Convergence Rates for Exponentially Ill-Posed Inverse Problems with Impulsive Noise

This paper is concerned with exponentially ill-posed operator equations with additive impulsive noise on the right hand side, i.e. the noise is large on a small part of the domain and small or zero outside. It is well known that Tikhonov regularization with an $L^1$ data fidelity term outperforms Tikhonov regularization with an $L^2$ fidelity term in this case. This effect has recently been explained and quantified for the case of finitely smoothing operators. Here we extend this analysis to the case of infinitely smoothing forward operators under standard Sobolev smoothness assumptions on the solution, i.e. exponentially ill-posed inverse problems. It turns out that high order polynomial rates of convergence in the size of the support of large noise can be achieved rather than the poor logarithmic convergence rates typical for exponentially ill-posed problems. The main tools of our analysis are Banach spaces of analytic functions and interpolation-type inequalities for such spaces. We discuss two examples, the (periodic) backwards heat equation and an inverse problem in gradiometry.Comment: to appear in SIAM J. Numer. Ana

Decentralized or Collective Bargaining in a Strategy Experiment

We present an experiment where two players bargain with a third player. They can bargain either separately or form a joint venture to bargain collectively. Our theoretical benchmark solution predicts decentralized bargaining, as only one player has an interest in forming a joint venture. However, we observe a significant amount of collective bargaining. Collective bargaining, when compared with decentralized bargaining, has no significant effect on the payoffs of the players in the joint venture but reduces the payoff of the third player. Nous présentons une expérience dans laquelle deux joueurs négocient avec un troisième joueur. Les deux joueurs peuvent négocier séparément ou former une coalition pour négocier collectivement avec le troisième. La solution théorique de référence prédit des négociations décentralisées, car seulement un des joueurs a intérêt à former une coalition. Les résultats de l'expérience montrent un nombre significatif de négociations collectives. Lorsque comparée à la négociation décentralisée, la négociation collective n'a pas d'effets significatifs sur les profits des joueurs de la coalition,0501s réduit le profit du troisième.Bargaining, joint venture, experimental economics, equilibrium selection, Négociation, coalition, économie expérimentale, sélection d'équilibre

Holocene fluctuations of neodymium isotope ratios in eastern Fram Strait sediments - An indication for deepwater variability?

EGU2012-11739 The Fram Strait as the only deep water connection of the world’s oceans to the Arctic plays a substantial role for the heat influx to the Arctic Ocean and controls freshening of the Nordic Seas through Arctic sea ice export. Large amounts of warm and saline Atlantic Water derived from the North Atlantic Drift transport most of the heat through eastern Fram Strait to the Arctic basin, resulting in year-round ice-free conditions. Arctic sea ice and cold and fresh waters exit the western part of the strait southward along the Greenland shelf. However, little is still known about the water mass transport at intermediate and bottom water depths in the Fram Strait. High-resolution Holocene sediment sequences from the Western Svalbard margin have been investigated for its neodymium isotope ratios stored in ferromanganese oxyhydroxide coatings of the sediment to derive information on the source of bottom seawater passing the site. The radiogenic isotope data are compared to a multitude of proxy indicators for the climatic and oceanographic variability in the eastern Fram Strait during the past 8,500 years. In order to obtain a calibration of the Nd isotope compositions extracted from sediments to modern bottom water mass signatures in the area, a set of core top and water samples from different water depths in the Fram Strait was additionally investigated for its present-day Nd isotope signatures. A significantly higher inflow of deepwater produced in the Nordic Seas to the core site is inferred for the earlier periods of the Holocene. Cooler surface water conditions and increased sea ice abundances during the late Holocene coincide with more radiogenic Nd isotope ratios likely resembling the neoglacial trend of the northern North Atlantic

Phase I study of everolimus and mitomycin C for patients with metastatic esophagogastric adenocarcinoma

This study aimed at determining the recommended dose of the mammalian target of rapamycin inhibitor everolimus in combination with mitomycin C (MMC) in patients with previously treated metastatic esophagogastric cancer. In this phase I trial, patients received escalated doses of oral everolimus (5, 7.5, and 10 mg/day) in combination with intravenous MMC 5 mg/m2 every 3 weeks. Endpoints were the dose-limiting toxicity (DLT), safety, and response rates. Tumor tissues were tested for HER2-status and mutations in the PTEN, PIK3CA, AKT1, CTNNB1, and E-cadherin type 1 genes. Sixteen patients (12 male, four female) with gastric/gastroesophageal junction cancer were included. All patients were previously treated with a platinum-based chemotherapy. Treatment cohorts were: 5 mg/day, three patients; 7.5 mg/day, three patients; and 10 mg/day, 10 patients. No DLTs occurred during dose escalation. Most frequent grade 3 toxicities were leukopenia (18.8%) and neutropenia (18.8%). All other grade 3 toxicities were below 10%. No grade 4 toxicities occurred. Three (18.8%) patients experienced partial responses and four patients had stable disease (SD). Antitumor activity according to Response Evaluation Criteria In Solid Tumors (RECIST)-criteria was highest in the 10 mg/day cohort. No associations between HER2-status or detected mutations and response were observed. The recommended dose of everolimus combined with MMC is 10 mg/day. Encouraging signs of antitumor activity were seen (http://www.ClinicalTrials.gov; Clinical trial registration number: NCT01042782)

Enhanced Productivity and Fish Abundance at a Submarine Spring in a Coastal Lagoon on Tahiti, French Polynesia

Submarine groundwater discharge (SGD), the direct discharge of groundwater into the sea, is abundant around the globe. Fresh SGD can occur as focused flow in submarine springs. However, little is known on the impact of submarine springs on marine organisms. For a better understanding of the interaction between SGD and its surrounding organisms, the impact of SGD on the abundance of fish was investigated in a coastal lagoon of Tahiti, French Polynesia. The study is based on the assumption of an enhanced biological production due to increased amounts of nutrient input caused by terrestrial groundwater supply into the sea. Biofouling processes and zooplankton samples were used as indicators for elevated nutrient input due to submarine springs. The main objective was to investigate the effect on the abundance of fish assuming a higher fish abundance possibly caused by a bottom-up control. Presented data show a significantly higher abundance around a submarine spring as well as significantly larger growth of algal turfs exposed to groundwater discharge. Zooplankton evaluations suggest slightly higher abundances around the submarine spring. The results suggest elevated nutrient concentrations transmitted by submarine springs may cause a bottom-up control resulting in a higher abundance of fish around the investigated submarine spring

Model-Based Evaluation of Energy Systems for Multirotor UAV Based on Batteries and Fuel Cells

In this study, two multirotor unmanned aerial vehicle (UAV) energy systems are comparatively evaluated via a modelling process, namely a battery electric system and a hybrid fuel cell and battery system. Technical, economic, and ecological evaluation parameters are considered. The evaluation is performed on three different mission types: a 10 km delivery mission, a 3000 m2 facade inspection, and a nine-minute drone show, to represent the transport, monitoring, and event sectors. Results are calculated via a modelling process first simulating the required power profiles for each mission and then simulating both energy systems’ operational behavior during each mission. The resulting technical parameters show that the battery electric UAV has 1.7 times higher efficiency than the fuel cell hybrid UAV. However, the fuel cell hybrid UAV allows potential flight durations 3.1 times longer than the battery electric UAV. Considering economic parameters, the battery electric UAV is the more economical choice due to the higher investment costs of the fuel cell hybrid UAV, even when considering future cost developments for investment and energy costs. For ecological parameters, the fuel cell hybrid UAV has the potential to produce significantly less emissions, but only when using hydrogen produced from renewable energy (green hydrogen). All in all, the battery electric UAV is sufficient for the three concrete missions considered and should be chosen over the fuel cell hybrid UAV. However, the fuel cell hybrid UAV should be considered for missions with longer required flight times than the battery electric UAV is capable of, especially in the transport and monitoring sectors

Moderating Effects of Requirements Uncertainty on Flexible Software Development Techniques

Partially due to increasing requirements uncertainty, flexibility has been in the focus of many software development activities for many years. Only few studies have analyzed the indirect effect that different levels of requirements uncertainty have on the effects of established flexible development techniques. This study analyzes how requirements uncertainty moderates the well studied effects of (1) sequential development, (2) investment in architectural design, and (3) intensity of early feedback on the performance of contract development projects. It finds that requirements uncertainty negatively moderates the effects of sequential development. It also points out that requirements uncertainty negatively moderates the effect of investment in architectural design. For agile development approaches, the value of investment in architectural design falls with increasing uncertainty. However, for plan-driven approaches, investment in architectural design is positive at any level of requirements uncertainty. Finally, the paper finds that early feedback throughout the development process is helpful at any level of requirements uncertainty

Comparative Evaluation of Investigation Methods for Estimating the Load-Dependent State of Charge and End of Discharge of a Multirotor UAV Battery

As the scope of multirotor unmanned aerial vehicle (UAV) applications increases, more attention is being paid to UAV energy requirements, which vary depending on the mission profile. To obtain accurate information about the UAV battery during flight, the idea of a digital twin including a battery state estimation model is promising. For battery state estimation, a Kalman filter combination is the preferred approach in the literature. Comparing different Kalman filters, the unscented Kalman filter has a more accurate estimation for nonlinear systems compared to the extended Kalman filter. In the application of UAV flight with load-dependent flight missions, the comparison of different Kalman filter estimation methods has not yet been researched. In order to evaluate the applicability of different state of charge estimation methods applied to different UAV flight missions, an extended Kalman filter, an unscented Kalman filter, and the Coulomb-counting method are implemented in this research and combined with an end of discharge estimation. To compare the estimation methods based on a delivery mission and a facade inspection mission, a parameter identification of the UAV battery is performed, and an equivalent circuit model is developed and combined with the estimation methods to estimate the battery state. The results of the investigation show that the unscented Kalman filter achieves more accurate state of charge estimation results than the extended Kalman filter, even in the field of UAV application. The results also show that the choice of estimation method is mainly influenced by the accuracy of the parameter identification process, while the dynamic load of a UAV mission has less impact. Contrarily, the end of discharge estimation does not correlate with the accuracy of the state of charge estimation, indicating that the end of discharge estimation is more dependent on the dynamic load

Multiscale scanning with nuisance parameters

We investigate the problem to find anomalies in a $d$-dimensional random field via multiscale scanning in the presence of nuisance parameters. This covers the common situation that either the baseline-level or additional parameters such as the variance are unknown and have to be estimated from the data. We argue that state of the art approaches to determine asymptotically correct critical values for the multiscale scanning statistic will in general fail when naively such parameters are replaced by plug-in estimators. Opposed to this, we suggest to estimate the nuisance parameters on the largest scale and to use the remaining scales for multiscale scanning. We prove a uniform invariance principle for the resulting adjusted multiscale statistic (AMS), which is widely applicable and provides a computationally feasible way to simulate asymptotically correct critical values. We illustrate the implications of our theoretical results in a simulation study and in a real data example from super-resolution STED microscopy. This allows us to identify interesting regions inside a specimen in a pre-scan with controlled family-wise error rate