of ankerite decreased to 16.7±1.4 wt%. The average empirical formula of untreated and treated siderite is Fe0.8Mg0.1Mn0.1CO3, that of untreated ankerite changed slightly from (Ca1.0Mg0.2Mn0.1Fe0.7)(CO3)2 to (Ca0.9Mg0.3Mn0.1Fe0.7)(CO3)2 during CO2 exposure. Fluid data obtained during these experiments show similar behavior for Ca2+ and Mg2+, as well as Fe2+ and Mn2+, respectively. The clay separate initially consists of 84.2±6.9 wt% illite, 11.9±0.4 wt% orthoclase and 3.9±0.2 wt% quartz with untreated illite actually being an illite-smectite mixed-layer mineral composed of 87.2±1.5 wt% illite and 12.8±1.5 wt% Ca-smectite. During the experiments using the clay separate it was found that the composition changed to 88.3±7.8 wt% illite, 9.2±0.5 wt% orthoclase, and 2.5±0.2 wt% quartz, with CO2-treated illite now consisting of 89.0±1.7 wt% illite and 10.5±1.6 wt% Ca-smectite.Fluid data show, besides others, increase Ca2+ concentrations over time. Analyses of the feldspar separate reveal pure labradorite with a stoichiometric composition of Na0.5-0.6Ca0.4-0.5Al1.3-1.6Si2.4-2.6O8. During labradorite exposure experiments cation brine concentrations (e.g. Ca2+, Ba2+ and Al3+) increased. Based on the acquired geochemical data sets, the experiments using individual mineral separates indicate (i) dissolution of ankerite and stable siderite, (ii) preferred dissolution of the Ca-smectite component out of the illite-smectite mixed-layer mineral, and (iii) dissolution of labradorite
Petrophysical Characterization of in Situ Cores after CO2 Injection and Comparison with Batch Experiments of the German Ketzin Pilot site
No full textThe DELPHI Expert Process of the German Umbrella Project AUGE - Status of CO2 Storage in Germany and Recommendations to the Review Process of the German CO2 Storage Legislation
No full textAbstractTo scientifically underpin the German national “Carbon Dioxide Storage Law” (KSpG) and derive recommendations for its review and implementation, a Delphi expert process was initiated within the national German umbrella project AUGE. In two Delphi rounds experts from science, industry and regulatory bodies were asked for their assessment of CO2 storage in general and the KSpG in particular. Overall, CO2 storage is seen essential for reaching a 2°C target and experts agree that knowledge and technology allow implementing a demo-scale project. However, experts also agree that the current KSpG version prevents implementation of CCS in Germany and requires revision
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